Chapman’s Orthopaedic Surgery
3rd Edition

CHAPTER 169
ANGULAR DEFORMITIES OF THE LOWER EXTREMITIES IN CHILDREN
George H. Thompson
G. H. Thompson: Division of Pediatric Orthopaedics, Case Western Reserve University, Cleveland, Ohio 44106.
Angular deformities of the lower extremities in children are common and are a frequent reason for orthopaedic referral. They predominantly occur in the tibia; the femur is much less frequently involved. Angulation may occur in the frontal plane (varus and valgus), the sagittal plane (anterior and posterior), or a combination of both (anterolateral or posteromedial). Torsion may also be involved. It is important to understand the various physiologic and pathologic causes of angular deformities, the methods of evaluation, and the natural histories of the abnormalities to determine appropriate treatment (50,115,287). The classification for the differential diagnoses of genu varum (bowleg), genu valgum (knock-knee), and congenital angular deformities of the tibia and fibula are presented in Table 169.1, Table 169.2 and Table 169.3.
Table 169.1. Classification of Genu Varum or Bowleg Deformities of the Lower Extremities in Children
Table 169.2. Classification of Genu Valgum or Knock-knee Deformities of the Lower Extremities in Children
Table 169.3. Differential Diagnosis of Congenital Angular Deformities of the Tibia and Fibula
NORMAL DEVELOPMENTAL ALIGNMENT OF THE LOWER EXTREMITY
Mild to moderate bowing of the lower extremities is a common finding in infants and young children. It is the result of molding of the lower extremities in utero. The bowed appearance of the lower extremities is actually a combination of external or lateral rotation of the hip (tight posterior capsule) and internal or medial tibial torsion. This physiologic genu varum tends to persist during the first year of life with only minimal improvement. After a child begins to walk, the bowing corrects spontaneously.
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Complete correction may require up to 36 months of ambulation.
Physiologic genu valgum may appear by 3–4 years of age. This is true genu valgum, not the result of a torsional combination from in utero positioning. This deformity also undergoes spontaneous correction with normal adult knee alignment of mild genu valgum obtained by 5–8 years of age. Cahuzac et al. (55) demonstrated that girls have a consistent genu valgum alignment by 10 years of age that remains constant as they finish musculoskeletal growth. Boys, however, tend to have a decreasing valgus alignment until approximately 16 years of age. Thus, men have less valgus at maturity than do women.
Salenius and Vankka (242) analyzed the femoro-tibial angles clinically and radiographically in 1,279 children between birth and 16 years of age (Fig. 169.1). They found a mean varus alignment of 15° in newborns. This decreased to approximately 10° of varus alignment by age 1 year. Neutral alignment occurred between 18 and 20
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months of age. The maximum valgus of approximately 12° was achieved by 3–4 years of age. The results were similar for boys and girls. By age 7 years, the children’s valgus alignments had corrected to those of normal adults (8° in women, 7° in men). The researchers estimated that in approximately 95% of the children physiologic genu varum or valgum alignments resolved spontaneously with growth. In a follow-up study of 20 children between 1 and 4 years of age with pronounced physiologic varus (16° to 33°) or valgus (15° to 20°) deformities of the knees, Vankka and Salenius (279) found that even these pronounced deformities resolved during growth, although some did not completely correct until adolescence. They recommended that surgical correction be cautiously considered for children between 10 and 13 years of age, when corrective osteotomies are usually performed.
Figure 169.1. Normal development of knee alignment from infancy through childhood. (Adapted from Salenius P, Vankka E. The Development of the Tibio-femoral Angle in Children. J Bone Joint Surg Am 1975;57:259.)
GENU VARUM
Genu varum, or bowleg, is a common childhood deformity and one of the most common causes of parental concern. In the majority of cases, it will be physiologic in origin and will correct with normal growth and development. However, there are pathologic genu varum disorders that may progress and produce functional impairment (Table 169.1).
The evaluation of a child with genu varum consists of a careful history and physical examination. The history will frequently distinguish physiologic from pathologic genu varum. Obtain a birth history, family history, the age at which developmental milestones occurred, a nutritional history, and the previous percentiles for height and weight. A family history of short stature or varus alignment or progression of the deformity may indicate a pathologic process.
On physical examination, measure height and weight, and determine the percentile for age. Shortening of the extremities relative to the trunk may indicate a skeletal dysplasia. In ambulatory children, the appearance to the lower extremities during standing and gait can provide important information. Determine the location of the deformity, as well as whether there is a lateral knee thrust while walking. Measure the range of motion of the hips, knees, and ankles. Assess the presence of ligamentous laxity. Measure the degree of genu varum in the standing and the supine positions. Measure and record the distance between the medial femoral condyles in centimeters. In addition, measure the torsional profile as described by Mosca and Staheli (see Chapter 168). This includes the foot progression angle, hip range of motion in extension, the thigh–foot angle, and the shape of the foot. Torsional changes in the femur and tibia are common in angular deformities of the lower extremities. Obtain serial photographs, if possible, and place them in the child’s chart as an aid in documentation of improvement or worsening over time.
Radiographs are not routinely necessary in genu varum. However, if the child is short, the deformity is asymmetric, there is a history of progression, or the child is older than 3 years, obtain radiographs consisting of a standing anteroposterior (AP) projection of the lower extremities, including the hips, knees, and ankles. Position the patellae pointing forward. Measure the femoro-tibial angle, the mechanical axis, and the metaphyseal–diaphyseal angles. Assess the physes of the femur and tibia, especially those about the knee. Metaphyseal and physeal widening suggest an underlying metabolic disorder.
The history, physical examination, and radiographic evaluation then provide the basis for an accurate assessment of whether the child has a physiologic or pathologic genu varum deformity. The specifics of further evaluation and treatment are based on the diagnosis.
PHYSIOLOGIC GENU VARUM
Pathophysiology
Physiologic genu varum due to in utero positioning is a common finding in children between birth and 2 years of age. It is usually associated with a toe-in gait due to medial tibial torsion.
While the child is standing, the lower extremities appear bowed. However, physical examination demonstrates excessive lateral rotation of the extended hip and medial tibial torsion (Fig. 169.2). Contracture of the posterior capsule is a normal finding in children up to 1 year of age. It tends to improve during the first 3 years of life, and ultimately medial rotation slightly exceeds lateral rotation (222). Medial tibial torsion is the major component of physiologic genu varum. The knees are normal, except for possibly a slight residual knee-flexion contracture. A lateral knee thrust during gait is uncommon and indicates a pathologic genu varum deformity (161,163). The degree of varus can be measured by a goniometer (femoro-tibial angle) or the distance between the medial femoral condyles (55,65,126).
Figure 169.2. A: Physical examination of a 9-month-old boy with physiologic genu varum. The infant may still comfortably assume the in utero position with the hips flexed, abducted, and laterally rotated. The knees are flexed, with the lower legs and feet medially rotated. This position results in a hip flexion contracture, a contracture of the posterior aspect of the hip capsule, knee flexion contracture, and medial tibial torsion. B: When the lower extremities are extended, the posterior hip capsule contracture results in increased lateral rotation (80° to 90°) and limited medial rotation (0° to 10°). When the patellae point laterally, the medial tibial torsion is not readily apparent. C: When the hips are maximally rotated medially and the patellae are directed anteriorly, the medial tibial torsion is more apparent. The medial tibial torsion can be measured by the thigh–foot angle or the transmalleolar axis. The medial tibial torsion may also produce in-toeing during ambulation. This can be assessed by measuring the foot progression angle.
On radiographs, the typical features of physiologic genu varum include the following (268):
Transverse planes of the knees and the ankle joints are tilted medially.
Tibia is slightly bowed laterally at the junction of its proximal and middle thirds and the femur at its distal third.
Medial cortices of the tibia and femur are thickened and sclerotic.
Epiphyses, physes, and metaphyses have normal appearances, and there is no evidence of intrinsic bone disease.
Involvement is usually symmetric.
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It can be difficult to differentiate radiographically between physiologic genu varum and tibia vara (Blount’s disease) in children younger than 3 years of age. Levine and Drennan (176) developed the metaphyseal–diaphyseal angle to aid in differentiating these two disorders (Fig. 169.3). An angle of 11° or less indicates physiologic genu varum, and angles greater than 11° suggest that progressive tibia vara is likely (Fig. 169.4). However, a later study by Feldman and Schoenecker (101) indicated that angles greater than 16° are predictive of tibia vara, whereas angles of 9° or less suggest physiologic genu varum and angles between 10° and 15° are indeterminate. The metaphyseal–diaphyseal angle has been shown to have good interobserver and intraobserver reproducibility (104). However, it is important that standing radiographs be obtained with the knees in a neutral position, as rotational changes can alter measurements (265).
Figure 169.3. Metaphyseal–diaphyseal angle. Draw a line between the radiographic corners of the medial and the lateral metaphyses of the proximal tibia, and another line parallel to the longitudinal axis of the tibial diaphysis. Then construct a line perpendicular to the diaphyseal line at the intersection of the metaphyseal and diaphyseal lines, and measure the angle between the right-angle line and the metaphyseal line. (Adapted from Levine AM, Drennan JC. Physiologic Bowing and Tibia Vara: The Metaphyseal–Diaphyseal Angle in the Measurement of Bowleg Deformities. J Bone Joint Surg Am 1982;64:1158.)
Figure 169.4. Standing AP radiograph of an 18-month-old girl with asymmetric bowing of the lower extremities. The metaphyseal–diaphyseal angle is 14° on the right, indicating infantile tibia vara; it is 10° on the left, representing physiologic genu varum. There is already medial metaphyseal irregularity and beaking, as well as mild medial epiphyseal flattening on the right.
If a metabolic disorder is suspected, obtain serum calcium, phosphorus, and alkaline phosphatase levels. Obtain a pediatric endocrinology evaluation to assist in diagnosis and management.
Physiologic genu varum resolves spontaneously with normal growth and development (94,124,161,163,190,242,252,268,279). Operative treatment is rarely indicated. Orthoses or corrective shoes are not recommended because there is no evidence that they improve alignment of the extremity. Follow infants and young children with physiologic genu varum at 6-month intervals (Fig. 169.5). Recording accurate clinical measurements is useful in reassuring anxious parents that improvement is occurring.
Figure 169.5. A: A 16-month-old girl with physiologic genu varum. Observe the lateral rotation of the thighs and knees and the medial tibial torsion. B: One year later, with no treatment, there has been complete resolution of the physiologic genu varum.
Operative Techniques
The techniques for correction of genu varum are listed in Table 169.4. The usual procedures for physiologic genu
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varum include a proximal tibial valgus derotation and diaphyseal fibular osteotomies, proximal tibial hemiepiphyseal stapling, or proximal tibial hemiepiphysiodesis. The latter two procedures are based on adequate remaining growth to achieve complete correction (39). The graph developed by Bowen et al. (38) can be helpful in determining proper timing.
Table 169.4. Surgical Options for Genu Varum Deformities
Proximal Tibial Valgus Osteotomy and Diaphyseal Fibular Osteotomy
This is the most common procedure in persistent physiologic genu varum because it addresses both the varus and the medial tibial torsion. A variety of techniques can be used, including closing-wedge, opening-wedge, oblique, or dome osteotomies. These are essentially the same procedures as for tibia vara or Blount’s disease. A diaphyseal fibular osteotomy is performed concomitantly because the fibula is usually too long and may be contributing to the deformity. The technique of a closing-wedge proximal tibial and diaphyseal fibular osteotomy is discussed in the section on tibia vara (see below). Internal or external fixation to maintain alignment is necessary and usually supplemented by a long-leg cast until complete healing has occurred.
Proximal Tibial Hemiepiphyseal Stapling
Temporary retardation of growth in the lateral aspect of the proximal
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tibial epiphysis with staples is an effective method for correction of persistent physiologic genu varum. If the deformity is severe or there is limited remaining growth, a combined lateral stapling of the distal femoral and the proximal tibial epiphyses may need to be performed. This procedure will not correct any coexistent medial tibial torsion.
Proximal Tibial Hemiepiphysiodesis
Percutaneous closure of the lateral aspect of the proximal tibial epiphysis can be effective in correcting persistent physiologic genu varum in adolescents. The indications are essentially the same as for stapling. However, once complete correction has been achieved, a second procedure may be necessary on the medial side to prevent overcorrection. The proximal fibular epiphysis is usually closed concomitantly. This procedure will not correct any medial tibial torsion.
Rehabilitation and Postoperative Principles
In general, children treated with a proximal tibial valgus derotation and diaphyseal fibular osteotomies are managed similar to patients undergoing the same procedure for tibia vara. In children treated with a proximal tibial hemiepiphyseal stapling or hemiepiphysiodesis, apply a knee immobilizer postoperatively for approximately 2 weeks. This allows healing of the skin incision and minimizes discomfort. Then begin active range of motion exercises, and allow return to normal activities, typically at 4–6 weeks postoperatively.
Pitfalls and Complications
Complications of proximal tibial osteotomies have been well described in the orthopaedic literature (88,103,148,187,202,204,263). There is a risk for injury to the peroneal nerve as it passes around the lateral aspect of the proximal fibula, and to the anterior tibial artery as it passes into the anterior compartment through the hiatus between the proximal tibia and fibula. Compartment syndromes have been described, and a child must be carefully evaluated for the first 24–48 hours postoperatively. Perform prophylactic anterior compartment fasciotomies at the time of surgery.
Complications of hemiepiphyseal stapling or epiphysiodesis occur much less frequently. Physeal damage with asymmetric closure and complete closure secondary to prolonged compression are the most common problems but are fortunately rare.
Conclusion
Physiologic genu varum rarely persists to such a degree that surgical intervention is necessary. There is a relationship between this disorder and tibia vara (Blount’s disease). Persistent varus deformity may progress to the latter disorder. It has been my experience that the most common residual abnormality of physiologic genu varum is persistent medial tibial torsion. This is a more common indication for surgical treatment (see Chapter 168).
PATHOLOGIC GENU VARUM DEFORMITIES
Tibia Vara
Idiopathic tibia vara (Blount’s disease) is the most common pathologic genu varum deformity. It is characterized by abnormal growth of the medial aspect of the proximal tibial epiphysis that results in progressive varus angulation beneath the knee. This disorder was first described by Erlacher (95) in 1922 and further analyzed by Blount (35) in 1937.
Classifications
Tibia vara may occur at any age in a growing child. It was initially classified into two broad groups, depending on the age at clinical onset: infantile, with onset between 1 and 3 years of age; and adolescent, with onset inconsistently described as occurring after 6–8 years of age or just before puberty (33,35,97,110,111,157,158,260). In 1984, Thompson et al. (275) proposed a three-group classification based on the age at onset: infantile (1–3 years), juvenile (4–10 years), and adolescent (11 years or older). The juvenile and adolescent forms are commonly combined as late-onset tibia vara. However, the incidence of recurrent deformity after a corrective valgus osteotomy of the proximal tibia is much higher in the juvenile group, justifying a three-group classification. All three groups share relatively common clinical characteristics, although the radiographic changes in the late-onset groups are less pronounced. Although the exact cause of tibia vara remains unknown, it appears to be secondary to growth suppression from increased compressive forces across the medial aspect of the knee (22,29,33,35,59,60,69,111,157,168,171,172,274,275,286). Familial cases have been reported (23,111,173,250,253).
The natural history of tibia vara is one of progressive varus deformity. Infantile tibia vara can produce the greatest degree of deformity because of the greater amount of growth time remaining. In 1952, Langenskiöld (172) described six stages of progressive deformity in infantile tibia vara. Each grade advanced the degree of physeal growth inhibition (Fig. 169.6). It is possible to restore normal growth and development of the proximal tibial physes in grades I and II and probable grades III and IV. Grades V and VI represent severe damage to the medial proximal tibial physis and probable premature or asymmetric closure. The rate of deformity in grades V and VI is rapid, resulting in severe deformity and articular malformation. There is relatively good interobserver agreement with the use of this classification, especially for the early and late stages (264).
Figure 169.6. Six grades of radiographic changes in infantile tibia vara as described by Langenskiöld (172). These represent a continuum of progressing deformity over time.
Assessment, Indications, Relative Results
Comparison of the clinical characteristics of the infantile (22,23,33,35,46,90,91,95,97,103,110,111,116,151,167,168,169,172,173,180,181,223,248,260)
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and late-onset (juvenile and adolescent) (29,46,129,167,274,275,286) forms of tibia vara shows similarities as well as distinct differences (Table 169.5). The infantile form is the most common (Fig. 169.7). However, the late-onset forms also occur frequently (Fig. 169.8). Anterior cruciate ligament incompetence may occur in severe deformities (28).
Table 169.5. Comparison of the Clinical Characteristics of Tibia Vara
Figure 169.7. A: Clinical photograph of a 5-year-old African-American girl with left infantile tibia vara. Observe the obesity, the unilateral left genu varum deformity, and the associated medial tibial torsion. B: Standing radiograph of the left knee demonstrates Langenskiöld grade III changes in the medial aspect of the proximal tibial epiphysis and metaphysis. Notice the metaphyseal beaking.
Figure 169.8. A: Standing preoperative photograph of a 13-year-old African-American boy with bilateral adolescent or late-onset tibia vara. A previous proximal tibial osteotomy was performed on the right, producing only partial correction. Observe the marked obesity and the untreated left genu varum deformity and its medial tibial torsion. The patient subsequently underwent a laterally based closing-wedge proximal tibial osteotomy, including the physis, and a diaphyseal fibular osteotomy for correction of this deformity. B: On a standing AP radiograph of the left knee, the radiographic changes in adolescent tibia vara are less striking than in the infantile form. There is narrowing of the medial aspect of the proximal tibial epiphysis, physeal irregularity, and increased height of the lateral aspect of the epiphysis.
Radiographically, fragmentation with a protuberant step deformity and beaking of the proximal medial tibial metaphysis are the major features of infantile tibia vara (Fig. 169.7B) (54,116,151,260). The changes in the proximal medial tibia are less conspicuous in the late-onset forms and are characterized by wedging of the medial portion of the epiphysis, a mild posteromedial articular depression, a serpiginous cephalad-curved physis, and mild or no fragmentation or beaking of the proximal medial metaphysis (Fig. 169.8B) (29,46,54,77,78,254,255 and 256,274,275,286). The differences among the three tibia vara groups appear to be primarily due to the age at onset, the amount of remaining growth, and the magnitude of the medial compression forces on the involved side.
The major deformity that must be differentiated from tibia vara is physiologic genu varum deformity. It is difficult to differentiate these disorders in patients younger than 2 years. Children with tibia vara are typically African-American and obese and have a clinically apparent lateral thrust of the knee during the stance phase of gait. The deformities are progressive and may be asymmetric. Radiographic differentiation may be difficult. Standing radiographs of the lower extremities in children younger than 18 months of age with genu varum deformities are typically normal. However, normal knee radiographs do not eliminate infantile tibia vara from consideration. A metaphyseal–diaphyseal angle greater than 16° is an early prognosticator of infantile tibia vara (Fig. 169.3) (101). After 2–3 years of age, the radiographic characteristics become apparent, and the condition can be classified according to the six grades of Langenskiöld (172). The radiographic changes in late-onset forms of tibia vara are less dramatic but nevertheless diagnostic.
Pathophysiology
Histopathologic studies indicate a similar pathologic process for all three groups. Only a few biopsies of the proximal medial tibial condyle have been obtained from patients with infantile tibia vara (35,95,111,171,173). Histopathologic abnormalities included islands of densely packed chondrocytes exhibiting a greater degree of hypertrophy than would be expected from their topographic position, areas of almost acellular cartilage, and abnormal groups of capillaries. Langenskiöld (171) and Golding and McNeil-Smith (111), in studies of nine
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and six biopsies, respectively, concluded that the abnormalities were localized principally to the physes and that there was no evidence of avascular necrosis.
More extensive histopathologic data are available for the late-onset forms of tibia vara (59,60,223,274,275,286). The major histologic aberrations include the following:
Disorganization and misalignment of the physeal zones
Abnormal histochemical staining and excess of hypocellular matrix
Cystic degeneration and necrosis
Multidirectional clefts and fissures
Transphyseal canals of capillaries
Intraphyseal ossification centers
Increased necrotic chondrocytes throughout the proliferative and hypertrophic zones
Abnormal collagen fibers in the cartilage matrix
Chondrocytes at the apex of the vascular invasion front, which has increased width and length
Extension of noncalcified cartilaginous bars into the proximal and distal metaphyses
These changes are found uniformly throughout the medial and lateral aspects of the physes, although they are quantitatively greater on the medial side. They are remarkably similar to the changes observed in infantile tibia vara and in slipped capital femoral epiphysis, suggesting a common cause (1,2). Lovejoy and Lovell (182) described two patients with late-onset tibia vara associated with slipped capital femoral epiphysis.
The histopathologic abnormalities indicate that asymmetric compression and shear forces acting across the proximal tibial physis result in suppression and deviation of normal endochondral ossification, producing tibia vara. This concept, which reflects the Heuter–Volkmann law, has been confirmed experimentally by Arkin and Katz (13). Golding and McNeil-Smith (111) concluded that children who had significant physiologic varus deformity, walked early and stretched their knee ligaments. This resulted in asymmetric compression with subsequent suppression of posteromedial physeal growth and ultimate formation of an osseous bridge, producing a permanent and progressive varus deformity. This pathogenesis is consistent with Blount’s (33,35) initial observations that infantile tibia vara is first recognized when there is an increase of physiologic bowing during the first 3 years of life. Langenskiöld (172,173) emphasized that necrosis of the physeal cartilage is the principal cause of growth disturbance, leading to varus deformity; he attributed the abnormal cartilage to abnormal pressure or shear in overweight children with physiologic bowleg. Others agreed that abnormal pressure is probably the primary etiologic factor in infantile tibia vara (22,35,46,111,157,162).
In predisposed older children or adolescents with minimal residual deformity after physiologic bowleg, rapid growth and weight gain repetitively injure the posteromedial portion of the proximal tibial physis, resulting in a cycle of varus-growth suppression similar to the cycle described by Golding and McNeil-Smith (111) for the infantile form (127,129,274,275,286). Progressive genu varum deformity is not due to an osseous bridge but is caused by suppression of normal endochondral growth after repetitive local injury (29,162,260,274,275,286). The concept of physeal growth suppression in tibia vara has been confirmed biomechanically by Cook et al. (69) in a finite element analysis. As varus increases, the forces in the proximal medial tibial physis increase. Obesity and mild varus (10°) in older children create enough force to suppress growth. However, Henderson and Green (127) reported a case of late-onset tibia vara in an adolescent with previously documented neutral mechanical alignment, suggesting that, at least in some cases, preexisting varus alignment is not a prerequisite.
Preoperative Management and Planning
If radiographic findings confirm the diagnosis of infantile tibia vara, begin treatment immediately. Orthotic management may be considered for children 3 years of age or younger with Langenskiöld’s grade II and possibly grade III involvement. Approximately 50% to 65% of these in children can be corrected with an orthosis (151,180,232,248). Children with suspected infantile tibia vara with metaphyseal–diaphyseal angles of 10° to 15° are more likely to benefit from orthotic management (232). Use a knee–ankle–foot orthosis with a single medial upright without a knee hinge. Place pads, straps, or elastic webbing over the distal femur and proximal tibia to apply a valgus force. The orthosis should be worn for 22–23 hours each day. Tighten the straps at 1–2-month intervals to provide progressive correction. Obtain standing radiographs at 3-month intervals to document correction of the tibia vara deformity. The metaphyseal–diaphyseal angle should decrease (122). After obtaining an absolute valgus mechanical axis, begin weaning from the orthosis. Follow the child carefully thereafter to ensure maintenance of correction.
A maximum trial of 1 year of orthotic management is currently recommended. If correction is not obtained after 1 year of bracing, corrective osteotomy is indicated. Orthotic treatment is not indicated after 3 years of age or for severe deformities. Bracing children older than 3 years risks delaying performance of a corrective osteotomy. Loder and Johnston (180) showed that delay in performing corrective osteotomy, even by a few months, beyond 4 years of age risks failure to achieve lasting reversal of the physeal inhibition of the proximal tibia. This predisposes a child to repeated operative procedures to maintain a satisfactory result.
Conservative management in the late-onset forms of tibia vara is contraindicated. The children are too large and the remaining growth is too small to allow adequate
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correction. Compliance with an orthosis in this age group is difficult to achieve.
The indications for surgical treatment in infantile tibia vara include age 4 years or less, failure of orthotic management, and Langenskiöld grade III or higher. The possible procedures are presented in Table 169.4. Proximal tibial valgus osteotomy with fibular diaphyseal osteotomy is usually the procedure of choice. Perform an anterior compartment fasciotomy concomitantly. Tibial osteotomy techniques include closing-wedge, opening-wedge, dome, and oblique osteotomies. The procedure selected must correct the varus deformity and any associated medial tibial torsion. Tibial length is usually not a problem in infantile tibia vara. It is important that the selected osteotomy overcorrect the mechanical axis of the knee to 5° or more of valgus. This ensures that the supine correction obtained in the operating room is adequate. Overcorrection compensates for the tendency of the knee to fall back into varus after a patient resumes weight bearing because of the depression in the posteromedial articular surface and the ligamentous relaxation laterally. The goal is to transfer the line of weight bearing to the lateral compartment of the knee. Schoenecker et al. (248) reported that correction within 5° of neutral usually proves satisfactory. However, others recommend overcorrection (168,173,180,229). Considering the physeal inhibition phenomena as proposed by Cook et al. (69), overcorrection to absolute valgus alignment is necessary to relieve the excessive compressive forces medially.
Rab (229) described an oblique osteotomy of the proximal tibia for tibia vara. It is a single-plane osteotomy that allows simultaneous correction of the varus and medial tibial torsion deformities and permits postoperative cast wedging, if necessary, to improve position. This ability to adjust the osteotomy postoperatively is important because of the difficulty in achieving satisfactory alignment intraoperatively.
In older children with infantile tibia vara, especially those with Langenskiöld grade IV lesions or higher, a single osteotomy of the proximal tibia is usually insufficient to restore normal alignment and physeal growth. Langenskiöld grades IV and V act effectively as medial physeal arrests. Possible procedures for these children include the following (25,47,65,87,103,117,130,152,158,159,166,177,195,217,229,245,246,247 and 248,255,261,274,275):
Multiple proximal tibial metaphyseal osteotomies and fibular diaphyseal osteotomies
Proximal tibial osteotomy with physeal resection
Intraepiphyseal osteotomy to elevate the medial tibial articular surface (elevation of the medial tibia plateau)
Physeal bridge resection and replacement with interposition material such as fat or Silastic
Hemiepiphysiodesis of the lateral aspect of the proximal tibial epiphysis
Oblique proximal tibial osteotomy
Ilizarov ring fixation system and callotasis technique
In the juvenile and adolescent forms of tibia vara, surgical correction is necessary to restore the mechanical axis of the knee. The same surgical options as those for older children with infantile tibia vara are applicable in these groups. Correction to physiologic genu valgum with careful preoperative biotrignometric planning for the tibial osteotomy is the goal (57). Kline et al. (160) demonstrated that distal femoral varus is a part of the deformity in late-onset tibia vara. Evaluate this possibility, and perhaps consider it in the treatment plan.
Obtain intraoperative radiographs with the knee in extension and with slight varus stress to ensure contact between the medial femoral condyle and the posteromedial articular depression of the proximal tibia. This technique can help minimize undercorrection of the deformity. Aim to achieve at least 5° of valgus at the time of osteotomy. The recurrence rate for the juvenile-onset group approaches 25% overall and is even higher in boys (274,275). Evaluate all juvenile-onset patients with tomography or magnetic resonance imaging (MRI) before surgery for evidence of premature closure or impending closure of the proximal medial tibial physis. If premature closure is not present, a simple closing-wedge metaphyseal osteotomy or oblique proximal tibial osteotomy with correction to physiologic valgus may be performed (229). Correction using the Ilizarov ring fixation system and callotasis may be applicable, especially if there is a significant lower-extremity length discrepancy (227).
If the deformity recurs, indicating significant physeal inhibition, then additional surgery is necessary; techniques include physeal bridge resection and interposition graft, intraepiphyseal osteotomy, elevation of the medial tibial plateau, and physeal excision (117,152,174,177,185,245,248,255,289). Internal or external fixation is usually necessary to maintain alignment until satisfactory healing occurs. Physeal distraction with an external fixator has also been used in Europe (86,88), but it is not widely used. The procedure selected depends on the patient’s age, the amount of growth remaining, and the severity of the deformity. Proximal tibial physeal excision with proximal fibular epiphysiodesis is usually recommended for recurrent deformities with premature medial tibial physeal closure or for patients 12 years of age or older (274). Healing is rapid and the correction permanent. Measure any residual lower-extremity length discrepancy with scanograms, and manage by contralateral epiphysiodesis, when necessary.
Henderson et al. (128) reported results in nine children with late-onset tibia vara treated by hemiepiphysiodesis of the lateral aspect of the proximal tibial epiphysis. The average preoperative varus was 13° (range, 3° to 25°).
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They found a correction rate of 7° per year. Three patients required a proximal tibial osteotomy because of incomplete correction. The authors thought that hemiepiphysiodesis was an effective procedure with less morbidity for managing varus deformities of the extremities of obese children. Similar results can probably be anticipated with staples, although they were not used in this study.
Operative Techniques
Proximal Tibial Valgus Osteotomy and Fibular Diaphyseal Osteotomy
  • Make a 5 cm horizontal or transverse skin incision below the level of the tibial tubercle (Fig. 169.9).
    Figure 169.9. A: Intraoperative photograph shows the location and extent of the incisions for a proximal tibial and diaphyseal fibular osteotomy. B: After a transverse osteotomy of the proximal tibia, derotate the leg to correct the associated medial tibial torsion. Remove an appropriate, laterally based wedge to correct the residual varus deformity. C: Insert a threaded Steinmann pin above and below the proximal tibial osteotomy. Take care to ensure that the proximal pin is inferior and posterior to the apophysis of the tibial tubercle. Secure the pins with an external fixation clamp. D: Postoperative radiograph after correction shows that there has been some distraction at the osteotomy site. This is usually not a problem. Ideally, the osteotomy should remain closed. The external fixation clamp is incorporated into the cast, providing secure fixation. E: AP radiograph in a long leg cast shows that there is partial healing and the external fixation system has been removed. F: AP radiograph obtained 3 months after surgery demonstrates satisfactory healing of the osteotomy and correction of the tibia vara deformity. The extremity is in approximately 5° to 7° of genu valgum.
  • Expose the proximal tibia subperiosteally.
  • Release the fascia of the anterior compartment. The fibers of the patellar tendon insertion are usually visible in the proximal portion of the incision.
  • Perform a fibular diaphyseal osteotomy through a 3 cm vertical incision at the junction of the middle and proximal thirds of the fibula.
  • Identify the muscles of the lateral compartment, and retract them anteriorly. Split the periosteum of the fibula longitudinally, and reflect it circumferentially.
  • Make an oblique osteotomy with a small oscillating saw.
  • With the fibular osteotomy completed, proceed with the proximal tibial osteotomy. This may be a closing-wedge, opening-wedge, or dome osteotomy. The procedure should allow correction of the medial tibial torsion and the varus deformity. I prefer a closing-wedge osteotomy. It is important to correct the medial tibial torsion first and then perform the laterally based, closing-wedge osteotomy. Excessive correction and unnecessary bone excision may occur if the torsion is not corrected first.
  • Fix the osteotomy with crossed Steinmann pins, compression plate and screws, or an external fixation device. I prefer the latter because the pins can be removed in the outclinic without a separate operative procedure.
  • Obtain intraoperative radiographs with the knee in extension to confirm that approximately 5° of valgus alignment have been obtained.
  • After closure, immobilize the leg in a long-leg cast with the knee in extension and a slight valgus stress.
Oblique Tibial Osteotomy
  • Make a transverse incision just beneath the tibial tubercle. Make a Y-shaped incision in the periosteum, and elevate it circumferentially
  • Insert a small Steinmann pin at a cephalad angle of approximately 45° 1 cm distal to the tibial tubercle, and advance it under image-intensifier control until it passes through the posterior cortex distal to the proximal tibial physis. The angle of insertion determines the amount of correction for the varus and the medial tibial torsion. Have a nomogram available to assist in preoperatively determining the appropriate angle of guide-pin insertion.
  • Carefully perform the osteotomy immediately beneath the Steinmann pin.
  • After completion of the tibial osteotomy, perform a fibular diaphyseal osteotomy. This results in free mobility at the tibial osteotomy.
  • Drill a hole in the anteroposterior direction across the osteotomy and lateral to the tibial tubercle.
  • Insert a single 3.5 mm cortical or cancellous lag screw, align the osteotomy, and loosely tighten the screw to allow later adjustments, if necessary.
  • After an anterior compartment fasciotomy, close the incisions. Insert a suction drain at the time of closure.
  • Apply a long-leg cast. Rab (229) advised injection of contrast material into the knee to enhance the ability to check the radiographic alignment after the dressings are applied but before the long-leg cast is applied.
Excision of the Proximal Tibial Physis
If the deformity recurs in an older child with the adolescent form of tibia vara, excision of the proximal tibial physis may be advantageous.
  • This procedure is similar to the proximal tibia osteotomy previously described. Make a similar incision, although more proximally.
  • Mobilize the patellar tendon on its medial and lateral sides.
  • Place a smooth Steinmann pin through the epiphysis just below the articular surface.
  • Excise the entire physis in a closing-wedge osteotomy. Insert a second pin distally, and apply an external fixator.
Always perform a fibular diaphyseal osteotomy. The advantage of this procedure is that it is performed at the site of the deformity and therefore allows maximal correction and physiologic realignment of the tibia. Healing is usually rapid, and there is no risk of recurrent deformity. A contralateral proximal tibia epiphysiodesis may be performed at the same time. However, in most cases, the degree of lower-extremity length discrepancy is followed scanographically, and any residual leg-length discrepancy is corrected by a contralateral distal femoral epiphysiodesis at the appropriate time.
Other Techniques
In the late-onset form of the disease, a callotasis technique may be beneficial with either a cantilever or Ilizarov ring fixation system. The advantage of this procedure is that it allows slow, progressive correction.
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Because the patient is bearing weight, the precise degree of desired correction can be achieved. This procedure is being used more frequently today (see Chapter 171).
General Rehabilitation and Postoperative Principles
The postoperative management of children is similar after any corrective osteotomy of the proximal tibia. Continue immobilization until healing is complete; then place the children on a physical therapy program at home for approximately 2 weeks. After complete rehabilitation, allow them to return to normal activities. Because of associated obesity, these children frequently benefit from a dietary consultation.
Complications
Complications during and after a proximal tibial osteotomy are common. They include peroneal nerve palsy, injuries to the anterior tibial artery, and compartment syndromes (88,103,148,187,202,204,249,263). Occurrence of a compartment syndrome may be minimized by performing an anterior compartment fasciotomy at the time of surgery. If a compartment syndrome occurs, temporarily reduce the correction, and perform a four-compartment fasciotomy. Children with the infantile form of tibia vara require long-term follow-up to assess the results of surgery. The deformity may recur, especially in older children and those with advanced Langenskiöld grades. Deformity persisting after skeletal maturity predisposes to degenerative osteoarthritis (137,291).
Conclusion
I prefer a proximal tibial valgus derotation and fibular diaphyseal osteotomy to correct infantile tibia vara. This allows simultaneous correction of both components of the deformity. It is important that the deformity be slightly overcorrected so that the mechanical axis passes medial to the ankle joint. It can be difficult to assess the degree of correction intraoperatively because radiographs on a long cassette cannot be obtained. A helpful hint is to visualize the iliac crest on the involved side. The cord from the electrocoagulation knife can be used to measure the mechanical axis on the fluoroscope. This can be stretched between the anterosuperior iliac spine and the middle of the patella. Its distal extension can then be judged with respect to the ankle joint. Undercorrection is a common problem that prevents adequate alignment. Radiographic contrast material in the knee joint at the time of surgery may also be helpful. Manually manipulate the knee into varus after the osteotomy is internally stabilized, as this gives a more realistic feeling for the alignment of the extremity during weight bearing.
In older children with infantile or late-onset tibia vara, especially the juvenile type, a preoperative MRI may be helpful in assessing the integrity of the physis. However, even if the physis appears open, it may still be abnormal and not respond to normalization of the compressive forces postoperatively. Correction in these children can be accomplished using an Ilizarov frame and callotasis. This allows precise correction of the deformity. Weight-bearing radiographs may be obtained during treatment.
In children with recurrent deformities in whom a physeal bridge is suspected, I would suggest excision of the physis with concomitant correction of both the residual tibia vara deformity and any medial tibial torsion. Postoperatively, patients will need to be evaluated for residual lower-extremity length discrepancy. An appropriately timed contralateral epiphysiodesis will be necessary to achieve relatively equal leg lengths at skeletal maturity.
Tibia Vara Caused by Focal Fibrocartilaginous Dysplasia
Tibia vara secondary to focal fibrocartilaginous dysplasia involving the medial aspect of the proximal tibial metaphysis was first reported by Bell et al. (26) in 1985. Since then, additional cases have been reported (3,45,67,131,145,208,290). Tibia vara may also involve other areas of the body. Lincoln and Birch (178) reported upper-extremity involvement. It is an uncommon cause of pathologic genu varum but one that must be differentiated from Blount’s disease because the natural histories of the two disorders are distinctly different.
Pathophysiology
Biopsy of the lesion at the time of corrective osteotomy or for diagnostic purposes has shown consistent histopathologic features. Grossly, there is a white cartilaginous lesion with well defined margins deep to the insertion of the pes anserinus. Histopathologic findings include acellular or sparsely cellular collagenous tissue, inactive fibrocytes, plump cells resembling chondrocytes in lacunae, and dense, nondescript fibrous tissue (26,45,155,192,208). No giant cells, osteoid, or bone are found within these lesions. The lesions suggest fibrocartilage centrally and tendinous tissues peripherally. They do not involve the physis or epiphysis. Bell et al. (26) observed that the tissue resembles that normally found at the site of the insertion of tendons into cortical bone, as described by Cooper and Misol (70) in 1970. They suggested that these children had abnormal development of fibrocartilage at the insertion of the pes anserinus. The exact mechanism of this abnormal growth is unknown. The defect may be congenital.
Assessment
All children with tibia vara caused by focal fibrocartilaginous dysplasia present with unilateral bowing. There is no apparent sex or side predilection. The onset is usually before age 1 year, and the deformity progresses until approximately age 2 years and then begins to resolve. During the time of progression, the deformity may become quite prominent, reaching 20° to 30° of varus. Medial tibial torsion and mild tibial length discrepancy (0.5–1.0 cm) are common associated findings (26, 45).
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The lesions are characteristically not tender to palpation, and there is no prominence of the proximal medial metaphysis, as seen in infantile tibia vara.
Radiographically, there is a cortical defect in the medial metaphyseal region of the proximal tibia with an area of surrounding sclerosis (Fig. 169.10). MRI will demonstrate dense fibroconnective tissue (192). Computed tomography shows similar findings, with an elliptical fibrous cortical defect but no soft-tissue mass (131,290). On the basis of reported cases, it appears that the metaphyseal lesion resolves spontaneously after age 2 years, followed by correction of the tibia vara deformity. Significant improvement is usually evident by 4 years of age (26,45). Use of an orthosis does not increase the rate of improvement.
Figure 169.10. A: Standing AP radiograph of a 2-year-old Caucasian boy shows asymmetric genu varum involving the left lower extremity. B: Observe the typical radiographic features of focal fibrocartilaginous dysplasia of the proximal tibia. There is a cortical defect involving the medial aspect of the proximal tibial metaphysis. There is associated sclerosis, as well as the mild tibia vara deformity. C: The lateral radiograph is relatively normal.
Preoperative Planning
Although data are limited, it appears that only children with no evidence of spontaneous correction by 4 years of age are candidates for corrective osteotomy (290). This typically involves a proximal tibial osteotomy distal to the apophysis of the tibial tubercle and a diaphyseal fibular osteotomy. Because of the associated medial tibial torsion, the procedure of choice is a laterally based closing derotation osteotomy or an oblique proximal tibial osteotomy as described by Rab (229).
Operative Techniques
The procedures for focal fibrocartilaginous dysplasia are the same as those for tibia vara. There is no intrinsic osseous pathology that interferes with bone healing. Immobilization in a long-leg cast or a one-and-one-half spica cast is necessary, depending on the child’s age. A spica cast is usually advised for younger children. After healing, there is usually rapid rehabilitation and return to normal activities. Prolonged follow-up is necessary to assess resolution of the lesion and subsequent growth and development of the proximal tibia. Periodic scanograms are necessary to assess the length of the extremities.
Complications
A peroneal nerve palsy and persistent valgus deformity into adolescence were reported by Bradish et al. (45) after corrective osteotomy. This appears to
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have been a technical problem. No other complications have been reported for operative treatment of this lesion.
Other Pathologic Genu Varum Deformities
Vitamin D–Resistant and Nutritional Rickets
Persistent or progressive genu varum deformities are common in children with metabolic disorders such as vitamin D–resistant rickets (hypophosphatemic rickets) or nutritional rickets. Vitamin D–resistant rickets is an X-linked dominant disorder due to vitamin D resistance that results in defective bone mineralization. Affected children typically have bilateral symmetric genu varum; they are relatively short, usually being in the tenth percentile. The varus deformity is due to a combination of bowing and involvement of the distal femur and the proximal tibia. Hematologic studies reveal normal serum calcium and decreased phosphate values. In nutritional rickets, the child has been receiving an unusual diet from the parents.
Radiographically, the features are widening of the metaphyses, widening of the physes, and a cup-shaped relationship between the physis and the metaphysis. The bowing is usually symmetric throughout the femur and the tibia. Marked osteopenia and thinning of the cortices are also common. Obtain serum calcium, phosphorus, and alkaline phosphatase levels, as well as a pediatric endocrinology consultation to confirm the diagnosis.
Medical treatment is important before any form of orthopaedic intervention is considered (96,239). This typically includes oral phosphate supplementation and high doses of vitamin D for vitamin D–resistant rickets, and dietary changes for nutritional rickets. Surgical measures to correct genu varum deformities are usually unsuccessful unless adequate medical control has been obtained preoperatively. If such control cannot be obtained, it is usually best to wait until skeletal maturity before attempting to realign the mechanical axes.
If metabolic control can be obtained and a child is young, observation is appropriate. Spontaneous improvement may occur in children younger than 5 years. However, in older children or those who are not improving spontaneously, surgical treatment is necessary (96,239). This may consist of osteotomies of the distal femur, proximal tibia, or both. If involvement is extensive, proximal femoral and distal tibial osteotomies may be necessary to adequately realign the lower extremities. Cast immobilization postoperatively may result in immobilization-induced hypercalcemia and may require modification of medical management. When osteotomies are done, healing time may be twice normal. It is often advantageous to postpone major alignment procedures until adolescence to minimize the recurrence that is common in younger children.
Renal Osteodystrophy
Children who have end-stage renal disease may manifest renal osteodystrophy. The physes in these children show the same pathologic changes found in tibia vara and slipped capital femoral epiphysis. These include disorganized endochondral ossification at the physeal–metaphyseal junctions. Because end-stage renal failure occurs more commonly in older children who have achieved physiologic valgus alignment, valgus deformities are much more common. Varus is more likely when renal failure occurs at 3 years of age or younger. Renal osteodystrophy has many of the same radiographic features as vitamin D–resistant and nutritional rickets. There is physeal cupping and widening at both the distal femoral and proximal tibial physes. Marked osteopenia and thinning of the cortical bone are also present.
Treatment of genu varum deformities secondary to renal osteodystrophy is similar to that for vitamin D–resistant and nutritional rickets. Surgical treatment is usually postponed until the renal status has stabilized in response to medical treatment, hemodialysis, or kidney transplantation. There will be a rapid recurrence of the deformity if the underlying metabolic bone disease is not corrected first.
Skeletal Dysplasias
Many skeletal dysplasias may result in a progressive genu varum deformity (Table 169.1). Metaphyseal chondrodysplasia (both Jansen and Schmid types), which results in abnormal chondroblast function and chondroid production, is a common cause. Occasionally, these may be difficult to distinguish from rickets. Although the physes are widened and cupped in the Schmid type, the epiphyses are normal, and the presence of short stature may be helpful in making the correct diagnosis.
Genu varum frequently occurs in achondroplasia. This rhizomelic dwarfing condition is due to abnormal endochondral bone formation. Affected children have short stature and characteristic craniofacial features. The genu varum deformity is due to asymmetric growth of the proximal tibial epiphysis and overgrowth of the fibula. These children rarely have knee pain.
For some surgeons, the treatment options for genu varum deformities secondary to achondroplasia must be surgical because orthotic management historically has not been effective. Their usual procedure is a proximal tibial valgus osteotomy and proximal fibular epiphysiodesis (Fig. 169.11). The latter must be done early in childhood to prevent recurrence and progression of the genu varum deformity. Others feel that genu varum in achondroplasia is not associated with functional difficulty or increased risk of osteoarthritis, and surgery may not be recommended (see Chapter 180).
Figure 169.11. A: Standing preoperative radiographs of a 6-year-old Caucasian boy with achondroplasia genu varum demonstrating the typical epiphyseal and metaphyseal changes, as well as overgrowth of the fibulae. B: Postoperative radiograph after proximal tibial and fibular diaphyseal valgus derotation osteotomies of the right leg shows that internal fixation was achieved with percutaneous smooth Steinmann pins. C: Postoperative radiograph of the left lower leg. D: Standing radiographs 6 months postoperatively demonstrates satisfactory healing and excellent correction of the genu varum deformities.
Osteogenesis imperfecta results from a defect in type I collagen and produces varying degrees of skeletal fragility. Repeated fractures often lead to bowing and torsional malalignment of the lower extremities. The distal third of the femur is a common location for these fractures, which frequently result in anterolateral angulation. Residual deformities
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after fractures are common, and the varus angulation often increases as a result of repeated fractures. Occasionally, in the more severe cases, osteotomies with intramedullary fixation may be beneficial (see Chapter 180).
Other Causes
Any condition, such as infection or trauma, that damages the physis may result in asymmetric growth and deformity. The distal femur is the most common site of growth disturbance following a physeal fracture. Physeal fractures of the proximal tibia occur much less commonly. The management of genu varum deformities secondary to physeal growth disturbance is complex. If an asymmetric physeal bar is present, it may be resected and grafted with fat or Silastic. The deformity is corrected concomitantly by an osteotomy. If the physeal damage is extensive, complete physeal closure and management of the associated leg-length discrepancy may need to be considered (see Chapter 164).
GENU VALGUM
Genu valgum, or knock-knee, is a common condition affecting the lower limbs in children and adolescents. Physiologic genu valgum is the most common form, but pathologic genu valgum disorders occur and may require treatment (Table 169.2). The most common pathologic causes of genu valgum are posttraumatic and renal osteodystrophy.
Evaluation of a child with genu valgum is similar to that for genu varum and includes a careful history and physical examination. In the majority of children with genu valgum, the femoro-tibial angles are within the physiologic range of two standard deviations above or below the mean. Only those with an angle greater than two standard deviations from the mean are considered to have a deformity. Fat thighs, ligamentous laxity, and flat feet are often the results of associated out-toeing, and this can accentuate the appearance of the knock-knee, making physiologic genu valgum appear more severe. Measurements of the femoro-tibial angle (with a goniometer) and the intermalleolar distance are methods for assessing and following genu valgum (55,65,126). However, the intermalleolar distance may be misleading. The same intermalleolar distance in an individual of short stature may be more significant than the same distance in a taller individual. Torsional malalignment is less common in genu valgum, but the combination of femoral anteversion or torsion and compensatory external tibial torsion gives the appearance of a valgus knee.
The indications for radiographs for genu valgum are similar to those for genu varum. Short stature, asymmetry, history of injury, or history of progression are indications. Standing AP radiographs of the lower extremities, including the hip, knee, and ankle, are the best method (Fig. 169.12). The majority of children with genu valgum have physiologic genu valgum or its persistence into later childhood and early adolescence. However, there are other pathologic genu valgum disorders that may progress and cause functional impairment.
Figure 169.12. Standing AP radiographs of the lower extremities of a 3-year-old boy with physiologic genu valgum show no radiographic abnormalities of the distal femoral or proximal tibial epiphyses or metaphyses.
PHYSIOLOGIC GENU VALGUM
Pathophysiology
Physiologic genu valgum is a normal finding in children between 2 and 6 years of age (Fig. 169.13). The maximal deformity occurs between 3 and 4 years of age. It rarely causes symptoms or disability unless the deformity is severe. In these cases, the knees may rub, and the child walks and runs with a circumduction gait. With severe genu valgum deformities, the feet are pronated. In older children or adolescents, malalignment of the quadriceps mechanism may occur, resulting in patellar subluxation or dislocation. Severe genu valgum occurs more frequently in obese
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children. The abnormal weight may produce a medial thrust that can result in laxity of the medial collateral ligament and possibly early degenerative osteoarthritis.
Figure 169.13. Typical appearance of physiologic genu valgum in a 4-year-old boy. With the knees approximated, there is a wide separation between the ankles. There is approximately 15° of genu valgum bilaterally.
Preoperative Management and Planning
In 95% of cases, physiologic genu valgum resolves spontaneously with normal growth (94,161,163,190,197,207,242,268,279). Use of an orthosis is controversial and is not recommended. Even significant deformities persisting into adolescence can be expected to improve or resolve if slow, steady improvement can be documented. Persistent deformities that are not improving may benefit from surgical treatment.
The major indication for surgical intervention in physiologic genu valgum is a persistent, severe deformity (>15°) in the immediate preadolescent years (ages 11 years in girls and 12 years in boys). After this age, significant spontaneous improvement is not likely to occur (141).
The methods for surgical correction of genu valgum are presented in Table 169.6. Three methods are usually employed for physiologic genu valgum:
Table 169.6. Surgical Options for Genu Valgum Deformities
Medial physeal stapling
Medial physeal hemiepiphysiodesis
Osteotomy
These procedures are applicable in the distal femur, proximal tibia, or both, depending on the patient’s age and the severity and location of the deformity.
Operative Techniques
Medial Physeal Stapling of the Distal Femur or Proximal Tibia
Retardation of growth about the medial aspect of the distal femur or proximal tibia by medial physeal stapling is a relatively easy, reliable method of correcting a genu valgum deformity if there is sufficient remaining growth to produce satisfactory alignment (Fig. 169.14) (36,105,141,193,221,282,294). If the deformity is pronounced or there is insufficient remaining skeletal growth, a combined stapling of the medial aspect of the distal femoral and the proximal tibial physes may be necessary (105,221).
Figure 169.14. A: A 14-year-old boy with persistent severe physiologic genu valgum. B: Standing AP radiograph of both lower extremities demonstrates a valgus deformity in the distal femora and proximal tibiae. Observe the physeal widening at the proximal tibial physes. A metabolic evaluation was normal. C: Postoperative radiograph of the left knee after stapling of the medial aspect of the distal femoral and proximal tibial epiphyses shows the three staples used to bracket each epiphysis. D: Lateral radiograph. E: Standing radiograph of both knees 9 months postoperatively shows excellent correction of the genu valgum deformities. F: On a standing radiograph 6 months after staple removal, physiologic alignment is being maintained. G: Clinical photograph.
The medial aspect of the distal femoral epiphysis is palpable at the junction of the maximal metaphyseal flare and the medial femoral condyle. Stapling of the distal femoral epiphysis proceeds as follows.
  • Approach the physis through a 4–5 cm longitudinal incision between the anterior and posterior margins of the medial femoral condyle. Begin the incision approximately 1–1.5 cm distal to the physis, and extend it proximally.
  • Divide the subcutaneous tissues, deep fascia, and patellar retinaculum. If necessary, retract the medial margin of the vastus medialis anteriorly. Identify the physeal plate with a straight Keith needle or by fluoroscopy. Identification of the physis and insertion of the staples occur more quickly and more accurately with fluoroscopy. If the physeal plate is identified by probing with
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    a Keith needle, the plate is softer than the adjacent cancellous bone.
  • Select Blount staples that are rectangular or oblique, depending on the shape of the medial femoral condyle and metaphysis. Vitallium staples cause less reaction, are stronger, and are less likely to be extruded than stainless steel staples.
  • Avoid subperiosteal stripping to protect the perichondrial ring and the physeal plate.
  • With a staple holder, partially insert three staples. Insert one directly medially and one each in the anteromedial and the posteromedial aspects of the distal femur. Before completely setting the staples, confirm their location and orientation with radiographs or fluoroscopy. The physis should be in the mid portion of each staple. Insert the ends of the staple parallel to the physis to avoid physeal injury. If position and orientation are satisfactory, drive the staples flush with the periosteum. Do not bury the staples into the bone to avoid injury to the perichondrial ring.
  • Close the patellar retinaculum and the deep fascia separately. It is important that the patellar retinaculum not be bound down by the staples because it can cause loss of knee motion, local swelling, and pain.
  • Close the subcutaneous tissues and skin with absorbable sutures. A subcuticular closure of the skin gives the best cosmesis. Reinforce the incision with adhesive closure strips, and apply sterile dressings and a knee immobilizer.
If the proximal tibial physis is selected for stapling, the procedure is similar to that for the distal femur.
  • Make a 4–5 cm longitudinal incision directly over the medial aspect of the knee. The incision usually begins just distal to the joint line and proceeds distally.
  • Identify and retract anteriorly the medial border of the pes anserinus, if possible. Occasionally, the pes anserinus must be split. After the periosteum of the proximal tibia is visualized, identify the physeal plate with a Keith needle or by fluoroscopy.
  • Insert one staple directly medially and one each in the anteromedial and the posteromedial aspects of the proximal tibia. The oblique or angulated Vitallium Blount staples are quite useful in this location because they conform to the flare of the medial aspect of the proximal tibia. Insert the staples parallel to the physis and the articular surface. Center the staples over the physeal plate. Before setting the staples, confirm the position radiographically.
  • Close the wound in layers. If the pes anserinus is split, repair it with absorbable sutures. Close the subcutaneous tissues and skin in a similar manner, and apply sterile dressings.
Postoperatively, use a knee immobilizer for approximately 2 weeks. Follow up at 2–3-month intervals, and assess radiographically for correction. After the desired amount of correction has been achieved, remove the staples. However, there is frequently rebound overgrowth and slight recurrence of the deformity. Zuege et al. (294) recommended allowing 5° of rebound. Accomplish this by allowing the correction to proceed to slight overcorrection before staple removal. However, Fraser et al. (105) found that the amount of rebound overgrowth was minimal and unpredictable. They also advised against leaving the staples in place for longer than 1 year because of possible premature closure of the physis. The amount of correction can be calculated mathematically on the basis of the width of the physis and the amount of remaining growth (38).
Medial Hemiepiphysiodesis of the Distal Femur or Proximal Tibia
Partial or hemiepiphysiodesis of the medial aspect of the distal femur or proximal tibia has been proposed as a method for gradual correction of genu valgum deformity. The table devised by Bowen et al. (38) can be used to determine the appropriate time for epiphysiodesis. However, because of the variability in the data necessary to make these determinations, a second operative procedure is often required to close the remaining lateral portion of the epiphysis.
Rotational bone blocks, as described by Phemister (218), were once popular. However, the percutaneous techniques of epiphysiodesis using curet, drills, burrs, or a combination of these are now preferred (37,39,58,207,276). These are as accurate and much more cosmetic than the open bone graft epiphysiodesis techniques. Although this technique is most commonly used for lower-extremity length discrepancies, it can also be used successfully in the correction of persistent angular deformities such as genu valgum and genu varum (39).
Percutaneous Epiphysiodesis
  • Position the patient supine on a fluoroscopy table. Identify and mark the mid portion of the medial aspect of the distal femoral physis.
  • Make a 2–3 mm incision directly over the physeal plate.
  • Enter the medial aspect of the physis with a small curet or drill, and remove the medial portion of the physis. This allows the formation of a medial bone bridge. Do not extend the epiphysiodesis across the midline of the physis to avoid symmetric closure.
  • Only a single subcutaneous suture is usually necessary to close the wound.
A similar procedure may be performed on the medial aspect of the proximal tibial epiphysis, if necessary.
After epiphysiodesis of the distal femur or proximal tibia, use a knee immobilizer for approximately 2 weeks. This allows skin and soft-tissue healing. The physis after epiphysiodesis is weak and must be protected for a short
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period to prevent complete physeal separation. At the end of 2 weeks, discontinue the knee immobilizer and allow the child active range-of-motion exercises and full weight bearing. Continue restriction of activities until 6 weeks postoperatively. Institute quadriceps and hamstring strengthening exercises at that time, with a gradual return to normal activities. After the desired correction has been achieved with medial epiphysiodesis, a lateral epiphysiodesis of the distal femur or proximal tibia is necessary to prevent overcorrection if the lateral physes remain open.
Osteotomy of the Distal Femur or Proximal Tibia
Correction of a genu valgum deformity by distal femoral or proximal tibial and fibular diaphyseal osteotomies allows full correction of the deformity with a single operative procedure. However, both procedures are extensive and require internal or external fixation to maintain alignment until healing has occurred. In the correction of a valgus deformity, attention must be given to the peroneal nerve because neurapraxia or partial paralysis may occur if the nerve is stretched. The osteotomy may be performed in early adolescence or after skeletal maturity. Several techniques are available, including opening-wedge, closing-wedge, and dome osteotomies. The choice of technique is frequently based on the length of the lower extremity and the individual bones. An opening-wedge or dome-shaped osteotomy adds length to the extremity. DePablos et al. (87) described a progressive opening-wedge osteotomy using an external fixator; a fibular osteotomy is not required, and the osteotomy allows progressive and adjustable correction. Both lower extremities can be corrected simultaneously. Ordinarily, osteotomies are considered for boys age 14 years or older and girls age 12 years or older.
Varus osteotomy of the proximal tibia and diaphyseal osteotomy of the fibula are indicated if the valgus deformity is in the proximal tibia below the knee joint and there is no associated lateral tilt to the articular surface. The osteotomy is usually performed at the junction of the metaphysis and the diaphysis, just distal to the tibial tubercle. If there is associated lateral torsion of the tibia, derotation may also be accomplished. If a closing-wedge osteotomy is to be performed, perform the derotation initially because it frequently decreases the amount of bone requiring resection to correct the angular deformity. After satisfactory correction has been achieved, internal or external fixation is required. Compression plate and screws, crossed Steinmann wires, or an external fixator are suitable. In some cases, the Ilizarov ring fixator and the callotasis technique may be beneficial; this allows slow correction of the valgus and the derotation. Hemichondrodiastasis, or asymmetrical physeal lengthening, has been recommended by some, but it is not popular in the United States. This procedure allows simultaneous correction of limb-length inequality and correction of the genu valgum deformity. Because the physeal plate closes after this procedure, it is best performed for patients in late adolescence.
Treat a genu valgum deformity associated with a valgus alignment of the distal femur with an osteotomy of the distal femur. Deformities in this area are associated with a lateral tilt to the joint line that cannot be corrected by a proximal tibial osteotomy. The osteotomy may be performed through a medial or a lateral approach to the distal femur. The medial approach is more complex because of the proximity of the femoral artery, but it allows easier visualization of the operative site. The lateral approach is simpler, and there is less risk to the femoral artery as it passes posteriorly at the upper margin of a medial incision. Opening- or closing-wedge osteotomies are commonly performed because it is difficult to perform a dome osteotomy of the distal femur. After the osteotomy is complete, internal or external fixation is performed with a compression plate and screws, crossed threaded Steinmann pins, or an external fixation device. See Chapter 30 and Chapter 31 for additional information on osteotomies of the femur and the tibia, respectively.
General Rehabilitation and Postoperative Principles
After an osteotomy has been performed, postoperative management depends on the type of internal or external fixation. If rigid internal fixation has been achieved with a compression plate and screws, immobilization is usually unnecessary, other than perhaps a knee immobilizer for 1–2 weeks for comfort. Allow only toe-touch weight bearing until early callus formation; then increase weight bearing, although not to full weight bearing, until the osteotomy site is completely healed. Remove the compression plate and screws 12–18 months postoperatively.
If simple external fixation is used, supplement it with a long-leg cast. Have the patient avoid weight bearing for 3–4 weeks, until there is early radiographic callus formation. Then allow toe-touch weight bearing. Usually, at 4–6 weeks after surgery, there is sufficient healing to allow removal of the external fixation device in the clinic. Apply a cylinder cast for an additional 2 weeks to allow solid union. After this has been accomplished, institute range-of-motion exercises. Failure to obtain a full range of motion at the end of 2 weeks is an indication for a referral to physical therapy. After full motion has been regained, begin strengthening exercises of the quadriceps and hamstring muscles. Return the patient to full activities after rehabilitation of the leg is complete.
Complications
The problems of asymmetric growth retardation associated with physeal stapling were outlined by Tachdjian (268): unpredictability of growth after the staples have been removed, possibility of asymmetric medial physeal closure, widening or loosening of the staples with eventual
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extrusion requiring revision, irregular patterns of initial growth retardation after stapling, the need for a second surgical procedure to remove the staples or to perform a lateral epiphysiodesis, and long and frequently wide operative scars due to stretching with knee motion. In 49 patients with genu valgum treated with stapling by Pistevos and Duckworth (221), there were no complications other than scarring, although six patients did not obtain complete correction. Staples may be painful; however, this resolves after removal.
Osteotomies of the distal femur or proximal tibia may result in peroneal nerve palsy, injury to the femoral or anterior tibial arteries, and anterior compartment syndrome (148,187,202,204,249,263,268). These severe complications are more common after proximal tibial osteotomies. Monitor patients closely postoperatively so that immediate intervention can be taken if a complication occurs. Postoperative wound infection, delayed union, nonunion, overcorrection, and undercorrection may occur after corrective osteotomies.
Conclusion
Because physiologic genu valgum does not usually have a rotational component, medial physeal stapling is my procedure of choice. This is usually performed on the proximal tibial epiphysis. In severe deformities, however, the distal femur may be included. I have not used the chart described by Bowen et al. (38). Once slight overcorrection is achieved, I remove the staples, and I have not encountered a case of premature physeal closure. This procedure is simple and effective and requires minimal postoperative immobilization.
PATHOLOGIC GENU VALGUM DEFORMITIES
Genu Valgum after Fractures of the Proximal Tibial Metaphysis
Fractures of the proximal tibial metaphysis are relatively common and tend to occur most frequently in children between 3 and 6 years of age (range, 1–12 years) (79,146,150,205,237). Three times as many boys are affected as girls, which is typical for all tibial fractures (123). Skak et al. (258) reported an incidence of 5.6 fractures per 100,000 children per year. The fractures are usually the result of direct injury to the lateral aspect of the extended knee. The primary injury patterns are compression (i.e., torus fracture), incomplete tension–compression (i.e., greenstick fracture), or complete fractures (235). The fibula is typically intact but may be fractured or have a plastic deformation. The incomplete tension–compression or greenstick fracture is the most common pattern. The medial cortex on the tension side fractures, whereas the lateral cortex on the compression side remains intact or hinges slightly. The distal fragment may angulate into a slight valgus deformity, but there is no displacement and the apposition remains normal. However, most fractures are nondisplaced and without angulation.
The most common sequelae of the fracture of the proximal tibial metaphysis are valgus deformity and overgrowth of the tibia. In 1953, Cozen (72) reported on four patients with valgus deformities after nondisplaced or minimally angulated fractures of the proximal tibial metaphysis. Many other reports of this complication have been published (16,18,21,27,30,44,51,66,71,76,79,109,113,133,146,147,150,153,183,184,226,258,273,281,283,292,293). Similar valgus deformities were observed after other insults to the immature proximal tibial metaphysis, such as osteomyelitis, bone-graft harvest, osteochondroma excision, and osteotomy (18,243,280).
The incidence of genu valgum deformity after proximal tibial metaphyseal fractures varies. It appears to occur in approximately 50% of cases. Salter and Best (244) reported on 21 patients with proximal tibial metaphyseal fractures, observing the development of a valgus deformity of 11° to 22° in 13 (62%) of them. Robert et al. (235) reported the development of a genu valgum deformity in 12 (48%) of 25 patients. However, Skak et al. (258) reviewed 40 consecutive patients and found the development of deformity in only 4 (10%). Boyer et al. (44) reported no valgus deformity in seven children 2–5 years of age who sustained fractures while jumping on a trampoline with a heavier child or adult. Valgus deformities occur predominantly in association with greenstick or complete fractures and are uncommon after a torus fracture (235,258).
Theories about the cause of valgus deformity include injury to the lateral aspect of the proximal tibial physis, inadequate reduction, premature weight bearing, hypertrophic callus formation, dynamic muscle action, soft-tissue interposition, tethering from the intact fibula, and asymmetric physeal growth stimulation (14,16,18,21,27,30,34,51,61,66,71,72,76,80,113,133,139,140,146,147,153,183,184,191,205,206,226,230,237,243,244,257,273,281,283,292,293).
In 1990, Ogden et al. (206) measured the medial and the lateral metaphyseal–diaphyseal–metaphyseal tibial distances in 17 children with 19 proximal tibial metaphyseal fractures. They found four patients in whom the medial distance of the injured tibia was longer than the lateral distance, which was the same distance as the uninjured tibia. In 11 patients, there was overgrowth on both the medial and the lateral sides of the injured tibia. This indicates that a valgus deformity following a proximal tibial metaphyseal fracture is usually due to eccentric proximal medial overgrowth.
Assessment, Indications, and Relative Results
Valgus deformity usually develops within 5 months of injury, reaches its maximum in 1–2 years, stabilizes, and then
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begins to improve by longitudinal growth through the proximal and distal physes (Fig. 169.15) (216). Unfortunately, there are no data indicating how much improvement can be anticipated. Salter and Best (244) found no improvement in 21 patients, and 13 later required proximal tibial varus osteotomies. Visser and Veldhuizen (281) reported no spontaneous improvement in the valgus deformity from the proximal tibial physis but observed some correction in alignment from the distal tibial epiphysis. Taylor (273) found improvement in some patients but not all. Of the 12 children with valgus deformity described by Jordan et al. (153), 11 had documented improvement, although four subsequently required corrective osteotomies. Two of these children had their deformities recur, and two had compartment syndromes. Six children had complete correction of their deformities.
Figure 169.15. A: Standing AP radiograph of a 5-year-old boy after treatment for a greenstick fracture of the right proximal tibial metaphysis. At the time of cast removal, there was already 22° of genu valgum on the right but only 5° on the left. B: One year later, there was increased genu valgum deformity.
Jackson and Cozen (147) and later Ippolito and Pentamalli (146) observed that deformities of 15° or less usually remodeled completely, especially in young children. The more severe deformities, however, did not completely correct. Bahnson and Lovell (16) found some improvement in the valgus deformities in five children followed for a minimum of 3 years after injury. Balthazar and Pappas (18) reported that two of nine patients who were treated nonoperatively had resolution of their valgus deformity in 1–3 years. Skak et al. (258) found that valgus deformities tended to increase during the first year after injury and then remained constant for 1–2 years and finally improved. Only one of their six patients had residual deformity at final follow-up.
MacEwen and Zionts (183,293) followed seven children with posttraumatic tibial valgus deformities for a mean of 39 months after injury. These children were 11 months to 6 years of age. The valgus deformities progressed most rapidly during the first year after injury and then continued at a slower rate for as long as 17 months. Overgrowth of the tibia accompanied the valgus deformities. The mean overgrowth was 1 cm (range, 0.2–1.7 cm). Clinical correction with subsequent growth occurred in six of their seven patients. They recommended that the
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alignment of the lower extremities be measured by the mechanical femoro-tibial angle as described by Visser and Veldhuizen (281) rather than the metaphyseal–diaphyseal angle of Levine and Drennan (176). The latter measured only the alignment of the proximal tibia. Much of the late correction of the deformity is due to distal realignment (183,258,281). The distal epiphysis tends to realign itself perpendicular to the applied forces, resulting in asymmetric growth and an S-shaped appearance of the tibia radiographically (216).
Preoperative Management and Planning
The treatment of proximal tibial metaphyseal fractures must consist of correction of any associated valgus angulation by manipulative reduction and immobilization in a long-leg cast with the knee in extension for 4–6 weeks or until the fracture is well healed (238). If closed reduction is required, it is best performed under general anesthesia. Radiographic evaluation of fracture alignment may be difficult unless radiographs of both lower extremities with the knee in extension are obtained on a long cassette. Greenstick fractures with slight valgus angulation may require that the intact hinged lateral cortex be manually fractured. This usually allows correction of the deformity. Slight overcorrection is desirable (205).
Displaced fractures also require correction of any residual angulation. However, normal apposition is not always necessary. There are limited indications for open reduction of these fractures. Inability to correct a significant valgus deformity by manipulation under general anesthesia rather than failure to close the medial fracture gap is currently the major indication. Most angulated displaced fractures are amenable to reduction by nonoperative methods.
The final step in initial management is to advise the family that although anatomic alignment of the fracture has been obtained, the possibility of valgus angulation and tibial overgrowth exist as a natural consequence of this fracture. This information prepares the family for complications if they occur.
Assess fracture alignment radiographically at least weekly during the first 3 weeks after injury. Correct any loss of alignment. During this initial period, children should avoid bearing weight to minimize compression forces and the possibility of valgus angulation within the cast.
Treatment of valgus deformities after proximal tibial metaphyseal fractures is predominantly nonoperative with prolonged observation. The use of orthoses has been suggested, but there is no evidence to substantiate the efficacy of this method (89,133,146). MacEwen and Zionts (183) recommended observation until early adolescence. If spontaneous improvement fails to provide sufficient clinical correction, surgical intervention may be necessary. McCarthy et al. (188) reported no difference in the long-term results between 10 patients treated nonoperatively and five managed operatively.
The major indications for surgical intervention include severe valgus deformities (>25°) and failure to achieve satisfactory correction by the immediate preadolescent years. All children should be allowed 2–4 years of growth after injury to allow spontaneous correction to occur. Most deformities of 15° or less resolve, and those that are 25° or more may not. Deformities between 15° and 25° must be carefully followed. The development of a medial thrust during this observation period is an indication for surgical intervention to prevent laxity in the medial collateral ligament.
Operative Techniques
The operative procedures to correct genu valgum deformities after proximal tibial metaphyseal fractures are similar to those for other valgus deformities and include the following:
Medial physeal stapling
Medial physeal epiphysiodesis
Osteotomy with internal or external fixation
Because the deformity is usually restricted to the tibia, these procedures are most commonly applicable to the proximal tibia. They are described in the section on physiologic genu valgum. If surgical intervention is contemplated, it is important to assess the degree of tibial-length inequality. Surgery must address the valgus deformity and residual tibial overgrowth. In young children with severe genu valgum deformities that are not improving with spontaneous growth and development, a corrective osteotomy may be indicated. This should include shortening of the tibia by approximately 5 mm to allow recurrent overgrowth. Similar consideration is necessary in the early adolescent years when surgical intervention is planned.
Recurrence of Deformity
Recurrence has been attributed to the same overgrowth phenomenon that led to the initial valgus deformity. Balthazar and Pappas (18) reported that the valgus deformity recurred, although lesser in magnitude, in six children undergoing a proximal tibial varus osteotomy. Four of the six also had further longitudinal overgrowth of the tibia. DalMonte et al. (80) reported recurrent valgus deformities in 7 (44%) of 16 patients after proximal tibial osteotomies. The recurrence rate for children younger than 5 years was 60%, and for those between 5 and 10 years of age, it was 36%. The authors concluded that the osteotomy is essentially a second fracture and therefore has the same risks of deformity. If surgery is undertaken, families should be advised that the deformity can recur and that prolonged follow-up is required.
Conclusion
With the recent demonstration that the majority of children with genu valgum following a proximal
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tibial metaphyseal fracture will undergo spontaneous correction during growth, I now feel that these children should be observed for as long as possible. Only a severe disabling deformity should be considered for early surgical correction. Deformities persisting into adolescence can be corrected with a proximal tibial or distal femoral medial hemiepiphyseal stapling (or both). Typically, this allows for rapid correction of any residual deformity. I try to avoid corrective osteotomy because this may induce the same genu valgum deformity that followed the initial fracture.
Other Pathologic Genu Valgum Deformities
Metabolic Disorders
Metabolic causes of pathologic genu valgum include vitamin D–resistant rickets, nutritional rickets, and renal osteodystrophy. These disorders are more likely to produce genu valgum rather than genu varum. This is due to their later onset, at which time the physiologic valgus alignment of the knee has already been achieved. Renal osteodystrophy is the most common metabolic disorder producing genu valgum (12,19,32,62,75,81,132,143,210). Oppenheim et al. (210) described changes in the lateral proximal tibial epiphysis and metaphysis in children with renal osteodystrophy similar to those seen in the medial proximal tibia in Blount’s disease.
Treatment is generally initiated after correction of the underlying metabolic disorder. Treatment before that time has a high incidence of recurrence. After the metabolic condition has been controlled, treatment may be by either osteotomy or physeal stapling of the distal femur or proximal tibia. The latter is a particularly effective method, provided there is sufficient remaining growth (Fig. 169.16).
Figure 169.16. A: Preoperative standing radiograph of a 15-year-old boy 2 years after renal transplantation. His genu valgum has not been improving, although the physes now appear normal. B: Postoperative radiograph after insertion of staples about the medial aspect of the distal femoral epiphyses. C: Standing radiograph at 18 months postoperatively and 9 months after staple removal demonstrates physiologic alignment and no evidence of growth disturbance.
Trauma
Injuries to and about the distal femoral or proximal tibial epiphyses is a common cause of genu valgum (142,233). The deformities are progressive and require surgical treatment if there is an asymmetric physeal bar or bridge. The extent of the bar can be assessed by tomography or, preferably, MRI. Treatment options consist of physeal bar excision and grafting with fat or Silastic (Langenskiöld [169] procedure), together with a corrective osteotomy. If the bar is extensive, then complete physeal closure and corrective osteotomy may be performed, with delayed management of the leg-length discrepancy (see Chapter 164).
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Neuromuscular
Ambulatory children with neuromuscular disorders, such as cerebral palsy, often have a pes valgus and excessive external tibial torsion that may produce a progressive genu valgum. This is more likely to be a torsional malalignment than a true genu valgum deformity. Treatment may involve soft-tissue releases to restore muscle balance and osteotomies to correct torsional and angular deformities (see Chapter 177).
Infection/Osteomyelitis
Osteomyelitis may cause genu valgum directly by damaging the physis or producing a reactive hyperemia and asymmetric growth stimulation. Asymmetric physeal arrest is managed similarly to trauma (see Chapter 176).
Skeletal Dysplasia
Genu valgum will occur in children with skeletal dysplasia, including multiple epiphyseal dysplasia, spondyloepiphyseal dysplasia, metaphyseal dysplasia, and pseudoachondroplasia. Treatment is based on the diagnosis. Orthotic management is usually ineffective in skeletal dysplasia. Surgery with either stapling or corrective osteotomies is usually necessary (Fig. 169.17) (see Chapter 180).
Figure 169.17. A: Preoperative standing radiograph of a 13-year-old boy with spondyloepiphyseal dysplasia and severe genu valgum. B: Intraoperative radiograph after closing-wedge distal femoral osteotomies. Staples were used to maintain alignment. C: Standing radiograph 3 years postoperatively demonstrates that normal alignment is being maintained. Note the proximal migration of the staples with growth.
Inflammatory Disorders
Juvenile rheumatoid arthritis may produce a progressive genu valgum deformity, but
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this is uncommon. Correction can be achieved by physeal stapling (240). In older children and adolescents, an osteotomy may be necessary.
CONGENITAL ANGULATION DEFORMITIES OF THE TIBIA AND FIBULA
Congenital angular deformities of the tibia and fibula are uncommon (Table 169.3). Anterior and anterolateral angulation or bowing is the most common form and is usually associated with other congenital anomalies, such as congenital pseudarthrosis (8,11,15,120,125,135,165,200,212,231). Congenital posteromedial angulation is less common, resolves spontaneously, and is not associated with significant osseus pathology other than residual lower-extremity length inequality.
CONGENITAL ANTEROLATERAL BOWING OF THE TIBIA: CONGENITAL PSEUDARTHROSIS
Anterolateral bowing of the tibia is usually associated with significant pathologic disorders (Table 169.3). The most common are congenital pseudarthrosis of the tibia, congenital longitudinal deficiency of the tibia (paraxial tibial hemimelia), and congenital longitudinal deficiency of the fibula (paraxial fibular hemimelia) (see Chapter 174).
Congenital pseudarthrosis of the tibia is a rare congenital malformation that includes all congenital fractures of the tibia and pseudarthrosis of the tibia arising after pathologic fracture in a tibia with congenital anterolateral angulation (4). Usually, anterior or anterolateral bowing of the tibia is recognized shortly after birth. Only occasionally are the fracture and pseudarthrosis present at birth, and the pseudarthrosis is therefore not truly congenital. Its incidence has been estimated to be 1 in 190,000 live births (149). The left side is affected slightly more often than the right (270); bilateral involvement is rare. Beals and Fraser (24,106) reported cases with bilateral and familial involvement. Congenital pseudarthrosis of the tibia is one of the most difficult and challenging deformities confronting orthopaedic surgeons (120,213,270).
Pathophysiology
The exact cause of congenital pseudarthrosis of the tibia is unknown (43,49,52). Between 40% and 80% of children with this disorder are ultimately diagnosed with neurofibromatosis (5,49,52,56,74,186,203,213,214,262). Others have fibrous dysplasia or no associated disorders. Brown et al. (52), in a study of 17 children with a congenital pseudarthrosis, found that eight had neurofibromatosis, three had fibrous dysplasia, and six had no apparent disorder. Despite the clinical association with neurofibromatosis, the cause remains obscure.
Biopsy material removed from the tibia in the area of the pseudarthrosis shows a dense, cellular, fibrous connective tissue with variable areas of cartilage formation (43,49,52,114). Electron microscopy reveals the lack of a basement membrane, and the cells resemble fibroblasts rather than Schwann cells or perineural cells, even in children with known neurofibromatosis (49). Only rarely is neurofibromatosis tissue observed in these specimens, and these samples are usually from intraosseous neurofibromas (114). In some cases, the tissue does resemble fibrous dysplasia (42). This dense, fibrous connective tissue with fibrocartilage and occasional bone trabeculae fills a poorly vascularized gap between the sclerotic bone ends to create the nonunion. This is not a true pseudarthrosis. The defective tissue occurs within the bone itself, the periosteum, the surrounding soft tissue, and possibly in the nerve and vascular supply to the involved area.
Assessment, Indications, and Relative Results
An infant predisposed to congenital pseudarthrosis of the tibia characteristically presents with anterior or anterolateral bowing of the tibia (Fig. 169.18). This rarely occurs
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in conjunction with an acute fracture. The bowing is rarely anteromedial. The angular deformity of the tibia is congenital. Unless there is a fracture, the area is not tender, and a bony prominence is palpable. With an acute fracture, the area is unstable and is usually painful.
Figure 169.18. A: Photograph of a 3-month-old girl with anterolateral bowing of the left tibia shows numerous café-au-lait spots involving the left lower extremity. B: Lateral view shows anterior bowing of the tibia. C: On the posterior view, observe the café-au-lait spots. D: AP radiographs of the lower extremities demonstrate anterolateral bowing of the left tibia. The central portion of the tibia is sclerotic, and there is thinning of the fibula. This indicates a congenital prepseudarthrosis. E: Lateral radiograph demonstrates marked anterior bowing of the tibia. The apical sclerosis is more easily visualized in this view.
Because of the high incidence of neurofibromatosis in these patients, the hallmarks of this disease must be sought. The criteria used by Crawford (73) for diagnosis required at least two of the following:
Multiple café-au-lait spots
Positive family history
Definitive biopsy
Characteristic bony lesions, such as pseudarthrosis of the tibia, hemihypertrophy, or a short, sharply angulated spinal curvature
Café-au-lait spots are typically smooth-edged. The presence of at least five spots measuring more than 0.5 cm in diameter is considered diagnostic. The number of spots increases with the patient’s age. Subcutaneous nodules (i.e., fibroma molluscum) are uncommon until adolescence and are typical of chronic disease. Although other bones may be involved in neurofibromatosis, involvement of more than one bone is extremely rare. Isolated cases of congenital pseudarthrosis of the fibula with an intact tibia have been reported (79,92,170). They were usually associated with anterior bowing of the tibia and ankle valgus. Curly and overlapping toes have been reported, as well as congenital constriction bands (201,271).
In children younger than 2 years presenting with anterior or anterolateral bowing of the tibia, there may be no clinical evidence of neurofibromatosis. The clinical features of neurofibromatosis usually become more apparent with growth and development. Radiographs of the tibia before the establishment of a pseudarthrosis may show an intact bowed tibia exhibiting sclerosis in the area of angulation without a medullary canal. After a fracture has occurred and a pseudarthrosis has been established, the proximal and the distal ends of the fracture site become tapered. Both tapered bone ends remain sclerotic.
Classification
Many classifications of pseudarthrosis have been based on the prognosis for various radiographic types (6,7,15,20,40,73,125,186,270). The classification by Boyd (40) is one of the most commonly used methods of assessment (Table 169.7). Crawford (73) proposed a four-group functional classification:
Table 169.7. Boyd Classification of Congenital Pseudarthrosis
Type I Anterolateral bow with a normal medullary canal
Type II Anterolateral bow with a narrow, sclerotic medullary canal (Fig. 169.19 )
Figure 169.19. A: AP radiograph of a 5-year-old boy with neurofibromatosis with a type II lesion of the left tibia. He has been managed in an ankle–foot orthosis since he began ambulation, and he has not had a fracture. B: Lateral radiograph demonstrates the apical sclerosis, which has been slowly improving.
Type III Anterior bow with a cystic lesion
Type IV Anterolateral bow with a fracture, cyst, or frank pseudarthrosis (Fig. 169.20 )
Figure 169.20. A: AP radiograph of a 3-month-old child with a type IV congenital pseudarthrosis of the left tibia. Notice the cystic lesion and fracture. There is thinning of the distal aspect of the fibula. B: Lateral radiograph demonstrates anterior bowing.
The type of radiographic deformity is related to the recommended treatment. In Crawford’s classification, a type I lesion has the best prognosis, and the remaining three types have progressively worse prognoses. However, the relation between the type of pseudarthrosis and the clinical result is not always predictable (4,73,183,198). The presence or absence of established neurofibromatosis makes no difference in the classification and is not a factor in determining treatment or prognosis. Cases in which bone-end resorption and sclerosis are evident radiographically and bone graft rapidly resorbs postoperatively have a poor prognosis. Those with a cystic lesion have a more favorable prognosis (198).
The natural history of anterior or anterolateral bowing of the tibia secondary to neurofibromatosis or fibrous dysplasia is a fracture with the establishment of a pseudarthrosis. The treatment of anterior and anterolateral bowing with an intact tibia is directed toward prevention
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of the fracture and pseudarthrosis. Congenital pseudarthrosis of the tibia is more than a mechanical problem (199); it represents a complex biologic problem because the established pseudarthrosis is extremely difficult to manage.
Preoperative Management and Planning
Patients with anterior or anterolateral bowing of the tibia without pseudarthrosis are best treated initially with a total-contact plastic orthosis. This is usually an ankle–foot orthosis. Prophylactic treatment may delay or prevent a fracture and subsequent pseudarthrosis. These orthoses are worn for years. With growth and in the absence of a fracture, the tibial bowing usually improves. There is typically some residual shortening within the bone. The medullary canal develops slowly over 5–10 years. It is possible, although unlikely, that a fracture and pseudarthrosis can be avoided with the use of an orthosis alone. If the tibia has straightened sufficiently, the medullary canal has reconstituted, and there is adequate cortical thickness, the orthosis may be discontinued as skeletal maturity is approached. Vigorous physical activities should be avoided. There are no long-term reports of successful orthotic management in adolescents or adults.
After a pathologic fracture and pseudarthrosis have occurred, the treatment is usually surgical. Casting alone rarely results in healing. However, Roach et al. (234) demonstrated that a late-onset fracture in a dysplastic tibia may heal with prolonged immobilization. Six of 11 fractures healed, but four of the six had a residual anterior bow susceptible to a stress fracture.
Operative Techniques
The indication for surgical management is an established pseudarthrosis. The goals of treatment include obtaining union at the pseudarthrosis site, maintaining union throughout growth and development, and obtaining an acceptable limb length at maturity (213,278). Previously, surgery was advised only for children age 4 years or older (6,125,203). Most physicians now recommend early surgical intervention and revision if the first procedure does not result in union of the pseudarthrosis (186,199,213,214). Morrissey et al. (199) reported that a good result did not occur in any child whose tibia was not united by 6 years of age. Masserman et al. (186) reported that union was more related to the pathologic process than the age at surgery. Earlier union produces more normal growth of the distal tibial epiphysis and less lower-extremity length discrepancy.
The current methods of surgical treatment include bone grafting alone, bone grafting and internal fixation, electrical stimulation, microvascular bone grafting, Ilizarov external fixation methods, and amputation.
Bone Grafting Alone
Prophylactic bone grafting has been used for the deformed tibia before a pathologic fracture occurs (179,191,266,270). This was thought to strengthen the deformed area and decrease the risk for pathologic fracture. The technique described by McFarland (191) is the most common procedure. A long corticocancellous graft from the opposite tibia is placed posteriorly, spanning the deformity in the normal biomechanical longitudinal axis of weight bearing. Lloyd-Roberts and Shaw (179), however, reported success in only three of their seven patients, while Tachdjian (270) reported success in all five children. Recently, Strong and Wong-Chung (266) prevented fracture in six of nine children with a prepseudarthrosis secondary to neurofibromatosis. Paterson (213), however, felt that the procedure was indicated primarily for cystic prepseudoarthrosis. Tachdjian (270) suggested concomitant curettage and bone grafting of any cystic lesions.
Many possible bone-grafting procedures have been used to treat an established congenital pseudarthrosis of the tibia (41,42 and 43,98,100,191,225,228). Morrissey et al. (199) reviewed 167 operations performed in 40 patients. The Farmer procedure, using a composite bone graft from the opposite tibia, demonstrated the best result, with a success rate of 53% (100). Other procedures had lower success rates, including onlay grafts (13%), bypass grafts (7%), Sofield procedure (25%), sliding grafts (33%), bone allograft (17%), and autogenous grafts (10%).
Bone Grafting and Internal Fixation
Surgical excision of the pseudarthrosis, correction of the angular deformity of the tibia, and rigid internal fixation in addition to bone grafting have improved the rate of primary union. Stabilization has been achieved with compression plates and intramedullary rods. The former is rarely used because of difficulties involved in achieving adequate fixation (6,213). The most common methods at this time are tibial or dual tibial and fibular intramedullary rods. These techniques usually transfix the ankle and subtalar joints to adequately stabilize the distal tibial segment (4,9,17,63,108,278). These joints are progressively freed with growth of the tibia and proximal migration of the rod. This method does not result in significant stiffness of the joints. Postoperatively, immobilize with a unilateral hip spica cast followed by a long-leg cast and then a knee–ankle–foot orthosis. Anderson et al. (9) reported that 10 of 13 pseudarthroses healed with an intramedullary rod technique. However, their mean follow-up time was short (6.9 years).
Several researchers used extending intramedullary rods and bone grafting (e.g., double cortical onlay, cancellous) (31,102). These rods extended with growth, decreasing the need for revision surgery and protecting the union until skeletal maturity. They were not inserted across the ankle or subtalar joint. Bitan et al. (31) reported satisfactory
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extension of the rods in four of seven patients when these rods were used in revision surgery after primary union. Fern et al. (102) recommended that the outer sleeve of an extendable rod be inserted across the pseudarthrosis site to provide more strength and decrease the risk of refracture. They reported primary union in all five patients in whom extendable rods and bone grafting were used. All rods expanded with growth up to a maximum of 6.4 cm.
The use of intramedullary rods, especially those that stabilize the hind foot, and cancellous bone grafting increases the rate of primary union. The correction of anterior or anterolateral bowing undoubtedly enhances healing by allowing compression across the pseudarthrosis. These rods are not removed until after skeletal maturity because the tibia may undergo progressive bowing or refracture.
Electrical Stimulation
Electrical stimulation has been used in the treatment of congenital pseudarthrosis of the tibia for the past two decades (20,48,164,214,215,251,267). The various techniques include implanted direct-current bone growth stimulators and external stimulation devices with pulsating electromagnetic fields. The addition of electrical stimulation has improved success rates after bone-grafting procedures (213,214). Most reports recommend that electrical stimulation be used in conjunction with internal fixation and bone grafting. In 1982, Kort et al. (164) observed that the most important variable in healing was the radiographic morphology of the nonunion. Patients with spindled bone ends, a large gap, and gross mobility had a poor prognosis, whereas those with a cystic or sclerotic transverse fracture and a gap of less than 5 mm had better responses.
Paterson and Simonis (214) described a technique of excision of the pseudarthrosis and abnormal tissue, fibular osteotomy, intramedullary rod fixation (i.e., large Steinmann pin or Kuntscher nail), cancellous bone grafting, and an implanted direct-current electrical bone growth stimulator. The leg was protected in a long-leg plaster cast until clinical and radiographic healing was achieved. Weight bearing was allowed and encouraged. They reported primary union in 20 (74%) of 27 patients. The average time for union was 7.2 months (range, 3–18 months). During a mean follow-up period of 3.8 years (range, 6 months to 10 years), no refractures were reported. The reasons for failure in seven patients included inadequate correction of the anterior tibial bowing, poor internal fixation, incorrect placement of the cathode, and extensively diseased bone. Brighton et al. (48) reported that only one of four patients with congenital pseudarthrosis of the tibia healed with direct-current stimulation from an implanted single cathode. However, they did not excise abnormal tissue, provide internal fixation, or use bone grafting. The extremities were immobilized in a plaster cast, and weight bearing was not allowed. They thought that the results did not prove the efficacy of this technique for congenital pseudarthrosis of the tibia.
In 1981, Bassett et al. (20) reported the results in 34 patients with congenital pseudarthrosis of the tibia treated with pulsed electromagnetic fields (PEMFs) by way of external coils. They reported that 17 of 34 patients achieved complete healing with reconstitution of the medullary canal. An additional seven (21%) patients achieved union with function but required continued protection with an orthosis. Healing of the pseudarthrosis occurred in 24 (71%) of 34 patients. Analysis of the failures demonstrated that most occurred in male patients with a history of early fracture (younger than 1 year) and with an atrophic, spindled, hypermobile pseudarthrosis. The researchers did not employ any additional surgical procedures in the initial treatment. However, after early healing was demonstrated radiographically, surgical realignment, immobilization, and bone grafting were combined with the PEMFs. This did not have an adverse affect on the ultimate outcome. In 1982, Sutcliffe and Goldberg (267) reported the results of 49 patients treated for congenital pseudarthrosis of the tibia with PEMFs. The definite end point of treatment was reached in 37 patients, and in 26 (70%) of them there was a successful outcome. Fifteen pseudarthroses healed with PEMFs alone. The remaining 11 patients required subsequent surgery, usually cancellous bone grafting, and a second course of PEMFs before healing was obtained.
It appears that electrical stimulation may help induce bone formation in the area of a pseudarthrosis and abnormal tissue. Electrical stimulation alone is effective in approximately 50% of the successful cases. In the remainder, additional procedures are necessary before primary union can be achieved, including excision of the pseudarthrosis and abnormal tissue, correction of existing deformity, intramedullary fixation, and cancellous bone grafting. However, in approximately 30% of cases, electrical stimulation with or without surgical intervention results in failure. The incidence of refracture appears to be low.
Microvascular Bone Graft
Free vascularized bone grafts represent another popular procedure for congenital pseudarthrosis of the tibia (64,68,84,85,93,108,112,121,154,175,196,219,220,259,272,277,284,285,295). Vascularized rib, iliac crest, and fibula grafts have been used, and the latter appears to be superior in congenital pseudarthrosis of the tibia (64,68,84,85,92,108,121,154,175,219,220,284,285). The graft can be ipsilateral if it is of sufficient size (68,196,259,295). The procedure consists of transferring the contralateral fibular diaphysis on its vascular pedicle with a cuff of muscle to maintain the periosteal blood supply into a defect created by resecting the pseudarthrosis and abnormal soft tissue on the involved side (Fig. 169.21). Supplemental cancellous bone
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grafting may be included to facilitate bone healing. The fibular graft is advantageous because it is straight, a long segment can be harvested, and it tends to hypertrophy after healing. Leung (175) reported three successful microvascularized iliac crest grafts in congenital pseudarthrosis of the tibia. He thought that it was easier to harvest the iliac crest and there was a more rapid healing because the graft was predominantly corticocancellous bone rather than cortical bone alone. Iliac crest grafts ranging from 3 to 10 cm may be obtained in children age 4 years or older. Rib grafts are less advantageous because of their curvature. Hagan and Buncke (121) reported that this curvature does not tend to correct with growth after satisfactory incorporation and the curvature may increase. Use of extensive corticocancellous grafting may prevent progressive bowing of the vascularized rib graft. Donor site problems after vascularized fibula transfers have been reported (209).
Figure 169.21. A: AP radiograph of the right lower leg of a 6-month-old boy with neurofibromatosis and a congenital pseudarthrosis of the distal tibia. B: Lateral radiograph. C: A procedure using a vascularized fibula graft from the left leg was performed at 17 months of age. Internal fixation was not used, and the ends of the fibula graft were inserted into the medullary canal proximally and into the metaphysis distally. D: Lateral radiograph. E: Two months after vascularized-fibula grafting, there is extensive subperiosteal new bone formation and hypertrophy of the graft. F: Lateral radiograph. G: Twenty-two months later, the tibia is healed, but the leg is protected in a knee–ankle–foot orthosis. H,I: Thirty-three months postoperatively, the tibia has healed well, and the medullary canal is reforming in the area of the vascularized fibula.
In 1990, Weiland et al. (285) reported on the long-term results in 19 consecutive children with congenital pseudarthrosis of the tibia treated with a vascularized fibula graft. The mean age at surgery was 5.1 years (range, 1.4–11.4 years). The mean follow-up was 6.3 years (range, 2–11 years). They reported that 18 (95%) of the 19 pseudarthroses healed. The lower-extremity length discrepancy at follow-up was a mean of 1.6 cm (range, 0–4 cm). Sixteen of the children had been treated with electrical stimulation techniques, which failed, for at least 1 year before surgery. However, the fibular graft hypertrophied rapidly, and no graft fractured during follow-up. Five patients required secondary procedures for nonunion and angulation. Only one child failed and subsequently required an amputation. Four patients ultimately achieved healing, although they required nine bone-grafting procedures. Two children had fractures through normal bone distal to the vascularized bone graft; they also required bone-grafting procedures to achieve union. Morbidity of the donor site was minimal, but one patient sustained a nondisplaced fracture of the tibia through a screw hole, and a 20° valgus deformity requiring osteotomy developed in another. Thirteen tibiae had residual deformity: valgus deformity (five patients); anterior angulation (two patients), or both (six patients). The mean valgus deformity was 25° (range, 5° to 45°), and the mean anterior angulation was 24° (range, 10° to 30°). Two patients with a valgus deformity required correction with an osteotomy. Four patients had anterior bowing of more than 20°, but none required additional surgery. All children
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were treated with orthoses until skeletal maturity was achieved.
The five basic steps of free vascularized bone grafts are applicable whether iliac crest or fibula graft is used (220):
  • Harvest of the vascularized bone with an intact vascular pedicle
  • Excision of the tibial pseudarthrosis and abnormal tissue
  • Fixation of the vascularized bone in situ
  • Microvascular anastomosis
  • Skin closure
The procedure is usually performed with two surgical teams. One team harvests the vascularized bone, and the second prepares the recipient site. Some form of internal fixation is usually necessary to maintain alignment of the extremity. One advantage of microvascularized bone grafts is the simultaneous correction of any residual deformity and possible tibial lengthening, depending on the mobility of the tibial segments. Prolonged immobilization is necessary until healing occurs, with protected weight bearing allowed thereafter. Weiland et al. (285) maintain their children in hip spica casts for 2–3 months to allow healing. After healing occurs, protected weight bearing with a knee–ankle–foot orthosis is allowed. The orthosis is worn until skeletal maturity (see Chapter 36).
Ilizarov Fixation System
The Ilizarov method has been shown to be effective in achieving union at the pseudarthrosis site and in simultaneously correcting any associated angular deformity and lengthening of the tibia to restore length (85,99,119,144,211,224). The apparatus can be used in four ways: compression of the pseudarthrosis, compression with metaphyseal tibial lengthening, compression followed by distraction for hypertrophic nonunion, and distraction alone for hypertrophic nonunion. Excellent short-term results for union were reported. Whether the union is maintained in the long term remains uncertain.
Amputation
In children with persistent congenital pseudarthrosis of the tibia after previous surgical procedures, an amputation may be advised. This should be a Boyd or Symes ankle-disarticulation amputation of the foot (82,134,149,189). See Chapter 175 on principles of pediatric amputation and Chapter 120 and Chapter 122 on lower-extremity amputations and prostheses. Amputation with appropriate prosthetic fitting allows rapid rehabilitation and return to normal function. McCarthy (189) recommended amputation for several criteria: failure to achieve bony union after three surgical attempts, a significant lower-extremity length inequality (usually 5 cm or greater), development of a deformed foot, undue functional loss from prolonged hospitalizations, and high medical costs.
The Boyd or Symes amputation is usually the procedure of choice. It preserves the heel pad and distal tibial epiphysis, which allows end bearing on the stump. The bone and skin are lengthened as a unit to avoid problems with overgrowth (82). A below-knee amputation through the pseudarthrosis produces a poor end-bearing stump for ambulation. The abnormal tissue and previous surgical scar provides poor skin coverage and predisposes to breakdown. There are also the problems of overgrowth and frequent revision. Amputation above the pseudarthrosis site provides better skin coverage, but there are problems with bony overgrowth.
Jacobsen et al. (149) reported the results of Symes amputation in eight children with pseudarthrosis of the tibia. The average age at amputation was 8.2 years, and the mean follow-up was 5.9 years. These children had a mean of 3.8 surgical procedures performed before amputation. None of the pseudarthroses healed, but with an appropriate Symes prosthesis, the children were able to engage in normal activities, including sports. The lower-extremity length inequality and some of the angular deformity were corrected within the prosthesis. Herring et al. (134) reported that 21 children (none with congenital pseudarthrosis) who had 23 Symes amputations had better psychological functioning than children undergoing multiple corrective surgical procedures. The better psychological function correlated with their better orthopaedic function. The level of family stress influenced the child’s behavior, self-perception, and intelligence. The physicians thought that an early Symes amputation in a young patient was compatible with good athletic and psychological functioning, which closely approached that of a nonhandicapped child of the same age. Similar results were reported by Davidson and Bohne (82) for 23 children, including one with a congenital pseudarthrosis of the tibia that did not heal.
Because of the complexities associated with the treatment of pseudarthrosis of the tibia, it is recommended that Symes amputation be discussed as an alternative method of treatment with the parents and child from the outset. Discussion should not be delayed until later in the treatment. Tell the family of the difficulties that will be encountered in attempting to obtain primary tibial union and satisfactory function.
General Rehabilitation and Postoperative Principles
Each surgical procedure has its specific postoperative regimen, but all share long-term orthotic management. The extremity needs to be protected with a plastic ankle–foot orthosis. This helps prevent recurrent refracture. Protection is required at least until skeletal maturity and perhaps even longer. This decision is based on the radiographic appearance of the tibia, the degree of residual deformity,
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and the presence or absence of a reconstituted medullary canal.
Rehabilitation to restore maximum strength and function after healing of a congenital pseudoarthrosis of the tibia is very important. Karol et al. (156) recently performed gait analysis on 12 patients with healed lesions and four patients treated by amputation. Gait and muscle strength were markedly disturbed. Early onset of fracture, early surgery, and transankle fixation lead to an inefficient gait compared with that of amputees.
Complications
Congenital pseudarthrosis of the tibia is a difficult and challenging deformity. Refracture, tibial and lower-extremity length discrepancy, stiffness of the ankle and subtalar joints, progressive anterior angulation of the tibia, and ankle valgus are the major complications (270,285). Surgical complications are also common. Most children have had multiple surgical procedures and are at risk for infection and neurovascular injury. Because of these problems, the true outcome of a congenital pseudarthrosis cannot be fully assessed until skeletal maturity. Crossett et al. (74) found that the clinical results for their patients remained stable after skeletal maturity. Neurofibromatosis does not increase the incidence of complications or adversely affect the final clinical result (198).
Conclusion
Probably, the most important aspect of the management of children with congenital pseudarthrosis of the tibia is to minimize the number of operative procedures and to maintain as normal function as possible. Prevention of fractures in children with prepseudarthrosis lesions is critically important. This can sometimes be achieved with a clamshell ankle–foot orthosis. After a pseudarthrosis is established, the best results with respect to union are achieved with a vascularized fibula graft or intramedullary rod. I feel that the initial surgical procedure should be the latter. This allows straightening of the tibia, with weight bearing providing compression across the pseudarthrosis. The results of a vascularized fibula transfer are also good, but I am concerned about a major operative procedure on the uninvolved extremity. Once it is apparent that a pseudarthrosis cannot be satisfactorily healed, Symes amputation and prosthetic replacement permit restoration of relatively normal function.
CONGENITAL POSTEROMEDIAL ANGULATION OF THE TIBIA AND FIBULA
Pathophysiology
The cause of congenital posteromedial angulation of the tibia and fibula is unknown. There is some evidence to indicate a primary chondro-osseous defect in the embryologic development of the distal tibial and fibular epiphyses (138,212). Pappas (212) demonstrated delayed development of the secondary center of ossification of the distal tibia and a relative reduction in the height of the distal epiphysis. Other possibilities include intrauterine fracture of the tibia and fibula with malunion, restriction of growth from soft-tissue contractures, or intrauterine malpositioning with the affected leg molded under the buttock (15,83,107,165).
Assessment, Indications, and Relative Results
Congenital posteromedial angulation of the tibia and fibula has three associated clinical problems (120,135,136,194,212,231,236):
Angular deformity
Calcaneovalgus foot
Lower-extremity length inequality
The tibia and fibula are shortened and bowed posteriorly and medially at the junction of the middle and distal thirds of their shafts. The deformity, which is obvious at birth, is usually unilateral. The right and left sides are equally affected, and there is no sex predilection (138). Infants are typically normal, and there is no increased incidence of other congenital anomalies (288). Hofmann and Wenger (138) reported on a child who had a contralateral talipes equinovarus (clubfoot) deformity. Angulation can vary from 25° to 65°, with the magnitude of deformity in the posterior and medial directions being almost equal (241). The foot is hyperdorsiflexed and has a marked calcaneovalgus posture. It appears to fit into the anterior cavity of the lower leg. The anterior compartment muscles appear shortened and limit plantar flexion of the foot. The posterior bow of the shaft causes the distal portion of the tibia and fibula at the ankle to angulate anteriorly. This makes the limitation of plantar flexion seem even more severe. There is no true bone deformity of the ankle or foot. The calf musculature is usually slightly atrophic, and the foot is smaller than on the opposite, normal side (8,138). There may be a dimple at the apex of the posteromedial angulation (8,53,135,138,212). Occasionally, an extra skin crease is associated with the dimple (212).
Anteroposterior and lateral radiographs of the lower extremities of an affected child are necessary for complete assessment. The proximal aspects of the tibia and fibula, including their epiphyses, are normal. The degree of posteromedial angulation of the distal aspect of the tibia and fibula can be measured directly from the radiographs. The cortices in the concave aspect of the posterior and medial bows are thickened, and the distal aspects of the tibia and fibula are broader than the opposite, uninvolved side (212). The intramedullary cavities at the apex of the bowing are usually poorly developed or obliterated by sclerotic bone. The alignment of the tarsal and metatarsal bones is relatively normal, although occasionally there may be a
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slight valgus orientation. Radiographs of the femora and pelvis should be obtained for thorough assessment of the lower extremities. Special diagnostic studies, such as MRI, are rarely indicated.
The posteromedial angulation or bowing resolves with growth, especially during the first 3 years of life (Fig. 169.22). The posterior bowing resolves more quickly than the medial bowing, which may not resolve until 5 years of age (120,212). However, the associated shortening of the tibia and fibula, which is unrelated to the bowing, persists and progresses during growth (8,138,212,288). The fibula is frequently slightly shorter than the tibia; there is usually no shortening in the femur. The mean growth inhibition in the involved tibia and fibula averages 12% to 13% (range, 5% to 27%). This percentage of growth inhibition persists throughout growth and development. There appears to be a direct correlation between the degree of tibial shortening and the degree of posteromedial angulation: The greater the angulation, the more severe is the lower-extremity length discrepancy (135,136,138,165). The mean tibial length difference is approximately 1.2 cm in the first 2 months of life, 2.4 cm by 5 years of age, 3.3 cm at 10 years, and 4.1 cm (range, 3.3–6.9 cm) at maturity (138,212). It is possible to determine the percentage of inhibition and the ultimate leg-length inequality by annual scanographic evaluation and bone-age determination after the posteromedial angulation has resolved. During the first 6 months of life, correction of the bowing is rapid, and by 2 years of age approximately 50% of the angulation has undergone spontaneous correction. After 3 years of age, improvement in the deformity occurs at a much slower rate.
Figure 169.22. A: Clinical photograph of a 1-month-old boy with congenital posteromedial bowing of the left tibia. Observe the medial bowing of the distal aspect of the tibia. B: The posterior bow of the distal tibia produces a calcaneovalgus appearance of the left foot. C: AP radiograph of the left leg confirms the severe medial bowing of the distal third of the tibia and fibula. D: Lateral radiograph demonstrates the posterior bowing and the calcaneovalgus appearance to the foot. The alignment of the foot is due to the dorsal angulation of the distal tibia and ankle. E: AP radiograph obtained at 1 year demonstrates decreased medial angulation of the distal tibia. F: Lateral radiograph shows a significant decrease in the posterior bow of the tibia and improved alignment of the ankle joint. G: Clinical photograph at 2 years of age shows marked improvement in the appearance of the left lower leg. H: There is only slight residual posterior angulation of the tibia in the sagittal plane. I: AP radiograph at 2 years of age shows further improvement in the medial angulation of the distal tibia. J: Lateral radiograph confirms further improvement in posterior angulation.
The appearance of the foot gradually improves with growth and development. As the posterior bowing decreases, the degree of plantar flexion improves. A pes planovalgus appearance of the foot may persist. Hofmann and Wenger (138) found mild loss of ankle dorsiflexion in older children. They thought that this was due to mild equinus contracture from toe-walking to compensate for the length discrepancy. It may also be due to the slightly shorter fibula.
Preoperative Management
Because posteromedial angulation of the tibia and fibula in children undergoes spontaneous resolution, treatment is predominantly conservative. In newborn and young infants, passive stretching exercises of the hyperdorsiflexed foot may be performed to stretch the anterior compartment muscles and improve plantar flexion. It is important to assess maximal plantar flexion of the foot on a lateral radiograph because of the anterior angulation of the distal tibia, fibula, and ankle joint. What appears to be limited plantar flexion may only be secondary to the anterior tilt to the articular surface of the distal tibia. The talus may be in full plantar flexion in the ankle mortise, but the foot still may not appear plantigrade.
In selected cases, use serial short-leg casts to hold the foot in maximal plantar flexion and inversion (83,194,231,288). In 3–6 weeks, maximal stretching of the anterior compartment musculature and anterior ankle capsule is usually achieved. Yadav and Thomas (288) reported that six children with a unilateral posteromedial bow of the tibia did well with serial casting, although one patient underwent an anterior soft-tissue release before initiation of casting. After complete correction has been obtained, passive exercises may be continued to maintain alignment. In severe cases, Tachdjian (269) recommended the use of night splints to hold the foot in plantar flexion and inversion. After 2–3 years of age, a University of California Biomechanics Laboratory or similar foot orthosis may be worn to support the planovalgus foot deformity. However, in view of the natural history and management of posteromedial bowing, the use of casts and orthoses is probably not indicated. Heyman and Herndon (135) initially thought that an orthosis was necessary to reduce the posterior thrust at the apex of the deformity during weight bearing. However, in their later report, they stated that the use of an orthosis was unnecessary (136).
Follow children with posteromedial angulation of the tibia and fibula with annual scanograms and bone-age determinations (10,118,200) (see Chapter 170 on leg-length inequality).
Operative Techniques
Typically, there are only two operative procedures utilized in this disorder:
  • Osteotomy to correct severe or persistent angulation
  • Equalization of lower-extremity length inequality
Tibia and Fibula Osteotomy
Osteotomy to correct posteromedial bowing of the tibia is rarely indicated. If severe medial bowing persists after 3 or 4 years of age, corrective osteotomy may be considered. Bone healing is not a problem after a corrective osteotomy or a fracture because there is no underlying bone disorder affecting healing (8,83,165,231). Hofmann and Wenger (138) suggested corrective osteotomy in cases of severe bowing with progressive shortening during the first 5 years of life. They thought that an osteotomy would add length by correcting the deformity and realigning the physes perpendicular to the axis of weight bearing, stimulating growth. These concepts were not confirmed clinically. Osteotomy can realign the tibia, but it has a minimal effect on the ultimate lower-extremity length inequality. Krida (165) reported that all three patients treated by corrective osteotomies had significant residual leg-length discrepancies.
Leg-length Equalization
Lower-extremity length discrepancy is the most common sequela of posteromedial
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angulation of the tibia and fibula. Most affected children have enough inequality (2 cm) to require equalization. The procedure performed to equalize the leg length depends on the estimated tibial length inequality at maturity and the predicted normal height of the child (see Chapter 170).
Conclusion
In patients with posteromedial angulation of the tibia, I prefer prolonged observation. Casting of the foot is rarely indicated, as the limitation of dorsiflexion is due primarily to the alignment of the ankle. This will correct with growth. The associated lower-extremity length inequality is followed by scanograms at 1- or 2-year intervals. An appropriately timed contralateral percutaneous proximal tibial and fibular epiphysiodesis is the procedure of choice for most patients. Leg-lengthening techniques are usually not necessary, unless the discrepancy is severe or the patient has short stature.
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