Chapman’s Orthopaedic Surgery
3rd Edition

CHAPTER 158
SPINAL SURGERY IN CONGENITAL SYNDROMES
Paul D. Sponseller
P. D. Sponseller: Department of Pediatric Orthopaedics, Johns Hopkins Hospital School of Medicine, Baltimore, Maryland, 21287.
The development of the spine may be upset by abnormalities of connective tissue, muscle balance, or ossification. Although a congenital syndrome is by definition present at birth, an associated spinal deformity in most cases is not. It may develop with growth as a result of bone dysplasia, a connective tissue disorder, or miscellaneous chromosomal abnormalities. The orthopaedic surgeon must understand the natural history of these growth disturbances to determine when, as well as how, to intervene. Three factors should always be kept in mind when evaluating the patient with a congenital syndrome: (a) coexisting medical problems, (b) characteristics of bone shape and quality, and (c) the effect of the syndrome on the neural elements.
CERVICAL SPINE ABNORMALITIES
The cervical spine in many congenital syndromes is vulnerable to deformity, stenosis, and, most important, instability. The surgical team must rule out or characterize the potentially unstable cervical spine before general anesthesia is administered or any skeletal surgery is performed. Plain film radiography with or without flexion–extension may be helpful. Table 158.1 lists characteristic cervical spine problems in most common congenital syndromes.
Table 158.1. Characteristic Cervical Spine Problems in Common Congential Syndroms
ODONTOID HYPOPLASIA/ATLANTOAXIAL INSTABILITY
The term hypoplastic odontoid generally refers to an odontoid process that does not extend to the midportion of the ring of the atlas. It may be seen in numerous conditions;
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the most common are skeletal dysplasia and Down syndrome (21,31,35). Odontoid hypoplasia may also be an idiopathic occurrence. In extreme cases, the dens may be essentially absent (aplasia). The majority of these cases of odontoid hypoplasia are the result of skeletal dysplasias. Another condition that exhibits similar clinical symptoms is transverse ligament insufficiency, which may be caused by ligamentous laxity or damage to the ligament. Finally, a number of patients have an os odontoideum, a chronic condition in which the odontoid is present only as a small ossicle, not united to the body of the axis. Although os odontoideum was long presumed to be a congenital lesion, more recent evidence suggests that most cases may be the result of unrecognized fracture of the odontoid.
Patients with any of these four problems share a variety
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of symptoms: (a) They may show signs and symptoms of neck instability, manifested by the muscles’ response to guard it: neck pain and spasm, torticollis, or headache. These symptoms appear most often after activity or a fall. (b) Neurologic symptoms involving the long cervical tracts may be present, such as developmental delay, hyporeflexia or hyperreflexia, and weakness. (c) Finally, cerebrovascular symptoms may prevail, from ischemia to stroke involving the posterior circulation. Plain radiographs are helpful in establishing the diagnosis, and computed tomography (CT) can usually demonstrate the pathology clearly, if needed.
Plain films that include lateral views in flexion and extension will help to quantify the instability. The normal space available for the cord at this level should be at least 13 mm, and the translation of the ring of the atlas should be less than 5 mm. Magnetic resonance imaging (MRI) may be helpful to demonstrate cord impingement, but this can often be deduced from plain films and clinical exam alone.
If radiography reveals signs of instability beyond a critical limit (more than 5–8 mm of translation on flexion/extension films), stenosis, or neurologic signs, surgical fusion of C-1 to C-2 is indicated (24). Reduction to a neutral position is the goal; if this cannot be accomplished, decompression may also be required.
CERVICAL STENOSIS
When cervical stenosis is seen in children, the diagnosis is usually achondroplasia, Klippel-Feil syndrome (36), or idiopathic congenital cervical stenosis. Signs and symptoms include those of acute compression (numbness and tingling in the extremities, acute weakness) or chronic myelopathy with developmental delay, spasticity, weakness, and muscle atrophy. In the teenage athlete with idiopathic cervical stenosis, transient quadriparesis is a common presenting phenomenon, with forced hyperextension in the presence of a narrowed spinal canal (41). Fortunately, this symptom tends to resolve rapidly if there is no vertebral subluxation or dislocation. In the child with achondroplasia, the greatest degree of stenosis occurs at the foramen magnum, causing failure to meet developmental milestones and a tendency to develop sleep apnea. Clinically significant stenosis of the remainder of the cervical spine in the person with achondroplasia generally develops only in adulthood, if at all.
Certain other skeletal dysplasias (such as spondyloepiphyseal dysplasia and mucopolysaccharidoses) may produce localized stenosis of the ring of the axis as well as atlantoaxial instability; these can cause additive damage to the cord. On lateral radiographs, cervical stenosis should be suspected if the distance from the posterior laminar line to the posterior vertebral body line is less than 80% of the width of the vertebral bodies (Pavlov’s ratio) (41). Also, the distance from the posterior laminar line to the line of the facets is diminished (Fig. 158.1). In patients with Klippel-Feil syndrome, this finding may be missed because attention is drawn to the vertebral fusions. The stenosis is made more problematic if there are large blocks of fusion with just a few motion segments.
Figure 158.1. Torticollis in a young child, in this case due to three consecutive hemivertebrae in the upper cervical spine. In infants, computed tomograms provide superior visualization compared with plain films, because of the baby’s large head, difficulty positioning, and the complexity of the case. Treatment was by realignment with distraction of the concave side and derotation in a halo-vest, followed by fusion.
Patients with known cervical stenosis should be counseled to avoid contact sports, especially those that produce forcible flexion or extension of the cervical spine, such as wrestling and playing lineman in American football. Surgical decompression of the lower cervical spine is generally best avoided, as it could produce a region of decreased stability adjacent to further stenosis. Localized decompression and fusion may be carried out if indicated. Patients with congenital stenosis of the upper cervical spine may require decompression. If this is so, fusion should be considered if there is associated instability or if the decompression involves more than two segments, in order to prevent development of localized kyphosis.
CERVICAL SPINA BIFIDA
Occult defects in the cervical spine occur primarily in two congenital syndromes: Larsen syndrome and diastrophic dysplasia. Larsen syndrome is characterized by multiple joint dislocations, foot deformities, and an accessory calcaneal apophysis. In one series, more than half the patients
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had cervical spina bifida and resultant kyphosis (22). In diastrophic dysplasia, diastrophic patients are often born with significantly short stature, rigid clubfeet, joint contractures, and a closed cervical spina bifida, although the incidence of kyphosis is not as high.
The presence of spina bifida in the cervical region indicates a deficiency of posterior ligamentous support (interspinous ligament, ligamentum flavum) as well as of posterior muscle control. This may be a reason for the development and progression of kyphosis. In addition, the vertebral bodies in the region are hypoplastic and may be rounded or wedge shaped. The kyphosis may progress as the child becomes upright. Initially, the physical features of kyphosis are not externally evident, except for a slight loss of the normal cervical lordosis. There are no external clues to the presence of bifid cervical laminae. Therefore, a high index of suspicion must be maintained for these conditions.
Patients may exhibit myelopathy, which may be difficult to detect in children with severe skeletal deformities. Signs such as muscle weakness, failure to achieve normal milestones, and hyperreflexia or clonus may be seen. Endotracheal intubation for other surgical procedures in the presence of this kyphosis may worsen the neurologic condition if not done by knowledgeable persons. In some patients with diastrophic dysplasia, a mild cervical kyphosis may improve spontaneously with time (18). Observation may be indicated if there are no established signs of neurologic compromise. Bracing, however, does not seem to be feasible or warranted. In Larsen syndrome, progression is more likely (22).
Posterior Fusion
The optimal treatment is an early posterior fusion, which may function as a tether and allow spontaneous correction of the deformity.
  • Perform fusion early in the patient with Larsen syndrome, before the kyphosis exceeds 50° and becomes rigid. Consider fusion in patients with diastrophic dysplasia who do not improve over the first several years of life, or whose deformity or neurologic condition worsens.
  • Perform posterior fusion over the levels involved in the kyphosis, using autogenous bone graft from the iliac crest or the tibial metaphysis.
  • Use a halo-vest or halo-cast to control the head and prevent the kyphosis from worsening during incorporation of the fusion. For mild deformities, a Minerva-type cast or orthosis is also an option. Order them in advance of the procedure.
  • Take care in exposing the spine, because of the open laminae.
  • Dissect the muscles off only the extent of the spine intended for fusion, since extension of the fusion to adjacent exposed levels is a risk. Confirm levels radiographically.
  • Decorticate the spine gently and perform a bone graft.
Instrumentation of the spine is not possible for patients of a very young age. Some degree of correction in the halo-vest may be possible by a combination of three maneuvers: (a) positioning the head in slight extension and posterior translation, (b) securing the shoulder straps of the vest so that they are snug (but not too tight), to maintain the length of the cervical spine rather than allowing it to settle, and (c) placing a padded sling behind the apex of the kyphosis, which is attached to the bars of the halo-vest, to prevent the kyphosis from settling posteriorly. When this is done, the tension of the strap must be checked periodically to be certain that there is not too much pressure on the skin.
If the deformity is severe or there is significant neurologic compromise, an anterior decompression and strut graft may be needed in addition to the posterior fusion. The spine should be immobilized for a minimum of 3 months, and continuity of the fusion mass should be demonstrated radiographically at the end of this period to prevent loss of position due to a pseudarthrosis.
Congenital fusion of the cervical spine, or Klippel-Feil syndrome, may occur with congenital upper or lower thoracic or lumbar fusion, or it may be present as an isolated finding. It has been classified into three types: Type I involves fusion of cervical and upper thoracic vertebrae, type II involves isolated fusions of the cervical spine, and type III refers to cervical fusions associated with lower thoracic or upper lumbar fusion (36). Surgery is almost never required for the cervical anomaly itself.
The main significance of the diagnosis is to encourage a search for other anomalies both within and outside the spine, such as Sprengel deformity, hearing impairment, spina bifida, and associated scoliosis. Scoliosis is most common in types I and III. Progressive congenital cervical scoliosis is rare and usually involves the cervicothoracic junction. Monitor young children with this finding closely, since the shoulder tilt it produces may be highly deforming. Perform surgery if progression of more than 10° is seen. A posterior fusion in situ is the gold standard for this region.
Scoliosis of the upper cervical spine is quite rare and usually presents as torticollis, which must be differentiated from muscular torticollis, Grisel syndrome, ocular disturbance, and abnormalities of the brainstem and cord. Other causes of fusion in a young child include juvenile rheumatoid arthritis, as well as residua of infection in the region. The upper cervical spine may be very hard to image in children under age 5; it is frequently necessary to obtain a multiplanar CT or an MRI under sedation. If a vertebral anomaly is seen that is deforming, surgery may be indicated (Fig. 158.1).
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OPERATIVE TECHNIQUES
Because in many congenital syndromes, age and bone quality affect halo application and upper cervical fusion, these techniques deserve special consideration (10).
Halo Application
Check the halo size and shape in advance, and modify it if there is plagiocephaly or cranial disproportion (14). Also, if there is risk of positional neurologic damage in children too young to cooperate with examination, evoked potentials are useful.
  • General anesthesia is preferred for halo application, although local anesthesia and sedation are possible.
  • Because of the danger of hyperflexion caused in part by children’s relatively large head size, elevate the torso or have an assistant hold the head off the end of the table.
  • Do not place pins in the thin temporal regions (14).
  • In children under 2 years of age, Mubarak et al. (28) recommend placement of six to ten pins at low torque (finger tightness through 2 inch-pounds) in the four traditional regions (Fig. 158.2).) Kopits and Steingass (25) found four pins to be sufficient in most cases, and loads up to 5 inch-pounds to be safe in older children. My experience confirms these findings. At our institution, we use 4 inch-pounds of torque for children up to age 4 years, 6 inch-pounds for those aged 5 to 10, and 8 inch-pounds for those over 10.
    Figure 158.2. A technique of halo application in the infant or child under age 2. The increased number of pins allows decreased torque on each. (Reproduced with permission from Mubarak SJ, Camp JF, Vuletich W, et al. Halo Application in the Infant. J Pediatr Orthop 1989;9:612.)
  • The vest may be custom ordered from a prior cast or from tape measurements, or it may be made of plaster using a special frame. The pins may be retightened on the first or second day after halo placement using intravenous analgesia, but do not retighten after this time. If a pin becomes painful later, it is usually that it has become loose or infected. Try oral antibiotics first if there is no obvious loosening; if there is no relief, replace the pin in an alternative site.
Posterior Cervical Fusion
Many congenital disorders require fusion of the upper cervical spine for deformity or instability. Techniques of fusion are well described elsewhere (in Chapter 139, Chapter 140, and Chapter 154). Two special aspects require further comment. First, anomalies of the posterior arches are common in several syndromes. Second, in very young children, the posterior elements and occipital cortex may not allow wire fixation of any substantial strength, or the lamina may be resected in cases of stenosis. Study good plain radiographs and, in most cases, CT scans in the areas of planned fusion to rule out spina bifida or anomalies of the arches. If anomalies are present, start dissection from a “normal” area, where depth can safely be established, and proceed up and down over the facets in the deficient areas.
Posterior Occipitocervical Fusion
Koop Technique
Koop et al. demonstrated a union rate of greater than 90% for upper cervical fusion in children with halo immobilization, even when grafts are not wired in place (24). This finding is relevant for infants or certain patients with skeletal dysplasia who do not have adequate bone size or quality for wire fixation.
  • Apply the halo as described previously for young children.
  • Turn the patient prone and affix the halo to a halo-holder. Use spinal cord monitoring during turning and throughout the entire procedure.
  • Check a lateral radiograph to confirm proper alignment of the neck.
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  • Gently expose the spine, taking care to remain medial to the vertebral arteries at C1–C2.
  • Avoid unnecessary exposure of caudal levels, which often leads to unwanted extension of the fusion distally. If a distal level is exposed unintentionally, covering it with bone wax may prevent it from incorporating into the fusion mass.
  • After exposure and wide decortication, place autologous bone in the desired areas (Fig. 158.3).
    Figure 158.3. Technique of occipitocervical fusion in infants. A,B: An occipital periosteal flap is raised and sutured distally. C,D: An air drill is used for decortication, and the graft is inserted. (Reproduced with permission from Koop SE, Winter RB, Lonstein JE. The Surgical Treatment of Instability of the Upper Part of the Cervical Spine in Children and Adolescents. J Bone Joint Surg Am 1984;66:403.)
  • When fusion to the occiput is desired, use a triangular periosteal flap equal to the distance to C-2. Using a stay suture, dissect the flap, leaving it attached at its base, and suture it to C-1 and C-2. Place the bone graft on top, abutting the decorticated occiput.
The average time in halo until radiographic union is seen is 5 months.
Dormans and Drummond Technique
An alternative technique has been described by Dormans and Drummond for children whose bone is adequate to permit wire fixation (11). Use of autogenous bicortical iliac crest in combination with occipitocervical wires forms a construct that is stable in flexion and extension.
  • Perform the halo placement, with positioning and exposure as previously described.
  • Fashion a trough in the outer table of the base of the occiput below the inion, at a level so that a graft can be inserted on top of the laminae (Fig. 158.4).
    Figure 158.4. Technique of occipitocervical fusion (Drummond), used for children with slightly better bone density that can support wire fixation. A: A trough is made in the base of the occiput, and two burr-holes are made on either side. B: A corticocancellous graft is taken from the ilium and shaped to fit the space between the occiput and the second or third cervical vertebra. C: Four strands of wire are passed to be ready to twist together: one from each side of the occiput, and one Drummond button-wire from each side of the C-2 or C-3 spinous process. D: The wires are twisted together to lock the graft into place. (Redrawn from Dormans JP, Drummond DS, Sutton LN. Occipitocervical Arthrodesis in Children: A New Technique and Analysis of Results. J Bone Joint Surg Am 1995;77:1234.)
  • Make two burr holes through both cortices of the occiput just superior and lateral to the trough.
  • Loop a 16- to 18-gauge wire through these holes.
  • Make a hole at the base of the most caudal lamina to be fused, and pass a pair of Wisconsin (Drummond) wires through the hole in opposite directions.
  • Obtain a corticocancellous autogenous iliac crest graft the width of the laminae and the height of the combined levels to be fused.
  • Fashion a notch in the inferior edge to fit around the lowest spinous process, and lay it in place after the Wisconsin wires have been placed.
  • Start each Wisconsin wire distally under the graft, then pass it around the graft and over it, across to the spinal wire in the opposite side of the occiput.
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  • Control the extension of the spine by the head position and the size and shape of the graft.
  • Tighten the wires and take a lateral radiograph to confirm alignment.
  • Place extra bone graft at the upper and lower edges of the main graft.
  • Take flexion–extension radiographs about every 4 weeks.
  • The halo may be removed after a mean of only 8 weeks with excellent results; have the patient wear a hard collar for 4–6 weeks after the halo is removed.
This technique is also applicable even if laminectomy has been performed at levels above the lowest level to be fused.
Posterior Atlantoaxial Fusion
For children with intact laminae and an isolated mild to moderate C1–C2 instability, Mah et al. (27) described a modified Gallie method of wiring around the base of the spinous process to preserve strength yet avoid the risks of wire passage under C-2 (Fig. 158.5). It also avoids the risks of cutout or dorsal displacement of the wires, which could otherwise occur in children with standard Gallie technique.
Figure 158.5. Atlantoaxial fusion by the modified Dewar technique. A: After C-1 and C-2 are exposed, a threaded Steinmann pin is inserted percutaneously through the base of C-2. B: A sublaminar wire is passed under the C-1 arch. C,D: The wire is brought over the contoured graft and held under the Steinmann pin. (Reproduced with permission from Mah JY, Thometz J, Emans J, et al. Threaded K-Wire Spinous Process Fixation of the Axis for Modified Gallie Fusion in Children and Adolescents. J Pediatr Orthop 1989;9:675.)
  • Position the patient in the standard fashion, with the cervical spine reduced to an optimal position, and the neck draped widely, allowing access to the lateral portion of the neck from both sides.
  • Contour a rectangular unicortical iliac crest graft to fit over the C-1 arch and straddle the C-2 spinous process.
  • Drill a threaded Steinmann pin percutaneously through the widest portion of the base of the spinous process of C-2 and cut it to leave 1 cm on each side.
  • Pass an 18-gauge sublaminar wire under the C-1 arch.
  • Place the loop of the wire deep to the Steinmann pin and draw it tightly over the graft, keeping it apposed to the lamina. This placement allows the wire to obtain good cortical purchase around C-2 and prevents dorsal migration.
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  • Add extra cancellous graft. Tie the free ends of the wire transversely over the graft.
Postoperatively, use a soft collar until union, if the translatory instability of the atlantoaxial segment is not too great. A halo-vest may be used at the surgeon’s discretion.
Bone Graft
Some bone graft is almost always obtainable from the posterior ileum in children. If the amount is inadequate, such as in an infant with a small pelvis in whom long cortical and cancellous grafts are needed, the grafts may be obtained from one or both tibiae (see Chapter 9).
THORACOLUMBAR ABNORMALITIES
CONGENITAL STENOSIS
Congenital stenosis of the thoracic and lumbar spine is seen mainly in achondroplasia; to a lesser degree, it is seen in other skeletal dysplasias such as hypochondroplasia, diastrophic dysplasia, and spondyloepiphyseal dysplasia. Patients with isolated congenital spinal malformations such as scoliosis and kyphosis also commonly have associated narrowing of the spinal canal in the region. Take this narrowing into account when planning deformity correction and instrumentation.
A rare syndrome of focal, severe congenital stenosis, termed segmental spinal dysgenesis, has been described (13). It is usually present at the thoracolumbar junction and may be associated with segmental instability, scoliosis, or kyphosis. In patients with complete neurologic deficit, return has not been seen after decompression and stabilization, but these are indicated in those with preservation of at least some distal neurologic function who have progression or instability.
In addition, there are some young patients without any congenital malformation, who exhibit spinal stenosis that has been made symptomatic by disc protrusion or mild degenerative change. Symptoms include pain and tingling or numbness in the lower extremities more than pain in the back. Standing or walking worsens these symptoms, and rest usually relieves them. Plain films suggest stenosis by virtue of the narrow distance between the posterior laminar line and the posterior vertebral line, but they are less accurate in identification of stenosis in the thoracic and lumbar spine than they are in the cervical spine. MRI more clearly delineates the degree of neurologic compression.
Conservative treatment such as activity modification or a flexion back brace may alleviate symptoms. Hip flexion contractures may need to be addressed, as they increase the obligatory lumbar lordosis. Decompressive laminectomy may be necessary if these measures fail; careful examination and judgment are necessary to determine the extent of unroofing required. Techniques of decompression may involve traditional laminectomy, laminoplasty (enlarging the canal by hinging open the lamina), or fenestration (removal of the stenotic inferior portion of each involved lamina and the medial facets). Further details are discussed in the later section on achondroplasia.
CONGENITAL AND ACQUIRED KYPHOSIS
Congenital kyphosis is less common but has potentially more serious neurologic consequences than congenital scoliosis. The basic types include failure of vertebral formation (type I) and failure of segmentation (type II) (see Chapter 161). If progression is seen, treatment is required. Bracing has no value in halting the increase of the curve.
Surgery is indicated at an early age if any progression at all is discovered. It should take the form of an in situ posterior fusion of the level above and the one below the abnormal vertebra in a type I kyphosis, unless it exceeds about 55°. If it exceeds this value, the fusion mass will be under tension and will not effectively halt growth; an anterior epiphyseodesis may be needed as well. A type II kyphosis may be fused posteriorly between the two involved vertebrae, to match the anterior bar; this may be extended one level above and one below in young children if it is desired to achieve some correction with cast and growth.
Postoperative cast immobilization for 3 months is the rule; follow-up should be performed to rule out pseudarthrosis and progression. Undertake osteotomy or vertebrectomy in treatment of congenital kyphosis only if the deformity is severe and is causing neurologic compromise or an unacceptable appearance.
Acquired kyphosis in children is seen most often after laminectomy, especially of the cervicothoracic or thoracolumbar junctions. In congenital syndromes, this situation may occur after decompression of spinal stenosis (in achondroplasia) or of intradural tumors (in neurofibromatosis) (17,19). More detail is given later in the sections on these conditions. It is important to realize that the risk of this phenomenon is greater in children than it is in adults. When there is preexisting kyphosis or vertebral wedging, it becomes even more likely.
Prevention of kyphosis is much easier than later treatment of an established deformity, if it can be anticipated. Limited posterior fusion in situ over the region of the junction is usually effective. Another alternative is laminoplasty, which allows many of the interlaminar ligaments to remain intact and may prevent kyphosis from developing.
CONGENITAL SCOLIOSIS
Congenital scoliosis may be an isolated finding, or it may be associated with various syndromes. The most common
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association is with the VATER syndrome (vertebral anomalies, anal atresia, tracheoesophageal fistula, renal and radial abnormalities). Some physicians include a C for cardiac abnormalities. The vertebral anomalies are the most common component of the VATER syndrome, so orthopaedic surgeons will see most of these children. Other syndromes that include congenital vertebral anomalies are Goldenhar (oculoauriculovertebral) syndrome, myelomeningocele, Klippel-Feil syndrome, and Jarcho-Levin syndrome (spondylothoracic dysplasia).
Although there may be a dimple, a vascular marking, or a patch of hair over the spine in the occasional case of congenital scoliosis, often patients have no external physical findings except for the deformity, which may be mild in early childhood. Early diagnosis usually comes about because of an incidental event such as a radiograph for trauma or a chest film. Vertebral anomalies are frequently seen on ultrasound of fetuses, and concerned parents as well as sonographers often consult the orthopaedist for a prognosis. Isolated hemivertebrae without neural tube defects or other sonographic anomalies typically have a good outcome. The presence of other abnormalities reduces the rate of survival.
Radiographic findings in congenital scoliosis usually include hemivertebra, wedged vertebra, or fusion of vertebrae (bar). Many times there are elements of both in a given curve. The best opportunity to understand the underlying growth abnormality is to study the films of the patient at the youngest possible age; they will show the asymmetries of ossification and allow diagnosis of hemivertebrae and fusion.
If a hemivertebra does not have a growth plate on both surfaces, or if it is “carved into” the adjacent vertebra (incarcerated), it is less likely to produce an increasing curve. Upon diagnosis of congenital scoliosis, do a thorough exam, searching for limb atrophy or other deformities. Chest auscultation should be done, but cardiac imaging is not routinely indicated. However, the genitourinary tract should be visualized at least once by ultrasound or intravenous pyelogram. Some experts recommend a routine MRI on all children with this diagnosis, since at least 25% will show some abnormality such as a Chiari malformation, syrinx, or tether. This is not a well-accepted recommendation, however, as the indications for treating these conditions in the asymptomatic stage are highly debatable. Most surgeons instead prefer to order an MRI only when corrective surgery is planned, or if unexplained progression occurs.
Treatment of congenital scoliosis is largely surgical. There is no documented efficacy of brace treatment. Some curves such as those with a segmented hemivertebra and a contralateral bar have a virtual certainty of progression and should be fused when first seen. All others should be followed during growth with serial radiographs, always comparing them to the first film, rather than to the last prior film.
If progression of more than 5° to 10° is seen, I recommend surgery. There are several surgical options, whose indications depend on the characteristics of the curve, the acceptability of the current deformity, and the likelihood of future increase in the curve. Options include the following:
  • Posterior fusion in situ
  • Anterior and posterior fusion
  • Hemiepiphyseal fusion
  • Hemivertebral excision
  • Spinal osteotomy for correction
Operative Techniques
Posterior Fusion in Situ
Posterior fusion in situ is the most widely accepted procedure. It is indicated for progressive curves if the deformity is acceptable and the likelihood of anterior crankshaft progression is not high.
  • Take care in exposing the spine, since midline laminar defects are sometimes seen in congenital curves.
  • Fuse all vertebrae within the curve.
  • Some correction may be obtained through bracing if there is flexibility in the curve.
  • Postoperatively, immobilize the patient in a cast or brace for 3 to 4 months, when consolidation of the fusion should be demonstrated.
Anterior and Posterior Fusion
If you suspect that significant growth potential also exists anteriorly that could cause a deformity due to the crankshaft phenomenon, perform anterior and posterior fusion.
  • Perform the anterior procedure in the traditional open fashion, through a thoracoscopic approach, or by a transpedicular or costotransversectomy approach. See Chapter 155.
  • Consider a hemiepiphyseodesis, as a variation on this theme, for young patients’ curves with some growth potential on the concave side.
  • Fuse the curve anteriorly and posteriorly only on the convexity, to allow for some corrective growth on the concavity. Measurable correction is seen only in children under age 6 at surgery, and the amount of correction rarely exceeds 10° to 20°.
  • Hemivertebra excision is now accepted as a safe alternative for curve correction in experienced hands (8) (see the Surgical Techniques section later). It is mostly, although not solely, applicable to anomalies at or below the thoracolumbar junction. Use this technique for curves too large to be fused in situ.
  • Both anterior and posterior procedures may be performed in the same operative session.
  • Spinal osteotomy may be needed to correct large, stiff curves composed of multiple bars, or ones that have
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    been fused previously. It carries an element of risk and should be performed by experienced surgeons and only for curves that are significantly disabling.
  • In all cases where corrective surgery is planned for congenital deformities, a preoperative MRI of the spinal canal is indicated.
MANAGEMENT OF SPECIFIC SYNDROMES
Down syndrome (trisomy or translocation involving chromosome 21) is commonly associated with cervical abnormalities. Anterior subluxation of C-1 on C-2 of more than 5 mm in flexion is seen in 15% to 20% of patients. Over 4 mm posterior translation of the occiput on C-1 is seen in 60% (29,31). Also seen is increased frequency of os odontoideum, ossiculum terminale, and spina bifida of any upper cervical vertebra (31). Management of the instability is controversial.
Screen all Down syndrome children, and restrict from high-risk sports those with more than 5 mm C1–C2 subluxation. Perform fusion for those with more than 1 cm subluxation, neurologic deficit, or persistent neck pain. In cases to be fused, it may be necessary to extend the fusion to the occiput (42) if there is significant posterior atlanto-occipital translation in extension. Increasing quadriparesis during surgery has been reported in cases of preoperative myelopathy or longstanding displacement. It appears that in such cases there may be chronic degeneration within the cord, rendering it extremely susceptible to insult. In addition, the space available for passing wires is decreased. Reduction, if necessary, should be achieved before surgery with evoked potential monitoring or preoperative awake traction. If significant reduction cannot be achieved but the patient’s neurologic condition is acceptable, only a fusion without wires is recommended. Use a CT scan to rule out spina bifida.
SKELETAL DYSPLASIAS
Cervical spine abnormalities are common in many skeletal dysplasias. Odontoid hypoplasia and ligamentous laxity are common in spondyloepiphyseal dysplasia (congenita more than tarda), Morquio syndrome, Kniest syndrome, and metatrophic dysplasia (2,38). It may also be seen in the occasional patient with pseudoachondroplasia. Symptomatic instability frequently results. In addition, cervical stenosis may be seen with metatrophic dysplasia, Maroteaux-Lamy syndrome, or achondroplasia. Obtain neutral, flexion, and extension cervical spine films in all patients with these conditions. Diagnosis of cervical myelopathy is difficult in infants and may be aided by checking motor milestones, and spinal cord monitoring, flexion–extension MRI, and sleep studies. Metatrophic patients may also have painful torticollis due to rotatory C1–C2 instability (Fig. 158.6).
Figure 158.6. A: A 15-month-old child with metatrophic dysplasia and painful torticollis. The head is kept in marked hyperextension. B: Lateral roentgenogram shows some anterior C-1 displacement with rotation and stenosis. C: CT-myelogram confirms rotational malalignment and stenosis. D: Posterior C1–C2 decompression and occiput to C-3 fusion done by the method of Koop. Wires seen are through facets (Southwick type). Tibial graft is used. Unfortunately, the patient died 3 months postoperatively due to the restrictive lung disease associated with metatrophic dysplasia.
In contrast to the upper cervical abnormalities seen in other dysplasias, diastrophic dysplasia frequently causes mild cervical kyphosis and spina bifida (19). Surprisingly, many of these kyphoses, especially those that are less than 80°, resolve over time with or without bracing. Quadriplegia has been reported with some larger kyphoses, however, so surgical treatment is indicated for those with progression or neurologic deficit.
If the curve is flexible, correction may be accomplished by postural reduction and posterior fusion. Place the patient in a halo body jacket, and gradually extend the head over several days with serial neurologic examinations. A posterior sling may be added at the apex of the curve. If satisfactory improvement is obtained, identify bifid areas on CT and perform a posterior fusion with a tibial cortical graft. If the kyphosis is rigid, anterior release and strut graft fusion, followed by posterior fusion, are indicated. Apply the halo before the fusion, to protect the strut graft in young patients. The anterior bar of the frame should be removable on the side of the anterior approach.
Larsen syndrome of multiple joint dislocations with flattened facies is occasionally associated with cervical spondylolysis and kyphosis, causing neurologic deficit (22). Screening of the cervical spine is recommended for all patients with this diagnosis. Treatment follows the guidelines given for diastrophic dwarfism. Note, however, that spontaneous resolution has not been documented in this condition, and the posterior arches may also be deficient.
Achondroplasia
In achondroplasia, panspinal developmental stenosis, sagittal deformity, and arthrosis combine to produce compressive neurologic lesions in 30% to 80% of patients. Infantile kyphosis at the thoracolumbar junction, resulting from muscular hypotonia, ligamentous laxity, and a relatively large head, resolves in 75% to 85% of cases but persists or progresses in the remainder, leading to wedging of thoracolumbar vertebrae (19,26,37,40). Wedging may be focal, involving a single vertebra, or gradual, involving multiple levels. Some geneticists feel that it is important to prevent children with achondroplasia from sitting unsupported, and to use hard-backed sitting devices (30). I feel that it is impossible to prevent a child from sitting who is developmentally ready, and that the only effective support is a thoracolumbosacral orthosis. Therefore, it seems prudent to brace all achondroplastic children with significant kyphosis after 2 to 3 years of age.
Correction of kyphosis should be undertaken in the following situations:
  • For any curve more than 50° to 60° with focal wedging, in patients over age 5 to 6 years
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  • In any patient undergoing laminectomy with a curve over 30° in the thoracolumbar region or 50° in the thoracic region
  • For any curve that progresses on its own (37)
Fusion should always be both anterior and posterior because of deformity and small posterior elements, especially after laminectomy. If the kyphosis is sharp and angular, and if neurologic deficit is present, perform a corpectomy with strut graft fusion. Follow with posterior fusion. Both procedures can be done on 1 day if the patient is young, or 1–2 weeks apart in older patients or those requiring extensive laminectomy. Correction of deformity may be either by cast or instrumentation. There is a 25% or greater chance of somatosensory evoked potential or clinical neurologic deterioration when instrumentation is used, although recovery is common (37). This effect is probably caused by instrumentation impinging on a narrowed canal, downward pressure on apical laminae, or stretch of nerve roots in lordotic segments. This risk can be minimized by using cast correction only, with 4–6 months of recumbency. If instrumentation is used, it should include only pedicle screws in the lower thoracic or lumbar region (Fig. 158.7). Stabilization and fusion, rather than significant correction, should be the goals. It is best not to fuse below L-4 in most cases, because mobility is always a problem in patients with achondroplasia. Laminectomies should be done in marginally stenotic levels. Spinal stenosis in achondroplasia is caused by deficient endochondral growth in the neurocentral synchondroses, with decreased sagittal and coronal canal dimensions, increasing in severity caudally. Foramen magnum and cervical
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stenosis may occur in addition to the more common thoracolumbar stenosis.
Figure 158.7. A: A 6-month-old girl with achondroplasia, never braced. B: The same patient at age 12 with severe 90° wedging of L-2 with early weakness. C: One year after anterior decompression and posterior fusion. The patient had an initial postoperative increase in weakness, but recovered fully within 3 months.
Degenerative changes or disc bulge may make the narrowing symptomatic. True disc herniations are a distinct minority, however. Symptoms in older teenagers or adults include leg pain while standing or walking, decreased endurance, numbness, and urgency or incontinence. On examination, an upper or lower motor neuron picture may be seen, depending on the level of compression. Evaluation should include CT-myelography, cystometrogram, and postvoid residual. MRI is less helpful because it does not show the bony compressive structures as well. If stenosis symptoms or any neurologic deficit is present, decompressive laminectomy should be done, after ruling out disc herniation (43). Laminectomy should include all involved levels, most commonly T8–S1. The most frequently reported surgical error is insufficient length of laminectomy. Because of the limited canal space, dural tear or cord contusion during decompression is not infrequent.
Diastrophic Dysplasia
In diastrophic dysplasia, scoliosis or kyphosis is extremely common (4,5,18), having been seen in over 70% of patients in the largest reported series. Only 30% of the curves, however, were over 30°. Two curve types are seen: benign and idiopathic-like, and severe, rigid types with kyphosis. The latter are considered by Tolo to be the result of wedged or unsegmented vertebrae like those seen in congenital scoliosis (39). These curves are apparent before age 4, often in infancy.
Try bracing early, for all curves. It is sometimes successful for the gradual idiopathic-like curves. If the curve progresses past 45° despite bracing, consider instrumentation without fusion in young children if there is not too much kyphosis. Tolo and Kopits (39) state that significant growth ceases at age 9–10 in these patients, so fusion at this age, if it is necessary, would have little effect on height. At any point where the curve progresses significantly despite subcutaneous instrumentation, perform fusion, for little of what is lost in progression can be regained.
To arrest progression effectively, add anterior release and fusion if the kyphosis or scoliosis is large or if there is much growth remaining before skeletal maturity. Although the canal is relatively stenotic in the lower lumbar region, hook placement can be done safely (38). The incidence of postoperative neurologic deficit in hook placement was more than 50% in one series (5). The deficit
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seems to be due to zealous attempts to correct these rigid curves, rather than to the instrumentation itself.
Pseudoachondroplasia
Pseudoachondroplasia is occasionally associated with thoracolumbar kyphosis and hip flexion contractures. Treat the kyphosis by anterior and posterior fusion if severe. Neurologic injury from surgery is less common than in achondroplasia because the canal is larger. Sublaminar instrumentation may be used. If excessive lumbar lordosis is present and flexible, correction of any hip flexion contracture by femoral extension osteotomies should be the first step.
Metatrophic Dysplasia
Metatrophic dysplasia is usually associated with curves that appear early and are difficult to control. The most common pattern is a double major scoliotic curve with a severe junctional kyphosis, which may equal or exceed the scoliosis in magnitude. The curves are rigid, and bracing is poorly tolerated. The kyphosis and poor bone quality contraindicate subcutaneous instrumentation. Definitive spine fusion is frequently necessary at an early age. Restrictive lung disease is common because of short ribs. Consult a pulmonary specialist if you are contemplating anterior fusion or to determine if even posterior fusion will be tolerated. Fusion with cast correction is the most common method used.
Kniest Syndrome
Kniest syndrome and its resultant scoliosis are similar to metatrophic dysplasia but less severe. Rib length is normal, and restrictive lung disease is not as frequent as in metatrophic dysplasia (2).
Mucopolysaccharidoses
Of the mucopolysaccharidoses, kyphosis with or without scoliosis is common in Hurler syndrome. It most often has an apex at the thoracolumbar junction, where wedging of vertebrae and translation may occur. Bracing is warranted, but its efficacy remains unproven. The limited life expectancy of these patients historically has made fusion untenable. With the increasing success of bone marrow transplantation, patients who are longer-term survivors may require treatment by a limited posterior fusion over the kyphotic segment if it is progressive.
Spondyloepiphyseal Dysplasia
Spondyloepiphyseal dysplasia is manifested in the spine by marked platyspondyly and, frequently, thoracic kyphosis and scoliosis (2). Bracing is advised for scoliosis less than 45° or for any increased kyphosis in growing children. In some cases, the kyphosis has been permanently improved by bracing. Scoliosis should be fused if the curve is over 45°. Pseudarthrosis is common after posterior fusion of either kyphosis or scoliosis, resulting in significant loss of correction. Therefore, patients with severe curves may need an anterior as well as a posterior fusion if the curve is rigid, if the patient is adult, or if he has had prior laminectomy.
OSTEOGENESIS IMPERFECTA
Spine deformity in osteogenesis imperfecta correlates with bone involvement (3,16,47) (see Chapter 180). Although many classification systems have been proposed, the radiographic system of Hanscom has been best correlated with spinal involvement (16). Type A patients, those with only bowing of the long bones, have the best bone quality and generally maintain some correction if scoliosis surgery and instrumentation are required. Type B patients, who also have biconcave vertebrae, and type C, who have a trefoil pelvis, have a greater tendency to kyphosis. Type D patients are more severely involved, having also cystic changes in the metaphyses. With these latter three types, less correction is obtainable, and there is more postoperative loss. Type E patients, with absent long-bone cortices, should not be subjected to instrumentation at all.
Brace treatment has little if any role in osteogenesis imperfecta curves except for postoperative protection because of the potential for rib deformation. Posterior fusion should be done for curves of more than 45° in type A, or 35° to 40° in types B through E. Even at a young age, delaying fusion to preserve trunk height should not be a consideration, because the trunk is so short in nonscoliotic adults of these types, let alone those with curves.
In some cases of severe deformity with poor bone stock, carefully applied halo–gravity traction after anterior release may be used to decrease the amount of force that must be applied through the rods. All patients should be evaluated preoperatively for basilar invagination and for pulmonary compromise. Segmental fixation using hooks at as many levels as possible, augmented when necessary by doubled Luque wires, is the preferred technique. The following points should be noted:
  • Hooks placed on fragile laminae may be supplemented with methylmethacrylate.
  • Pack the methylmethacrylate after the hook is inserted; it should extend to the lamina above and below.
  • Preserve the spinous processes at these levels.
  • Supplement the fusion with banked bone.
  • Bone from other spinous processes is also helpful; these may be relatively large in osteogenesis imperfecta.
  • Blood loss is usually greater than in other conditions.
  • Use postoperative recumbency and orthoses as the quality of fixation dictates.
ARTHROGRYPOSIS MULTIPLEX CONGENITA
Scoliosis is present in up to one third of patients with the diagnosis of arthrogryposis multiplex congenita. Usually
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the curve is a long, uncompensated, “paralytic” type. Increased lumbar lordosis may occur, especially with hip flexion contractures. In a sizable minority, congenital anomalies may occur; take care to distinguish these patients from those with multiple pterygium syndrome.
Congenital curves should be treated according to the usual rules. Noncongenital curves can be braced if less than 50°, but fusion should be performed for larger curves. The spine, like the joints, is stiff, and correction is not often great unless the spine is mobilized extensively anteriorly and posteriorly. Bone is osteoporotic and hypervascular. Low lumbar curves with pelvic obliquity should have fixation extended to the pelvis. Where excessive lumbar lordosis is the main problem, patients respond poorly to posterior distraction, and anterior column shortening by multiple partial vertebrectomies is most successful.
NEUROFIBROMATOSIS
Neurofibromatosis is estimated to make up 1% to 2% of a scoliosis clinic population, so its signs should be looked for on all initial examinations (9,44). The diagnosis can be made with the presence of two or more of the criteria from the 1987 Consensus Development Conference of the National Institutes of Health (Table 158.2). In a patient with neurofibromatosis, it is important to make the distinction between dystrophic and nondystrophic curves (44). Nondystrophic curves can be treated with brace or surgery according to guidelines for idiopathic scoliosis. They are in the minority, however, making up 25% to 35% of most series.
Table 158.2. Relevant Aspects of Neurofibromatosis
Dystrophic curves require more aggressive treatment. Bracing is unsuccessful. Obtain cervical spine films and MRI or a myelogram with CT before surgery. To rule out cervical deformity, which is frequently associated with thoracolumbar deformity, obtain radiographs of the neck before general anesthesia is done or halo traction is applied (46). Abnormalities identified within the canal by MRI or myelogram, such as thinning of laminae, neurofibromas, meningoceles, and rib penetration, have obvious implications for both the technique of the dissection and the choice of fixation levels (6,12,23).
Dystrophic curves more than 35° to 45° should be fused regardless of age because progression may be rapid, and loss of height will be greater if the curve is allowed to progress than if early fusion is accomplished. If the curve is less than 50°, kyphosis less than 60°, and no obvious anterior scalloping or bony involvement is present, posterior fusion alone is indicated (9). Six months postoperatively, obtain oblique films or tomograms, or perform routine reexploration to detect and treat early pseudarthrosis.
Curves with kyphosis over 50°, anterior scalloping or deficiency, or scoliosis more than 50° should have anterior and posterior fusion. Because of potential vertebral body destruction by tumor, anterior surgery has a more important mechanical role in neurofibromatosis than in other conditions. Note the following points:
  • Fuse all involved levels.
  • If there is significant anterior tumor, use strut grafts of fibula or vascularized rib, and establish good bone continuity with vascularized tissue on the concavity of the curve.
  • Halo traction may be used to optimize correction at the time strut grafts are inserted.
  • Posteriorly, segmental hook fixation is desirable; increasing rigidity of fixation will increase success of surgery (20).
  • Use postoperative bracing if the vertebrae are weakened or the severity or location of the kyphosis is causing excessive strain on end hooks, or if there are not optimum numbers of fixation points above and below the apex (three on each side).
Treatment of neurologic deficit depends on its cause. If it is due to intracanal tumor or rib penetration, decompress it posteriorly and do subsequent fusion according to previous guidelines. If it is due to kyphosis, correct it anteriorly and posteriorly with decompression if focal.
In summary, spinal curvature in neurofibromatosis patients ranks as a major threat to patient welfare. Take all possible care in preoperative planning, surgery, and postoperative follow-up.
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MARFAN SYNDROME
Improved cardiovascular management has greatly increased the life expectancy of patients with Marfan syndrome to nearly that of the general population, thereby increasing the importance of appropriate treatment of spinal disorders. Scoliosis of greater than 10° is present in approximately half of these patients. Less than 10%, however, will require a brace or surgery (33). There is no typical curve: In Marfan syndrome, the patient may have any of the curve types seen in idiopathic scoliosis. Sagittal plane deformities are equally common and vary from hyperkyphosis to hypokyphosis. There is a fairly common finding of thoracolumbar kyphosis. Use bracing for the same standard indications as in idiopathic scoliosis; although the success rate is lower, there are cases where the brace has been associated with curve stabilization.
Severe infantile or early juvenile curves are in some cases treated with subcutaneous distraction instrumentation if they are greater than 50° (34). This technique is contraindicated, however, in cases where significant kyphosis exists. The rod should be contoured to match the patient’s sagittal profile—that is, not too straight. Dorsal displacement of hooks is a frequent cause of failure of this technique, and it is due in part to inadequate contouring. Postoperative bracing is mandatory. Despite all of these precautions, the rate of hook cutout or continued progression is significant. If cutout occurs, undertake posterior fusion with or without anterior fusion, depending on curve size and the patient’s overall condition.
Curve patterns in adolescents and adults are similar to idiopathic patterns (33). One difference is the tendency to develop moderate thoracolumbar kyphosis and the marked rotational listhesis that sometimes occurs in lumbar curves. Evidence suggests an increased risk of pseudarthrosis in patients with Marfan syndrome, especially in regions of kyphosis at the thoracolumbar junction (7). Anterior release and fusion should be added in such cases (Fig. 158.8) or when curves are large and rigid. Spondy lolisthesis of severe degree occurs in approximately 2% of Marfan patients. Check for it on lateral radiographs.
Figure 158.8. Progressive kyphoscoliosis in Marfan syndrome. A,B: Posteroanterior and lateral films at age 25, with 53° thoracolumbar scoliosis and 22° kyphosis. C,D: Repeat films 8 years later (after two pregnancies) show increase of scoliosis to 64° and, especially, of kyphosis to 64°. E,F: One year after anterior release and fusion and posterior fusion with Cotrel-Dubousset instrumentation. Note that standard rods were not long enough in this patient; longer rods may be specially ordered.
Other features of Marfan syndrome that should be kept in mind include the following: (a) The rate of dural ectasia is high (63%) in the lower lumbar or sacral canal (32) (Fig. 158.9). The dural ectasia is probably another manifestation of the effect of gravity on abnormal connective tissues. The enlarged sac has thin dural walls and may leak or erode laminae; take care with decortication and instrumentation in these areas. (b) Instrumentation of
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double curves in these already tall patients may require special ordering of long rods (Fig. 158.8). (c) The patients have implanted cardiovascular devices that must be considered when ordering prophylactic antibiotics or treating a postoperative infection.
Figure 158.9. CT scan without contrast shows dural ectasia with foramenal meningocele. This is common in Marfan syndrome, in the lower lumbar spine and sacrum. Exercise care if working inside the canal. Marked thinning of laminae may compromise fixation strength.
SURGICAL TECHNIQUES
Some authors advocate subcutaneous instrumentation for young patients with considerable growth remaining. I try to avoid subcutaneous instrumentation in almost all cases, because the gains over time are minimal and not worth the time and morbidity.
HEMIEPIPHYSEODESIS FOR CONGENITAL DEFORMITY DUE TO HEMIVERTEBRAE
Hemiepiphyseodesis (Winter technique) is intended not only to prevent progression of a congenital curve but also to allow some correction of the curve with growth (45). It is indicated for patients under about age 6 years who have some growth potential on the concavity of the curve. The advantage of the procedure is that it does not destabilize the spine and does not require internal fixation, even though it is a corrective procedure. The disadvantage is that it does not work for very large curves and is not recommended for curves over 70°. There should be no significant kyphosis or lordosis in the area to be fused. Although the anterior portion of the procedure may be performed endoscopically, the patient must be a satisfactory candidate for a thoracotomy. Take bending films to assess the flexibility of the spine preoperatively. If some correction of the curve is possible, accomplish it in the cast after surgery.
  • Place the patient in the lateral position so that both anterior and posterior exposures may be performed without repositioning (Fig. 158.10B).
    Figure 158.10. Technique of hemiepiphyseodesis for congenital scoliosis. A: Concept: The spine is fused anteriorly and posteriorly over the convexity, allowing some correction to occur with growth. B: The patient is placed in the mid-lateral position so that anterior and posterior approaches may be made simultaneously. C: Anteriorly, 30% to 50% of the disc and endplates are removed and replaced with bone graft; a strut graft is added if available. D: Posteriorly, only the convex side of the curve is exposed and grafted over the involved levels. (Redrawn with permission from Winter RB, Lonstein JE, Denis F, de la Rosa HS. Convex Growth Arrest for Progressive Congenital Scoliosis due to Hemivertebrae. J Pediatr Orthop 1988;8:633.)
  • In the open technique, expose the spine anteriorly through the rib that is one level above the most cranial to be fused.
  • Confine dissection primarily to the convexity of the curve, and confirm the levels either by the characteristic shapes of the vertebrae, or by an intraoperative radiograph with markers both anteriorly and posteriorly over the levels to be fused.
  • Remove the lateral one third to one half of the disc along with the corresponding portion of the endplates of the vertebrae.
  • Obtain bone graft from the morcelized rib or from another source and pack into the disc spaces to promote fusion (Fig. 158.10C).
  • Make a trough across consecutive vertebrae to allow a bone graft (such as rib) to be placed longitudinally, bridging them.
  • Perform posterior exposure at the same time, to be sure that the levels fused in the front and in the back correspond exactly (Fig. 158.10D).
  • Expose only the convexity of the posterior curve.
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  • Avoid elevating the muscles from the concavity of the curve, to prevent fusion from occurring on this side as well.
  • Verify which levels are the end vertebrae to be fused by palpating the vertebrae from the front and the back simultaneously.
  • If in doubt, pass small Kirschner wires from front to back at the tip of a transverse process to help confirm levels.
  • Excise the convex facets and decorticate the spine.
  • If additional correction is desired, a level above and below the curve itself may be partially fused as well, to allow further correction with growth.
  • Postoperatively, place the patient in a cast to correct as much of the flexible portion of the deformity as possible. Apply the cast either in the operating room, or a few days after surgery, if there is significant edema or need to have access to the patient. The patient wears the cast, or a cast followed by a brace, for at least 6 months postoperatively. In the series of 13 patients reported by Winter et al. (45), prevention of curve progression was achieved in all but one, and in five of these, curve correction occurred with growth. The mean correction for these five patients was 10° (Fig. 158.11).
    Figure 158.11. Result of convex hemiepiphyseodesis at 6-year follow-up. A: Curve measures 27° at age 4, due to unincarcerated hemivertebra with a bar just distal to it on the opposite side. The hemiepiphyseodesis extended two levels above and one level below the hemivertebra. B: At age 10½, the curve has corrected itself to 10°.
HEMIVERTEBRA EXCISION
Excision is indicated for rigid decompensation of the spine due to a hemivertebra. It entails somewhat more risk than a hemiepiphyseodesis because the spinal canal is entered both anteriorly and posteriorly, and the spine is partially destabilized to achieve the correction. A significant degree of correction is possible, however, and the risks are generally acceptable with current techniques in experienced hands (8).
Preoperative assessment may include bending films to determine whether the desired degree of correction can be obtained without vertebral resection. In addition, MRI should be performed in all patients preoperatively because there is an increased frequency of abnormalities within the spinal canal (Chiari malformation, syrinx, diastematomyelia, and fibrous tether), which may predispose the patient to neurologic complications. Hemivertebra excision in the thoracic spine generally entails more neurologic risk as well as less correction, but it is not contraindicated.
Usually, both the anterior and the posterior portions of the procedure are performed in the same surgical session, if possible. Use sensory and motor spinal cord monitoring.
  • Place the patient in the straight lateral position (Fig. 158.12).
    Figure 158.12. Hemivertebra excision. A: Remove discs and endplates above and below the hemivertebra. B: Curet and remove the hemivertebra. C: Resect the corresponding posterior elements. D: Complete the correction with posterior compression rod or wire fixation.
  • Make a transpleural, transdiaphragmatic, or retroperitoneal anterior approach as dictated by the level of the curve.
  • Identification may be possible by local landmarks as well as by the shape of the vertebrae, but it should be confirmed by a radiograph if there is any question.
  • If segmental arteries are to be ligated in the thoracic spine of a patient with congenital anomalies, some surgeons
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    recommend placing a “bulldog” vascular clamp on the vessels to occlude flow for 10 minutes, using spinal cord monitoring to be sure that the intended vessels do not provide critical perfusion to the cord (1).
  • Resect the discs above and below the vertebrae first, followed by the body.
  • Leave the posterior portion of the vertebra and the medial cortex of the pedicle intact until last, as their resection may cause epidural bleeding.
  • Place bone graft into the defect, but not so much as to limit the correction.
  • Resect the posterior elements over the corresponding level.
In young patients whose correction is maintained without excessive difficulty, a pantaloon cast may be all that is necessary for correction. However, if the patient’s size and bone density are adequate, use internal fixation, which may include a wire for a simple resection, or more rigid and complex fixation. It is the surgeon’s judgment whether to perform these procedures in the same position, or whether to turn the patient prone for the posterior fixation. It depends on the complexity of the fixation intended.
The entire extent of the curve should generally be fused. Bone from the resected vertebra and rib usually provides adequate graft. The need for a postoperative brace depends on the security of fixation and the presence of other, noncongenital curves in the spine (Fig. 158.12, Fig. 158.13). In the largest recently reported series (21), the mean final correction was 35%, and there were 16% neurologic complications, but only 3% were permanent.
Figure 158.13. Patient with congenital scoliosis due to thoracic hemivertebra, treated with anterior and posterior convex hemiepiphyseodesis. A: At age 4, immediately before surgery, the curve had progressed to 27°. B: At 6 years postoperatively, the curve has improved to 10°.
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THORACOLUMBAR LAMINOPLASTY VERSUS LAMINECTOMY
Spinal decompression in young people is most commonly indicated for tumor or for stenosis, as in achondroplasia. In both cases, the presence of mild preexisting kyphosis when there is remaining growth increases the risk of progression postoperatively. This is greatest at the cervicothoracic and thoracolumbar junctions. Progressive kyphosis may be prevented by performing a fusion at the time of decompression, or in some cases by performing a laminoplasty.
To accomplish a safe and effective decompression in achondroplasia, Uematsu et al. recommend a technique that involves minimal use of instruments in the canal (Fig. 158.14) (43). Spinal motor and sensory monitoring is helpful.
Figure 158.14. A 5-year-old girl with congenital scoliosis due to hemivertebra at <2. She has the VATER association. Her curve has progressed to 45°. Treatment by hemivertebra excision was selected because the hemivertebra is easily accessible and the patient is significantly off-balance. A: Preoperatively, the hemivertebra may be easily seen. B: Two years after excision and fusion, the patient is in much better balance.
  • Position the patient prone, taking care to reverse as much of the increased lumbar lordosis as possible.
  • Make bilateral laminar grooves just medial to the facets, using a high-speed burr.
  • Carry these down to the deep cortex, and gently lift off the laminae.
  • Preserve the facets if possible.
  • Perform the amount of length and width of decompression necessary.
  • A small (#10) rubber catheter should be able to pass centrally into the opening in the canal when the decompression is adequate.
  • Suture paraspinous muscles over the defect.
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If there is kyphosis more than 30° over the area to be decompressed, posterior (with possible anterior) fusion should be done as described previously. Even if no significant kyphosis is present preoperatively, it should be watched for postoperatively and fused if it develops. If laminoplasty is to be performed, the laminae with interspinous ligaments are elevated in one continuous strip, and reattached at the end with sutures into the adjacent facets, using bony “shims” if needed to elevate the laminae.
REFERENCES
Each reference is categorized according to the following scheme: 01, classic article; #, review article; !, basic research article; and +, clinical results/outcome study.
+ 1. Apel DM, Marrero G, King J, et al. Avoiding Paraplegia during Anterior Spine Surgery: The Role of Somatosensory Evoked Potential Monitoring with Temporary Occlusion of Segmental Spinal Arteries. Spine 1991;16(suppl):365.
# 2. Bassett GS, Scott CI Jr. The Osteochondrodysplasias. In: Morrissy RT, Weinstein SL, eds. Pediatric Orthopaedics, 4th ed. Philadelphia: Lippincott-Raven, 1996:203.
+ 3. Benson DR, Newman DC. The Spine and Surgical Treatment in Osteogenesis Imperfecta. Clin Orthop 1981;159:147.
+ 4. Bethem D, Winter RB, Lutter L, et al. Spinal Disorders of Dwarfism. J Bone Joint Surg Am 1981;63:1412.
+ 5. Bethem D, Winter RB, Lutter L. Disorders of the Spine in Diastrophic Dwarfism. J Bone Joint Surg Am 1980;62:529.
+ 6. Betz RR, Iorio R, Lombardi AV, et al. Scoliosis Surgery and Neurofibromatosis. Clin Orthop 1989;245:53.
+ 7. Birch JG, Herring JA. Spinal Deformity in Marfan Syndrome. J Pediatr Orthop 1987;7:546.
+ 8. Bradford DS, Boachie-Adjei O. One-Stage Anterior and Posterior Hemivertebral Resection and Arthrodesis for Congenital Scoliosis. J Bone Joint Surg Am 1990;72:536.
+ 9. Crawford AH. Pitfalls of Spinal Deformities Associated with Neurofibromatosis in Children. Clin Orthop 1989;245:29.
+ 10. Dormans JP, Criscitiello AA, Drummond DS, Davidson RS. Complications in Children Managed with Immobilization in a Halo Vest. J Bone Joint Surg Am 1995;77:1370.
+ 11. Dormans JP, Drummond DS, Sutton LN, et al. Occipitocervical Arthrodesis in Children: A New Technique and Analysis of Results. J Bone Joint Surg Am 1995;77:1234.
+ 12. Flood BM, Butt WP, Dickson RA. Rib Penetration of Intervertebral Foraminae in Neurofibromatosis. Spine 1986;11:172.
+ 13. Flynn JM, Otsuka NY, Emans JB, e al. Segmental Spinal Dysgenesis: Early Neurologic Deterioration and Treatment. J Pediatr Orthop 1997;17:100–104.
+ 14. Garfin SR, Roux R, Botte MJ, et al. Skull Osteology as It Affects Pin Placement. J Pediatr Orthop 1986;6:434.
+ 15. Graziano G, Herzenberg JE. Halo Ilizarov Distraction Cast for Correction of Cervical Deformity. Report of Six Cases. J Bone Joint Surg Am 1993;75:996.
# 16. Hanscom DA, Bloom BA. The Spine in Osteogenesis Imperfecta. Orthop Clin North Am 1988;19:449.
+ 17. Hensinger RN. Kyphosis Secondary to Skeletal Dysplasias and Metabolic Disease. Clin Orthop 1987;128:113.
# 18. Herring JA. The Spinal Disorders of Diastrophic Dwarfism. J Bone Joint Surg Am 1978;60:177.
+ 19. Herring JA. Kyphosis in an Achondroplastic Dwarf. J Pediatr Orthop 1982;3:250.
+ 20. Holt RT, Johnson R. Cotrel-Dubousset Instrumentation in Neurofibromatosis Spinal Curves. Clin Orthop 1989;245:19.
+ 21. Holte DC, Winter RB, Lonstein JE, Denis F. Excision of Hemivertebrae and Wedge Resection in the Treatment of Congenital Scoliosis. J Bone Joint Surg Am 1995;77:159.
+ 22. Johnston CE III, Birch JG, Daniels JL. Cervical Kyphosis in Patients Who Have Larsen Syndrome. J Bone Joint Surg Am 1996;78:538.
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