Treatment of Severe Pediatric Spinal Deformities Stephen J. Lewis, MD, MSc, FRCSC, Juan Jose Zamorano, MD, and Christina L. Goldstein, MD, FRCSC
Key Words: spine, severe spinal deformity, osteotomy, traction, neuromonitoring, alternative, fixation methods
the anteroposterior dimension of the mediastinum. The use of a thoracotomy seems paradoxical in these patients with respiratory dysfunction; however, the benefit of expanding the mediastinum and relieving the vertebral compression on the bronchial tree can provide significant respiratory improvement to this select group of patients.2,3 Spinal reconstructions for neuromuscular scoliosis may benefit from anterior release and fusions. Patients with spinal bifida have deficient posterior elements and require anterior surgery for fusion. This is generally done in conjunction with the posterior construct, wherein the correction and fixation can be obtained through the posterior procedure, and fusion of the bifid segments is achieved through the anterior approach. Although some cases of severe neuromuscular scoliosis with pelvic obliquity may benefit from anterior releases in conjunction with posterior correction, the authors prefer intraoperative traction with or without posterior column releases or osteotomies instead of anterior releases in cases with intact posterior elements.
(J Pediatr Orthop 2014;34:S1–S5)
Posterior Column Release
Abstract: The management of severe pediatric spinal deformities continues to evolve as advances in spinal instrumentation, surgical techniques, and neuromonitoring occur. The techniques of spinal osteotomies have been refined to allow surgeons to perform better corrections with less operative time, more safely, and through a posterior approach alone, making multiple patient positioning changes during surgery a less common occurrence. With these techniques comes a learning curve for the entire surgical team, wherein communication and planning can help minimize major complications and morbidity. This overview will review various techniques used in the correction of severe spinal deformities. Topics reviewed include the role of anterior release, traction, posterior releases, and osteotomies. Indications, techniques, and pitfalls will be reviewed. A clear understanding of the patient’s deformity, normal sagittal parameters, spinal anatomy, and the principles of neuromonitoring will help improve surgical planning and patient outcome.
RELEASES IN SEVERE DEFORMITIES Anterior Release Although anterior release for scoliotic curves >80 degrees was quite common with hook-based implant systems, the emergence of pedicle screw systems has improved corrections through a posterior-only approach.1 As a result, anterior release surgery is currently less commonly performed. Despite this, deformities associated with fixed lordosis remain a strong indication for anterior release. Fixed thoracic lordosis can narrow the mediastinum leading to bronchial obstruction and respiratory impairment.2 Similarly, fixed lumbar hyperlordosis has a negative effect on respiratory function and sitting balance (Fig. 1). Resection of the disks and anterior column shortening in combination with posterior correction can help optimize the sagittal plane, providing the required kyphosis to expand From the The Hospital for Sick Children, Toronto, ON, Canada. The authors declare no conflicts of interest. Reprints: Stephen J. Lewis, MD, MSc, FRCSC, The Hospital for Sick Children, S107 – Burton Wing, 555 University Ave, Toronto, ON, Canada M5G1X8. E-mail: [email protected]. Copyright r 2014 by Lippincott Williams & Wilkins
J Pediatr Orthop
Apical release of the posterior ligamentous structures including the ligamentum flavum, the interspinous ligaments, the facet capsule, and resection of the superior facets4 provides significant release of the curve. This release can be performed at multiple levels at the apex providing sufficient flexibility to maximize both coronal and sagittal plane correction.5 Distraction of the concavity during the decompression provides greater room for the Kerrison rongeur to safely decompress/release the rigid concave apex and remove the superior facets.
Traction Traction continues to play a role in severe spinal deformity. Preoperative traction can provide gradual release of the curve and facilitate correction during surgery. It requires an extended in-patient stay or a facility that can provide safe monitoring of these patients. Generally, a number of weeks are required to obtain the desired results before the index procedure.6 Intraoperative traction is another alternative to achieve release in rigid deformities.7 After induction of the anesthesia, skull tongs and distal femoral traction pins are placed intraoperatively, and weights are applied through the skull and distal femurs. Immediate correction is achieved (Fig. 2). Generally, up to 50% of body weight can be used. After an initial intraoperative radiograph,
Volume 34, Number 1 Supplement, October/November 2014
www.pedorthopaedics.com |
S1
Lewis et al
J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
FIGURE 1. Patient (A and C) and radiographs (B and D) of neuromuscular spinal deformity associated with severe hyperlordosis. Correction achieved (E–H) through anterior discectomies and posterior instrumented fusion supplemented with intraoperative skull-skeletal traction.
the weight is decreased during the exposure and screw placement, and increased back to 50% of body weight just before rod placement. An alternative method to traction involves the use of internal distraction through placement of temporary internal fixation anchors.8 Gradual distraction on the concavity provides correction of the curve, which complements the ultimate correction achieved through the main rods. In either case, correction of the deformity can be partially obtained before the final rods. Correction maneuvers including derotation, translation,
S2 | www.pedorthopaedics.com
and in situ bending, along with posterior column releases, can be added to achieve the final correction. The temporary traction is removed after rod placement. No preoperative traction is required with this method. Both of these methods have demonstrated excellent final correction without the need for anterior surgery. These methods, which stretch the spinal column, should not be used without accurate neuromonitoring.9 Motor evoked potentials (MEPs) provide real-time information on the status of the spinal cord and its function.10 It is r
2014 Lippincott Williams & Wilkins
J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
Treatment of Severe Spinal Deformities
FIGURE 2. Preoperative standing (A), benders (B and C), and lateral (F) of a patient with an 80-degree Lenke II curve. Intraoperative skull-skeletal traction (D) provides excellent correction before final instrumentation (E and G).
imperative that the MEPs are closely followed when utilizing these techniques so that appropriate adjustments in the traction or distraction can be made to maintain adequate spinal cord perfusion and function.9
SPINAL OSTEOTOMIES When the disks are mobile, posterior column releases can provide adequate release in combination with the posterior construct. However, in larger fixed
deformities, 3-column spinal osteotomies can provide the necessary correction.
Pedicle Subtraction Osteotomy (PSO) For predominantly sagittal plane deformities, the PSO can provide approximately 20 to 25 degrees of sagittal plane correction in the thoracic region and 30 to 35 degrees in the lumbar region.11 The PSO is a posteriorbased closing wedge osteotomy, in which the pedicles and complete posterior elements are resected along with a
FIGURE 3. Standing radiographs (A and B) of a patient with a 100-degree Scheuermann kyphosis. C and D, Correction following T2 to L2 posterior instrumentation with T8 pedicle subtraction osteotomy and T11-12 Smith Petersen Osteotomy. r
2014 Lippincott Williams & Wilkins
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J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
FIGURE 4. Clinical (A and E) and radiographs (B and F) of a 14-year-old boy with severe kyphoscoliosis. The patient was treated with a T10 vertebral column resection. Immediate postop clinicals (C and G) and 1-year radiographs (D and H) demonstrating good correction of the deformity.
triangular wedge of the vertebral body. Some offset to the osteotomy can be performed to allow for some coronal plane correction as well. The PSO is particularly useful in cases of severe Scheuermann kyphosis (Fig. 3), severe proximal junctional failure, and in other cases of severe kyphosis. The PSO does not rely on any change of length of the anterior column, so that correction can be achieved even when previous anterior fusions have been performed. For sagittal plane deformities with mobile anterior columns, the use of simpler osteotomies such as the Ponte12 or Smith Petersen (SPO)13 can be performed at multiple levels to achieve correction. Closing the osteotomies can be difficult in these rigid deformities. After the posterior resection, the use of a central rod with laminar hooks is very effective in reducing the osteotomy.14 A downgoing supralaminar hook is placed centrally on the lamina proximal to the osteotomy and an upgoing infralaminar hook is placed on the lamina distally. Gradual central compression provides powerful force to reduce the osteotomy and gain the desired sagittal correction. The use of the central rod is particularly helpful in cases of sagittal deformity. For coronal plane deformities, central compression will worsen the scoliosis, so convex rod closure would be preferable.
tebrae, the spinal cord will be draped over the concave pedicle, and extra care during dissection and removal of this pedicle is required. Once the concave release is performed, a temporary rod can be placed on this side, providing the necessary stability required during the convex resection. Once the vertebral body is removed, placement of an anterior graft, either a piece of the resected vertebral body or a cage, is placed in the ventral defect and the osteotomy is closed with posterior rods. The temporary concave rod is left in place with the set screws loosened to prevent translation, while the convex rod is placed. The authors prefer proximal to distal closure with a rod that is contoured in the desired sagittal plane, using cantilever as the primary reduction maneuver. Adjustments of the rod through compression and distraction and in situ bending are helpful. Use of distal reduction screws is another way of facilitating rod placement. Other described methods include using a 4-rod technique,17 whereby the proximal and distal ends are controlled through separate rods. The osteotomy is reduced and the rods are secured to each other with a side-to-side connector.
Vertebral Column Resection When multiplanar corrections are required, resection of the complete vertebral segment can provide the necessary apical mobility to allow for correction of the deformity (Fig. 4).15,16 Correction is achieved while allowing for some simultaneous shortening of the vertebral column to minimize the stretch on the spinal cord. In the thoracic region, the medial portion of the ribs including the rib heads should be removed to ensure the plane of dissection is in the prevertebral region and not the mediastinum. Once control of the ventral part of the vertebra is achieved, which is difficult on the concavity but relatively easy on the convexity of the curve, spoon retractors can be placed around the ventral body for ventral protection. After this, a posterior laminectomy and removal of the remaining posterior elements is performed. Releasing the proximal and distal disks provide the mobility to remove the vertebral body. With severely rotated ver-
S4 | www.pedorthopaedics.com
FIGURE 5. Axial computed tomography scan postoperatively demonstrating placement of a fusion mass screw in the posterior fusion mass at the level of L2 in a patient with Marfan syndrome. r
2014 Lippincott Williams & Wilkins
J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
Achieving fusion along the construct and at the osteotomy site remains a high priority. Leaving gaps in the posterior column can lead to pseudarthrosis and rod failure. Supplementing the fusion with structural grafts such as the local resected ribs18 or vertebra provide the required bridging of posterior column defects to achieve the necessary fusion.
Neuromonitoring in Severe Deformities MEPs are the key monitoring modality in severe deformities.10 Loss in amplitude in the MEPs alerts the surgeon to either injury or decrease in perfusion to the spinal cord. In all cases of MEP changes, the hemodynamic stability of the patient and the anesthetic agents being used should be addressed to rule out systemic causes for the changes. The timing of the loss of signal is very important.19 If the change occurs during placement of the fixation, the fixation should be removed or adjusted. If the MEP change occurs during decompression for the osteotomy, closing the osteotomy may decrease the tension on the spinal cord and improve perfusion. If the changes occur after osteotomy closure, the osteotomy should be reopened and adjustments in the decompression or the anterior cage should be made before reclosing the osteotomy. Somatosensory evoked potentials (SSEP) provide feedback on the function of the dorsal columns.10 The posterior cord is at risk to injury through placement of laminar hooks or wires, or by direct trauma, such as with translation at the osteotomy during closure. There may be a delay in the onset of SSEP changes and the timing of the injury, compared with the MEP, and this is typically a poor prognosis. The SSEPs do not provide information related to the perfusion of the spinal cord through the anterior spinal artery.
Alternative Fixation Options The anatomy in cases of severe deformities can be very atypical. Patients with various syndromes and previous fusions may have bony anatomy that precludes the use of pedicle screws. Alternative fixation options include sublaminar wires or polyethylene straps or hooks. Laminar or fusion mass hooks remain good alternatives (Fig. 5).20,21 For patients with thick laminae or fusion masses, pedicle screws placed across the lamina or fusion mass will provide excellent fixation to both reduce the deformity and maintain the correction over time. Careful preoperative planning of the computed tomography scans will alert the surgeon to levels of difficult fixation and determine whether some of the alternatives are feasible options.
CONCLUSIONS There are multiple surgical options in the treatment of severe spinal deformities. Traction and posterior column releases can provide excellent correction in the majority of cases with mobile anterior columns. Anterior release is especially useful in shortening the anterior column to provide correction in cases with fixed lordosis. Fixed sagittal deformities (kyphosis) can be effectively treated with pedicle subtraction osteotomies. Vertebral r
2014 Lippincott Williams & Wilkins
Treatment of Severe Spinal Deformities
column resection provides excellent multiplanar correction with spinal shortening, but carries risks of bleeding and neurological monitoring change. In all situations, a skilled and experienced surgical and perioperative team is key to the successful management of these complex patients. REFERENCES 1. Luhmann SJ, Lenke LG, Kim YJ, et al. Thoracic adolescent idiopathic scoliosis curves between 70 degrees and 100 degrees: is anterior release necessary? Spine. 2005;30:2061–2067. 2. Graham EJ, Lenke LG, Lowe TG, et al. Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis. Spine. 2000;25:2319–2325. 3. Lenke LG, Newton PO, Marks MC, et al. Prospective pulmonary function comparison of open versus endoscopic anterior fusion combined with posterior fusion in adolescent idiopathic scoliosis. Spine. 2004;29:2055–2060. 4. Shah SA, Dhawale AA, Oda JE, et al. Ponte osteotomies with pedicle screw instrumentation in the treatment of adolescent idiopathic scoliosis. Spine Deformity. 2013;1:196–204. 5. Sangiorgio SN, Borkowski SL, Bowen RE, et al. Quantification of increase in three-dimensional spine flexibility following sequential ponte osteotomies in a cadaveric model. Spine Deformity. 2013;1:171–178. 6. Watanabe K, Lenke LG, Bridwell KH, et al. Efficacy of perioperative halo-gravity traction for treatment of severe scoliosis (Z1001). J Orthop Sci. 2010;15:720–730. 7. Jhaveri SN, Zeller R, Miller S, et al. The effect of intra-operative skeletal (skull femoral) traction on apical vertebral rotation. Eur Spine J. 2008;18:352–356. 8. Buchowski JM, Bhatnagar R, Skaggs DL, et al. Temporary internal distraction as an aid to correction of severe scoliosis. J Bone Joint Surg Am. 2006;88:2035–2041. 9. Lewis SJ, Gray R, Holmes LM, et al. Neurophysiological changes in deformity correction of adolescent idiopathic scoliosis with intraoperative skull-femoral traction. Spine. 2011;36:1627–1638. 10. Luk KD, Hu Y, Wong YW, et al. Evaluation of various evoked potential techniques for spinal cord monitoring during scoliosis surgery. Spine. 2001;26:1772–1777. 11. Bridwell KH, Lewis SJ, Rinella A, et al. Pedicle subtraction osteotomy for the treatment of fixed sagittal imbalance. Surgical technique. J Bone Joint Surg Am. 2004;86-A(suppl 1):44–50. 12. Geck MJ, Macagno A, Ponte A, et al. The Ponte procedure: posterior only treatment of Scheuermann’s kyphosis using segmental posterior shortening and pedicle screw instrumentation. J Spinal Disord Tech. 2007;20:586–593. 13. Smith-Petersen MN, Larson CB, Aufranc OE. Osteotomy of the spine for correction of flexion deformity in rheumatoid arthritis. Clin Orthop Relat Res. 1969;66:6–9. 14. Watanabe K, Lenke LG, Daubs MD, et al. A central hook-rod construct for osteotomy closure: a technical note. Spine. 2008;33:1149–1155. 15. Suk S-I, Chung E-R, Kim J-H, et al. Posterior vertebral column resection for severe rigid scoliosis. Spine. 2005;30:1682–1687. 16. Lenke LG, O’Leary PT, Bridwell KH, et al. Posterior vertebral column resection for severe pediatric deformity: minimum two-year follow-up of thirty-five consecutive patients. Spine. 2009;34:2213–2221. 17. Javidan P, Kabirian N, Mundis GM Jr, et al. Delayed postoperative neurological complication in a patient with congenital kyphoscoliosis: recovered by revision of the 4-rod instrumentation technique. J Neurosurg Spine. 2013;19:595–599. 18. Lewis SJ, Kulkarni AG, Rampersaud YR, et al. Posterior column reconstruction with autologous rib graft after en bloc tumor excision. Spine. 2012;37:346–350. 19. Jarvis JG, Strantzas S, Lipkus M, et al. Responding to neuromonitoring changes in 3-column posterior spinal osteotomies for rigid pediatric spinal deformities. Spine. 2013;38:E493–E503. 20. Lewis SJ, Canavese F, Keetbaas S. Intralaminar screw insertion of thoracic spine in children with severe spinal deformities: two case reports. Spine. 2009;34:E251–E254. 21. Lewis SJ, Arun R, Bodrogi A, et al. The use of fusion mass screws in revision spinal deformity surgery. Eur Spine J. 2014;23(suppl 2):181–186.
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Key Words: spine, severe spinal deformity, osteotomy, traction, neuromonitoring, alternative, fixation methods
the anteroposterior dimension of the mediastinum. The use of a thoracotomy seems paradoxical in these patients with respiratory dysfunction; however, the benefit of expanding the mediastinum and relieving the vertebral compression on the bronchial tree can provide significant respiratory improvement to this select group of patients.2,3 Spinal reconstructions for neuromuscular scoliosis may benefit from anterior release and fusions. Patients with spinal bifida have deficient posterior elements and require anterior surgery for fusion. This is generally done in conjunction with the posterior construct, wherein the correction and fixation can be obtained through the posterior procedure, and fusion of the bifid segments is achieved through the anterior approach. Although some cases of severe neuromuscular scoliosis with pelvic obliquity may benefit from anterior releases in conjunction with posterior correction, the authors prefer intraoperative traction with or without posterior column releases or osteotomies instead of anterior releases in cases with intact posterior elements.
(J Pediatr Orthop 2014;34:S1–S5)
Posterior Column Release
Abstract: The management of severe pediatric spinal deformities continues to evolve as advances in spinal instrumentation, surgical techniques, and neuromonitoring occur. The techniques of spinal osteotomies have been refined to allow surgeons to perform better corrections with less operative time, more safely, and through a posterior approach alone, making multiple patient positioning changes during surgery a less common occurrence. With these techniques comes a learning curve for the entire surgical team, wherein communication and planning can help minimize major complications and morbidity. This overview will review various techniques used in the correction of severe spinal deformities. Topics reviewed include the role of anterior release, traction, posterior releases, and osteotomies. Indications, techniques, and pitfalls will be reviewed. A clear understanding of the patient’s deformity, normal sagittal parameters, spinal anatomy, and the principles of neuromonitoring will help improve surgical planning and patient outcome.
RELEASES IN SEVERE DEFORMITIES Anterior Release Although anterior release for scoliotic curves >80 degrees was quite common with hook-based implant systems, the emergence of pedicle screw systems has improved corrections through a posterior-only approach.1 As a result, anterior release surgery is currently less commonly performed. Despite this, deformities associated with fixed lordosis remain a strong indication for anterior release. Fixed thoracic lordosis can narrow the mediastinum leading to bronchial obstruction and respiratory impairment.2 Similarly, fixed lumbar hyperlordosis has a negative effect on respiratory function and sitting balance (Fig. 1). Resection of the disks and anterior column shortening in combination with posterior correction can help optimize the sagittal plane, providing the required kyphosis to expand From the The Hospital for Sick Children, Toronto, ON, Canada. The authors declare no conflicts of interest. Reprints: Stephen J. Lewis, MD, MSc, FRCSC, The Hospital for Sick Children, S107 – Burton Wing, 555 University Ave, Toronto, ON, Canada M5G1X8. E-mail: [email protected]. Copyright r 2014 by Lippincott Williams & Wilkins
J Pediatr Orthop
Apical release of the posterior ligamentous structures including the ligamentum flavum, the interspinous ligaments, the facet capsule, and resection of the superior facets4 provides significant release of the curve. This release can be performed at multiple levels at the apex providing sufficient flexibility to maximize both coronal and sagittal plane correction.5 Distraction of the concavity during the decompression provides greater room for the Kerrison rongeur to safely decompress/release the rigid concave apex and remove the superior facets.
Traction Traction continues to play a role in severe spinal deformity. Preoperative traction can provide gradual release of the curve and facilitate correction during surgery. It requires an extended in-patient stay or a facility that can provide safe monitoring of these patients. Generally, a number of weeks are required to obtain the desired results before the index procedure.6 Intraoperative traction is another alternative to achieve release in rigid deformities.7 After induction of the anesthesia, skull tongs and distal femoral traction pins are placed intraoperatively, and weights are applied through the skull and distal femurs. Immediate correction is achieved (Fig. 2). Generally, up to 50% of body weight can be used. After an initial intraoperative radiograph,
Volume 34, Number 1 Supplement, October/November 2014
www.pedorthopaedics.com |
S1
Lewis et al
J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
FIGURE 1. Patient (A and C) and radiographs (B and D) of neuromuscular spinal deformity associated with severe hyperlordosis. Correction achieved (E–H) through anterior discectomies and posterior instrumented fusion supplemented with intraoperative skull-skeletal traction.
the weight is decreased during the exposure and screw placement, and increased back to 50% of body weight just before rod placement. An alternative method to traction involves the use of internal distraction through placement of temporary internal fixation anchors.8 Gradual distraction on the concavity provides correction of the curve, which complements the ultimate correction achieved through the main rods. In either case, correction of the deformity can be partially obtained before the final rods. Correction maneuvers including derotation, translation,
S2 | www.pedorthopaedics.com
and in situ bending, along with posterior column releases, can be added to achieve the final correction. The temporary traction is removed after rod placement. No preoperative traction is required with this method. Both of these methods have demonstrated excellent final correction without the need for anterior surgery. These methods, which stretch the spinal column, should not be used without accurate neuromonitoring.9 Motor evoked potentials (MEPs) provide real-time information on the status of the spinal cord and its function.10 It is r
2014 Lippincott Williams & Wilkins
J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
Treatment of Severe Spinal Deformities
FIGURE 2. Preoperative standing (A), benders (B and C), and lateral (F) of a patient with an 80-degree Lenke II curve. Intraoperative skull-skeletal traction (D) provides excellent correction before final instrumentation (E and G).
imperative that the MEPs are closely followed when utilizing these techniques so that appropriate adjustments in the traction or distraction can be made to maintain adequate spinal cord perfusion and function.9
SPINAL OSTEOTOMIES When the disks are mobile, posterior column releases can provide adequate release in combination with the posterior construct. However, in larger fixed
deformities, 3-column spinal osteotomies can provide the necessary correction.
Pedicle Subtraction Osteotomy (PSO) For predominantly sagittal plane deformities, the PSO can provide approximately 20 to 25 degrees of sagittal plane correction in the thoracic region and 30 to 35 degrees in the lumbar region.11 The PSO is a posteriorbased closing wedge osteotomy, in which the pedicles and complete posterior elements are resected along with a
FIGURE 3. Standing radiographs (A and B) of a patient with a 100-degree Scheuermann kyphosis. C and D, Correction following T2 to L2 posterior instrumentation with T8 pedicle subtraction osteotomy and T11-12 Smith Petersen Osteotomy. r
2014 Lippincott Williams & Wilkins
www.pedorthopaedics.com |
S3
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J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
FIGURE 4. Clinical (A and E) and radiographs (B and F) of a 14-year-old boy with severe kyphoscoliosis. The patient was treated with a T10 vertebral column resection. Immediate postop clinicals (C and G) and 1-year radiographs (D and H) demonstrating good correction of the deformity.
triangular wedge of the vertebral body. Some offset to the osteotomy can be performed to allow for some coronal plane correction as well. The PSO is particularly useful in cases of severe Scheuermann kyphosis (Fig. 3), severe proximal junctional failure, and in other cases of severe kyphosis. The PSO does not rely on any change of length of the anterior column, so that correction can be achieved even when previous anterior fusions have been performed. For sagittal plane deformities with mobile anterior columns, the use of simpler osteotomies such as the Ponte12 or Smith Petersen (SPO)13 can be performed at multiple levels to achieve correction. Closing the osteotomies can be difficult in these rigid deformities. After the posterior resection, the use of a central rod with laminar hooks is very effective in reducing the osteotomy.14 A downgoing supralaminar hook is placed centrally on the lamina proximal to the osteotomy and an upgoing infralaminar hook is placed on the lamina distally. Gradual central compression provides powerful force to reduce the osteotomy and gain the desired sagittal correction. The use of the central rod is particularly helpful in cases of sagittal deformity. For coronal plane deformities, central compression will worsen the scoliosis, so convex rod closure would be preferable.
tebrae, the spinal cord will be draped over the concave pedicle, and extra care during dissection and removal of this pedicle is required. Once the concave release is performed, a temporary rod can be placed on this side, providing the necessary stability required during the convex resection. Once the vertebral body is removed, placement of an anterior graft, either a piece of the resected vertebral body or a cage, is placed in the ventral defect and the osteotomy is closed with posterior rods. The temporary concave rod is left in place with the set screws loosened to prevent translation, while the convex rod is placed. The authors prefer proximal to distal closure with a rod that is contoured in the desired sagittal plane, using cantilever as the primary reduction maneuver. Adjustments of the rod through compression and distraction and in situ bending are helpful. Use of distal reduction screws is another way of facilitating rod placement. Other described methods include using a 4-rod technique,17 whereby the proximal and distal ends are controlled through separate rods. The osteotomy is reduced and the rods are secured to each other with a side-to-side connector.
Vertebral Column Resection When multiplanar corrections are required, resection of the complete vertebral segment can provide the necessary apical mobility to allow for correction of the deformity (Fig. 4).15,16 Correction is achieved while allowing for some simultaneous shortening of the vertebral column to minimize the stretch on the spinal cord. In the thoracic region, the medial portion of the ribs including the rib heads should be removed to ensure the plane of dissection is in the prevertebral region and not the mediastinum. Once control of the ventral part of the vertebra is achieved, which is difficult on the concavity but relatively easy on the convexity of the curve, spoon retractors can be placed around the ventral body for ventral protection. After this, a posterior laminectomy and removal of the remaining posterior elements is performed. Releasing the proximal and distal disks provide the mobility to remove the vertebral body. With severely rotated ver-
S4 | www.pedorthopaedics.com
FIGURE 5. Axial computed tomography scan postoperatively demonstrating placement of a fusion mass screw in the posterior fusion mass at the level of L2 in a patient with Marfan syndrome. r
2014 Lippincott Williams & Wilkins
J Pediatr Orthop
Volume 34, Number 1 Supplement, October/November 2014
Achieving fusion along the construct and at the osteotomy site remains a high priority. Leaving gaps in the posterior column can lead to pseudarthrosis and rod failure. Supplementing the fusion with structural grafts such as the local resected ribs18 or vertebra provide the required bridging of posterior column defects to achieve the necessary fusion.
Neuromonitoring in Severe Deformities MEPs are the key monitoring modality in severe deformities.10 Loss in amplitude in the MEPs alerts the surgeon to either injury or decrease in perfusion to the spinal cord. In all cases of MEP changes, the hemodynamic stability of the patient and the anesthetic agents being used should be addressed to rule out systemic causes for the changes. The timing of the loss of signal is very important.19 If the change occurs during placement of the fixation, the fixation should be removed or adjusted. If the MEP change occurs during decompression for the osteotomy, closing the osteotomy may decrease the tension on the spinal cord and improve perfusion. If the changes occur after osteotomy closure, the osteotomy should be reopened and adjustments in the decompression or the anterior cage should be made before reclosing the osteotomy. Somatosensory evoked potentials (SSEP) provide feedback on the function of the dorsal columns.10 The posterior cord is at risk to injury through placement of laminar hooks or wires, or by direct trauma, such as with translation at the osteotomy during closure. There may be a delay in the onset of SSEP changes and the timing of the injury, compared with the MEP, and this is typically a poor prognosis. The SSEPs do not provide information related to the perfusion of the spinal cord through the anterior spinal artery.
Alternative Fixation Options The anatomy in cases of severe deformities can be very atypical. Patients with various syndromes and previous fusions may have bony anatomy that precludes the use of pedicle screws. Alternative fixation options include sublaminar wires or polyethylene straps or hooks. Laminar or fusion mass hooks remain good alternatives (Fig. 5).20,21 For patients with thick laminae or fusion masses, pedicle screws placed across the lamina or fusion mass will provide excellent fixation to both reduce the deformity and maintain the correction over time. Careful preoperative planning of the computed tomography scans will alert the surgeon to levels of difficult fixation and determine whether some of the alternatives are feasible options.
CONCLUSIONS There are multiple surgical options in the treatment of severe spinal deformities. Traction and posterior column releases can provide excellent correction in the majority of cases with mobile anterior columns. Anterior release is especially useful in shortening the anterior column to provide correction in cases with fixed lordosis. Fixed sagittal deformities (kyphosis) can be effectively treated with pedicle subtraction osteotomies. Vertebral r
2014 Lippincott Williams & Wilkins
Treatment of Severe Spinal Deformities
column resection provides excellent multiplanar correction with spinal shortening, but carries risks of bleeding and neurological monitoring change. In all situations, a skilled and experienced surgical and perioperative team is key to the successful management of these complex patients. REFERENCES 1. Luhmann SJ, Lenke LG, Kim YJ, et al. Thoracic adolescent idiopathic scoliosis curves between 70 degrees and 100 degrees: is anterior release necessary? Spine. 2005;30:2061–2067. 2. Graham EJ, Lenke LG, Lowe TG, et al. Prospective pulmonary function evaluation following open thoracotomy for anterior spinal fusion in adolescent idiopathic scoliosis. Spine. 2000;25:2319–2325. 3. Lenke LG, Newton PO, Marks MC, et al. Prospective pulmonary function comparison of open versus endoscopic anterior fusion combined with posterior fusion in adolescent idiopathic scoliosis. Spine. 2004;29:2055–2060. 4. Shah SA, Dhawale AA, Oda JE, et al. Ponte osteotomies with pedicle screw instrumentation in the treatment of adolescent idiopathic scoliosis. Spine Deformity. 2013;1:196–204. 5. Sangiorgio SN, Borkowski SL, Bowen RE, et al. Quantification of increase in three-dimensional spine flexibility following sequential ponte osteotomies in a cadaveric model. Spine Deformity. 2013;1:171–178. 6. Watanabe K, Lenke LG, Bridwell KH, et al. Efficacy of perioperative halo-gravity traction for treatment of severe scoliosis (Z1001). J Orthop Sci. 2010;15:720–730. 7. Jhaveri SN, Zeller R, Miller S, et al. The effect of intra-operative skeletal (skull femoral) traction on apical vertebral rotation. Eur Spine J. 2008;18:352–356. 8. Buchowski JM, Bhatnagar R, Skaggs DL, et al. Temporary internal distraction as an aid to correction of severe scoliosis. J Bone Joint Surg Am. 2006;88:2035–2041. 9. Lewis SJ, Gray R, Holmes LM, et al. Neurophysiological changes in deformity correction of adolescent idiopathic scoliosis with intraoperative skull-femoral traction. Spine. 2011;36:1627–1638. 10. Luk KD, Hu Y, Wong YW, et al. Evaluation of various evoked potential techniques for spinal cord monitoring during scoliosis surgery. Spine. 2001;26:1772–1777. 11. Bridwell KH, Lewis SJ, Rinella A, et al. Pedicle subtraction osteotomy for the treatment of fixed sagittal imbalance. Surgical technique. J Bone Joint Surg Am. 2004;86-A(suppl 1):44–50. 12. Geck MJ, Macagno A, Ponte A, et al. The Ponte procedure: posterior only treatment of Scheuermann’s kyphosis using segmental posterior shortening and pedicle screw instrumentation. J Spinal Disord Tech. 2007;20:586–593. 13. Smith-Petersen MN, Larson CB, Aufranc OE. Osteotomy of the spine for correction of flexion deformity in rheumatoid arthritis. Clin Orthop Relat Res. 1969;66:6–9. 14. Watanabe K, Lenke LG, Daubs MD, et al. A central hook-rod construct for osteotomy closure: a technical note. Spine. 2008;33:1149–1155. 15. Suk S-I, Chung E-R, Kim J-H, et al. Posterior vertebral column resection for severe rigid scoliosis. Spine. 2005;30:1682–1687. 16. Lenke LG, O’Leary PT, Bridwell KH, et al. Posterior vertebral column resection for severe pediatric deformity: minimum two-year follow-up of thirty-five consecutive patients. Spine. 2009;34:2213–2221. 17. Javidan P, Kabirian N, Mundis GM Jr, et al. Delayed postoperative neurological complication in a patient with congenital kyphoscoliosis: recovered by revision of the 4-rod instrumentation technique. J Neurosurg Spine. 2013;19:595–599. 18. Lewis SJ, Kulkarni AG, Rampersaud YR, et al. Posterior column reconstruction with autologous rib graft after en bloc tumor excision. Spine. 2012;37:346–350. 19. Jarvis JG, Strantzas S, Lipkus M, et al. Responding to neuromonitoring changes in 3-column posterior spinal osteotomies for rigid pediatric spinal deformities. Spine. 2013;38:E493–E503. 20. Lewis SJ, Canavese F, Keetbaas S. Intralaminar screw insertion of thoracic spine in children with severe spinal deformities: two case reports. Spine. 2009;34:E251–E254. 21. Lewis SJ, Arun R, Bodrogi A, et al. The use of fusion mass screws in revision spinal deformity surgery. Eur Spine J. 2014;23(suppl 2):181–186.
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