AUTHOR AND EDITOR INFORMATION

Section 1 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

INTRODUCTION

Section 2 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Kyphosis refers to the normal apical-dorsal sagittal contour of the thoracic and sacral spine. As a pathologic entity, kyphosis is an accentuation of this normal curvature. Kyphosis can occur as a deformity solely in the sagittal plane, or it can occur in association with an abnormality in the coronal plane, resulting in kyphoscoliosis. Many potential etiologies of kyphosis have been identified.

Problem

Normal kyphosis is defined as a Cobb angle of 20-40° measured from T2-T12.

Pathologic kyphosis can affect the cervical and lumbar spine as well the thoracic spine, but cervical and lumbar involvement is uncommon. Any kyphosis in these areas is abnormal.

Kyphosis can cause pain and potentially lead to neurologic deficit and abnormal cardiopulmonary function.

Etiology

Many potential causes of kyphosis have been described.¹ Scheuermann disease and postural round back are often identified in adolescents.^{2, 3, 4} Congenital abnormalities, such as failure of formation or failure of segmentation of the spinal elements, can cause a pathologic kyphosis. Autoimmune arthropathy, such as ankylosing spondylitis, can cause rigid kyphosis to develop as the spinal elements coalesce. Kyphosis can also develop as a result of trauma, a spinal tumor, or an infection. Iatrogenic causes of kyphosis include the effects of laminectomy and irradiation, which lead to incompetence of the anterior or posterior column. Finally, metabolic disorders and dwarfing conditions can lead to kyphosis.

This article focuses on kyphosis due to Scheuermann disease and postural, postinfectious, posttraumatic, or iatrogenic etiologies.

Pathophysiology

The pathophysiology of kyphosis depends on the etiologic factor. The exact cause of Scheuermann disease is still imprecisely defined. Scheuermann postulated that the condition resulted from avascular necrosis of the apophyseal ring. Other theories include histologic abnormalities at the endplate, osteoporosis, and mechanical factors that affect spinal growth.⁵  A Danish study demonstrated an important genetic component to the entity.⁶

Postural kyphosis is present when accentuated kyphosis is observed without the characteristic 5° of wedging over 3 consecutive vertebral segments that defines Scheuermann kyphosis.⁷  This is felt to be due to muscular imbalance leading to the round-back appearance of these individuals.

When focal kyphosis occurs after a fracture, more height is lost in the anterior aspect than in the posterior aspect; this is the typical fracture pattern. The angulation can increase as the fracture heals, placing pressure on the spinal cord. Patients with fractures have historically been treated with laminectomy alone, especially in the thoracic spine, and they often had progressive kyphosis at the fracture site.⁸

Postinfectious kyphosis occurs in a manner similar to that just described. Mechanical integrity of the anterior column is lost due to the infectious process. Bending forces then accentuate the normal sagittal contour.

Related eMedicine topics:
Scheuermann Kyphosis
Lower Cervical Spine (C3-T1), Trauma
Lumbar Spine, Trauma
Thoracic Spine, Trauma
Upper Cervical Spine, Trauma

Related Medscape topics:
The Medscape Medical Minute - MRI Is the New Gold Standard for Excluding Cervical Spine Injury in Patients With Blunt Trauma
CME  Computed Tomography Improves Detection of Cervical Spine Injuries
Resource Center Spinal Disorders

Clinical

Patients with a symptomatic kyphosis often present with axial back pain. They may also be concerned about the cosmesis of their rounded back.

Patients with kyphosis should be carefully questioned about and examined for neurologic problems, especially myelopathy. Difficulty with gait and hyperreflexia should prompt further investigation of the kyphosis.

A 10- to 42-year, natural-history study of Scheuermann disease revealed that patients, as compared with a control group, tended to have increased back pain.⁹ However, they were not more likely than the control group to take pain medication, to have sedentary jobs, or to lose motion of the spine. The investigators found no differences in educational level, absenteeism, self-consciousness, or reports of numbness in the legs. Of interest, restrictive lung disease was observed in patients with a curve greater than 100°.

INDICATIONS

Section 3 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Indications for treatment of kyphosis include unremitting pain, neurologic changes, progression of deformity, and cosmesis.⁵ Indications for surgical treatment of Scheuermann kyphosis have changed fairly substantially; however, precise indicators have not been elucidated.

Authors from early clinical series simply cited pain or deformity as reasons to perform fusion. Proposed indications more specific than these are kyphosis greater than 75°, kyphosis greater than 65° with pain, and an unacceptable appearance of the trunk.¹⁰

Other possible indications in severely affected patients are problems with balance while sitting and skin problems due to pressure at the apex of the deformity.

Surgical intervention for posttraumatic kyphosis is recommended if the patient's neurologic status changes, if the condition progresses, if the kyphosis is 30° or more, or if the loss of anterior vertebral height is more than 50%.¹¹

RELEVANT ANATOMY

Section 4 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Detailed working knowledge of the anatomy of the spine is essential for the treatment of kyphosis.

CONTRAINDICATIONS

Section 5 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Contraindications to surgery for kyphosis include a clinically significant cardiopulmonary risk and medical unfitness for surgery.

WORKUP

Section 6 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Lab Studies

• Standard laboratory results should be evaluated whenever surgical intervention is being considered. The laboratory workup should include determination of a complete blood count, coagulation studies, and routine chemical analyses.
• Autodonation of blood can be recommended to the patient in anticipation of the need for intraoperative transfusion.
• In patients with a known or suspected infectious etiology, the sedimentation rate and C-reactive protein level should be measured to help identify a potential infection or to help track the progress of treatment.
• Before a major operation, the patient's nutritional status might also be checked, because it considerably influences a patient's ability to heal.

Imaging Studies

Radiography

Radiographs are crucial for both diagnosing kyphosis and for planning treatment.

The most useful radiographs are upright posteroanterior and lateral images of the entire spine. These views enable the reviewer to assess the sagittal balance of the entire spine and to determine if a scoliosis is present.

Measurements are made on radiographs by using the standard Cobb technique for scoliosis, which has been adapted to the measurement of kyphosis. Thoracic kyphosis is measured from T1-T12, though the upper thoracic vertebral endplates are often difficult to see. Normal measurements for thoracic spine vary widely, but the accepted definition of normal according to the Scoliosis Research Society is 20-40°. A plumb line dropped from C7 should pass through or just anterior to S1 on a lateral full-length image. This technique helps in assessing and quantifying the patient's overall sagittal alignment.

Radiographs obtained with the patient in a supine lateral hyperextension position over a bolster can be used to determine the flexibility of the curve. This information is useful in surgical planning. A flexible curve is best corrected with only posterior fusion, whereas an anterior only or combined anterior and posterior procedure may be needed for a stiff curve. A curve that corrects to 50° or less on hyperextension can be treated with posterior-only fusion.^{12, 13} Postural kyphosis is rarely more than 60°, and it should correct to normal with hyperextension.

Magnetic resonance imaging

MRI can be a useful adjunct in planning treatment for patients with kyphosis. If a neurologic abnormality is present, MRI may aid in localizing impingement on neural structures.

If surgery is being planned for the treatment of postinfectious kyphosis, an MRI helps in planning an anterior approach with regard to the amount of resection needed (if any) to remove diseased bone.

Other Tests

Ensuring the adequacy of bone density is imperative when surgical correction of kyphosis is being considered. Correction of the kyphosis relies on instrumentation to reduce the spine, and considerable forces are placed on the instrumentation-bone interface. Osteopenic bone can predispose to loss of correction over time, if the instrumentation cuts through the relatively less dense vertebrae. If a patient's bone density is in question, bone densitometry can be perform to quantify it. Efforts should be made to a patient's improve bone density before and following surgery. When bone density is poor, the surgeon must usually increase the number of points of fixation to reduce the stress at each point.

TREATMENT

Section 7 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Medical therapy

Medical therapy for kyphosis consists of exercise, medication, and bracing. Physical therapy, which usually consists of extension-focused activities, may be of some benefit; however, this has not been proven.¹⁰

Medications to treat discomfort associated with kyphosis should be limited to nonsteroidal anti-inflammatory drugs and, possibly, muscle relaxants. Narcotics should be avoided as long-term treatment of pain associated with kyphosis.

If a patient has an active infection, such as diskitis or vertebral osteomyelitis, appropriate antibiotics based on culture results should be started as soon as possible.

Bracing is effective in some skeletally immature patients with Scheuermann kyphosis. However, the correction obtained may diminish as patients approach and pass skeletal maturity. Treatment with a Milwaukee brace improved deformity in 76 of 120 (63%) patients who wore the brace regularly. Brace treatment seemed to be least effective when the curve was more than 74° at the beginning of treatment.¹⁴ Bradford et al reported modest success in treating adults with a brace, with some correction of their deformities.¹³ As far as the present authors are aware, no other reports of brace treatment in adults with kyphosis have been published.

Surgical therapy

Surgical planning for kyphosis is crucial to a successful operation. The goal of surgery is to correct the deformity and remove any neural compression, if present. The correction can be done anteriorly, posteriorly, or both. Posterior surgery is most commonly described and performed. Posterior arthrodesis for kyphosis can be an extensive operation, with many spinal segments typically included in the fusion mass. This procedure is most helpful for long, sweeping, flexible curves. In cases of rigid deformity, osteotomies can be performed to improve the correction.

Smith-Peterson osteotomy, pedicle subtraction osteotomy, and vertebral column resection

Specific osteotomies are aggressive facetectomies at each level, Smith-Peterson osteotomy, pedicle subtraction osteotomy, and vertebral column resection.

Smith-Peterson osteotomy is wedge-shaped resection of posterior elements from the pedicles of the superior vertebra to the pedicles of the inferior vertebra. When closed posteriorly, the spine hinges on the disk space; therefore, an open, mobile disk is crucial to the success of this procedure. Smith-Peterson osteotomy can be performed at 1 or multiple levels, if necessary. This allows for significant correction, approximately 1 mm of resection yielding 1° of lordosis.¹ Some recommend anterior diskectomy and fusion with Smith-Peterson osteotomy to decrease the pseudarthrosis rate.^{15, 16}

Pedicle-subtraction osteotomy is relatively aggressive resection of a wedge of bone, including posterior elements, the pedicles, and the vertebral body.¹⁷

Vertebral column resection entails removal of posterior elements, the vertebral body, and adjacent disk material. Both anterior and posterior fixation are often required because of the destabilizing effect of this resection.

As kyphosis becomes notably sharp and/or focal, increasingly aggressive techniques are required for correction. Cho et al demonstrated that the corrections per segment were 10.7° for Smith-Peterson osteotomy and 31.7° for pedicle subtraction osteotomy.¹⁸ Procedures involving the anterior column are usually followed by posterior instrumentation and fusion.

Anterior surgery

Anterior surgery can include single or multiple diskectomies to increase the flexibility of the spine, followed by a posterior arthrodesis. The transthoracic approach allows for decompression of the neural elements before the spine is corrected with posterior instrumentation. Anterior-only fusion is most useful in relatively short and focal kyphosis, such as posttraumatic or postinfectious kyphosis.¹²

A novel technique for single-curve scoliosis may also be used to correct kyphosis. The bone-on-bone technique involves an anterior-only approach to perform complete annulectomy and diskectomy at each level in the Cobb angle of the deformity. Then, using sequential compression along 2 rods, which are affixed with a staple and 2 screws in each vertebral level, the surgeon brings the bony endplates into immediate contact. Substantial correction can be achieved in this manner.¹⁹

Preoperative details

Patients with kyphosis may have subtle neurologic abnormalities that are easily missed during examination. MRI of the affected area can help in determining if decompression is necessary before instrumentation and correction of the deformity.

Selection of the fusion level is important. The proximal level is usually the most cranial vertebra rotated into the kyphosis. In the distal aspect, the fusion is extended to the last lordotic segment. Recommended correction should not exceed 50%, to prevent junctional kyphosis at the ends of the fusion.²⁰

Intraoperative details

The spinal cord and its roots are at risk during correction of kyphosis, especially when the canal is stenotic or when the cord is tethered at the apex of the kyphosis. In these situations, consider performing anterior decompression before the posterior arthrodesis. The cord is also at risk for ischemia if blood flow is altered with the change in spinal alignment.¹

Manipulation of the spinal cord, especially during osteotomies in the thoracic spine, should be avoided. Evidence suggests that the lower lumbar roots are vulnerable during pedicle subtraction osteotomy, more than the upper lumbar roots are.²¹ Pay careful attention to the removal of posterior bone and ligament, which may buckle into the canal as the osteotomy is closed. Thorough central decompression is recommended to help prevent neurologic compromise. Subluxation of the spine can also occur when an osteotomy is being closed; therefore, intraoperative radiography is essential to rapidly identify and correct subluxation.

Neural monitoring may be helpful for identifying correctable neurologic injury before the case is concluded. Monitoring of somatosensory and motor evoked potential can be helpful in detecting reversible neural injury due to stretching during correction of deformity or misplaced devices, for example. However, neural monitoring may not be useful with isolated root injuries.^{15, 16} A wake-up test can also be performed to assess the patient's gross motor function after the deformity is corrected.

Blood loss can be clinically significant during correction of kyphosis, especially if anterior procedures and large osteotomies are being performed. Bleeding should be controlled at every step of the operation to keep overall loss to a minimum. Clinically significant blood loss can cause hypotension and potentially injure the spinal cord, myocardium, and/or retina.

In terms of intraoperative considerations related to instrumentation, ensure that the substantial cantilever force applied to the spine with posterior instrumentation is spread over multiple levels. In the thoracic spine, sublaminar wires, hooks, or screws can be used. With hooks, multiple claws on each side are usually recommended. Some surgeons have applied thoracic pedicle screws to spread the force throughout each vertebra that receives instrumentation. Pedicle screws are also useful with aggressive osteotomies, which tend to destabilize the spine. Segmental fixation increases the surgeon's control over the coronal plane, where a deformity can coexist with a sagittal deformity.^{1, 22, 23}

In the lumbar spine, pedicle screws are most often used for the reasons just mentioned. Osteoporosis should be addressed with multiple points of posterior fixation, and maintain a low threshold for performing concomitant anterior fusion. This approach may help to prevent implant pull-out or postoperative collapse and loss of correction.

Postoperative details

Patients usually require clinically significant pain medication after undergoing correction of kyphosis, especially extensive procedures. The amount of narcotics given should be carefully titrated because the drugs may cause ileus, atelectasis, and/or difficulty in mobilizing the patient after surgery.

The patient should be monitored for anemia, as blood losses can be substantial. Electrolytes should be checked as well, as notable fluid shifts are common in the perioperative period.

Careful postoperative neurologic examination is important to identify any changes from the patient's preoperative status.²⁴

Follow-up

Standing posteroanterior and lateral full-length radiographs of the spine should be obtained as soon as possible after surgery and serially for follow-up. Full-length scoliosis films obtained yearly allow evaluation of the patient's curve over time.  Comparison of the postoperative and follow-up images with the preoperative images helps in defining the amount of correction achieved and in determining if correction is being lost over time. Loss of correction should prompt a careful evaluation for implant pull-out or breakage, for subsidence of an anterior strut (if any), or for the lack of adequate fusion mass.²⁵

Postoperative measurements of the C7 plumb line should be at or within a few centimeters of S1.

COMPLICATIONS

Section 8 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Possible complications of treatment range from superficial wound infection to complete neurologic injury. The nervous system is at risk with correction because of direct manipulation, traction, or compression resulting from the altered anatomy of the spine. In addition, blood flow to the cord or roots can be impeded. Neurologic changes are most often transient. However, transience cannot be assumed if a new deficit is identified postoperatively. Imaging of the spine should be done to identify any reversible cause of the deficit, and, if identified, the cause should be addressed rapidly. Removing the fixation and allowing the kyphosis to settle may help relieve cord compromise.

Intraoperative blood loss can be clinically significant. Blood losses put the patient at risk for transfusion, hypotension, ischemia to critical tissues, and potentially death. Therefore, careful attention to blood loss is essential.

Mechanical complications are possible as well. Pseudarthrosis can occur, especially with long fusions, inadequate support of the anterior column, and fusions at the thoracolumbar junction.²⁶ Other risk factors in long fusions to treat scoliosis include age greater than 55 years,²⁷ thoracolumbar kyphosis greater than 20°, and fusion of more than 12 levels.²⁸ Implant failure can lead to loss of correction, especially at the proximal portion of the instrumentation. Patients with osteoporosis are at somewhat increased risk of implant failure or even fracture at levels contiguous with the fusion mass. In some individuals, posterior instrumentation can be prominent and cause discomfort. Overcorrection of the deformity (>50%) and inadequate selection of fusion levels can predispose a patient to junctional kyphosis at the proximal and distal extent of the fusion mass.²⁰

Postoperative wound infections can be superficial or deep. As with any surgery, use of prophylactic antibiotics and sterile technique are imperative to lower the incidence of postoperative wound infection. Maximizing the patient's nutritional status before surgery can also help reduce the risk of infection.

OUTCOME AND PROGNOSIS

Section 9 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

Results of surgical correction vary depending on the etiology of the deformity.

Malcolm et al reviewed 48 patients and achieved a deformity correction rate of 26% and at least partial pain relief in 98% of patients with posttraumatic kyphosis with anterior and/or posterior fusions.⁸

Lehmer et al studied 38 patients who underwent a single-stage closing wedge procedure to treat posttraumatic and postlaminectomy kyphosis. They obtained a mean correction of 35° with 3 pseudarthroses. Eight of 14 preoperative neurologic deficits improved, and 76% of the patients treated said they would undergo the surgery again if needed.²⁹

Kostuick achieved fusion in 36 of 37 patients receiving anterior-only fusion. Pain significantly improved in 78%, and 3 of 8 patients with paraparesis improved.³⁰

Outcomes in Scheuermann kyphosis are similar to those just presented, though the amount of correction achieved may not be correlated with pain relief.

In a series of patients who were treated with a posterior Harrington rod, all had pain relief. However, 16 of 22 lost correction.¹³

Lowe and Kasten used posterior instrumentation to achieve a mean correction of 85° down to 43°.²⁰

With anterior-posterior and posterior–only surgery, Speck and Chopin gained an average deformity correction of 40%, and 28 of 45 patients were pain-free. However, 4 patients had infections, 9 lost more than 10° of correction, and 1 person had Brown-Sequard syndrome postoperatively.³¹

Investigators have evaluated advanced techniques, such as osteotomies and new instrumentation. Bridwell et al reported a series of 33 patients treated with pedicle subtraction osteotomy for sagittal imbalance.^{15, 16} The C7 plumb line improved from 16.6 cm positive to 1.7 cm. Pain and Oswestry disability indexes significantly improved. Eight patients had pseudarthrosis, and 1 had a wound infection. No permanent neurologic injuries occurred.

Video-assisted thoracoscopic release followed by posterior arthrodesis has been successful. In one study, deformity correction was 84.8° to 45.3° in patients with thoracic kyphosis associated with Scheuermann disease. Mean loss of correction was 1.6°, and 1 hook pulled out. No cases of junctional kyphosis were observed.³²

In a retrospective study, anterior-posterior correction was compared with posterior-only instrumentation with all pedicle screws. The posterior-only group had significant improvement in terms of blood loss, correction of deformity, and number of complications.³³

FUTURE AND CONTROVERSIES

Section 10 of 11  

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

As surgical implants and techniques have improved, so have results of surgery. Patient safety should be the foremost goal of the treating physician. Future prospective trials will help in defining the best way to care for patients with clinically significant sagittal imbalances.

REFERENCES

Section 11 of 11

• Authors and Editors
• Introduction
• Indications
• RELEVANT ANATOMY
• Contraindications
• Workup
• Treatment
• Complications
• Outcome And Prognosis
• Future And Controversies
• References

1. Macagno AE, O'Brien MF. Thoracic and thoracolumbar kyphosis in adults. Spine. Sep 1 2006;31(19 Suppl):S161-70. [Medline].
2. Shelton YA. Scoliosis and kyphosis in adolescents: diagnosis and management. Adolesc Med State Art Rev. May 2007;18(1):121-39, x. [Medline].
3. Lowe TG. Scheuermann's kyphosis. Neurosurg Clin N Am. Apr 2007;18(2):305-15. [Medline].
4. Lowe TG, Line BG. Evidence based medicine: analysis of Scheuermann kyphosis. Spine. Sep 1 2007;32(19 Suppl):S115-9. [Medline].
5. Tribus CB. Scheuermann's kyphosis in adolescents and adults: diagnosis and management. J Am Acad Orthop Surg. Jan-Feb 1998;6(1):36-43. [Medline].
6. Damborg F, Engell V, Anderson M, et al. Prevalence, concordance, and heritability of Scheuermann kyphosis based on a study of twins. J Bone Joint Surg Am. 2006;88(10):2133-6. [Medline].
7. Sorensen KH. Scheuermann's Juvenile Kyphosis: Clinical Appearances, Radiography, Aetiology and Prognosis. Copenhagen: Munksgaard; 1964.
8. Malcolm BW, Bradford DS, Winter RB, Chou SN. Post-traumatic kyphosis. A review of forty-eight surgically treated patients. J Bone Joint Surg Am. 1981;63:891-9. [Medline].
9. Murray PM, Weinstein SL, Spratt KF. The natural history and long-term follow up of Scheuermann kyphosis. J Bone Joint Surg Am. 1993;75(2):236-48. [Medline].
10. Wenger DR, Frick SL. Scheuermann kyphosis. Spine. Dec 15 1999;24(24):2630-9. [Medline].
11. Vaccaro AR, Silber JS. Post-traumatic spinal deformity. Spine. Dec 15 2001;26(24 Suppl):S111-8. [Medline].
12. Bradford DS, Ganjavian S, Antonious D, et al. Anterior strut-grafting for the treatment of kyphosis. Review of experience with forty-eight patients. J Bone Joint Surg Am. 1982;64:680-90. [Medline].
13. Bradford DS, Moe JH, Montalvo FJ, Winter RB. Scheuermann's kyphosis. Results of surgical treatment by posterior spine arthrodesis in twenty-two patients. J Bone Joint Surg Am. 1975;57:439-48. [Medline].
14. Sachs B, Bradford D, Winter R, et al. Scheuermann kyphosis. Follow-up of Milwaukee brace treatment. J Bone Joint Surg Am. 1987;69(1):50-7. [Medline].
15. Bridwell KH, Lewis SJ, Edwards C, et al. Complications and outcomes of pedicle subtraction osteotomies for fixed sagittal imbalance. Spine. Sep 15 2003;28(18):2093-101. [Medline].
16. Bridwell KH, Lewis SJ, Lenke LG, et al. Pedicle subtraction osteotomy for the treatment of fixed sagittal imbalance. J Bone Joint Surg Am. Mar 2003;85-A(3):454-63. [Medline].
17. Hehne HJ, Zielke K, Bohm H. Polysegmental lumbar osteotomies and transpedicled fixation for correction of long-curved kyphotic deformities in ankylosing spondylitis. Report on 177 cases. Clin Orthop Relat Res. Sep 1990;258:49-55. [Medline].
18. Cho KJ, Bridwell KH, Lenke LG, et al. Comparison of Smith-Peterson versus pedicle subtraction osteotomy for the correction of fixed sagittal imbalance. Spine. 2005;30(18):2030-7. [Medline].
19. Brodner W, Mun Yue W, Moller HB, et al. Short segment bone-on-bone instrumentation for single curve idiopathic scoliosis. Spine. 2003;28S(20):S224-33. [Medline].
20. Lowe TG, Kasten MD. An analysis of sagittal curves and balance after Cotrel-Dubousset instrumentation for kyphosis secondary to Scheuermann's disease. A review of 32 patients. Spine. Aug 1 1994;19(15):1680-5. [Medline].
21. Bridwell KH. Decision making regarding Smith-Petersen vs. pedicle subtraction osteotomy vs. vertebral column resection for spinal deformity. Spine. Sep 1 2006;31(19 Suppl):S171-8. [Medline].
22. Clement JL, Chau E, Kimkpe C, Vallade MJ. Restoration of thoracic kyphosis by posterior instrumentation in adolescent idiopathic scoliosis: comparative radiographic analysis of two methods of reduction. Spine. Jun 15 2008;33(14):1579-87. [Medline].
23. Song KS, Chang BS, Yeom JS, Lee JH, Park KW, Lee CK. Surgical treatment of severe angular kyphosis with myelopathy: anterior and posterior approach with pedicle screw instrumentation. Spine. May 15 2008;33(11):1229-35. [Medline].
24. Wilber RG, Thompson GH, Shaffer JW, et al. Postoperative neurological deficits in segmental spinal instrumentation. A study using spinal cord monitoring. J Bone Joint Surg Am. 1984;66:1178-87. [Medline].
25. Lonner BS, Newton P, Betz R, Scharf C, O'Brien M, Sponseller P, et al. Operative management of Scheuermann's kyphosis in 78 patients: radiographic outcomes, complications, and technique. Spine. Nov 15 2007;32(24):2644-52. [Medline].
26. Kim YJ, Bridwell KH, Lenke LG, et al. Pseudarthrosis in primary fusions for adult idiopathic scoliosis: incidence, risk factors, and outcome analysis. Spine. Feb 15 2005;30(4):468-74. [Medline].
27. Ball JM, Cagle P, Johnson BE, Lucasey C, Lukert BP. Spinal extension exercises prevent natural progression of kyphosis. Osteoporos Int. Jul 26 2008;[Medline].
28. Kim YJ, Bridwell KH, Lenke LG, et al. Pseudarthrosis in adult spinal deformity following multisegmental instrumentation and arthrodesis. J Bone Joint Surg Am. Apr 2006;88 (4):721-8. [Medline].
29. Lehmer SM, Keppler L, Biscup RS, et al. Posterior transvertebral osteotomy for adult thoracolumbar kyphosis. Spine. 1994;19(18):2060-6. [Medline].
30. Kostuik JP, Matsusaki H. Anterior stabilization, instrumentation, and decompression for post-traumatic kyphosis. Spine. Apr 1989;14(4):379-86. [Medline].
31. Speck GR, Chopin DC. The surgical treatment of Scheuermann's kyphosis. J Bone Joint Surg Br. 1986;68(2):189-93. [Medline].
32. Herrera-Soto JA, Parikh SN, Al-Sayyad MJ, Crawford AH. Experience with combined video-assisted thoracoscopic surgery (VATS) anterior spinal release and posterior spinal fusion in Scheuermann's kyphosis. Spine. Oct 1 2005;30(19):2176-81. [Medline].
33. Lee SS, Lenke LG, Kuklo TR, et al. Comparison of Scheuermann kyphosis correction by posterior-only thoracic pedicle screw fixation versus combined anterior/posterior fusion. Spine. Sep 15 2006;31(20):2316-21. [Medline].

Article Last Updated: Aug 18, 2008