Surgical Management of Congenital Cervical Kyphosis

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1 n Feature Article Surgical Management of Congenital Cervical Kyphosis Zhimin He, MD; Yang Liu, MD; Feng Xue, MD; Haijun Xiao, MD; Wen Yuan, MD; Deyu Chen, MD abstract Full article available online at Healio.com/Orthopedics. Search: Congenital cervical kyphosis is a rare clinical condition. The purpose of this study was to review the surgical management and outcomes of 12 consecutive cases of congenital cervical kyphosis management by the same surgical team. The authors retrospectively analyzed the records of 12 patients (5 men and 7 women) with an average age of 18.4 years (range, years) who underwent surgery for congenital cervical kyphosis at the authors institution between 2001 and All patients had congenital cervical kyphosis; those with secondary kyphosis deformity due to causes such as infection, tumors, and surgery were excluded. The indications for surgery were signs of spinal cord compression with progression of clinical symptoms such as decreased muscle strength and paresthesia. All patients had radiographic evidence of cervical kyphosis. Six patients underwent anterior decompression, autogenous bone grafting, and instrumentation, and the other 6 patients underwent combined anterior posterior surgery. All surgeries were performed successfully with no complications. Bone graft fusion occurred in 11 patients. In 1 patient who underwent anterior surgery, the bone graft was partly absorbed, and pseudarthrosis was noted at 3 years postoperatively. Mean Japan Orthopaedic Association cervical myelopathy score and mean Cobb angle were significantly improved at 1 week and 1 year postoperatively compared with preoperative values. Figure: Radiograph showing determination of the kyphosis Cobb angle. Anterior and combined anterior posterior surgical approaches are useful for the correction of congenital cervical kyphosis. Bone graft fusion is also critical for maintaining the surgical correction. Choice of surgical methods depends on the patient s clinical condition. Drs He, Xue, and Xiao are from the Department of Orthopaedic Surgery, Shanghai Fengxian Central Hospital, and Drs Liu, Yuan, and Chen are from the Department of Orthopaedic Surgery, Changzheng Hospital, Second Military Medical University, Shanghai, China. Drs He, Liu, Xue, Xiao, Yuan, and Chen have no relevant financial relationships to disclose. Correspondence should be addressed to: Wen Yuan, MD, Department of Orthopaedic Surgery, Changzheng Hospital, Second Military Medical University, No. 415 Fengyang Rd, Shanghai, China, (drwenyuan123@126.com). doi: / e1396 ORTHOPEDICS Healio.com/Orthopedics

2 Congenital Cervical Kyphosis He et al Cervical kyphosis is relatively common and can be due to infection, tumors, or surgery; however, congenital cervical kyphosis is rare and seldom reported. Congenital cervical kyphosis is defined as kyphosis induced by an abnormal vertebral body, including congenital failure of formation (type I), congenital failure of segmentation (type II), and mixed failure (type III). 1-4 Neurological symptoms can be caused by spinal cord compression or displacement because of accelerated degeneration of the cervical abnormalities. Paralysis often occurs in severe cases. 1-4 Significant congenital kyphosis is often associated with other congenital disorders, such as neurofibromatosis I, Larsen syndrome, and diastrophic dysplasia. 1,5,6 Congenital cervical kyphosis is not typically diagnosed until neurological symptoms occur. Treatment for congenital cervical kyphosis can range from expectant management with close monitoring of neurological function to palliative halo immobilization and traction. 2 Surgical management is required in cases of significant neurological dysfunction when conservative treatments are ineffective. 7 The rationale for the surgical treatment of congenital cervical kyphosis is that surgery can relieve the nerve compression from the anterior or posterior cervical spinal, completely or partially restore normal cervical physiological curvature, and improve the appearance of the cervical vertebrae. The purpose of this study was to retrospectively review the clinical characteristics, surgical strategies, complications, and outcomes of 12 patients with congenital cervical kyphosis who underwent surgery by the same surgical team over a 4-year period. Materials and Methods This study was approved by the Ethical Committee of Shanghai Fengxian Center Hospital. Informed consent from patients was waived by the committee due to the retrospective nature of the study. Figure 1: Radiograph showing determination of the kyphosis Cobb angle. A total of 12 patients who underwent surgery for congenital cervical kyphosis at the hospital between 2001 and 2005 were included in the study. Patients with secondary kyphosis due to infection, tumors, and surgery were excluded. Indications for surgery were signs of spinal cord compression such as decreased muscle strength and paresthesia. All patients had radiographic evidence of cervical kyphosis. The cervical kyphosis angle (Cobb angle) was measured on lateral cervical spine radiographs. A negative angle indicated kyphosis and a positive angle indicated lordosis. The angle was measured between the upper endplate line of the vertebral body above and lower endplate line of the vertebral body below the deformed apical vertebra (or intervertebral space) (Figure 1). All patients underwent cervical spine computed tomography with 3-dimensional reconstruction and magnetic resonance imaging. Kyphosis type was determined based on radiographic findings. Preoperative skull traction was used in 9 cases. Preoperative skull traction was used to judge the flexibility of the deformity, partially correct the Cobb angle of kyphosis to improve the correction rate, and decrease contracture of the anterior soft tissues as much as possible. Traction was applied with a weight of 5 to 15 kg for 6 to 15 days. Cervical spine lateral radiographs were performed every 3 days to evaluate the improvement of the deformity. Traction was discontinued in 1 patient because of increased symptoms (Figure 2). In the other 3 patients, preoperative skull traction was not performed because the kyphosis angle was relatively small. The surgical procedure was based on the general condition of the patient, the kyphosis angle, and the cause of spinal cord compression. Patients who were relatively older and had a relatively small kyphosis angle, nearly stable kyphosis deformity, and anterior spinal cord compression underwent anterior surgery to relieve spinal cord compression and achieve orthopedic fixation. Patients who were relatively younger and had hemivertebral deformities, rigid kyphosis with a larger kyphosis angle, and a high correction rate with preoperative skull traction underwent combined anterior posterior surgery. If the spinal cord compression was primarily anterior, anterior decompression, autogenous bone grafting, fixation, and posterior fixation were performed. An anterior posterior anterior procedure was used when necessary. Combined surgeries were performed in the same procedure. For patients with rigid kyphosis, laminectomy and partial resection of the joint facet, fixation using cervical posterior pedicle screws, and anterior decompression with bone grafting and fixation were performed. Cobb angle and Japan Orthopaedic Association (JOA) cervical myelopathy score were determined preoperatively and 1 week and 1 year postoperatively. Data were presented as mean6sd for continuous variables. The differences in JOA cervical myelopathy scores and Cobb angles between different operative stages (1 week and 1 year postoperatively vs preoperatively) were detected using 1 SEPTEMBER 2012 Volume 35 Number 9 e1397

3 n Feature Article the paired t test. Mean differences with 95% confidence intervals (CIs) were also presented. Statistical analyses were performed with SAS version 9.2 sortware (SAS Institute, Inc, Cary, North Carolina), and a 2-tailed P value less than.05 indicated statistical significance. Results A total of 12 patients (5 men and 7 women) with an average age of 18.4 years (range, years) were included. Patient demographics and disease characteristics are summarized in Table 1. Five patients had failure of formation (hemivertebra in 3 cases and wedge vertebra in 2 cases), 6 had failure of segmentation, and 1 had 2A 2B 2C 2D 2F 2E 2G Figure 2: Preoperative lateral cervical spine radiograph of a 19-year-old man showing a C4 semivertebrae deformity and severe kyphosis (Cobb angle, 260 ). (A) One-week postoperative lateral radiograph showing a Cobb angle of 0 (B). Eightmonth postoperative lateral radiograph showing maintenance of the cervical angle and bone graft fusion (C). Preoperative 3-dimensional computed tomography scans showing a C4 semivertebrae deformity (D) and corrected kyphosis (E). Preoperative T1-weighted magnetic resonance image of the cervical spine showing that the front and back of the cervical spinal cord were compressed and an intraspinal mass (arrow) filled more than 60% of the spinal canal volume (F). Oneweek postoperative T1-weighted magnetic resonance image showing anterior decompression, bone grafting, and internal fixation (G). mixed failure. One case of hemivertebral malformation was accompanied by soft tissue compression posterior to the spinal canal (Figure 2). In 1 patient with mixed kyphosis, atlantoaxial dislocation was observed and the compression was from the posterior portion of the vertebra and the intervertebral disk (Figure 3). All patients had little or no scoliosis of the cervical spine. All patients had neck discomfort or pain. Two patients had bilateral upperextremity numbness when flexing the neck, which was alleviated on extension. Four patients exhibited increased muscle tension. Six patients were treated with an anterior procedure, and 6 were treated with a combined procedure. Five cases of cervical subsegmentation and 1 case of mixed-type received anterior subtotal corpectomy with iliac bone grafting and plate fixation. In 1 patient, posterior decompression (resection of adipose tissue of tether-induced pressure) was performed, followed by anterior subtotal resection of the hemivertebra with iliac bone grafting and fixation (Figure 2). No surgical or postoperative complications occurred. In the anterior surgery group, mean blood loss was 571 ml (range, ml) and mean surgical time was 147 minutes (range, minutes). In the combined surgery group, mean blood loss was 920 ml (range, ml) and mean surgical time was 290 minutes (range, minutes). Bone grafts fused in 11 cases. One patient received occipitocervical graft fusion and gypsum fixation because of atlantoaxial dislocation 6 months after anterior surgery for kyphosis (Figure 3). Three years later, the patient reported neck pain with aggravated extremity numbness during cervical flexion. Radiographs revealed that the upper site of the anterior bone graft had been partly absorbed, the occipitocervical bone graft had been completely absorbed, and pseudarthrosis was present. However, no obvious loss of Cobb angle was observed. Mean preoperative JOA cervical myelopathy score was 9 (range, 7-11). Mean follow-up was 34.8 months (range, months). Mean preoperative and 1 week and 1 year postoperative JOA cervical myelopathy scores of patients who underwent an anterior procedure were , , and , respectively (Table 2). One week and 1 year postoperative scores were significantly higher than preoperative scores (mean difference, 4.83 and 5.17, respectively; P,.05). For patients who underwent combined surgery, mean 1 week and 1 year postoperative JOA cervical myelopathy scores were also significantly higher than preoperative scores (mean difference, 5.50 and 6.17, respectively; P,.05). e1398 ORTHOPEDICS Healio.com/Orthopedics

4 Congenital Cervical Kyphosis He et al Procedure Patient No./ Sex/Age, y Failure Type Scoliosis, deg Table 1 Patient Data Cobb Angle, deg JOA Score Pre 1 Wk Post 1 Y Post Pre 1 Wk Post 1 Y Post Anterior 1/F/31 C4-C5 subseg /F/21 C5-C6 subseg /F/18 C4-C5 subseg /F/17 C3-C4 subseg /M/16 C5-C6 subseg /M/15 C4-C6 mixed Combined 7/F/18 C3-C5 subseg /M/17 C5 hemi /F/16 C6 wedge /M/19 C4 hemi /M/16 C6 hemi /F/17 C3 wedge Mean Abbreviations: deg, degrees; hemi, hemivertebra; JOA, Japan Orthopaedic Association cervical myelopathy; Post, postoperatively; Pre, preoperatively; subseg, subsegmentation; wedge, wedge vertebra. The anterior portion of the vertebra sustains greater pressure whereas the posterior portion sustains greater tension, which leads to disk degeneration, protrusion, and osteophytosis. The small rear joint capsule may degenerate with possible secondary elongation of the articular cartilage, leading to a rigid kyphosis, and surgical cor- Followup, mo Mean preoperative and 1 week and 1 year postoperative Cobb angles of patients who underwent an anterior procedure were , , and , respectively (Table 3). One week and 1 year postoperative Cobb angles were significantly greater than preoperative values (mean difference, and 37.17, respectively; P,.05). For patients who underwent combined surgery, mean 1 week and 1 year postoperative mean Cobb angles were also significantly greater than preoperative values (mean difference, and 42.33, respectively; P,.05). kyphosis is primarily failure of formation and segmentation. 2,7 Stresses on the cervical spine are altered when the spine is changed from cervical lordosis to kyphosis; the skull is shifted to a more forward position, which enhances front bending and rear strengthening and further increases the malformation in a vicious cycle. 2,4 Discussion In this retrospective analysis of 12 patients who underwent surgery for congenital cervical kyphosis, bone graft fusion occurred in all but 1 patient at 1 year postoperatively, and mean JOA cervical myelopathy scores and Cobb angles were significantly improved from preoperative values. The etiology of congenital cervical 3A 3B 3C 3D Figure 3: Lateral radiographs of a 15-year-old boy with mixed-type congenital cervical kyphosis and atlantoaxial dislocation who underwent anterior surgery for kyphosis (A, B). Lateral radiograph 12 months later, after the patient underwent occipitocervical bone grafting for atlantoaxial dislocation and gypsum fixation (C). Lateral radiograph 42 months later, when the patient experienced recurrent neck pain and upper-extremity numbness with cervical flexion, showing partial absorption of the bone graft and complete absorption of the occipitocervical bone graft with pseudarthrosis. No obvious loss of Cobb angle was observed (D). SEPTEMBER 2012 Volume 35 Number 9 e1399

5 n Feature Article Table 2 Pre- and Postoperative JOA Scores Mean6SD Mean Difference (95% CI) Procedure n Pre 1 Wk Post 1 Y Post 1 Wk Post vs Pre P 1 Y Post vs Pre P Anterior ( ) ( ).0038 Combined ( ) ( ).0013 Abbreviations: CI, confidence interval; JOA, Japan Orthopaedic Association cervical myelopathy; post, postoperatively; pre, preoperatively. Table 3 Pre- and Postoperative Cobb Angles Mean6SD Mean Difference (95% CI) Procedure n Pre 1 Wk Post 1 Y Post 1 Wk Post vs Pre P 1 Y Post vs Pre P Anterior ( ) ( ).0033 Combined ( ) ( ).0002 Abbreviations: CI: confidence interval; post, postoperatively; pre, preoperatively. rection becomes more challenging as the deformity progresses. 2-4 In children still in the growth stage, the etiologic type and extent of deformity should be taken into consideration when evaluating treatment options. Children with a smaller kyphosis angle and no neurological dysfunction can be monitored closely. When neurological dysfunction or progressive deformity occurs, halo immobilization and traction can be tried. Surgical treatment is required when conservative treatments are ineffective and neurological symptoms due to spinal cord compression develop. 7 Patients with congenital cervical kyphosis due to failure of segmentation or hemivertebral deformities typically have large Cobb angles. A combined surgical approach is typically recommended due to the unique stresses to the spine associated with cervical kyphosis, as well as abnormal cervical structures such as elongation and possible fusion of vertebral lamina and articular process, especially in patients with hemivertebral deformities. 3,4 Anterior plate fixations and posterior screw fixations are suggested to prevent sliding of the bone graft, bone graft absorption, pseudoarthrosis, and loss of Cobb angle. 3,4 In the current study, 5 of 6 patients who underwent combined surgery had hemivertebral deformities and 1 had subsegmentation. Although the Cobb angles were greater, the patients were relatively young and had no obvious prolongation or fusion of the rear articular processes. Preoperative radiographs showed good flexibility, and the Cobb angle was improved by preoperative skull traction. Thus, 4 patients underwent an anterior procedure followed by a posterior procedure; 1 patient underwent an anterior posterior anterior procedure, which was selected according to the rectification rate of the kyphosis angle intraoperatively; and 1 patient underwent an anterior posterior procedure. Other authors have also reported good outcomes with combined procedures for cervical kyphosis correction due to infection and trauma and after laminectomy. 8,9 Six patients underwent an anterior procedure. These patients were older and had relatively smaller Cobb angles. Their symptoms were due to degeneration of the intervertebral disks of the proximal and distal vertebrae, disk protrusion, or spinal cord compression from the rear of the apical vertebra. The vertebral lamina and facet joint posterior to the vertebral body were stable in 5 cases of failed segmentation. Thus, anterior surgeries were chosen, including anterior subtotal corpectomy decompression, bone grafting, and cervical anterior plate fixation. To facilitate bone grafting and restoration of the cervical curve with instrumentation, a relatively wide decompression chute was made intraoperatively. Overcorrection and iatrogenic damage to the spinal cord must be avoided. Steinmetz et al 10 suggested that anterior cervical decompression and restoring the normal cervical physiological curvature as far as possible should be performed at the same time for congenital cervical kyphosis. The aim of surgery is to restore to the normal cervical curvature or at least achieve a neutral position. In the neutral position, front flexion torque and rear tension torque are in a relatively balanced state. Because spinal cord compression is mainly from the front of the cervical spi- e1400 ORTHOPEDICS Healio.com/Orthopedics

6 Congenital Cervical Kyphosis He et al nal canal, anterior surgery may effectively relieve neurological symptoms. However, anterior surgery alone cannot perfectly restore cervical lordosis, so a combined anterior posterior procedure may be needed When a neutral position is obtained and the physiological curvature of the spine is restored as much as possible, the occurrence of complications such as bone graft absorption, pseudarthrosis, Cobb angle loss, loosening of internal fixation, and recompression of the spinal cord can be reduced. Congenital cervical kyphosis can be associated with deformities such as myeloschisis, recessive myeloschisis with shortened filum terminale, fibrous bands, and lipoma in the spinal canal. 4 These deformities cause the spinal cord to be in a state of tension (tethered cord). Extension of the cervical spine will lead to further reduction of the effective spinal canal volume, and skull traction can result in more serious neurological symptoms. This occurred in a patient who exhibited progressive numbness of the limbs and increased muscle tension after skull traction was applied (Figure 2). For this type of patient, lesions in the spinal cord should be corrected first, followed by correction of the kyphosis; otherwise, significant neurological dysfunction can occur from bracing of the cervical spine. 10,11 In another patient, an anterior procedure was used for mixed-type congenital cervical kyphosis with atlantoaxial dislocation and iliac bone graft fusion (Figure 3). Internal fixation was performed after the anterior surgery for kyphosis. Simple posterior decompression for atlantoaxial dislocation, occipitocervical bone graft fusion, and gypsum fixation were performed after 6 months. For economic reasons, posterior surgery and fixation were not performed in the cervical vertebra; however, the patient s neurological symptoms improved significantly. Three years later, the patient experienced recurrent symptoms and bone graft absorption was noted. Although no obvious loss of cervical kyphosis or Cobb angle was observed, complications such as screw pullout or breakage and loss of Cobb angle may occur with progression of the disease. 13 Bone graft fusion is key to obtaining and maintaining correction of congenital cervical kyphosis. Autologous iliac or fibula bone grafts are frequently used, and the use of autologous skull bone grafts for posterior fusion of the upper cervical spine has been reported. 12 Supplementary internal fixation to improve the bone graft fusion rate is commonly performed. The primary limitation of the current study was the relatively short follow-up of 1 year. Long-term follow-up compliance was difficult to obtain in this population, and although follow-up ranged from 23 to 48 months, complete data for the 12 patients were only available for up to 1 year. Conclusion Anterior and combined surgical proceudres are useful for the correction of congenital cervical kyphosis, and the choice should be determined by the clinical situation of the patient. Bone graft fusion is critical for maintaining the surgical correction. References 1. Sakaura H, Matsuoka T, Iwasaki M, Yonenobu K, Yoshikawa H. Surgical treatment of cervical kyphosis in Larsen syndrome: report of 3 cases and review of the literature. Spine (Phila Pa 1976). 2007; 32(1):E39-E Iwasaki M, Yamamoto T, Miyauchi A, Amano K, Yonenobu K. Cervical kyphosis: predictive factors for progression of kyphosis and myelopathy. Spine (Phila Pa 1976). 2002; 27(13): Lerman JA, Sullivan E, Haynes RJ. The Pediatric Outcomes Data Collection Instrument (PODCI) and functional assessment in patients with adolescent or juvenile idiopathic scoliosis and congenital scoliosis or kyphosis. Spine (Phila Pa 1976). 2002; 27(18): Spivak JM, Giordano CP. Cervical kyphosis. In: Bridwell KH, DeWald RL, eds. The Textbook of Spinal Surgery. 2nd ed. Vol 1. Philadelphia, PA: Lippincott-Raven; 1997: Bethem D, Winter EB, Lutter L. Disorders of the spine in diatrophic dwarfism. J Bone Joint Surg Am. 1980; 62(4): Johnson CE II, Birch JG, Daniels JL. Cervical kyphosis in patients who have Larsen syndrome. J Bone Joint Surg Am. 1996; 78(4): Brockmeyer D, Apfelaum R, Tippets R, Walker M, Carey L. Pediatric cervical spine instrumentation using screw fixation. Pediatr Neurosurg. 1995; 22(3): Sin AH, Acharya R, Smith DR, Nanda. Adopting 540-degree fusion to correct cervical kyphosis. Surg Neurol. 2004; 61(6): Schultz KD Jr, McLaughlin MR, Haid RW Jr, Comey CH, Rodts GE Jr, Alexander J. Single-stage anterior-posterior decompression and stabilization for complex cervical spine disorders. J Neurosurg. 2000; 93(1 suppl): Steinmetz MP, Kager CD, Benzel EC. Ventral correction of postsurgical cervical kyphosis. J Neurosurg. 2003; 98(1 suppl): Bono CM, Vaccaro AR, Fehlings M, et al. Measurement techniques for lower cervical spine injuries: consensus statement of the Spine Trauma Study Group. Spine (Phila Pa 1976). 2006; 31(5): Casey AT, Hayward RD, Harkness WF, Crockard HA. The use of autologous skull bone grafts for posterior fusion of the upper cervical spine in children. Spine (Phila Pa 1976). 1995; 20(20): Shiba R, Murota K, Kondo H, Honma G. Cervical congenital kyphosis with atlantoaxial dislocation. A case report. Spine (Phila Pa 1976). 1993; 18(6): SEPTEMBER 2012 Volume 35 Number 9 e1401