A Safe Controlled Instrumented Reduction Technique for Cervical Osteotomy in Ankylosing Spondylitis

Study Design. A retrospective review of clinical and radiologic outcome in 13 consecutive patients with Ankylosing Spondylitis (AS) who underwent cervical osteotomy for correction of fixed cervicothoracic kyphotic deformity (CTKD) using an innovative technique. Objective. To report further refinements to an existing technique for instrumented reduction of cervical osteotomy and assess the safety and efficacy of this procedure in 13 patients. Summary of Background Data. Cervical osteotomy in AS has been used for correction of CTKD, but is associated with significant risks. We have previously reported a novel technique to perform this procedure safely. Even with this technique, there was a small risk of subluxation, and this risk has been further reduced with our new technique. Methods. Between 1993 and 2008, the senior author (SMHM) performed cervical osteotomy for severe CTKD in 13 AS patients. There were 11 male and two female patients, the average age being 56 (40-74) years. The main surgical indication was restricted frontal visual field. The average symptom duration was 2.7 (1-5) years. All patients had a general anesthetic and underwent cervical osteotomy and instrumentation from C3 to T5 in prone position. Results. The average duration of surgery was 4.7 (3-6.5) hours. The calculated blood loss was 1938 mL (1000-3600). The mean follow-up period was 6.5 (1.5-16) years. The mean preoperative chin brow vertical angle was found to be 54 degrees (20 degrees-70 degrees). After surgery, this improved to 7 degrees (2 degrees-12 degrees). The preoperative kyphotic angle measured was 19.2 degrees (14 degrees-28 degrees). This improved after surgery to -34 degrees (-21 degrees to -39 degrees). There were no instances of a neurologic deficit. At a mean follow-up of 6.5 years (18 months-6 yr), no instances of loss of correction or implant failure were noted. Conclusion. This innovative new technique provides for a safe, controlled reduction for cervical osteotomy for fixed cervicothoracic kyphosis in AS. The technique reliably renders rigid immobilization that obviates the risk of intra-and postoperative junctional subluxation, eliminates the need for postoperative halo-vest immobilization, and achieves satisfactory fusion.