Incidence and outcome of kyphotic deformity following laminectomy for cervical spondylotic myelopathy

Abstract

Object. The authors undertook a study to explore the predisposing risk factors, frequency of occurrence, and clinical implications of kyphosis following laminectomy for cervical spondylotic myelopathy (CSM). Methods. Preoperative radiological studies were available in 46 patients with CSM who had undergone laminectomy. Records were reviewed to obtain demographic data and operative reports. Preoperative radiographs were assessed to determine spinal alignment. In a follow-up interview the authors established clinical outcome and patient satisfaction. Postoperative cervical alignment and mobility was also determined by assessing lateral neutral, flexion, and extension x-ray films. Preoperatively, the cervical spine was shown to be kyphotic in four (9%) of 46, straight in 20 (43%) of 46, and lordotic in 22 (48%) of 46 patients. Nine (21%) of 42 patients with either straight or lordotic alignment demonstrated in the preoperative period developed kyphosis after surgery. Kyphosis developed in six (30%) of 20 patients in whom straight spinal alignment was demonstrated preoperatively and in only three (14%) of 22 patients in whom lordosis was found preoperatively. Clinically, 13 (29%) of 45 patients improved and 19 (42%) of 45 remained unchanged after an average 4-year follow-up period; 36 (80%) patients believed that their surgery was successful (one patient, who was mentally retarded, could not respond to the follow-up questionnaire). Spinal alignment was not predictive of outcome; cervical mobility as demonstrated on flexion and extension, however, correlated with improved functional performance (p = 0.005). Conclusions. Kyphosis may develop in up to 21% of patients who have undergone laminectomy for CSM. Progression of the deformity appears to be more than twice as likely if preoperative radiological studies demonstrate a straight spine. In this study, clinical outcome did not correlate with either pre- or postoperative sagittal alignment.