Effect and Prognostic Factors of Laminoplasty for Cervical Myelopathy With an Occupying Ratio Greater Than 50%.

STUDY DESIGN A retrospective study. OBJECTIVE The aim of this study was to evaluate the efficacy of laminoplasty for the treatment of patients with an occupying ratio greater than 50% and to determine possible factors related to surgical outcome of posterior decompression. SUMMARY OF BACKGROUND DATA Little data are available about effect and prognostic factors of laminoplasty for cervical myelopathy with an occupying ratio greater than 50%. METHODS Fifty-five consecutive patients with an occupying ratio greater than 50% who underwent cervical laminoplasty between January 2005 and December 2010 were reviewed in this study. Patients with cervical kyphosis were excluded. Clinical and radiologic outcomes were assessed. Univariate analysis was used to investigate the relationship between recovery rate and the age, duration of symptoms, preoperative Japan Orthopedic Association (JOA) score, posterior shift of the spinal cord, preoperative cervical lordosis, spinal cord compression ratio, and follow-up period. Multivariate linear regression analysis was used to determine the best surgical outcome predictor. RESULTS All patients maintained cervical lordosis. Average JOA score improved from 10.7 ± 1.7 points preoperatively to 14.0 ± 1.4 points at the last follow-up. The mean rate of recovery was 51.4 ± 25.7%. Final recovery rates showed 6 excellent results, 29 good results, 18 fair results, and 2 poor results. Univariate analysis showed significant correlation between the recovery rate and the spinal cord compression ratio, duration of symptoms, and posterior movement of the spinal cord. The multivariate linear regression analysis showed that the best surgical outcome predictor was the spinal cord compression ratio (β = 0.698, P < 0.001). R-square of the final multiple linear regression model was 0.509. CONCLUSION Laminoplasty can still be considered as a decompressive pattern for patients with a high occupying ratio greater than 50%. The spinal cord compression ratio, duration of symptoms, and posterior movement of the spinal cord play important roles in recovery rate. The best surgical outcome predictor is the spinal cord compression ratio. LEVEL OF EVIDENCE 4.