Surgical strategy for cervical myelopathy due to ossification of the posterior longitudinal ligament part 1: Clinical results and limitations of laminoplasty

Study Design. Retrospective study of 66 patients who underwent laminoplasty for treatment of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). Objectives. The present study describes surgical results of laminoplasty for treatment of cervical myelopathy due to OPLL and aims to clarify 1) factors predicting outcome and 2) limitations of laminoplasty. Summary of Background Data. During the period 1986 and 1996, laminoplasty was the only surgical treatment selected for cervical myelopathy at our institutions. Methods. We reviewed data obtained in 66 patients who underwent laminoplasty for treatment of cervical myelopathy due to OPLL. Mean duration of follow-up was 10.2 years (range, 5 - 20 years). Surgical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy. Results. Surgical outcome was significantly poorer in patients with occupying ratio greater than 60%. Multiple regression analysis showed that the most significant predictor of poor outcome after laminoplasty was hill-shaped ossification, followed by lower preoperative JOA score, postoperative change in cervical alignment, and older age at surgery. Conclusions. Laminoplasty is effective and safe for most patients with occupying ratio of OPLL less than 60% and plateau-shaped ossification. However, neurologic outcome of laminoplasty for cervical OPLL was poor or fair in patients with occupying ratio greater than 60% and/or hill-shaped ossification.