Long-term results of double-door laminoplasty for cervical stenotic myelopathy

Study Design. A retrospective study of the long-term results from double-door laminoplasty (Kurokawa's method) for patients with myelopathy caused by ossification of the posterior longitudinal ligament and cervical spondylosis was performed. Objective. To know whether the short-term results from double-door laminoplasty were maintained over a 10-year period and, if not, the cause of late deterioration. Summary of Background Data. There are few long-term follow-up studies on the outcome of laminoplasty for cervical stenotic myelopathy. Methods. In this study, 35 patients with cervical myelopathy caused by ossification of the posterior longitudinal ligament in the cervical spine and 25 patients with cervical spondylotic myelopathy, including 5 patients with athetoid cerebral palsy, underwent double-door laminoplasty from 1980 through 1988 and were followed over the next 10 years. The average follow-up period was 153 months (range, 120-200 months) in patients with ossification of the posterior longitudinal ligament and 156 months (range, 121-218 months) in patients with cervical spondylotic myelopathy. Neurologic deficits before and after surgery were assessed using a scoring system proposed by the Japanese Orthopedic Association (JOA score). Patients who showed late deterioration received further examination including computed tomography scan and magnetic resonance imaging of the cervical spine. Results. In 32 of the patients with ossification of the posterior longitudinal ligament and 23 of the patients with cervical spondylotic myelopathy, myelopathy improved after surgery. The improvement of Japanese Orthopedic Association scores was maintained up to the final follow-up assessment in 26 of the patients with ossification of the posterior longitudinal ligament and 21 of the patients with cervical spondylotic myelopathy. Late neurologic deterioration occurred in 10 of the patients with ossification of the posterior longitudinal ligament an average of 8 years after surgery, and in 4 of the patients with cervical spondylotic myelopathy, including the 3 patients with athetoid cerebral palsy, an average of 11 years after surgery. The main causes of deterioration in patients with ossification of the posterior longitudinal ligament were a minor trauma in patients with residual cervical cord compression caused by ossification of the posterior longitudinal ligament and thoracic myelopathy resulting from ossification of the yellow ligament in the thoracic spine. Conclusions. The short-term results of laminoplasty for cervical stenotic myelopathy were maintained over 10 years in 78% of the patients with ossification of the posterior longitudinal ligament, and in most of the patients with cervical spondylotic myelopathy, except those with athetoid cerebral palsy. Double-door laminoplasty is a reliable procedure for individuals with cervical stenotic myelopathy.