In 141 patients with ossification of posterior longitudinal ligament, open-door expansive laminoplasty was done from 1980 to 1998. A follow-up study was made. 10 patients with cervical cord injury and cerebral diseases before or after operation were excluded. 121 of 131 patients were followd directly one to fifteen years(mean: 5 years and 3 months). Subjects included 93 male and 28 female. At the time of operation, their ages ranged from 40 to 80 years(mean:59.5). Operative results were evaluated using the Japanese Orthopaedic Association’s Score(JOA Score) and Hirabayashi’s improvement rate. X-ray was taken to measure the range of cervical spine motion, curvature of the cervical spine and progression of ossified masses.

Preoperative JOA scores ranged from 2 to 14 points(mean:9.1), postoperative JOA scores ranged 7 to 17 points(mean:14.1). The mean improvement rate was 62%. The range of cervical spine motion decreased from 26.6 degrees prior to operation to 10.8 degrees after operation. Lordotic curvature also fell from 11.8 degrees before operation to 6.6 degrees after operation. In 20 patients, the postoperative kyphotic curvature increased to 5 degrees of more, although no difference was seen in their improvement rates compared with patients whose lordosis remained unchanged. 80 of 121 patients experienced progression of ossified masses. Three patients underwent additional laminectomy due to progression of ossification or insufficient expansion.

Operation took an average 80 minutes and mean amount of blood loss was 215 ml. No patients had postoperative motor paralysis caused by C5 or C6 nerve damage and no serious complications were seen.