We investigated the clinical results and progression of ossification in 113 patients with cervical OPLL. For analysis, patients were divided into two groups dependent on type of management those who recuved conservative treatment (natural history group: N-group), and the other group which recuved surgical treatment (Op-group). N-group consisted of 43 patients with a mean age of 58 years, and the Op-group of 70 patients who underwent expansive laminoplasty using sagittal splitting of the spinous process (Kurokawa method) had a mean age of 59 years. The mean follow-up period was 6 years and 2 months in N-group, and 2 years and 11 months in Op-group. In N-gruop, improvement of subjective symptoms was found in 26 patients (66.5%). However, improvement was found in only 21% of the patients with myelopathy. In Op-group, a recovery rate of 50% or more by JOA score was achieved in 38 patients (54.3%). Progressive OPLL was seen in 18 patients (41.9%) of N-group, and in 24 patients (34.3%) of Op-group. There was no significant difference in clinical results between those patients still having progressive OPLL and those patients with no progression.
