Roentgenological Findings and Operative Results of Open Door Laminoplasty for Ossification of the Posterior Longitudinal Ligament in the Cervical Spine.

We evaluated the roentgenological findings and operative results in 46 cases of ossification of the posterior logitudinal ligament in the cervical spine. All patients had open door laminoplasty at least a year previously. At follow-up ossification had elongated in size not less than 3mm in 31 cases, and thickened in size not less than 1mm in 17 cases. Ossification tended to expand after surgery in the cases with a short duration of myelopathy, young patients, and patients whose ossification edges were obscure and separated from the vertebral body or whose ossification seemed to grow twofold. In no patients did the ossification thicken by more than 2mm at the most stenotic site before surgery. Therefore we suggest that it is desirable that the spinal cord be decompressed even if the ossification is thickened by 2mm at the most stenotic site after surgery. It is necessary to enlarge the spinal canal sufficiently for the patient whose ossification is inclined to expand post-operatively, when we carry out open door laminoplasty.