Long-term results after expansive open-door laminoplasty for the segmental-type of ossification of the posterior longitudinal ligament of the cervical spine: a comparison with nonsegmental-type lesions.

OBJECT: The segmental-type of ossification of the posterior longitudinal ligament (OPLL) of the cervical spine is distinct from other types in its morphological features. Whether the results of expansive open-door laminoplasty for the segmental-type are different from those for other types remains unclear. To clarify this issue, the long-term results after surgical treatment of segmental-type OPLL were compared with those of other types. METHODS: Clinical results were documented in 57 patients who underwent expansive open-door laminoplasty and were followed for a minimum of 7 years, results were quantified using the Japanese Orthopaedic Association (JOA) scoring system to determine function. Segmental-type OPLL was observed in 10 patients (Group 1) and other types in 47 patients (Group 2). Preoperative JOA scores were not significantly different between the two groups. As many as 5 years after surgery, clinical results were favorable and maintained in both groups, and no significant intergroup difference in postoperative JOA scores was observed; however, after 5 years postoperatively, JOA scores decreased in both groups. The decrease was greater in Group 1, and a significant intergroup difference in JOA scores was demonstrated when analyzing final follow-up data. In Group 1, the authors found that the degree of late-onset deterioration relating to cervical myelopathy positively correlated with the cervical range of motion. CONCLUSIONS: The long-term results of expansive open-door laminoplasty in the treatment of segmental-type OPLL were inferior to those for other types. Cervical mobility may contribute to the development of late deterioration of cervical myelopathy.