Do Surgical Outcomes Differ Between Cervical Spondylotic Myelopathy and Ossification of the Posterior Longitudinal Ligament? A Prospective Multicenter Study of 935 Patients With Degenerative Cervical Myelopathy

Prospective multicenter cohort study. To compare surgical outcomes between patients with cervical spondylotic myelopathy (CSM) and those with ossification of the posterior longitudinal ligament (OPLL) who underwent cervical spine surgery. Although both CSM and OPLL cause degenerative cervical myelopathy (DCM), they differ in anatomic and pathologic characteristics. OPLL is more prevalent in East Asian populations and may present with distinct surgical challenges due to rigidity and multilevel ossification. Prior comparative studies were mostly retrospective with limited use of patient-reported outcome measures (PROMs), making it unclear whether disease etiology influences postoperative recovery. A total of 935 patients (725 with CSM and 210 with OPLL) who underwent cervical spine surgery at 10 high-volume centers in Japan were prospectively followed for two years. Clinical, surgical, and radiographic data were collected. Cervical alignment and range of motion were measured radiographically. Outcomes included the Japanese Orthopaedic Association (JOA) score, visual analog scale (VAS), 36-Item Short Form Health Survey (SF-36), JOA Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), and Neuropathic Pain Symptom Inventory (NPSI). General linear model analyses were used to adjust for potential confounding factors in the evaluation of these outcomes. OPLL patients were younger, had higher body mass index, and more frequently required instrumented fusion and multilevel decompression. They exhibited lower preoperative and postoperative cervical mobility and lordosis. However, both groups demonstrated similar improvements in JOA, VAS, SF-36, JOACMEQ, and NPSI scores at two years. Complication rates were comparable, and no progression of deformity or instability was observed. Although baseline PROMs were better in the OPLL group, postoperative outcomes were equivalent between the groups. Patients with CSM and OPLL achieved similarly favorable outcomes after cervical spine surgery. These findings support a unified surgical strategy for DCM, emphasizing functional severity rather than pathologic subtype in clinical decision-making. Level II.