Preoperative Disc Height as a Prognostic Factor in Laminoplasty for Cervical Spondylotic Myelopathy with Degenerative Spondylolisthesis.

Introduction: Laminoplasty (LP) is widely used to treat cervical spondylotic myelopathy (CSM) with degenerative spondylolisthesis (DS), but predictors of postoperative outcomes remain unclear. This study aimed to identify factors associated with neurological recovery after LP in patients with CSM and DS. Methods: We retrospectively reviewed 136 patients who underwent LP for CSM between 2005 and 2020. Of these, 29 patients (20 men, 9 women) with DS at the responsible level were included. The responsible level was defined as the segment showing intramedullary signal change or cerebrospinal fluid space obliteration on magnetic resonance imaging. The mean age was 71.7 years (range: 50-87), with a mean follow-up of 5.5 years (range: 2-12). Patients were grouped on the basis of achievement of a ≥50% recovery rate (RR) in the Japanese Orthopaedic Association (JOA) score, defined as the minimum clinically important difference (MCID). Radiographic parameters, including C2-7 alignment, C2-7 range of motion (ROM), C7 slope, slip distance, segmental ROM, and disc height at the responsible level, in addition to Pfirrmann grade, were compared. Results: The mean JOA RR was 50.2%, with 66% achieving MCID. No statistically significant differences were found between the two groups in terms of C2-7 alignment, C2-7 ROM, C7 slope, slip distance, segmental ROM, or Pfirrmann grade. However, preoperative disc height was significantly greater in the Good Improvement group (5.9 mm) than in the Poor Improvement group (4.8 mm) (p=0.03). Conclusions: Greater preoperative disc height was associated with better neurological recovery, suggesting its potential utility as a simple prognostic marker in CSM with DS.