Could Spinal Cord-Canal Mismatch Compromise Clinical Success of Cervical Disc Replacement in Cervical Myelopathy?

Study DesignRetrospective cohort study.ObjectiveTo evaluate whether spinal cord-canal mismatch (SCCM) affects clinical outcomes following cervical disc replacement (CDR) in patients with cervical myelopathy, using patient-reported outcome measures (PROMs), global rating of change (GRC), and minimal clinically important differences (MCIDs).MethodsA retrospective review of a prospectively maintained database identified patients who underwent 1- or 2-level CDR at a single institution from 2016 to 2024. SCCM is measured by the spinal cord occupation ratio (SCOR). Patients were categorized into SCCM (SCOR ≥ 0.7) and no-SCCM (SCOR < 0.7) groups. PROMs, including the Neck Disability Index (NDI), Visual Analog Scale for Neck (VAS-Neck), Arm Pain (VAS-Arm), and GRC, were assessed preoperatively and postoperatively. MCID achievement was analyzed at early (6-12 weeks) and late (6 months-2 years) follow-ups. Statistical tests and logistic regression identified predictors of MCID failure.ResultsNinety-eight patients (55 SCCM, 43 no-SCCM) were included. Both groups demonstrated significant postoperative improvements in PROMs. Early postoperative MCID rates for NDI, VAS-Neck, and VAS-Arm were 61.4%, 61.4%, and 56.8%, respectively, with no significant differences between groups. Similarly, late postoperative MCID rates and GRC outcomes showed no significant differences. SCCM was not a significant predictor of MCID failure, though male sex was associated with higher odds of MCID failure in NDI (P = .032).ConclusionOur findings suggest that SCCM may not adversely affect short-to mid-term clinical outcomes after CDR, although further validation is needed.