Changes in the Cervical Range of Motion and Clinical Outcomes After Laminectomy With Fusion for Ossification of the Posterior Longitudinal Ligament: Impact of K-Line and OPLL Subtypes.

BACKGROUND AND

OBJECTIVES

Laminectomy with instrumented fusion (LF) effectively manages multisegment cervical ossification of the posterior longitudinal ligament (OPLL). However, the influence of cervical sagittal alignment, range of motion (ROM), and OPLL subtype on outcomes remains unclear.

METHODS

Patients who were initially diagnosed with cervical OPLL and treated with posterior LF with a minimum of 2 years of follow-up were retrospectively included. Demographic data, surgical details, radiologic parameters, and ROM were evaluated. The Japanese Orthopedic Association (JOA) score was used to evaluate the myelopathic outcomes. Further comparisons were made according to K-line type and OPLL type among all participants. Cervical sagittal alignment and ROM in different K-line and OPLL types were evaluated. Correlations between patient baseline cervical sagittal alignment, K-line, and OPLL types and postoperative outcomes were assessed through logistic regression analysis. A P value of < .05 was considered statistically significant.

RESULTS

Among 133 OPLL patients who underwent posterior LF (mean follow-up of 28.8 months), significant improvements in JOA scores (9.2-12.8, P < .001; exceeding minimum clinically important difference), ROM, and neurological function (all P < .001) were observed, despite increased C-SVA ( P = .018). K-line (-) patients presented greater MRI signal changes (97.1% vs 72.4%, P < .001) and lower preoperative C2-7 angles. The OPLL subtypes differed in flexion angle and ROM ( P < .05), with the continuous type showing a postoperative lordotic shift ( P = .012). No predictors significantly influenced JOA score recovery.

CONCLUSION

LF significantly improved neurological function in OPLL patients regardless of K-line status or subtype. Although radiographic parameters vary across subgroups, these morphological differences do not predict 2-year clinical outcomes when sufficient decompression is achieved.