Association Between Cervical Paravertebral Muscle Degeneration, Sagittal Alignment, and Unilateral Cervical Disc Herniation

STUDY DESIGN: Retrospective cross-sectional study. OBJECTIVE: To investigate the relationship between cervical paravertebral muscle quality, sagittal alignment, and segmental disc herniation using quantitative CT. SUMMARY OF BACKGROUND DATA: Fatty degeneration of paravertebral muscles may influence cervical spinal biomechanics and disc pathology. While sagittal alignment is often assessed in cervical spine disorders, its predictive value compared with muscle quality remains unclear. METHODS: We retrospectively analyzed 222 patients undergoing cervical CT for disc herniation. Muscle quality was quantified using cross-sectional area and Hounsfield units. Sagittal alignment parameters (C2-C7 angle, T1 slope, and C2-C7 SVA) were measured. Correlation and ROC analyses assessed the relationship between muscle metrics, alignment, and disc herniation levels. The study adhered to the Declaration of Helsinki, and measurements were performed in a double-blind manner (ICC=0.80). RESULTS: Paravertebral muscle attenuation values demonstrated the strongest predictive ability for disc herniation levels (AUC=0.682-0.750), whereas sagittal alignment parameters showed limited predictive performance. Muscle density parameters were associated with segmental disc pathology independent of sagittal alignment measures. CONCLUSIONS: Quantitative CT assessment of cervical paravertebral muscle quality may provide complementary biomechanical information related to cervical disc herniation patterns. Given the retrospective cross-sectional design, findings indicate association rather than causation. LEVEL OF EVIDENCE: Level III.