Cervical Sagittal Alignment in Patients with Cervical Spondylotic Myelopathy

STUDY DESIGN Prospective cohort study. OBJECTIVE Among patients with cervical spondylotic myelopathy (CSM), we aimed to evaluate the extent to which: (1) pre-operative cervical sagittal alignment is associated with health-related quality of life, function, and symptoms; (2) surgery leads to changes in cervical sagittal alignment; and (3) post-operative cervical sagittal alignment is associated with health-related quality of life, function, and symptoms at 12 months of follow-up. SUMMARY OF BACKGROUND DATA The importance of maintaining or improving cervical sagittal alignment in the surgical management of patients with CSM has not been established. METHODS We measured C2-C7 cobb angle, T1 slope, and C2-C7 cervical sagittal vertical axis (cSVA). We tested for associations with Neck Disability Index, Pain Scales for neck and arm pain, EuroQol 5D, Short Form 12 (SF-12) Physical and Mental Component Summaries (PCS and MCS), and modified Japanese Orthopaedic Association scores. We adjusted for potential confounders using multiple linear regression, and we performed various pre-specified subgroup (cSVA >40 mm, surgical approach) and sensitivity analyses. RESULTS Among 250 patients, adjusted analyses yielded significant inverse associations prior to surgery between each of cSVA and T1 slope with SF12 PCS (T1 slope: -0.14, 95% CI -0.26 to -0.01, p = 0.03; C2-C7 cSVA: -0.13, 95% CI -0.21 to -0.05 p < 0.01). Surgery was associated with a small but statistically significant increase in cSVA across the cohort (+5.8 mm (SD 11.7), p < 0.01) but no change in cobb angle or T1 slope. At 12-months after surgery, there were no significant associations between alignment parameters or change in alignment and any measures of health-related quality of life, function, or symptoms. Results were consistent across subgroup and sensitivity analyses. CONCLUSIONS Increased cSVA and T1 slope were associated with inferior health-related quality of life at presentation among patients with CSM, but no significant associations were observed following surgical treatment.Level of Evidence: 3.