Association of paraspinal fat infiltration with postoperative clinical outcomes in older cervical spondylotic myelopathy patients undergoing anterior cervical discectomy and fusion.

OBJECTIVE: To investigate the association between preoperative cervical paraspinal muscle fat infiltration and 2‑year clinical outcomes in older patients with cervical spondylotic myelopathy (CSM) undergoing anterior cervical discectomy and fusion (ACDF), and to analyze its relationship with postoperative radiographic correction parameters and long‑term pain prognosis. METHODS: A retrospective analysis was conducted on 91 older CSM patients who underwent ACDF between January 2020 and June 2023. Based on preoperative MRI assessment using the Goutallier classification system, patients were stratified into three groups according to the degree of paraspinal muscle fat infiltration: mild (Grade 0-1, n = 36), moderate (Grade 1.5-2, n = 31), and severe (Grade 2.5-4, n = 24). Baseline data, key sagittal radiographic parameters, and clinical outcome scores (JOA, NDI, VAS) were compared among groups. Multiple linear regression analysis was performed to identify independent factors associated with the VAS score at 2-year follow-up. RESULTS: Postoperative radiographic parameters, including the T1 slope, C2 slope, C2-C7 Cobb angle, C0-C2 Cobb angle, sagittal segmental angle (SSA), and average segmental disc height (ASDH), significantly improved in all patients (P < 0.05). Clinical scores (JOA, NDI, VAS) also showed significant improvement at the 2-year follow-up (P < 0.05). However, the severe fat infiltration group demonstrated significantly worse immediate postoperative VAS scores, as well as worse NDI and VAS scores at the 2-year follow-up compared to the mild and moderate groups (P < 0.05). Multiple linear regression analysis confirmed that the preoperative Goutallier grade was a significant independent factor associated with a higher VAS score at 2 years (B = 0.962, P < 0.001), after adjusting for relevant covariates. CONCLUSION: ACDF effectively improves clinical symptoms and cervical alignment in older CSM patients. However, severe preoperative paraspinal muscle fat infiltration is independently associated with inferior postoperative pain relief and functional recovery. Assessment of paraspinal muscle status may be useful for risk stratification in older patients undergoing ACDF.