Impact of Cervical Multifidus Fatty Infiltration on Postoperative Clinical Outcomes Following ACDF

Objective The effect of fatty infiltration of the cervical paraspinal muscles, as assessed by the Goutallier classification, on 2-year postoperative clinical outcomes in patients undergoing Anterior cervical discectomy and fusion (ACDF) was evaluated. Study design: Retrospective cross-sectional study. Methods Clinical data from patients who underwent ACDF between January 2020 and June 2023 were retrospectively analyzed. Based on degree of fatty infiltration of the cervical multifidus based on the Goutallier classification, patients were categorized into a mild fatty infiltration group (grades 0–2, n = 46) and a severe fatty infiltration group (grades 3–4, n = 45). Perioperative parameters, imaging findings, and clinical outcome scores were compared between groups. Results This study ultimately included 91 patients. All patients completed the surgical procedure successfully, and no severe postoperative complications were observed. No significant between-group differences were noted in baseline characteristics or perioperative parameters, including sex, age, BMI, intraoperative blood loss, operative time, sternocleidomastoid cross-sectional area and fatty infiltration grade at the C5–C6 level, longus colli CSA and fatty infiltration grade, as well as C5 vertebral body CSA and length ( P >  0.05). Relative to preoperative measurements, both groups demonstrated significant postoperative improvements in T1 slope, C2–C7 Cobb angle, and ASDH after surgery ( P <  0.05). At the 2-week and 2-year postoperative follow-up assessments, JOA scores improved, whereas VAS and Neck Disability Index scores decreased significantly in both groups ( P <  0.05). At the 2-year follow-up, NDI and VAS scores were significantly lower in the mild fatty infiltration group ( P <  0.05). Multivariate analysis identified the degree of preoperative multifidus fatty infiltration (odds ratio,OR = 48.959) and the preoperative cross-sectional area of the longus colli muscle (OR = 1.071) as independent predictors of chronic pain following ACDF (both p < 0.05). Postoperative cervical parameters or their temporal changes indicated no differences ( P >  0.05). Conclusion Fatty infiltration of the cervical multifidus may be associated with less favorable pain relief and functional recovery in cervical spondylotic myelopathy patients undergoing ACDF within two years after surgery. Preoperative evaluation and targeted management of multifidus fatty infiltration may be warranted to enhance long-term postoperative clinical outcomes.