Comparison of Outcomes after Anterior vs. Posterior Surgery for Degenerative Cervical Myelopathy: A Pooled Analysis of Individual Patient Data: Anterior and posterior surgical approaches for DCM.

Abstract

Background context: Uncertainty exists regarding the optimal surgical approach to treat patients with degenerative cervical myelopathy (DCM). This uncertainty is particularly marked for patients with mild DCM who may be more sensitive to different management techniques.

Purpose: To determine the effect of surgical approach on one-year outcomes for DCM.

Study design/setting: Individual patient data meta-analysis of three independent, prospective, multicentre clinical trials (i.e., CSM-North America, CSM-International, CSM-Protect) that enrolled patients between 2005-2018 in academic hospitals, with 1yr follow up. Statistical analysis was performed from September 13, 2023-April 2, 2024.

Patient sample: From a total of 1047 adult subjects with DCM, 980 met the eligibility criteria who were surgical candidates with symptomatic and radiologically-evidenced DCM and no prior cervical surgery.

Outcomes measures: The primary endpoint was change in 36-Item Short Form Health Survey Physical Component Summary score (SF36-PCS; minimum clinically important difference [MCID]=4) at 1yr compared to pre-operatively. Secondary endpoints were change in modified Japanese Orthopedic Association (mJOA; MCID=2) score, Neck Disability Index (NDI; MCID=15) score, SF36 Mental Component Summary (SF36-MCS; MCID=4) score, and postoperative complications.

Methods: Two comparison cohorts were created: i) anterior surgery and ii) posterior surgery. Mean differences (MD) of outcomes with 95% confidence intervals (CI) were estimated using one-stage covariate-adjusted hierarchical mixed-effects meta-analyses with study and treatment exposure as random effects. A priori subgroup analysis in mild DCM patients (mJOA=15-17) was conducted.

Results: From 1047 adult subjects with DCM, 980 patients were eligible. The mean patient age was 56.9 years (SD=11.4), with 38.7% that identified as female. 560 patients (57.1%) received anterior cervical decompressive surgery for DCM. Patients who had anterior decompressive surgery experienced greater improvements in quality of life and disability at 1yr follow-up than those who underwent posterior decompressive surgery in SF36-PCS (MD=1.57 [95%CI 0.11-3.03], p=0.0348) and NDI (MD=3.32 [95%CI 0.58-6.05], p=0.017). Dysphagia was more likely after anterior surgery. Pseudoarthrosis and wound infections were more likely after posterior surgery. In a subgroup of patients with mild DCM, patients who underwent anterior decompressive surgery experienced even greater improvements in SF36-PCS (MD=5.45 [95%CI 1.73-9.18], p=0.0042), NDI (MD=10.37 [95%CI 3.43-17.31], p=0.0035), and mJOA (MD=0.95 [95%CI 0.12-1.77], p=0.0238; MCID=1) than posterior surgery patients.

Conclusion: Anterior surgical decompression for DCM is associated with greater improvements in 1yr patient-reported quality of life and disability than posterior surgical decompression. These results may assist clinicians in driving complex management decisions.