(I-722) The Effect of Surgical Approach on Long-term Outcomes of Mild and Symptomatic Degenerative Cervical Myelopathy: A Pooled Analysis of Individual Patient Data from 1031 Cases
Medical Student Temerty Faculty of Medicine, University of Toronto Toronto, Canada
Introduction: Controversy exists regarding the optimal approach to surgically treat degenerative cervical myelopathy (DCM). Moreover, patients with mild DCM may be more sensitive to slight changes in physical function when treated using different surgical approaches.
Methods: Individual patient data of subjects who underwent surgery for DCM was identified from a pooled dataset of the AO Spine CSM-North America, CSM-International, and CSM-Protect clinical studies. Primary outcomes were changes in Short Form 36 Physical Component Summary (SF36-PCS; minimum clinically important difference [MCID]=5) and modified Japanese Orthopedic Association (mJOA; MCID=1) scores at 12 months. Two comparison cohorts were created: i) anterior surgery and ii) posterior surgery. Unbalanced baseline variables were matched with 1:1 nearest-neighbour propensity-score matching. Afterwards, one-stage mixed-effects meta-analysis was performed and reported with mean differences (MD) and 95% confidence intervals. A subgroup analysis planned a priori in mild DCM patients (mJOA 15-17) was performed.
Results: From a total of 1031 patients with DCM, a well-matched cohort of 634 patients who received anterior vs posterior surgery was included for analysis. Patients who received anterior surgery did not significantly differ from those with posterior surgery in change of mJOA (MD: 0.035, 95% CI[-0.39–0.46]). However, anterior surgical patients had a significantly higher SF36-PCS score of 2.08 points, which did not reach MCID (MD: 2.08, 95% CI[0.51–3.32]). From 194 mild DCM patients, a well-matched cohort of 68 patients were included for analysis. Mild DCM patients that received anterior surgery had 9.0 points greater SF-PCS improvement at 12 months compared to posterior surgery patients (MD: 9.04, 95% CI[4.14–13.94]). Improvement in mJOA was also significantly greater by 0.9 points (MD: 0.89, 95% CI[0.07–1.70]), both of which reached MCID.
Conclusion : In general, anterior and posterior approaches for DCM result in similar gains in recovery of function or patient-reported physical functioning. However, in mild DCM, when surgery is clinically indicated, anterior surgery is associated with clinically important benefits in functional recovery and patient-reported physical functioning when compared with posterior techniques.
