Arthroscopic bursectomy less effective in the degenerative shoulder with chronic subacromial pain

Background Varying results after surgery in patients with subacromial pain syndrome (SAPS) have raised the question on whether there is a subgroup of patients that can benefit from surgery. Therefore, we aimed to identify preoperative and peroperative factors associated with a favorable patient-reported outcome after arthroscopic bursectomy in patients with SAPS. Methods Patients with chronic SAPS who underwent arthroscopic bursectomy after failed conservative management were included (n = 94). Patients were evaluated at the baseline, and 2 weeks, 8 weeks, 6 months, and 1 year after surgery. The primary outcome was the Western Ontario Rotator Cuff index (WORC) score one year after surgery. The secondary outcome measure was a visual analog scale for pain. Mixed model analyses were used to identify prognostic factors. Results The mean WORC (mean difference 39%, 95% confidence interval (CI) 32.8–45.3, P < .001) and visual analog scale pain scores (mean difference 41 mm points, 95% CI 3.37–4.88, P < .001) significantly improved one year after surgery. Nineteen patients (20%) developed a postoperative frozen shoulder. A longer duration of preoperative complaints and the peroperative identification of degenerative glenoid cartilage were associated with significantly worse WORC scores, with −0.086% per month (95% CI −0.156 to −0.016, P = .016) and −20% (95% CI −39.4 to −1.26, P = .037), respectively. Conclusion We identified demographic and clinical factors that predict the course after arthroscopic subacromial bursectomy. We found that arthroscopic bursectomy is less effective in patients with SAPS with a degenerative shoulder. This finding suggests that an improved treatment effect of arthroscopic subacromial bursectomy can be expected in patients with chronic SAPS if intra-articular pathologies such as glenohumeral osteoarthritis are sufficiently excluded.