Arthroscopic subacromial decompression (acromioplasty) is widely held to be effective, although pain may persist after the procedure. The objective of this study was to evaluate the proportion of patients with residual pain (i.e., the failure rate) after isolated subacromial decompression and to look for predictors of failure.

We conducted a retrospective multicentre study of 108 patients managed with isolated arthroscopic subacromial decompression between 2007 and 2011, for any reason. We excluded patients in whom surgical procedures on the rotator cuff tendons were performed concomitantly. Data were collected from the medical records, a telephone questionnaire, and radiographs obtained before surgery and at last follow-up. Failure was defined as persistent pain (visual analogue scale score>3) more than 6months after surgery and at last follow-up.

The failure rate was 29% (31/108). Two factors significantly predicted failure, namely, receiving workers’ compensation benefits for the shoulder condition and co-planing. Heterogeneous calcific tendinopathy and deep partial-thickness rotator cuff tears were also associated with poorer outcomes, but the effect was not statistically significant.

Co-planing may predict failure of subacromial decompression, although whether this effect is due to an insufficient degree of co-planing or to the technique itself is unclear. Nevertheless, in patients with symptoms from the acromio-clavicular joint, acromio-clavicular resection is probably the best option. Receiving workers’ compensation benefits was also associated with treatment failure, as a result of well-known parameters related to the social welfare system.

Isolated arthroscopic subacromial decompression is effective in 70% of cases. We recommend the utmost caution if co-planing is considered and/or the patient receives workers’ compensation benefits for the shoulder condition, as these two factors are associated with a significant increase in the failure rate.

IV (retrospective study).