Outcomes and retear rates after subacromial and glenohumeral injection of a chitosan-based thermosensitive anti-adhesive agent during arthroscopic rotator cuff repair: a propensity score-matched analysis

Background: A variety of agents are used during rotator cuff repair (RCR) to establish biophysical barriers against adhesion formation, including sodium hyaluronate and poloxamer. The aim of this study was to determine the role played by injection location and analyze the effects on shoulder function after cuff repair. Methods: We retrospectively reviewed data from 187 consecutive patients with rotator cuff tears who were treated with a thermosensitive medical chitosan-based anti-adhesive agent. The 45 patients in the glenohumeral joint (GH) group were matched 1:1 with patients in the subacromial space (SA) group based on propensity scores. Clinical outcomes and range of motion (ROM) were evaluated using a visual analog scale (VAS) score for pain and functional assessments conducted preoperatively, 6 months postoperatively, and at the final follow-up (minimum 12 months). Results: After excluding patients without 1 year of postoperative follow-up, 28 patients in each group were chosen for this study. The preoperative VAS score for pain, functional scores, and ROM did not differ significantly between the groups. At the final visit, the VAS score for pain was statistically significantly lower in the SA group (1.04±0.69 for GH group vs. 0.78±1.21 for SA group, P=0.038), but the difference did not meet the criteria for the minimal clinically important difference (MCID). Furthermore, none of the functional scores or ROMs differed significantly between the groups at the final visit. There were two retears in the GH group (7.1%) and three retears in the SA group (10.7%). Conclusions: Neither ROM nor the retear rate differed between glenohumeral and subacromial injection of a thermosensitive medical chitosan-based anti-adhesive agent after RCR. Although the SA group had a slightly lower VAS score for pain at the last follow-up, the difference did not reach the MCID criteria. Overall, the injection site did not appear to alter postoperative ROM recovery. Level of evidence: III.