Postoperative Graft Volume Reduction Is Associated With Inferior Clinical Outcomes of Superior Capsule Reconstruction Using an Acellular Dermal Matrix Allograft

Purpose: To evaluate whether postoperative graft volume reduction is associated with clinical outcomes after superior capsule reconstruction (SCR) and to identify factors related to graft volume change. Methods: Between May 2018 and June 2021, patients who underwent SCR with acellular dermal matrix allograft for irreparable rotator cuff tear with a minimum 1-year follow-up and who had intact graft continuity in postoperative 6-month magnetic resonance imaging were retrospectively reviewed. The lateral half to the medial half of the graft volume ratio was defined as lateral half graft volume ratio. The difference between the preoperative and postoperative lateral half graft volume ratio was defined as lateral half graft volume change. Patients were divided into 2 groups: those with preserved graft volume (group I) and those with reduced graft volume (group II). Intergroup differences in clinical and radiological characteristics were analyzed. Results: A total of 81 patients were included, with 47 (58.0%) in group I and 34 (42.0%) in group II. Group I showed significantly lower lateral half graft volume change (0.018 ± 0.064 vs 0.370 ± 0.177; P < .001) than group II. Group II showed significantly greater preoperative Hamada grade (1.3 ± 0.5 vs 2.2 ± 0.6, P < .001), an anteroposterior distance of the graft at the greater tuberosity (APGT) (30.3 ± 4.8 vs 35.2 ± 3.8, P < .001), and fatty infiltration of infraspinatus (2.3 ± 0.9 vs 3.1 ± 0.8, P < .001) and subscapularis (0.9 ± 0.9 vs 1.6 ± 1.3, P = .009) than group I. Group II had a significantly lower proportion of patients achieving MIC in Constant score than group I (70.2% vs 47.1%, P = .035). The Hamada grade, APGT, and fatty infiltration of infraspinatus and subscapularis were independent factors of graft volume change. Conclusions: Although SCR improved pain and shoulder function, postoperative graft volume reduction was related to a lower rate of minimal important change achievement in the Constant score compared with preserved graft volume. The preoperative Hamada grade, APGT, and fatty infiltration of infraspinatus and subscapularis were associated with graft volume reduction. Level of Evidence: Level III, retrospective case–control study.