Comparison of Anchor Hole Enlargement Between Biodegradable and All-Soft Suture Anchors After Arthroscopic Bankart Repair: Longitudinal 2-Year Follow-up Study.

Abstract

Arthroscopic Bankart repair (ABR) is one of the most common arthroscopic surgeries for recurrent dislocation of the shoulder. A few previous studies have reported anchor hole enlargement after ABR. All-soft suture anchors (ASSAs) and biodegradable anchors (BDAs) have been mainly used recently; however, to the authors' knowledge, no reports are available that compare anchor hole enlargement between ASSAs and BDAs over a 2-year follow-up period. To compare the changes in anchor hole diameter between ASSAs and BDAs. Cohort study; Level of evidence, 3. The anchor holes of 61 patients who underwent ABR for anterior shoulder instability were analyzed. The changes in anchor hole diameters were evaluated by 3-dimensional computed tomography performed immediately after surgery and at 6, 12, and 24 months postoperatively. The diameter enlargement ratio was calculated by dividing the diameters at 6, 12, or 24 months by their counterparts immediately postoperatively and was classified into enlargement (ratio >1.5), mild enlargement (1.1-1.5), no change (0.9-1.1), or reduction (<0.9). Furthermore, all anchors were divided into 2 groups-ASSA group and BDA group-to evaluate the effect of the anchor types on the anchor hole diameter changes. The differences between preoperative and postoperative results were compared using paired <i>t</i> test, Mann-Whitney <i>U</i> test, or Fisher exact test. The differences in hole enlargements between the time points were analyzed using the Kruskal-Wallis test. In total, 315 holes (232 ASSAs, 45 shoulders; 83 BDAs, 17 shoulders) were available for assessment. Among the overall holes, proportions of enlargement and mild enlargement at 6, 12, and 24 months were 8.3%, 8.0%, and 8.8% and 27.0%, 18.2%, and 16.9%, respectively. The anchor hole enlargement was observed in 35.4% of the ASSA group and 34.9% of the BDA group at 6 months compared with those immediately after surgery. The mildly enlarged anchor holes significantly decreased after 12 months in the ASSA group (26.3%, 15.3%, and 17.8% at 6, 12, and 24 months, respectively), whereas no significant decrease was observed in the BDA group (28.9%, 26.0%, and 17.4% at 6, 12, and 24 months, respectively). The enlarged anchor holes significantly decreased after 12 months compared with those immediately after surgery in the ASSA group (9.1%, 7.4%, and 6.7% at 6, 12, and 24 months, respectively) but did not decrease at 12 or 24 months in the BDA group (6.0%, 9.6%, and 10.9% at 6, 12, and 24 months, respectively). Enlarged anchor holes were decreased with ASSAs but not with BDAs. Enlarged anchor holes could be reduced over a longer observation.