Perianchor Cyst Formation Around Biocomposite Biodegradable Suture Anchors After Rotator Cuff Repair

Background: Biodegradable anchors may lead to perianchor cyst formation or osteolysis. A new generation of anchors containing osteoconductive material was recently presented, but there is currently no solid evidence that this concept decreases cyst formation around anchors. Hypothesis: The null hypothesis was that the prevalence and severity of cyst formation around anchors would be similar for all 3 anchor types. Study Design: Cohort study; Level of evidence, 2. Methods: To evaluate differences between anchor behaviors postoperatively, this study included 2 groups of patients who underwent rotator cuff repair. In group 1 (n = 38), transosseous-equivalent rotator cuff repair was performed in all patients. At the time of repair, 2 different anchors (anchor A: 23% microstructured -tricalcium phosphate plus 77% polylactic acid enantiomers [PLLA]; and anchor B: 30% hydroxyapatite plus 70% PLLA) were used for medial-row repair. Insertion locations (anterior or posterior) were randomly assigned. In group 2 (n = 38), the same procedure was performed; however, 1 of the anchors used in group 1 was changed (anchor A: as above; and anchor C: 30% -tricalcium phosphate plus 70% faster absorbing polylactic-co-glycolic acid copolymer [85% PLLA plus 15% polyglycolic acid]). The presence and severity of fluid collection around the anchors was evaluated by magnetic resonance imaging at approximately 1 year after rotator cuff repair (12.7 0.9 months for group 1 and 12.6 1.8 months for group 2). Results: In group 1, a fluid signal was observed in 14 patients (36.8%) for anchor A and in 12 patients (31.6%) for anchor B (P > .05). The severity of perianchor cyst formation was no different for the 2 anchors (respective fluid signal grades [0-4]: 24, 3, 9, 1, and 1 for anchor A; and 26, 4, 7, 1, and 0 for anchor B; P > .05). However, in group 2, cysts were observed in 19 patients (50%) for anchor A and in 3 patients (7.9%) for anchor C (P < .001). For anchor C, only 2 cases of grade 1 and 1 case of grade 2 fluid collection were observed. Intergroup analysis of anchor A revealed no significant differences in the prevalence or severity of perianchor cyst formation (P > .05). Healing failure was observed in 12 patients (31.6%) in group 1 and 10 patients (26.3%) in group 2 (P > .05). Conclusion: New-generation biodegradable suture anchors seem to decrease the severity of perianchor cyst formation. Future research is required to optimize the compositions and proportions of osteoconductive materials and polymers to improve adverse reactions. Nevertheless, controlling the properties of polymers and adding osteoconductive material both appear to enhance biocompatibility.