Changes in Perianchor Cyst Formation Over Time After Rotator Cuff Repair: Influential Factors and Outcomes

Background: There is a lack of knowledge about the changes in perianchor cysts over time and the factors related to perianchor cysts. Purpose: To evaluate the changes in perianchor cyst formation and anchor absorption over time after arthroscopic rotator cuff repair with a biocomposite suture anchor and to evaluate the factors affecting perianchor cyst persistence and their relationship with patient outcomes. Study Design: Case-control study; Level of evidence, 3. Methods: Forty consecutive patients (mean age, 61.10 ± 5.79 years) who underwent arthroscopic repair for medium- to large-sized rotator cuff tears using a single type of biocomposite (poly-L-lactic acid/polyglycolic acid–beta tricalcium phosphate) medial-row anchor were prospectively enrolled. Postoperative magnetic resonance imaging (MRI) at 2 different time points (6 and 18 months) was performed, and perianchor cyst formation, anchor absorption, and healing failures were evaluated using postoperative MRI. Demographic and clinical data were collected, and functional outcomes at a minimum of 18 months after surgery were assessed. Results: Perianchor cysts were observed in 24 patients (60.0% total; grade 1: 35.0%; grade 2: 10.0%; grade 3: 7.5%; grade 4: 7.5%) at 6 months, and 7 patients (18.4% total; grade 1: 7.9%; grade 2: 5.3%; grade 3: 2.6%; grade 4: 2.6%) had a persistent perianchor cyst at 18 months after surgery. No anchors were absorbed at 6 months, but 73.7% of patients revealed complete or near-full absorption at 18 months. Patients with persistent perianchor cysts showed a significantly larger tear size in the anteroposterior dimension (P =.002) and greater retraction (P <.001). There were no differences in healing failures and functional outcomes between patients with and without persisting perianchor cysts (all P >.05). No differences were found in perianchor cyst formation and anchor absorption between anchors inserted in the greater tuberosity and the lesser tuberosity (all P >.05). Conclusion: The incidence and severity of perianchor cysts decreased with time, and most biocomposite suture anchors were absorbed at 18 months after surgery. Persisting perianchor cysts correlated with a larger tear size in the anteroposterior dimension and greater retraction.