Magnetic resonance imaging for relationship between the severity of perianchor fluid collection and rotator cuff integrity after arthroscopic double-row suture-bridge rotator cuff repair

Purpose: The primary purpose of this study was to assess perianchor fluid collection (PFC) severity of medial anchor and rotator cuff integrity association after arthroscopic double-row suture-bridge rotator cuff repair (RCR) and the secondary purpose was to identify the demographic and radiologic risk factors for high-grade PFC. Hypothesis: Re-tear rate would be significant higher in patients with high-grade PFC. Methods: We retrospectively reviewed patients with arthroscopic double-row suture-bridge RCR for full-thickness rotator cuff tear (RCT) at our institution between February 2012 and May 2018. Based on the PFC severity, they were divided into the no-fluid (no fluid collection), low-grade (minimal or local fluid collection around the anchor), and high-grade (fluid collection beyond the entire length of the anchor) groups. Magnetic resonance imaging was performed 6 months postoperatively for assessing PFC severity and repaired rotator cuff integrity association, besides evaluating correlation between severity and various demographic and radiologic factors, including work level (low/medium/high) and RCT size. Results: This study included 312 patients, 181 (58%) in the no fluid group, 82 (26.3%) in the low-grade PFC group, and 49 (15.7%) in the high-grade PFC group. Re-tear occurred in 73 (23.4%) patients and was more frequent in the high-grade group (26/49 [53.1%]) than in the no-fluid (27/181 [14.9%]; p < 0.001) and low-grade (20/82 [24.4%]; p = 0.001) groups, without statistically significant differences between the latter two (p = 0.082). Among the demographic factors, work level (low/medium/high) differed significantly between the no-fluid (22.1%/58.0%/19.9%), low-grade (25.7%/46.3%/28.0%), and high-grade (26.5%/34.7%/38.8%) groups (p = 0.026). Among the radiologic factors, the mediolateral tear size differed significantly between the three groups (no-fluid group: 1.7 ± 0.8 cm, low-grade group: 1.8 ± 0.6 cm, high-grade group: 2.2 ± 1.0 cm; p = 0.003). Multivariate regression analysis showed that mediolateral tear size (odds ratio: 1.821; 95% confidence interval: 1.258–2.636; p = 0.001) was an independent risk factor for high-grade PFC. Conclusions: After arthroscopic double-row suture-bridge RCR, the highest re-tear rate was observed in patients with high-grade PFC, while there was no significant difference in rates between no-fluid and low-grade PFC groups. As PFC severity increased, the risk of re-tear increased. In particular, larger mediolateral tear size was associated with high-grade PFC. Level of evidence: III; case-control study.