Types of Retears After Knot-tying and Knotless Suture Bridge Rotator Cuff Repair: A Systematic Review and Meta-analysis

BACKGROUND: In conventional double-row repair for rotator cuff tears, tying the medial row of anchor sutures can strangulate the tendon. The knotless medial row technique has been recommended to improve vascularity and reduce retear rates. The researchers divided the retear pattern into 2 categories: type 1 (failure at the tendon-bone interface) and type 2 (failure at the musculotendinous junction with healed footprint). PURPOSE: To compare studies on knot-tying versus knotless double-row repair for rotator cuff tears according to retear type and clinical and radiological outcomes. STUDY DESIGN: Systematic review; Level of evidence, 3. METHODS: A search of the PubMed, Embase, Scopus, and Cochrane databases was performed following the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Included were studies that directly compared the knot-tying and knotless double-row techniques and provided postoperative patient-reported outcomes and retear rates. The Methodology Index for Non-Randomized Studies (MINORS) criteria were used for methodological quality assessment of the included studies. Odds ratios (ORs) were calculated for dichotomous outcomes, and mean differences (MDs) were calculated for continuous outcomes. RESULTS: Included were 12 studies (n = 1411 shoulders); 1 study had level 1 evidence, 3 studies had level 2 evidence, and 8 studies had level 3 evidence. The MINORS score ranged from 15 to 19, indicating that the methodology was fair to good. There was no statistically significant difference in retear rate between techniques (OR, 0.99; 95% CI, 0.67-1.47; P = .96); however, more type 1 retears were seen in the knotless technique (OR, 0.42; 95% CI, 0.23-0.77; P = .005), and more type 2 retears were seen in the knot-tying technique (OR, 3.15; 95% CI, 1.70-5.83; P = .0003). Higher postoperative Constant scores were seen in the knot-tying technique (MD, 1.28; 95% CI, 0.03-2.53; P = .04); however, there were no significant differences between techniques regarding other postoperative outcomes. CONCLUSION: There was no significant difference in overall retear rates between the knotless and knot-tying techniques, and both techniques demonstrated similar clinical outcomes. However, type 2 retear rates were significantly greater after knot-tying repair, and type 1 retear rates were significantly greater after knotless repair.