The association between the morphological patterns of medium to large rotator cuff tears and the retear rate after arthroscopic repair

Aims The aim of this study was to evaluate factors associated with retear of the rotator cuff after arthroscopic repair of cuff tears and to investigate whether these factors vary according to the pattern of the tear. Methods Between March 2014 and June 2021, patients who underwent arthroscopic complete rotator cuff r n epair for symptomatic 2 cm to 4 cm full-thickness cuff tears with a minimum follow-up of two years were retrospectively reviewed. The patterns of the tears were classified intraoperatively after debridement of degenerative tissues, as crescent-shaped, U-shaped, anterior L-shaped, and posterior L-shaped tears. Based on MRI or ultrasound performed six months postoperatively, patients were divided into healed and retear groups. Clinical and radiological parameters relating to retear were compared between the groups, and multiple regression analysis was performed to identify factors associated with retear. The interaction between the patterns of tear and each independent retear-related factor was assessed using logistic regression. Results Of 713 patients, the tendon healed in 605 (84.9%) and 108 (15.1%) had a retear. In the multiple regression analysis, an anterior L-shaped tear (odds ratio (OR) 3.26 (95% CI 1.58 to 6.71); p = 0.001) was the most powerful independent factor associated with retear, followed by age (OR 1.04 (95% CI 1.01 to 1.06); p = 0.008), anteroposterior tear size (mm) (OR 1.07 (95% CI 1.02 to 1.11); p = 0.002), fatty infiltration of the supraspinatus (OR 1.38 (95% CI 1.02 to 1.87); p = 0.037), and infraspinatus muscles (OR 1.44 (95% CI 1.06 to 1.96); p = 0.019). In the interaction analysis, the effect of fatty infiltration of supraspinatus on the risk of retear differed significantly by the pattern of the tear ( p interaction = 0.018), and was significantly associated with an increased risk of retear only in posterior L-shaped tears compared with crescent-shaped tears (OR 2.41 (95% CI 1.41 to 4.14); p = 0.001). Conclusion The pattern of the tear, especially anterior L-shaped tears, was identified as an independent risk factor for retear after rotator cuff repair. The impact of fatty infiltration of the supraspinatus muscle on the risk of retear varied by the pattern of the tear, with a significant association seen in posterior L-shaped tears. Cite this article: Bone Joint J 2026;108-B(6):808–817.