Preoperative rotator cuff tendon integrity, tear size, and muscle atrophy and fatty infiltration are associated with structural outcomes of arthroscopic revision rotator cuff repair

Purpose A few studies have focused on factors predisposing to retear after arthroscopic revision rotator cuff repair (ARRCR). This study aimed to retrospectively evaluate (1) the structural and clinical outcomes of ARRCR and (2) pre- and intraoperative factors affecting the integrity of the rotator cuff (RC) tendon by focusing on preoperative RC tendon integrity, tear size, muscle hypotrophy and fatty infiltration. Methods Patients who underwent ARRCR between 2006 and 2016 were reviewed. Preoperative variables included demographic data, RC tendon integrity, tear size, and muscle hypotrophy and fatty infiltration on preoperative magnetic resonance imaging (MRI). Intraoperative variables included repair technique and completeness of repair. The visual analog scale for pain (PVAS), functional VAS (FVAS), American Shoulder and Elbow Surgeons scores, and shoulder range of motion (ROM) were assessed. Postoperative tendon integrity was evaluated using over 6-month follow-up MRI. Patients were classified into groups A (healed) and B (retear), and their variables were compared. Results Overall 65 patients with a mean follow-up of 49.5 +/- 30.2 (range, 24.0-148.9) months were analyzed. Fifty-six of 65 (86.2%) patients underwent MRI at 9.1 +/- 9.7 (range, 4.4-40.2) months after ARRCR, and 20 of 56 (35.7%) patients (group B) exhibited retear. Group A (36/56, 64.3%) showed higher functional scores and ROMs than group B at the final follow-up, with significant differences in the FVAS scores (Group A versus B: FVAS, 7.6 +/- 1.8 versus 6.4 +/- 1.9, p = 0.036). Intraoperative variables, including preoperative tendon integrity (p = 0.021), tear size (p = 0.007), supraspinatus and infraspinatus muscle hypotrophy and fatty infiltration (p < 0.001 and p = 0.046), and completeness of repair (p = 0.030), differed significantly between the groups. Multivariate analysis revealed that preoperative supraspinatus muscle hypotrophy and fatty infiltration were independent predisposing factors for retear after ARRCR [odds ratio = 7.5, 95% confidence interval (CI) 1.1-55.8, p = 0.048]. Conclusion The retear was found in 20/56 patients (35.7%) after ARRCR for less than massive rotator cuff tears in this limited study population. Preoperative tendon integrity, tear size, supraspinatus and infraspinatus muscle hypotrophy and fatty infiltration, and completeness of repair was revealed to be associated with tendon integrity following ARRCR. Among them, preoperative supraspinatus muscle atrophy and fatty infiltration were the independent factors for retear after ARRCR, although generalization is limited.