Postoperative outcomes after arthroscopic repair of isolated subscapularis tears: a systematic review and meta-analysis.

purposeTo systematically synthesize pre- and postoperative outcomes of arthroscopic repair for isolated subscapularis (SSC) tears across functional scores, pain, strength, range of motion (ROM), and clinical tests. STUDY

designSystematic review and meta-analysis.

methodsA systematic literature search was conducted across PubMed, Cochrane Library, and SCOPUS for studies reporting pre- and postoperative outcomes after arthroscopic repair of isolated SSC tears in adults with a minimum 12-month follow-up. Data on functional outcome scores, pain measures, and subscapularis-specific clinical tests were assessed. Functional outcomes were assessed using validated shoulder scoring systems, including the Constant-Murley Score (CMS), University of California, Los Angeles Shoulder Score (UCLA), American Shoulder and Elbow Surgeons Score (ASES), Simple Shoulder Test (SST), and Subjective Shoulder Value (SSV). These scores generally evaluate a combination of pain, shoulder function, strength, and activities of daily living. Pain was assessed using the Visual Analogue Scale (VAS). Subscapularis-specific function was evaluated using clinical tests such as the lift-off, belly-press, and bear-hug tests. The outcomes were presented as a mean difference between the preoperative and postoperative values using random or fixed effects. Results are reported as mean difference (MD) or risk ratio (RR) with 95% confidence interval (CI) and exact P values. Certainty of evidence was evaluated using the GRADE approach. The evidence base consisted predominantly of non-randomized studies at serious risk of bias, with outcomes rated as low or very low certainty.

resultsSeventeen non-randomized studies (Level II-IV evidence) comprising 537 patients were included. In the absence of a control group, mean postoperative functional outcome scores were higher than preoperative values across studies, although individual patient outcomes varied. All included studies were judged to be at serious risk of bias using the ROBINS-I tool, and GRADE certainty of evidence was low to very low for all outcomes. Improvements were reported in multiple domains including shoulder function, strength, ROM, pain, and ability to perform daily activities. The mean differences ranged from 16.9 to 45.8 points for the CMS (pooled MD = 31.4, 95% CI [27.0-35.9]), 14.5 to 16.0 points for the UCLA (pooled MD = 15.4, 95% CI [14.8-15.9]), 33.0 to 58.3 points for the ASES (pooled MD = 48.1, 95% CI [46.8-49.9]), and 4.3 to 5.1 points for the SST (pooled MD = 4.9, 95% CI [4.4-5.5]). Consistent improvement was also observed in the SSV (pooled MD = 48.2, 95% CI [46.7-49.8]). In addition, pain assessed using the Visual Analogue Scale showed a significant postoperative reduction (MD =  - 5.0, 95% CI [- 5.2 to - 4.8]). Subscapularis-specific clinical tests showed a significant decrease in the rate of positive lift-off (RR = 0.19, 95%CI (0.14-0.27)), belly-press (RR = 0.36, 95% CI (0.29-0.46)), and bear-hug tests (RR = 0.46, 95% CI (0.35-0.61)). Furthermore, ROM, which was primarily assessed clinically through measures of internal rotation was evaluated using either the Constant-Murley internal rotation subscore or spinal level assessment scales, depending on the study, improved significantly postoperatively. Subscapularis strength, evaluated clinically using lift-off and/or belly-press strength testing, most commonly graded according to the Medical Research Council (MRC) scale ranging from 0 to 5, also demonstrated significant postoperative improvement. Although overall postoperative strength improved significantly at the study level, some patients continued to demonstrate residual weakness or persistent positive subscapularis-specific clinical tests following repair. A major confounder was the frequent co-performance of long head of the biceps tenotomy or tenodesis (reported in 55.6-100% of cases across studies), which limits the ability to attribute postoperative improvements to subscapularis repair alone.

conclusionArthroscopic repair of isolated SSC tears was associated with postoperative improvements in pain, functional scores, range of motion, and subscapularis-specific clinical tests in this predominantly observational evidence base. However, these findings should be interpreted with caution, as the certainty of evidence was low to very low for all outcomes (GRADE), all included studies were at serious risk of bias (ROBINS-I), and the frequent co-performance of long head of the biceps procedures (tenotomy or tenodesis) represents a major confounder that limits attribution of improvements to subscapularis repair alone. The durability of these outcomes and the extent to which muscle strength is restored remain uncertain, particularly in the long term, and may be limited by pre-existing muscle degeneration.