Tendon stump tendinosis and combined subscapularis tear as risk factors for healing failure after medium-sized rotator cuff repair

While age, tear size, and fatty infiltration are established prognostic indicators for arthroscopic rotator cuff repair (ARCR), little is known about the impact of tendon stump status and concomitant subscapularis tears on healing, especially in medium-sized tears. This study aimed to evaluate their impact on tendon healing following arthroscopic repair of medium-sized rotator cuff tears. This single-center retrospective cohort study included 136 patients who underwent primary ARCR for medium-sized tears between June 2019 and October 2022. Patients were classified into healing (Sugaya types 1-3) and nonhealing (types 4-5) groups based on postoperative magnetic resonance imaging (MRI) findings. Preoperative tendon stump characteristics-including signal intensity of the tendon stump (C signal), C/D signal ratio (tendon stump signal/deltoid muscle signal), tendon stump thickness, remnant tendon length, delamination, and anterior cable involvement-were evaluated on preoperative MRI and intraoperative findings. Univariable and multivariable logistic regression analyses were performed to identify independent risk factors for healing failure. Univariable logistic regression analysis identified C signal intensity, C/D signal ratio, tendon stump thickness, and subscapularis tear grade as significant risk factors for nonhealing (all P < .05). Only the C/D ratio remained independently associated in the multivariable model (adjusted odds ratio 11.518, P < .001). Cutoff value for C/D ratio was 1.09 (area under the curve 0.82, P < .001). Quantitative MRI assessment of tendon stump tendinosis using C/D ratio is strongly associated with ARCR healing in medium-sized tears. Comprehensive preoperative evaluation of both tendon stump quality and subscapularis integrity may inform surgical planning and improve prognosis for medium-sized tears.