LAUSR

Purpose The aim of the study was to analyze partial subscapularis tendon (SSC) tears and provide a descriptive classification. Methods The retrospective study included 50 patients with arthroscopically confirmed partial SSC tears. Internal rotation (IR) force measurements and IR ROM have been made and compared to the healthy contralateral side. Then the footprint of the SSC was routinely investigated by arthroscopy with standardized measurement of the bony footprint lesion. The partial tears were classified according to the mediolateral and craniocaudal extension of the rupture in the transverse and coronal plane, respectively. Results Partial SSC tears could be classified into split lesions (type 1, n  = 11) and 3 further groups depending on the mediolateral peeled-off length of the bony footprint (type 2: < 10 mm, n  = 20; type 3: 10–15 mm, n  = 10; type 4: > 15 mm, n  = 9). Type 2–4 could be further divided depending on the craniocaudal peeled-off length of the bony footprint (group A: < 10 mm, group B: 10–15 mm, group C: > 15 mm). Significantly decreased IR strength was shown for types 2–4 ( p  < 0.05) but not for split lesions as compared to healthy side. Types 1–4 showed significant decreased active IR ROM and all except type 3 (n.s.) which showed decreased passive IR ROM compared to the healthy side ( p  < 0.05). Conclusion We present a novel classification for partial SSC tears for a more detailed and reproducible description. This can help to improve the current knowledge about the appropriate treatment. It could be shown that partial tears of the subscapularis can have an impact on IR strength and motion. Level of evidence III