A classification for partial subscapularis tendon tears

Abstract

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.

Keywords: Classification; Partial lesion; Rotator cuff; Subscapularis.

Fig. 1

Schematic draw of the footprint of the subscapularis tendon on the lesser tuberosity. The measurements show the trapezoidal shape of the footprint at the tendon insertion site with a wider superior attachment. The mean length superior to inferior is 2.4–2.6 cm. The widest part is superior with a mean width of 1.6–1.8 cm while the most inferior aspect has a mean width of 0.3 cm. The mean width of the bare area is on the proximal part 3.2 mm and on the distal part 16.8 mm. All measurements have been proved in previous cadaveric study [19]

Fig. 2

a Schematic draw showing the classification in the transverse plane. The main measurement is in the transverse plane and is performed at the superior border (1 cm) of the footprint, where a specific bare area of approximately 5 mm has been defined in previous studies [19]. This measurement represents the mediolateral extension of the peeled-off length of the subscapularis tendon bony footprint and started at the cartilage rim to the intact subscapularis fibers under consideration of the bare area. Type 2 represents a tear smaller than 10 mm, type 3 a measured tear 10–15 mm, and type 4 a tear larger than 15 mm. b Arthroscopic view (left shoulder, viewing from posterior portal) showing the measurement of the mediolateral peeled-off length of the bony footprint using a calibrated probe

Fig. 3

a Schematic draw showing the classification in the coronal plane. The secondary measurement was in the coronal plane and represents the longitudinal extension of the lesion. This was measured from cranial point of the lesion to the caudal end as the peeled-off length of the coronal bony footprint. With this measurement, types 2–4 could be further subclassified depending on the craniocaudal peeled-off length of the bony footprint. Group A is the tear length < 10 mm, group B a lesion 10–15 mm, and group C a tear larger than 15 mm. b Arthroscopic view (left shoulder, viewing from posterior portal) showing the measurement of the craniocaudal peeled-off length of the bony footprint using a calibrated probe

Fig. 4

Tear pattern for partial subscapularis tear according to the mediolateral peeled-off length of the bony footprint taken in consideration the bare area (5 mm). a Split lesion is classified as type 1. b Type 2 tear represents a tear smaller than 10 mm. c Type 3 represents a tear 10–15 mm. d Type 4 a tear larger than 15 mm