Supraspinatus muscle length in the torn rotator cuff: associations with shoulder strength and tear size
Recommended Citation
Jalics AR, Zauel R, Klochko C, Moutzouros V, and Bey MJ. Supraspinatus Muscle Length in the Torn Rotator Cuff: Associations with Shoulder Strength and Tear Size. J Shoulder Elbow Surg 2025.
Document Type
Article
Publication Date
4-17-2025
Publication Title
Journal of shoulder and elbow surgery
Abstract
BACKGROUND: Rotator cuff tears are a prevalent condition, affecting more than 40% of individuals aged more than 60 years and leading to approximately 250,000 surgical repairs annually in the United States. The supraspinatus tendon is most commonly involved, resulting in retraction of the supraspinatus muscle-tendon unit. Clinically, retraction is often assessed through medial-lateral (ML) tear size or muscle-tendon junction (MTJ) position relative to the glenoid. However, muscle length is rarely measured despite its importance for force-generating capacity and patient outcomes postsurgery. This study aimed to compare supraspinatus muscle length in patients with and without rotator cuff tears and to determine the extent to which muscle length was associated with anterior-posterior (AP) tear size, ML tear size, and shoulder strength.
METHODS: A convenience sample of 32 patients with rotator cuff tears and a control group of 32 individuals with intact rotator cuffs were analyzed. All participants underwent magnetic resonance imaging scans with supraspinatus muscle length calculated using a previously validated approach that assessed the muscle-tendon junction position and supraspinatus fossa length. Normalized muscle length was determined by dividing muscle length by fossa length. Shoulder strength was measured with an isokinetic dynamometer during shoulder abduction (ABD), flexion, and internal and external rotation, with the strength data expressed relative to age-predicted maximum values and as strength ratios. Statistical analyses included t-tests for group comparisons and linear regression for association assessments, with significance set at P < .05.
RESULTS: No significant difference in patient age was detected between the 2 groups (torn: 59.3 ± 7.0; intact: 58.1 ± 4.9, P = .42). The average rotator cuff tear size was 16.8 ± 5.7 mm (AP) and 18.2 ± 8.7 mm (ML). Supraspinatus muscle length was significantly shorter in the rotator cuff tear group (96.6 ± 5.8% of fossa length) compared to the intact group (102.7 ± 6.3% of fossa length, P = .0002). In patients with tears, muscle length did not correlate with tear sizes (ML: r = 0.01, P = .95; AP: r = 0.27, P = .15). However, muscle length was significantly associated with normalized ABD strength (r = 0.41, P = .02) and the ABD/internal rotation strength ratio (r = 0.46, P = .008).
DISCUSSION: The findings indicate that supraspinatus muscle length is significantly reduced in rotator cuff tears and is associated with shoulder ABD strength, but not with tear size. This suggests that muscle shortening negatively impacts shoulder function and highlights potential implications for surgical repair strategies and postoperative recovery. Future studies should explore the effects of surgical interventions on muscle length and strength recovery in rotator cuff repair patients.
PubMed ID
40250825
ePublication
ePub ahead of print
