Description
Objectives: Lift-off, belly press, bear hug, and Napoleon tests are frequently employed in clinical practice to assess the subscapularis muscle. Nevertheless, it remains uncertain which method of muscle strength assessment most accurately reflects the extent of subscapularis muscle tears. The purpose of this study was to clarify the best measurement of muscle strength correlating with the tear size of the subscapularis tendon.
Methods: Isometric muscle strength was assessed in 66 patients (68 shoulders) with rotator cuff tears using a handheld dynamometer with three methods: the Belly-press, Napoleon, and Bear-Hug techniques. We calculated the intra-rater correlation coefficient based on three preoperative trials for each technique. The inter-rater correlation coefficient was determined using three trials conducted on the unaffected side before surgery, at 6 months, and 1 year postoperatively. In addition, we calculated the Spearman's rank correlation coefficient between muscle strength and the size of the subscapularis tendon tear.
Results: The intra-rater correlation coefficient values for each technique exceeded 0.95, while the inter-rater correlation coefficient values for the Belly-press, Napoleon, and Bear-hug techniques were 0.73, 0.89, and 0.72, respectively. The Spearman correlation coefficient values between muscle strength and the subscapularis tear size were -0.53, -0.56, and -0.53, respectively.
Conclusions: While the correlation coefficients with the extent of subscapularis muscle tear and intra-rater reliability were equivalent for all techniques, the inter-rater reliability was highest for the Napoleon technique.
