Strength profile of the superior and inferior rotator cuff: A comparison between painful and non-painful participants aged between 18 and 75 years.

Abstract

<title>Abstract</title> Background: The ideal force couple ratio of the superior cuff, supraspinatus versus anterior deltoid is yet to be determined in both an athletic and non-athletic population. Objective: To determine the muscle force and muscle force couple ratios of the superior cuff, between the supraspinatus and the anterior deltoid and of the inferior cuff, between the external rotators and the internal rotators in painful and non- painful shoulders in an adult non-athletic population. Methods: This was an analytical cross-sectional study. The shoulders of both painful and non-painful shoulders of adults, females and males aged between 18 years and 75 years of age were tested. The ratios of the superior cuff (supraspinatus versus anterior deltoid) and of the inferior cuff (external versus the internal rotators) were determined. Results: Specific force couple ratio of supraspinatus versus anterior deltoid was determined. Higher values for the force couple’s ratios were concluded in the non-painful group of supraspinatus: anterior deltoid of 1.25 (0.20) versus the lower value of the painful group of supraspinatus: anterior deltoid of 1.20 (0.23). Statistically significant difference was determined between supraspinatus: anterior deltoid in males (1.25) versus females of (1.16) (<italic>p</italic> &gt; 0.12) with a small effect size of (0.27). Statistically significant difference (<italic>p</italic> &lt; 0.001) of the external rotators force values between the non-painful and the painful participants were determined. No significant difference of the internal rotator force values between the non-painful and the painful participants were determined. Conclusions: All force couple ratios should be considered in the evaluation and rehabilitation of all population groups.