ROTATOR CUFF STRENGTH IN SUBJECTS WITH SHOULDER IMPINGEMENT SYNDROME COMPARED WITH THE ASYMPTOMATIC SIDE

Objective: To evaluate the strength of internal rotation, external rotation and elevation of the shoulders of symptomatic compared with asymptomatic patients, associating muscle strength with joint function. Methods: Forty-eight individuals diagnosed with unilateral SIS were evaluated in relation to isomeric muscle strength of symptomatic and asymptomatic shoulders (using a hand-held isometric dynamometer), in addition to evaluating function using the Constant-Murley scale. The subjects were divided into 2 groups: group 1 = 35 to 49 years, group 2 = 50 to 65 years. Results: A reduction in strength of internal rotation, external rotation and elevation of the symptomatic shoulder were found, compared with the asymptomatic side (p < 0.0001), but there was no reduction in the strength of medial rotation in the subjects of group 1. It was observed that muscle strength is directly proportional to shoulder function, with individuals with little strength of the rotator cuff having less function. Conclusion: SIS causes decreased muscle strength of internal rotation, external rotation and elevation compared with the asymptomatic side. It also causes decreased shoulder function. The reduced function is proportional to the decrease in muscle strength of the rotator cuff. Level of evidence: level III, analytical study.