Comparison of Isokinetic Strength between Stage 1,2 Impingement Syndrome and Rotator Cuff Tear

ABSTRACT

PURPOSE: The goal of this study was to evaluate differences in strength deficits between (i) patients with stage 1 or 2 impingement syndrome and (ii) patients with rotator cuff tears. MATERIALS AND METHODS: We enrolled 43 patients with stage 1 or 2 impingement syndrome (group 1) and 21 patients with rotator cuff tears (group 2). The isokinetic strength of both groups was evaluated at 60degrees/sec for external rotation, internal rotation, adduction and abduction. We measured the peak torque, total work, average power of bilateral sides, peak torque relationship to body weight, and the ratio between unilateral agonist and antagonist. RESULTS: The isokinetic strength deficits assessed in ratio of peak torque to body weight for group 1 and group 2 respectively were; 28.48+/-23.76% and 29.12+/-32.81% for abduction (p=0.929), 7.20+/-13.98% and 18.94+/-19.52%; for adduction (p=0.021), 16.88+/-13.76% and 25.80+/-24.07%; for external rotation (p=0.221), and 14.1+/-25.67% and 29.02+/-35.06% for internal rotation (p=0.059). For average power and total work, group 2 showed a significantly greater deficit for adduction and internal rotation than group 1. CONCLUSION: Those with rotator cuff tears have more isokinetic muscle strength deficits than those with stage 1 or 2 impingement syndrome. Progression from stage 1 and 2 impingement syndrome to stage 3 may result in greatest changes in strength deficits for internal rotation and adduction.