Isokinetic rotator muscles fatigue in glenohumeral joint instability before and after L atarjet surgery A pilot prospective study

We aimed to analyze the changes in isokinetic internal ( IR ) and external ( ER ) rotator muscles fatigue (a) in patients with non‐operated recurrent anterior instability, and (b) before and after shoulder surgical stabilization with the B ristow– L atarjet procedure. Thirty‐seven patients with non‐operated unilateral recurrent anterior post‐traumatic instability ( NG ) were compared with 12 healthy subjects [control group ( CG )]. Twenty patients with operated recurrent anterior instability group ( OG ) underwent isokinetic evaluation before and 3, 6, and 21 months after B ristow– L atarjet surgery. IR and ER muscles strength was evaluated with C on‐ T rex® dynamometer, with subjects seated and at a 45° shoulder abduction angle in scapular plane. IR and ER muscle fatigue was determined after 10 concentric repetitions at 180°·s −1 through the fatigue index, the percent decrease in performance ( DP ), and the slope of peak torque decrease. There were no differences in rotator muscles fatigue between NG and CG . In OG , 3 months post‐surgery, IR DP of operated shoulder was significantly ( P  < 0.001) higher than presurgery and 6 and 21 months post‐surgery. Rotator muscles fatigability was not associated with recurrent anterior instability. After surgical stabilization, there was a significantly higher IR fatigability in the operated shoulder 3 months post‐surgery, followed by recovery evidenced 6 months post‐surgery and long‐term maintenance over 21 months.