The impact of recurrent dislocation on shoulder rotator muscle balance (a prospective study of 102 male patients)

AbstractPurpose of the studyWe performed an isokinetic analysis of both shoulders in 102 male patients suffering from shoulder instability after several trauma-related anterior or anterior-inferior dislocations. The analysis was part of a comprehensive medical and radiological assessment (with standard X-rays and cross-sectional imaging) prior to surgery. The study's objective was to measure the strength of the patients’ internal and external rotators after recurrent dislocations (by comparing injured and healthy sides) and to evaluate the dislocations’ impact on the muscles on the injured side.Materials and methodsThe mean patient age was 24.8 (range: 16–47). We analysed the impact of instability on rotator muscle performance according to the side (dominant or non-dominant), the number of dislocations and the severity of any associated bone damage. The isokinetic analysis was performed at least one month after the last shoulder dislocation. The same operator performed all procedures. The modified Davies position was adopted, in order to record the peak torque of the internal and external rotators during concentric contractions at 60° and 180° per second. Means and standard deviations for peak torque to body weight ratios and external/internal rotator peak torque ratios were reported.ResultsAfter several anterior or anterior-inferior shoulder dislocations, there was a non-significant difference in the external rotator/internal rotator ratio when comparing injured and healthy sides - regardless of whether the injured side was dominant or not, the number of dislocations and the severity of bone damage.ConclusionSystematic, presurgical, isokinetic testing of the shoulder does not appear to be of value in post-traumatic instability in male patients