RELIABILITY OF CLINICAL ISOKINETIC DYNAMOMETRY IN PATHOLOGICAL ATHLETIC SHOULDERS

Abstract

There have been relatively few studies of the reliability of isokinetic shoulder testing, and only Malerba et al. (1993) have investigated patients with shoulder joint pathology (patients ranged in activity level from sedentary to highly active). Furthermore, all existing studies have involved a level of procedural standardisation which, while desirable, cannot always be achieved in a clinical environment, that is, where most isokinetic testing is performed. Therefore, the aim of this study was to assess the reliability of isokinetic testing of pathological athletic shoulders in a clinical environment, under routine clinical conditions. Twenty-two athletic patients (mean age 26 years) presenting with a range of pathologies including post-subluxation, post-dislocation, and post-surgical reconstruction were tested. Patients were tested on two occasions, separated by a time interval during which their clinical status was not expected to change (most tests were one week apart; mean interval 10 days). Bilateral isokinetic strength of the shoulder internal and external rotators were tested on a Cybex 6000 dynamometer at 2.09 and 4.19 radianslsecond (concentric) and 2.09 radianslsecond (eccentric). Patients were tested in a seated position, in 45 degrees of shoulder abduction, and 90 degrees of elbow flexion. Tests were performed in essentially the same fashion on each occasion by the same tester. However, the constraints of a busy clinical environment meant that precise control and exact replication may not have always been achieved. Intra-class correlation coefficients (ICC) for absolute concentric peak torque, work, and average power were all above 0.9. Eccentric ICCs were generally above 0.8. These values are as high as, or higher than, those reported in the literature for studies of healthy subjects conducted under more stringent conditions than can be achieved in a clinical environment. The reliability of commonly calculated ratios, such as agonistlantagonist and involved/uninvolved, was lower than that of the constituent absolute scores, and in some cases were quite poor. Caution is therefore warranted in the use of such ratios. Malerba JL; Adam ML, Harris BA, Krebs DE (1993) Reliability of dynamic and isometric testing of shoulder external and internal rotators. Journal of Orthopaedic and Sports Physical Therapy 18543-552.