Accuracy and reliability of observational motion analysis in identifying shoulder symptoms.

Introduction: Aberrations in shoulder movement patterns are believed to be associated with the presence of shoulder symptoms. However, the detection of movement aberrations has not been rigorously investigated. It is possible that manipulative physiotherapists use the clinical history to prejudge the existence of aberrations, rather than the actual observation of the movement pattern itself. There is a need to determine whether physiotherapists, in the absence of a clinical history, can relate observed anomalies of shoulder movement to the presence of symptoms and to determine the reliability for observation of such anomalous shoulder movement.

Methods: The sample comprised of 9 symptomatic subjects recruited from four physiotherapy clinics in Christchurch, New Zealand and a further 11 asymptomatic subjects recruited from Christchurch's general population. They were videotaped performing shoulder flexion, abduction, and scapular plane abduction. The video-recordings were evaluated by 11 manipulative physiotherapists who did not know which subjects were symptomatic and who were thus required to judge the symptomatic status as: asymptomatic, symptomatic left, symptomatic right or symptomatic both. Additionally, each physiotherapist completed a survey on each of the 20 subjects regarding the type of movement anomaly that was perceived (e.g. too much scapular elevation, too little glenohumeral movement, etc). Classification accuracy (percentage of correct responses) and agreement (kappa) among physiotherapists were computed.

Results: Out of the 220 responses by the physiotherapists regarding symptomatic status, 58% were correct, with 68% asymptomatic, 71% symptomatic left and 30% symptomatic right subjects correctly classified. Reliability analysis showed kappa statistics for all subjects was 0.23, for asymptomatic subjects 0.22, symptomatic left 0.34, and symptomatic right 0.17. Only five subjects had two or more evaluators agree on the type of anomalous movement.

Conclusions: Although movement analysis is considered an integral part of a physiotherapist's skill this research has shown that a sample of experienced manipulative physiotherapists had difficulty in determining the symptomatic status of patients with clinically diagnosed shoulder complaints by movement analysis alone.