OBSERVER VARIABILITY IN MEASURING ELEVATION AND EXTERNAL ROTATION OF THE SHOULDER

The aim of the study was to assess the observer variation between trai ned primary care physicians in their assessment of two key shoulder mo vements: elevation and external rotation. Six observers each examined and recorded their visual estimate of the range of movements in six pa tients assessed in random order. There was good agreement on the range of passive elevation assessed to the start of pain (if present): intr aclass correlation coefficient (ICC) = 0.84, and to the point of maxim um elevation: ICC = 0.95. There was no evidence of an important system atic bias between observers. By contrast, external rotation was poorly reproducible: ICC = 0.43, with important systematic differences betwe en observers. In the second experiment, six observers simultaneously w itnessed a range of movements in a single volunteer subject, and the a greement on their visual estimation of the angles achieved was assesse d. There was a marked reduction in the systematic bias in external rot ation, but agreement was still poor. Agreement for elevation remained high with a reduction in the small amount of bias observed in the firs t experiment when variability in both examination and visual assessmen t had been investigated. We conclude that shoulder elevation is a reli able measurement for use in multicentre studies by trained primary car e physicians. By contrast, external rotation is poorly reproducible be cause of systematic variation in examination technique and random vari ation in visual assessment.