Interrater reliability of physical examination tests in the acute phase of shoulder injuries

BACKGROUND: The physical examination is one of the cornerstones of the diagnostic process in patients with acute shoulder injuries. The discriminative properties of a given examination test depend both on its validity and reliability. The aim of the present study was to assess the interrater reliability of 13 physical examination manoeuvres for acute rotator cuff tears in patients with acute soft tissue shoulder injuries. METHODS: In a large walk-in orthopaedic emergency department, 120 consecutive patients ≥40 years of age were included in a diagnostic study. Patients who had follow-up within three weeks of an acute shoulder injury without fracture on radiographs were eligible. Four emergency department physicians participated as examiners. In a subset of 48 patients, the physical examination tests were performed by two physicians, randomly chosen by their work rotation. The physicians were blinded to the findings of each other and the results of the ultrasound screening. The interrater reliability was assessed by Cohen’s kappa, intraclass correlation coefficient (ICC), standard error of measurement (SEM) and Bland-Altman plots depending on whether the examination test result was registered as a binary, ordered categorical or continuous numerical variable. RESULTS: The median age was 55.5 years, 46% were female. Twenty-seven percent had a rotator cuff full-thickness tear on ultrasound screening; all but one involved the supraspinatus tendon. Cohen’s kappa for binary tests ranged from excellent to fair. Excellent agreement (kappa > 0.8) was found for the inability to abduct above 90° and abduction strength. External rotation strength expressed substantial agreement (kappa 0.7). The lowest scores were registered for Hawkins` test and the external rotation lag sign (kappa 0.25 and 0.40, respectively). The ICCs for active range of abduction and external rotation were 0.93 (0.88–0.96) and 0.84 (0.72–0.91), whereas the SEM was 15 and 9, respectively. CONCLUSIONS: The results indicate that examination manoeuvres assessing abduction and external rotation range of motion and strength are more reliable than manoeuvres assessing pain in patients in the acute phase of traumatic shoulder injury. The poor agreement observed is likely to limit the validity in the present setting of two commonly used tests. TRIAL REGISTRATION: The Norwegian Regional Ethics Committee South East (2015/195). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12891-021-04659-x.