Intertester reliability of clinical shoulder instability and laxity tests in subjects with and without self-reported shoulder problems

Abstract

Objective: First, to investigate the intertester reliability of clinical shoulder instability and laxity tests, and second, to describe the mutual dependency of each test evaluated by each tester for identifying self-reported shoulder instability and laxity. Methods: A standardised protocol for conducting reliability studies was used to test the intertester reliability of the six clinical shoulder instability and laxity tests: apprehension, relocation, surprise, load-and-shift, sulcus sign and Gagey. Cohen's kappa (κ) with 95% CIs besides prevalence-adjusted and bias-adjusted kappa (PABAK), accounting for insufficient prevalence and bias, were computed to establish the intertester reliability and mutual dependency. Results: Forty individuals (13 with self-reported shoulder instability and laxity-related shoulder problems and 27 normal shoulder individuals) aged 18-60 were included. Fair (relocation), moderate (load-and-shift, sulcus sign) and substantial (apprehension, surprise, Gagey) intertester reliability were observed across tests (κ 0.39-0.73; 95% CI 0.00 to 1.00). PABAK improved reliability across tests, resulting in substantial to almost perfect intertester reliability for the apprehension, surprise, load-and-shift and Gagey tests (κ 0.65-0.90). Mutual dependencies between each test and self-reported shoulder problem showed apprehension, relocation and surprise to be the most often used tests to characterise self-reported shoulder instability and laxity conditions. Conclusions: Four tests (apprehension, surprise, load-and-shift and Gagey) out of six were considered intertester reliable for clinical use, while relocation and sulcus sign tests need further standardisation before acceptable evidence. Furthermore, the validity of the tests for shoulder instability and laxity needs to be studied.