Reliability of intratester and intertester measurements derived from an instrumented ankle arthrometer

Context: Measurement reliability is critical when new sports-medicine devices or techniques are developed. Objective: To determine the reliability of laxity measurements obtained from an instrumented ankle arthrometer. Design: Intratester reliability was examined using a test-retest design, and intertester reliability was assessed using the measurements recorded by 2 different examiners on a separate group of participants. Setting: Sports-medicine research laboratory. Participants: 40 participants with no history of ankle injury, equally divided across the 2 studies. Measurements: Laxity measurements included anteroposterior (AP) displacement during loading to 125 N. Inversion-eversion (I-E) rotation was tested during loading to 4000 N-mm. The measures were analyzed using intraclass correlation coefficients (ICCs) and dependent t tests. Results: Good to excellent ICCs (80-99) for intratester and intertester reliability. A significant difference in measures was observed between testers for both AP displacement and I-E rotation. Conclusions: Laxity measurements from an instrumented ankle arthrometer are reliable across test days and examiners.