Application of Generalizability Theory in Estimating the Reliability of Ankle-Complex Laxity Measurement

Context: Generalizability theory is an appropriate method for determining the reliability of measurements obtained across more than a single facet. In the clinical and research settings, ankle-complex laxity assessment may be performed using different examiners and multiple trials. Objective: To determine the reliability of ankle-complex laxity measurements across different examiners and multiple trials using generalizability theory. Design: Correlational study. Setting: Laboratory. Patients or Other Participants: Forty male university students without a history of ankle injury. Main Outcome Measure(s): Measures of right ankle-complex anteroposterior and inversion-eversion laxity were obtained by 2 examiners. Each examiner performed 2 anteroposterior trials, followed by 2 inversion-eversion trials for each ankle at 0 degrees of ankle flexion. Using generalizability theory, we performed G study and D study analyses. Results: More measurement error was found for facets associated with examiner than with trial for both anteroposterior and inversion-eversion laxity. Inversion-eversion measurement was more reliable than anteroposterior laxity measurement. Although 1 examiner and 1 trial had .acceptable reliability (G coefficient >= .848), increasing the number of examiners increased reliability to a greater extent than did increasing the number of trials. Conclusions: Within the range of examiner and trial facets studied, any combination of examiners or trials (or both) above I can change ankle laxity measurement reliability from acceptable (1 examiner, 1 trial) to highly reliable (3 examiners, 3 trials). Individuals may respond to examiners and their procedural nuances differently; thus, standardized procedures are important.