Intratester and intertester reliability and criterion validity of the parallelogram and universal goniometers for active knee flexion in healthy subjects

Background and Purpose A new parallelogram goniometer was designed by the Rehabilitation Centre of the Royal Ottawa Health Care Group in 1983. The advantage of using such a goniometer is that the clinician is not required to estimate the joint axis of rotation when taking a measurement. The parallelogram goniometer has obtained a good intratester and intertester reliability when measuring active range of motion of hip abduction on eight individuals with hip pathologies. However, the validity of the parallelogram goniometer has not been examined. The purposes of this study were to examine the intratester and intertester reliability and the criterion validity of the parallelogram and universal goniometers for active knee flexion on healthy individuals. Subjects Sixty healthy university students (44 females and 16 males; mean age of 20.6 yrs.) participated to this study. Methods Measurements with the universal and parallelogram goniometers were taken in two different positions, the smaller and larger angles of active knee flexion. All measurements were taken by two trained testers. A radiograph was taken in both positions to serve as the ‘gold standard’. The sequence of the measurements and radiographs were randomly selected. The intra and intertester reliability of both goniometers were established by calculating the intraclass correlation coefficients (ICCs) using the repeated‐measures ANOVA. The criterion validity was examined by calculating Pearson product‐moment correlation coefficients (r) between each goniometric and radiologic measurements. A 0.05 level of significance was chosen for each statistical test. Results Intratester reliability ranged from good to excellent for the small angles (ICC=0.85 and 0.87) and the large angles (ICC=0.91 and 0.96) when using the parallelogram goniometer. Intertester reliability was fair for the small angles of flexion (ICC=0.43 to 0.52) and good to excellent for the large angles of flexion (ICC=0.82 to 0.88). The parallelogram goniometer was found to have greater validity when measuring the large angles of knee flexion (r=0.73 and 0.77) compared to the small angles of knee flexion (r=0.33 and 0.41). Similar results of reliability and validity were obtained with the universal goniometer. Conclusion The results of this study have clinical importance. The use of the parallelogram goniometer was found to be as reliable and valid as the universal goniometer when measuring active knee flexion. However, the parallelogram gon