Interobserver and intraobserver reliability in lower-limb deformity correction measurements

Planning for surgical correction of lower-limb deformity requires assessment of the character and extent of the deformity. Deformity measurements are defined; however, the reliability of these measurements has not been evaluated. This study was conducted to assess the interobserver and intraobserver reliability of lower extremity deformity measurements in the frontal and sagittal planes. Anteroposterior and lateral lower extremity radiographs were evaluated using Paley technique. Statistical analysis included intraclass correlation coefficient (2,1), median absolute difference, range, and agreement within 3 and 5 degrees. Reliability was good to very good for all measurements except for the anterior distal tibial angle, which had moderate reliability. Intraobserver reliability was higher than interobserver reliability, and measurements in the frontal plane had better reliability than measurements in the sagittal plane. Overall, these measurements are a reliable method of assessing lower extremity deformity and should be used to guide treatment and monitor outcome.