Measurement of leg-length discrepancy using laser-based ultrasound method.

BackgroundThe evidence on the role of leg-length discrepancy (LLD) in low back pain (LBP) is contradictory, possibly due to the diversity of measurement methods.PurposeTo assess the reliability of a laser-based ultrasound method and its agreement with the radiographic method.Material and MethodsThe measurement device consisted of a laser measure fixed to a rod holding the scanning head of the ultrasound and could be moved automatically by a linear actuator. The reliability of the measurement was evaluated using 20 healthy voluntary subjects with no known previous LLD (90% women, mean age 23 years). We assessed the agreement of the ultrasound method with a radiographic LLD measurement using 19 voluntary patients (95% men, mean age 38 years), who had had radiographic LLD measurements taken during the previous year. We used intraclass correlation co-efficients (ICC) and Bland & Altman analysis in the statistical analysis.ResultsThe ICC value for agreement between methods was 0.97 (95% confidence intervals [C...