Dynamic leg length measurement is a valid method for detecting anatomic leg length discrepancy

Even though the importance of leg length discrepancy (LLD), with its potential of causing several pathological conditions or gait deviations, is well known, measuring LLD is still challenging with limited reliability and validity. OBJECTIVE: To assess the capability of the dynamic leg length (DLL) measurement in detecting the presence of anatomic LLD. METHODS: A lower limb x-ray was performed on 15 participants with suspected LLD in addition to a gait analysis study using a motion analysis system to measure DLL (the absolute distance from the hip joint centre to the heel, to the ankle joint centre and to the forefoot). Average DLLs were compared between sides for symmetry by the paired t-test at 51 sample points during the gait cycle in conjunction with the differences between the sides based on the maximal stance phase and minimal swing phase DLLs. Differences were correlated with anatomic LLD by Pearson correlation. RESULTS: No significant differences in DLLs between sides throughout the gait cycle were found. Significant differences between sides were found between the maximal stance and minimal swing phase DLLs. CONCLUSIONS: DLL measurement is capable of detecting an anatomic leg length difference based on functional changes in leg length and functional discrepancy.