Motorized Leg Length Discrepancy Measure: A New Device for Clinical Use – A Cross-sectional Study

Abstract

Objectives: This study aimed to construct a device that could measure leg length discrepancy (LLD) automatically. Materials and Methods: The LLD measure device measures LLD with pelvic-tilt method (Program 1) and weight-based method (Programs 2 & 3). Tests were done in 3 phases. 1: Two examiners using the LLD Measure device made -50 to 75 mm artificial LLD in two healthy subjects measuring the degree of pelvic tilt and the load bearing of lower limbs. 2: Sixteen healthy volunteers were asked to stand on the device to measure LLD with program 2 and then with both knees extended to measure LLD with program one. 3: 32 patients who had underwent lower limbs CT scanogram enrolled, and the LLD measurement with program 1 compared with those obtained by CT scanogram. Results: Data’s obtained in the first phase showed excellent repeatability (intra-class correlation coefficient [ICC] > 0.9) and very good reproducibility (ICC > 80%) except for measuring the limb load while both knees were extended (ICC ≈ 60%). In the second phase, we found no statistically significant difference between measuring LLD using programs 1 and 2 (P = 0.49). In the third phase, there was no statistically significant difference between measuring LLD using program 1 and CT scanogram (P = 0.80). Conclusions: We have developed a device to measure LLD semiautomatic with less need for examiner expertise. The results of our new device would be reliable and accurate compared to CT measurements.