Abstract
Leg length discrepancy (LLD) is a significant factor influencing several pathological conditions. Gait analysis is based on biomechanical gait models calculating joint kinematics; however, no previous study has validated its ability to detect anatomical LLD. The aim of the present study was to compare the validity of the Vicon® Plug-in-Gait-model (PGM) in measuring femur and tibia segmental length discrepancy with measurements attained by X-ray. Fifteen participants with suspected leg length discrepancies underwent a lower limb X-ray and a standing calibration trial using a motion analysis system (Vicon®, Oxford Metrics, UK). Femur and tibia segment lengths were deducted from both measurements. No differences were found when measuring the discrepancies between sides for the femur (p = 0.3) and tibia (p = 0.45) segmental length. A high correlation was found between methods (r = 0.808–0.962, p < 0.001), however, a significant difference was observed when measuring the femur and tibia length (p < 0.0001). PGM was found to be a valid model in detecting segmental length discrepancy when based on the location of the joint centers compared to X-ray. A variance was noted in the femur and tibial segmental length. The impact of this inconsistency in segmental length on kinematics and kinetics should be further evaluated.
Highlights
Leg length discrepancy (LLD) is a significant factor influencing several pathological and physiological conditions such as foot pathologies [1,2], low back pain [3,4], functional scoliosis in children [5], osteoarthritis of the hip and knee [6], impaired functional outcomes and patient satisfaction after total hip replacement [7,8]
Anatomic LLD is defined as the structural difference between the lengths of the two limbs measured from the femoral head to the distal tibia [9,10,11]
Gait analysis is based on biomechanical gait models calculating joint kinematics [15,16]
Summary
Leg length discrepancy (LLD) is a significant factor influencing several pathological and physiological conditions such as foot pathologies [1,2], low back pain [3,4], functional scoliosis in children [5], osteoarthritis of the hip and knee [6], impaired functional outcomes and patient satisfaction after total hip replacement [7,8]. Radiography is considered the gold standard for measurement, with accepted methods such as full limb radiographs, scanograms, computerized tomography and computerized digital radiographs. These methods are highly reliable and valid but are expensive, not feasible for everyone and expose the subject to radiation, which limits their use in routine clinical settings. Three-dimensional motion analysis is extensively used today improving a comprehensive understanding of gait in musculoskeletal disorders. It assists in detecting gait deviations and impairments underlying reduced function, clinical decision making, quantifying rehabilitation
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