Anatomical leg length discrepancy in children: Can it be accurately determined using 3-D motion capturing?

Area of Science:

• Orthopedics
• Biomechanics
• Pediatric Health

Background:

• Leg length discrepancy (LLD) is a common condition in youth, often requiring accurate measurement.
• Long leg X-rays are the gold standard for LLD measurement but involve radiation exposure.
• Instrumented Gait Analysis (IGA) offers a radiation-free method for assessing LLD.

Purpose of the Study:

• To compare the accuracy and precision of different LLD measurement methods in pediatric patients.
• To evaluate tape measurement, IGA using markers, and IGA using joint centers against radiography.
• To determine if IGA-based joint center calculations are superior to simpler methods.

Main Methods:

• Retrospective study of 31 pediatric patients with varying LLD.
• Comparison of three LLD measurement techniques: tape measurement, IGA with markers, and IGA with calculated joint centers.
• Bland-Altman analysis was used to compare each method against radiography (gold standard).

Main Results:

• IGA utilizing joint centers demonstrated superior accuracy and precision compared to tape measurement and IGA markers.
• The Davis equations for hip joint center calculation yielded the highest accuracy (mean difference 0.7 mm).
• The Harrington method showed high precision (0.9 mm SD) and was significantly better than tape measurement (1.8 mm SD).

Conclusions:

• IGA, specifically using calculated joint centers, is a feasible and accurate method for determining LLD in pediatric patients.
• This method provides a reliable, radiation-free alternative for clinical LLD assessment.
• IGA offers a valuable tool for managing pediatric LLD.