Comparison of the OpenPose system and the reference optoelectronic system for gait analysis of lower-limb angular parameters in children.

Introduction: Quantitative Gait Analysis (QGA) is the gold-standard for detailed study of lower-limb movement, angles and forces, especially in pediatrics, providing a decision aid for treatment and for assessment of results. However, widespread use of QGA is hindered by the need for specific equipment and trained personnel and high costs. Recently, the OpenPose system used algorithms for 2D video movement analysis, to determine joint points and angles without any supplementary equipment or great expertise. The present study therefore aimed to validate application of OpenPose for gait analysis in children with locomotor pathology, thereby circumventing the limitations of QGA.

Hypothesis: The OpenPose system is as precise as QGA for measuring lower-limb angles in gait in children.

Materials and methods: Gait analysis was studied prospectively, between January and July 2023, in 20 children: 13 boys, 7 girls; mean age, 13 years. There was no selection for pathology or use of walking aids. QGA was performed, measuring joint angles in the hips, knees and ankles. The same measurements were then made using the points obtained on OpenPose. The Mann-Whitney test was used to compare the two methods.

Results: There were only slight differences in angle measurements (in degrees) for the knees: right, 0.54 [-0.61; 1.71], p = 0.361; left, -1.09 [-2.16; 0.01], p = 0.051. Differences were greater for the hips (right, 9.32 [8.28; 10.35]; left, 7.54 [6.55; 8.54], p < 0.01) and ankles (right, -6.67 [-7.22; -6.12]; left, -7.07 [-7.60; -6.54], p < 0.01).

Discussion: OpenPose provided angle values close to those of QGA for the knees in the sagittal plane, independently of pathology and walking aid. In the hips and ankles, on the other hand, differences were too great to allow clinical application of OpenPose.

Level of evidence: IV.