Dual-Camera Markerless Motion Capture System for Precise Lower-Limb Kinematic Analysis in Osteoarthritis

Abstract

Purpose: This study aimed to develop a dual-camera markerless system based on data from patients with osteoarthritis (OA) and validate its agreement with a marker-based motion capture system for measuring lower-limb kinematics. Methods: A total of 152 OA patients were divided into a training set (n = 120) and a test set (n = 32). Kinematic data during gait were collected simultaneously via both markerless and marker-based systems. The dual-camera markerless system consists of a 2D pose extractor based on a neural network and 3D triangulation, and the kinematic differences between the two systems were evaluated via the root mean square distance (RMSD) and root mean square error (RMSE) and intraclass correlation coefficient (ICC). Results: The markerless system demonstrated great performance, achieving a grand mean RMSD of 11.0 mm and an ICC of 0.95 for keypoints. Joint angle analysis revealed a mean RMSE of 4.25°, with ICC values for joint angle waveforms reaching 0.90 in the sagittal plane, 0.48 in the frontal plane, and 0.24 in the transverse plane compared with the marker-based system. Conclusion: These results indicate that the dual-camera markerless system provides accurate lower-limb kinematic measurements for patient populations while offering significant advantages in terms of cost-effectiveness, installation simplicity, and reduced operational expertise requirements, facilitating efficient biomechanical assessment in clinical use.