Development and validation of a subject-specific moving-axis tibiofemoral joint model using MRI and EOS imaging during a quasi-static lunge.

ABSTRACT

The aims of this study were to introduce and validate a novel computationally-efficient subject-specific tibiofemoral joint model. Subjects performed a quasi-static lunge while micro-dose radiation bi-planar X-rays (EOS Imaging, Paris, France) were captured at roughly 0°, 20°, 45°, 60°, and 90° of tibiofemoral flexion. Joint translations and rotations were extracted from this experimental data through 2D-to-3D bone reconstructions, using an iterative closest point optimization technique, and employed during model calibration and validation. Subject-specific moving-axis and hinge models for comparisons were constructed in the AnyBody Modeling System (AMS) from Magnetic Resonance Imaging (MRI)-extracted anatomical surfaces and compared against the experimental data. The tibiofemoral axis of the hinge model was defined between the epicondyles while the moving-axis model was defined based on two tibiofemoral flexion angles (0° and 90°) and the articulation modeled such that the tibiofemoral joint axis moved linearly between these two positions as a function of the tibiofemoral flexion. Outside this range, the joint axis was assumed to remain stationary. Overall, the secondary joint kinematics (ML medial-lateral, AP anterior-posterior, SI superior-inferior, IE internal-external, AA adduction-abduction) were better approximated by the moving-axis model with mean differences and standard errors of (ML -1.98 ±â€¯0.37 mm, AP 6.50 ±â€¯0.82 mm, SI 0.05 ±â€¯0.20 mm, IE 0.59 ±â€¯0.36°, AA 1.90 ±â€¯0.79°) and higher coefficients of determination (R2) for each clinical measure. While the hinge model achieved mean differences and standard errors of (ML -0.84 ±â€¯0.45 mm, AP 10.11 ±â€¯0.88 mm, SI 0.66 ±â€¯0.62 mm, IE -3.17 ±â€¯0.86°, AA 11.60 ±â€¯1.51°).