In Pursuit of Quantifying Patient Knee Contact Mechanics: Finite Element Model Validation of Cadaveric Knees in Axially Loaded MRI Scans.

Our long-term objective is to quantify patient-specific changes in contact mechanics after partial meniscectomy (PM) using knee-specific finite element (FE) models created from clinical MR scans under axial load. Before creating patient-specific models, a validation of our workflow and processes is required. The objective of this study was to validate knee-specific FE models of tibiofemoral joint contact mechanics by comparison to direct measurements of contact by electronic pressure sensors. We hypothesized that knee-specific FE model data would fall within direct measurements of the contact area and pressure values from sensors, but that detected differences in outcomes would be smaller than differences reported after PM. The workflow consisted of performing MRIs on five cadaveric knees using a patient-based loading system adapted to cadaveric knees where loaded and unloaded scans were acquired with and without a sensor in place, segmenting images to develop FE models, running those models with statistical approaches to model material property variation and comparing the model outputs to the outputs quantified physically by sensors. Overall, 53% of outcomes (32/60) from the FE models fell within the ranges of those directly measured. Of the values that fell outside, differences were lower than those identified from a literature review of the mechanical effects of partial meniscectomies, especially when meniscectomies were 30% or 60% of the meniscus volume. FE models developed using this workflow may be helpful in assessing or anticipating changes in joint force redistribution following partial meniscectomies in patients.