Intra-articular Contact Stress Distributions at the Ankle Throughout Stance Phase–patient-specific Finite Element Analysis as a Metric of Degeneration Propensity

Abstract

A contact finite element (FE) formulation is introduced, amenable to patient-specific analysis of cumulative cartilage mechano-stimulus attributable to habitual functional activity. CT scans of individual human ankles are segmented to delineate bony margins. Each bone surface is projected outward to create a second surface, and the intervening volume is then meshed with continuum hexahedral elements. The tibia is positioned relative to the talus into a weight-bearing apposition. The articular members are first engaged under light preload, then plantar-/dorsi-flexion kinematics and resultant loadings are input for serial FE solutions at 13 instants of the stance phase of level walking gait. Cartilage stress histories are post-processed to recover distributions of cumulative stress-time mechano-stimulus, a metric of degeneration propensity. Consistency in computed contact stress exposures presented for seven intact ankles stood in contrast to the higher magnitude and more focal exposures in an incongruously reduced tibial plafond fracture. This analytical procedure provides patient-specific estimates of degeneration propensity due to various mechanical abnormalities, and it provides a platform from which the mechanical efficacy of alternative surgical interventions can be estimated.

Physical validation of a patient-specific contact finite element model of the ankle

“…The FE method provides an ideal vehicle by which to study joint contact stresses on a patient-specific basis. Toward testing this proposed mechanopathology, an FE model has been developed to predict patient-specific joint contact stresses in the ankle throughout the entire stance phase of gait (Anderson et al, 2006).…”

Effect of Implantation Accuracy on Ankle Contact Mechanics with a Metallic Focal Resurfacing Implant

“…The latter two parametric studies worked from the baseline-height implantation case. The ankle contact finite element modeling approach was based on previous work 42 , with bone treated as rigid material and cartilage treated as linear elastic material. The resurfacing implant was included as an additional rigid surface.…”

Development and experimental validation of a finite element model of total ankle replacement

“…Most current finite element models of TAR are limited to the intra-articular aspects or to the prosthetic components (Anderson et al, 2006(Anderson et al, , 2010Reggiani et al, 2006;Espinosa et al, 2010;Barg et al, 2011). Therefore, the goal of this study was to develop and validate a finite element model of TAR, for future testing of hypotheses related to clinical issues.…”