Poroelastic Finite Element Analysis of Unstable Motion of an Incongruously Reduced Intra-articular Fracture

One of the goals of intraarticular fracture repair is the prevention of post-traumatic arthritis by avoiding mechanical environments that increase the stresses in cartilage. A previous cadaver study has shown that contact pressures in the ankle increase significantly under quasiphysiological loading in the presence of an articular incongruity (step-off) (McKinley, 2006). Of particular interest from that study are results in which the talus subluxated from the beneath the tibia in an unstable motion. This study investigates the biphasic response of cartilage to such transient loading. Contact stress transients from the cadaver study are applied to a poroelastic finite element model to investigate the influence of an unstable motion on the stress distribution throughout the cartilage depth.