New methods for assessing cartilage contact stress after articular fracture.

Progress in reducing the incidence and severity of posttraumatic arthritis depends in part on avoiding deleterious stress levels at residual local incongruities. Systematic efforts to elucidate factors adversely influencing cartilage's mechanical environment in turn depend on the availability of suitable modalities to assess intraarticular contact stresses. This has been and remains a challenging biomechanical problem. Technologic approaches used in the past have included mathematical analyses and indwelling physical sensors, each with advantages and limitations. Two emerging, mutually complementary capabilities show promise of dramatically altering the state of the art in this important field. The first of these methodologies, voxel-based contact finite element analysis, provides accurate computational estimates of cartilage stress on a patient-specific basis, and does so while accommodating arbitrarily idiosyncratic patterns of local articular incongruity. The second methodology, instrumentational, involves transient pressure distribution recordings using specially designed piezoresistive array sensors. Operational considerations for both of these new assessment technologies are described, and promising directions for future development are outlined.