Tibial cartilage damage and deformation at peak displacement compression during simulated landing impact.

Abstract

BACKGROUND: Structural changes of articular cartilage at the point of peak displacement compression during a landing impact are unknown. HYPOTHESIS: Extent of damage and deformation is significantly different for superficial, middle, and deep cartilage zones at peak displacement compression during simulated landing impact compared with after impact. STUDY DESIGN: Controlled laboratory study. METHODS: Explants were extracted from porcine tibial cartilages and divided into 3 test conditions: nonimpact control, impact and release, and impact and hold. Impact compression, with peak deformation of 2 mm, was applied based on a single 10-Hz haversine to simulate landing impact. For impact and release, explants were subjected to formalin fixation on removal of load after impact. For impact and hold, explants were immediately immersed in formalin with peak deformation maintained at 2 mm. After fixation, the explants underwent histology, whereby Mankin scores and cartilage thicknesses were obtained. RESULTS: Peak stresses of 9.8 to 28.1 MPa were noted during impact compression. For impact and release, substantial cartilage defects such as surface fraying and fissures were observed. For impact and hold, explants exhibited less severe matrix damage, such as superficial irregularities and tidemark disruption. Mankin scores were lower (indicating less damage; P