Damage and degenerative changes in menisci-covered and exposed tibial osteochondral regions after simulated landing impact compression-a porcine study.

The capacity of menisci-covered and exposed tibial osteochondral regions in resisting impact-induced damage and degeneration is not fully understood. This study sought to evaluate damage and degenerative changes in these regions upon a single simulated landing impact. We hypothesized that the menisci-covered regions are more susceptible to damage and degeneration than their exposed counterparts. Menisci-covered and exposed tibial osteochondral explants were extracted from fresh porcine hind legs and placed in culture up to 14 days. Impact compression, based on a single 10-Hz haversine, was performed at Day 1. Control (non-impact) and impacted explants were randomly selected for cell viability assessment, glycoaminoglycan and collagen content assays, histology, immunohistochemistry, and micro-computed tomography. When subjected to 2-mm displacement compression, exposed explants achieved a significantly higher peak impact stress (p < 0.05) than menisci-covered explants. No significant difference in cell viability, glycoaminoglycan and collagen content, and Mankin scores (p > 0.05) was observed between both explant groups. Both groups were observed with reduced proteoglycan and type II collagen staining at Day 14; the exposed group was noted with increased cartilage volume at Days 7-14. The inferior resistance of menisci-covered regions, against impact-induced damage and degeneration, is a potential factor that may contribute to the meniscectomy model of osteoarthritis. Copyright 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.