The study describes the changes of condrocytes and extracellular matrix occurring in Hip OA. 16 femoral heads were included in the study.

Cartilage explants were removed from 3 anatomical sites over the surface of 14 OA and 2 non-OA patients. Cartilage sections were evaluated with histological (EE, Alcian Blu and Mallory-Azan stainings) and immuno-histochemichal (antibodies directed against fibronectin, tenascin, laminin, type I and type IV collagen, metallo-proteinase-1,-2,-7 and -7) analysis.

Histological analysis of cartilage of central and per-hipheral biopsies from patients with severe OA showed significant reduced number of chondrocytes in both superficial and middle zones. In the lower cartilage layer with severe structural lesions a cospicous number of cartilagineous repair-islands were noticed. Immunohistochemical analysis showed high levels of tenascin in all cartilage layers of byopses showing structural damages. Frequently we observed an altered distribution of fibronectin. Metalloproteinase-2 (constitutive) is present in all stages during coxarthritis. Metalloproteinase-9 (not constitutive) is expressed at the final stages suggesting an important late role. Obtained results show that metalloproteinases have a peculiar behaviour during coxarthritis vs. other pathologies. Costitutive metal-loproteinases have a fundamental role in extracellular matrix remodelling, MMP-2 especially.