Mechanical strength of osteochondral junction.

Abstract

The junction between articular cartilage and bone in adult humans was tested in shear to determine their bonding strength in relation to the tensile strength of full thickness articular cartilage and shear strength of underlying subchondral bone. The site of failures was also studied under light microscope and scanning electron microscope. The junction failed at a shear strength of 7.25 +/- 1.35 MPa (n = 18). On the other hand, the tensile strength of cartilage and shear strength of subchondral bone were 3.75 +/- 0.75 MPa (n = 17) and 2.45 +/- 0.85 MPa (n = 15) respectively. Light and scanning electron microscopic examination revealed that in fact, failures occurred at the tidemark. The ultrastructure of the tidemark suggested that this region might have structural weakness against mechanical stresses. The relevance of the results were discussed in relation to the osteochondral fractures in adult humans.