Study of the nano-mechanical properties of human knee cartilage in different wear conditions

Osteoarthritis (OA) is a wear related disease that affects millions of people worldwide. Mechanical properties of cartilage surface play an important role in osteoarthritis initiation and progression. The objective of this study was to investigate the effective indentation modulus and its change in relation to the wear conditions of human knee cartilage. Following informed consent, samples were collected during orthopaedic surgery. Healthy and osteoarthritic cartilage samples at different OA stages were studied using atomic force microscopy. Unique to existing studies, the effective indentation moduli of the uppermost top surfaces of the healthy and osteoarthritic cartilage samples were measured. This study has shown that the modulus of the top surface changed significantly with wear severity progression. The findings have indicated that the effective indentation modulus measured at the nano-scale could be used to reveal changes in OA and to assist in understanding the wear process.