Reduced tissue hardness of trabecular bone is associated with severe osteoarthritis.

This study investigated whether changes in hardness of human trabecular bone are associated with osteoarthritis. Twenty femoral heads extracted from subjects without musculoskeletal diseases (subject age: 49-83 years) and twenty femoral heads extracted from osteoarthritic subjects (subject age: 42-85 years) were tested. Sixty indentations were performed along the main trabecular direction of each sample at a fixed relative distance. Two microstructures were found on the indenting locations: packs of parallel-lamellae (PL) and secondary osteons (SO). A 25gf load was applied for 15s and the Vickers Hardness (HV) was assessed. Trabecular tissue extracted from osteoarthritic subjects was found to be about 13% less hard compared to tissue extracted from non-pathologic subjects. However, tissue hardness was not significantly affected by gender or age. The SO was 10% less hard than the PL for both pathologic and non-pathologic tissues. A hardness of 34.1HV for PL and 30.8HV for SO was found for the non-pathologic tissue. For osteoarthritic tissue, the hardness was 30.2HV for PL and 27.1HV for SO. In the bone tissue extracted from osteoarthritic subjects the occurrence of indenting a SO (28%) was higher than that observed in the non-pathological tissue (15%). Osteoarthritis is associated with reduced tissue hardness and alterations in microstructure of the trabecular bone tissue. Gender does not significantly affect trabecular bone hardness either in non-pathological or osteoarthritic subjects. A similar conclusion can be drawn for age, although a larger donor sample size would be necessary to definitively exclude the existence of a slight effect.