This work aimed to establish a suitable procedure for establishing wear particle hardness and to investigate if the hardness of articular cartilage wear particles increases with increasing grades of osteoarthritis. To achieve the goals a selection of fresh sheep knee joints were obtained and consequently worn in a specially designed wear simulator. Wear particles were then removed from the joint using a syringe and prepared for hardness testing. In order to test the hardness of the wear particle samples nanoindentation was used. Once completed statistical analyses and correlation analyses were performed in order to find any relationships present. This was the first time that the hardness of the wear particles was tested and studied. As a result of the tests performed a general relationship between wear particle hardness and osteoarthritis grade was able to be determined. It was also determined that further work needed to be conducted on the experimental procedure to increase the accuracy of the results obtained.