Study subjects

Ten grade I and ten grade IV OA samples were collected from age-matched and sample-matched OA patients (grade IV OA in medial compartment and grade I OA in distal compartment of the same patient’s OA knee as outlined below) undergoing total knee replacement surgery. The patients were recruited for this study (mean age 57.1 ± 6.3 years) after the obtaining of informed consent from each participant. All OA patients had radiographic evidence of grade IV OA, according to the Kellgren and Lawrence criteria [9, 10]. Tibial plateaus were marked as medial and lateral compartments and were labelled with surgical marker at the anterior end of the tibia plateau, and inferior end for future orientation references. Patients with any bone disorders other than OA, or reported conditions that affect bone metabolism, or receiving treatment that affects bone metabolism such as anti-resorptive drugs, or hormonal replacement therapy, were excluded from the study. The study protocol was approved by the Human Research Ethics committees of the Queensland University of Technology and Prince Charles Hospital.