The study consisted of two groups: healthy control and symptomatic subjects who had undergone knee replacement. The subjects from the control group were obtained from a research database within the Musculoskeletal Research Centre, La Trobe University. The control group (6 females and 6 males) had a mean age, mass, height and body mass index (BMI) of 81.5 ± 4.6 years, 68.1 ± 15.6 kg, 166.4 ± 0.1 cm and 24.3 ± 2.5 kg•m-2 respectively. The symptomatic groups included 11 patients (2 females and 9 males) who had undergone unilateral knee replacement surgery for the primary diagnosis of osteoarthritis. The symptomatic group had a mean age, mass, height and body mass index (BMI) of 69.2 ± 6.4 years, 81.3 ± 11.3 kg, 173.2 ± 0.1cm and 28.1 ± 2.3 kg-m-2 respectively. All subjects from the symptomatic group were tested 2 months prior to undergoing knee replacement surgery, 10 subjects were tested again 2 months post surgery. Patients were excluded if they had uncontrolled systemic disease, previous knee surgery and a pre-existing neurological or other orthopaedic condition affecting walking. Clinical assessment, which evaluated the knee joint of the operated limb, was performed pre and post operatively using the Knee score [11]. The knee score gives a value between 0 to 50, where 50 points represents a well aligned knee with full range of motion and good stability.