To acquire a better understanding of how individuals adapt to knee osteoarthritis (KOA) and assess the effect of TKA, 3D gait analysis was conducted 17 pre-TKA KOA patients, 10 post-TKA KOA patients and 12 age-matched control subjects. Principle component analysis was used to extract waveform characteristics. Improved function was observed after TKA, but the overall lower limb capacity of post-TKA patients at 4 month post-surgery was still far below that of the control subjects. Post-TKA patients were characterized by reduced knee flexion, delayed joint motion and more gentle moments and ground reaction curves compared to controls.