PRINCIPAL COMPONENT MODELS OF KNEE KINEMATICS AND KINETICS - NORMAL VS PATHOLOGICAL GAIT PATTERNS

Gait data were collected on a group of 29 asymptomatic elderly subject s to describe knee joint kinematics and kinetics as measured by the th ree components of the bone-on-bone forces, net reaction moments and re lative knee angles. Each of these gait measures were considered separa tely in the development of Principal Component Models (PCMs) to descri be the variation of the normal subjects throughout the gait cycle. The statistical similarity of patients' gait curves (waveforms) to the pa ttern of normal subjects' gait waveforms was assessed using the PCMs. The PCMs consider data from the entire gait cycle and detect statistic ally significant waveform shapes using measures of distance from norma l. Osteoarthritic patients were selected from a clinical study of pre- operative and post-operative unicompartmental arthroplasty. Three case s were chosen to demonstrate the PCMs application on a waveform-by-wav eform basis. In addition, the overall assessment of three patients as indicated by eight kinematic and kinetic gait measures was performed. The outcome measured by the PCMs was shown to agree with the clinical results as measured by the Knee Society Score. The PCMs were able to q uantify the difference from normal with statistical significance and t he structure of the models allowed for interpretation in terms of port ions of the gait cycle.