[Truncated abstract] Autologous Chondrocyte Implantation (ACI) has shown early clinical success as a repair procedure to address focal articular cartilage defects in the knee, and involves isolating and culturing a patient's own chondrocytes in vitro and re-implantation of those cells into the cartilage defect. Over time, repair tissue can develop and remodel into hyaline-like cartilage. A progressive partial weight bearing (PWB) program becomes the critical factor in applying protection and progressive stimulation of the implanted cells, to promote best chondrocyte differentiation and development, without overloading the graft. The aim of this thesis was to investigate whether patients could replicate this theoretical load bearing model to possibly render the best quality tissue development. In addition, this proposed external load progression is only a means to loading the articular surface. Several factors, including those that may result from pathology, have the potential to influence gait patterns, and therefore, articular loading. The association between increasing external loads (ground reaction forces - GRF) and knee joint kinetics during partial and full weight bearing gait was, therefore, investigated in the ACI patient group, as was the contribution of other gait variables to these knee joint kinetics which may be modified by the clinician. Finally, current weight bearing (WB) protocols have been based on early ACI surgical techniques. With advancement in the surgical procedure and ongoing clinical experience, we employed a randomised controlled clinical trial to assess the effectiveness of an 'accelerated' load bearing program, compared with the traditionally 'conservative' post-operative protocol. ... Although similar spatio-temporal, knee kinematic and external loading parameters were observed between the traditional and accelerated rehabilitation groups, the accelerated group was 'more comparable' to the controls in their external knee adduction and flexion moments, where the traditional group had lower knee moments. Knee moments greatly affect knee articular loading, and large adduction moments have been related to poor clinical outcomes after surgery. Therefore, the return of normal levels may be ideal for graft stimulation, however, may overload the immature chondrocytes. Acceleration of the intensive rehabilitation program will enable the patient to return to normal activities earlier, whilst reducing time and expenses associated with the rehabilitative process, and may enhance long-term tissue development. However, continued follow-up is required to determine if there are any detrimental effects that may emerge as a result of the accelerated load bearing program, and assess the recovery of normal gait patterns and whether longer term graft outcomes are affected by the recovery time course of normal gait function, and/or abnormal loading mechanics in gait. Furthermore, analysis at all levels of PWB is needed to identify a more complete set of variables attributing to the magnitude of external knee joint kinetics and, therefore, knee articular loading, while the influence muscle activation patterns may have on articular loading needs to be investigated. This becomes critical when you consider loads experienced by the articular surface throughout the early post-operative period following ACI may be important to short- and long-term graft development.