Date on Master's Thesis/Doctoral Dissertation

12-2010

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Mechanical Engineering

Committee Chair

Quesada, Peter M.

Author's Keywords

Gait; Biomechanic; Prehabilitation; Knee OA

Subject

Knee--Mechanical properties; Knee--Pathophysiology; Gait in humans; Osteoarthritis

Abstract

Osteoarthritis (OA) of the knee is associated with decline in functional capacity and ultimately leads to Total Knee Arthroplasty (TKA) in many of these patients. Exercise regimens prior to surgery may potentially enhance pre and post TKA functional performance. However, assessment of such performance should involve biomechanical factors that characterize the mechanisms with which tasks are performed, and not just the quantity of task performed. The present overall study investigated walking biomechanics of end stage knee OA and TKA patients. Throughout the three sub-studies that comprised the overall investigation, particular emphasis was placed on heelstrike and the loading response phase of gait, in addition to functional ability parameters. The first sub-study investigated gait biomechanics and fatigue during a 6 minute walk for patients with end stage knee OA. Results demonstrated that even if patients were able to maintain their gait velocity throughout the walk, subtle but statistically significant differences at the ankle were present after the 6 minute walk. Knee OA patients may be experiencing higher loading conditions at the knee after 6 min. In order to adapt to fatigue, knee OA patients appear to adopt ankle strategies alleviating the load from a painful knee, rather than knee strategies, causing greater instability and reduced performances. A single walking trial for gait analysis may be insufficient to assess gait compensations due to fatigue in daily activities. In light of the initial results on end stage knee OA walking biomechanics, the second sub-study included investigation of the effects of a 4 to 6 weeks exercise program on TKA outcomes. Results demonstrated that exercise therapy was effective at improving function and reducing pain to a certain extent pre-surgery. However, assessment of the walking biomechanics raised the question of whether improving physical ability improved knee OA condition or caused further knee joint degeneration and possibly the onset of OA in the opposite leg. Control patients exhibited a more careful gait pattern with lower speed and gait parameters reflecting potentially lower impact at heelstrike which may be more beneficial for knee OA conditions. The exercisers' walking characteristics showed evidence of an overstriding gait pattern with potentially reduced shock absorption mechanisms that can lead to lower leg injuries. The third sub-study investigated walking biomechanics of prehab and non prehab subjects one month after surgery and results suggested that the effects of the pre-surgery exercise program did not remain post-surgery. Even if patients in the exercise group had increased physical ability performances and experienced less pain just prior to surgery compared to the control group, one month after surgery there was no difference between the groups. The lack of a significant effect of the exercise program on gait changes post surgery may indicate that the exercise regimen prior to surgery requires an additional component such as gait retraining. Adding a gait retraining component to the prehab protocol may improve the rate of recovery and help patients to maintain the prehab benefits even post TKA surgery.

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