Article

A consensus exists that high knee joint forces are a precursor to knee
osteoarthritis and weight loss reduces these forces. Because large weight loss
also leads to increased step length and walking velocity, knee contact forces may
be reduced less than predicted by the magnitude of weight loss. The purpose was
to determine the effects of weight loss on knee muscle and joint loads during
walking in Class III obese adults. We determined through motion capture, force
platform measures and biomechanical modeling the effects of weight loss produced
by gastric bypass surgery over one year on knee muscle and joint loads during
walking at a standard, controlled velocity and at self-selected walking
velocities. Weight loss equaling 412 N or 34% of initial body weight reduced
maximum knee compressive force by 824 N or 67% of initial body weight when
walking at the controlled velocity. These changes represent a 2:1 reduction in
knee force relative to weight loss when walking velocity is constrained to the
baseline value. However, behavioral adaptations including increased stride length
and walking velocity in the self-selected velocity condition attenuated this
effect by approximately 50% leading to a 392 N or 32% initial body weight
reduction in compressive force in the knee joint. Thus, unconstrained walking
elicited approximately 1:1 ratio of reduction in knee force relative to weight
loss and is more indicative of walking behavior than the standard velocity
condition. In conclusion, massive weight loss produces dramatic reductions in
knee forces during walking but when patients stride out and walk faster, these
favorable reductions become substantially attenuated.
CI - Copyright (c) 2016 Elsevier B.V. All rights reserved.

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