Swing phase kinetics and kinematics of knee replacement patients during obstacle avoidance.

Proper knee joint function is essential for safe and effective mobility within a complex environment. Following knee joint replacement, joint structure and function are altered, often requiring individuals to adjust normal movement patterns in order to adapt to these changes. Such adaptations may either improve function or lead to movement patterns that may potentially be unsafe for individuals. To investigate this issue, a group of individuals who had undergone knee replacement was examined while performing an obstacle avoidance task. Their performance was compared with that of healthy age-matched controls. Participants walked along a 10 m walkway a total 48 times. Trials were divided equally between unobstructed walking and clearing a 6 or 18 cm obstacle during both right and left limb lead. Lead limb kinetic and kinematic variables were examined and revealed that members of the surgical group exhibited decreased active surgical knee flexion and diminished surgical knee flexor work. In order to maintain toe clearance at control levels, patients were observed to increase hip hiking and hip flexor work, in addition to laterally displacing the surgical toe during swing over the obstacle. Despite allowing individuals to maintain adequate toe clearance, these compensatory strategies may lead to an increased instability and pose a threat to safety in this population. In addition, an increased demand placed on the hip joint of the surgical limb may be undesirable in this population. Research aimed at determining how to best maximize surgical knee function must continue if these potential negative sequela are to be minimized.