Investigations of standing balance efficiency on sloped surfaces in persons with transfemoral amputation

This study investigated the effects of stiffness and alignment properties of prosthetic foot/ankle devices during quiet standing on sloped surfaces. The prosthetic foot/ankle stiffness and alignment are normally set by a prosthetist in a clinic on a level surface. Most prosthetic foot/ankle devices cannot dynamically change these properties; therefore, persons with amputation use proximal joint compensations to maintain balance. It was hypothesized that: (1) able-bodied persons adapt to sloped surfaces using their foot/ankle systems with no increase in oxygen consumption; (2) decreasing prosthetic foot/ankle stiffness (without changing alignment) will decrease proximal joint compensations and reduce oxygen consumption of prostheses users; and (3) using adapted prosthetic foot/ankle alignment on sloped surfaces produce oxygen consumption, joint kinematics, and kinetic data that are similar to standing on level surfaces.;Ten able-bodied persons quietly standing on sloped surfaces were studied to quantify their energy consumption, kinematic, and kinetic adaptations. Oxygen consumption was not significantly altered (p=0.098). Able-boded persons' proximal body segment kinematics (p=0.334) and anterior/posterior center of pressure location (p=0.164) did not change significantly while standing on sloped surfaces. These results suggest that the able-bodied foot/ankle realigns its sagittal plane orientation to match the surface slope.;Ten persons with unilateral transfemoral amputation were studied to quantify their energy consumption, kinematic, and kinetic compensations. These persons quietly stood on sloped surfaces with three prosthetic foot/ankle stiffness values and two prosthetic foot/ankle alignments. Prosthetic foot/ankle stiffness did not have a significant effect on oxygen consumption (p=0.220); however, oxygen consumption was significantly increased for non-level standing trials (p=0.044). The adaptable alignment prosthetic foot/ankle condition decreased oxygen consumption on inclined surfaces compared to standard alignment (p=0.034). Realignment of the prosthetic foot/ankle device reduced sagittal plane hip compensations (p=0.005) and improved posture.;The results from these studies suggest current approaches using a single stiffness and alignment for prosthetic foot/ankle devices were not energy efficient for quiet standing on non-level surfaces. It is believed that prosthetic foot/ankle devices that can change stiffness and alignment dynamically for the task performed would have a positive impact on persons with lower limb amputation.