Mechanical testing of frontal plane adaptability of commercially available prosthetic feet.

INTRODUCTION: Prosthetic feet have limited adaptability in the frontal plane. Research shows walking on uneven terrain is difficult for many prosthesis users. A new prosthetic foot, the META Arc, was designed with a polycentric ankle joint that allows relatively free movement in the frontal plane to address this limitation. Previous simulations of the polycentric ankle mechanism found potential benefits such as reduced lateral movement of a proximal mass during forward progress and reduced forces being transferred upward from the ground through the foot.

METHODS: Standard mechanical testing protocols were used to evaluate the Meta Arc prosthetic foot's performance and six comparable feet commercially available.

RESULTS: The results found the META Arc prosthetic foot had increased frontal plane adaptability as well as reduced lateral forces, and reduced inversion eversion moment compared to the six comparison feet on 10-degree cross-slope test conditions. All included prosthetic feet had similar results for the percent of energy return and dynamic force in the sagittal plane.

CONCLUSIONS: These results suggest the inclusion of the polycentric ankle within the META Arc foot will provide more stability without sacrificing forward walking performance.