Modelling and gait evaluation of asymmetrical-keel foot prosthesis.
The paper documents a new concept in prosthetic foot design. It is based on the capacity of a flexible keel to allow a greater medio-lateral function than previously available. The heel has a complex curvature consisting of a medially concave shape that joins the mid-foot. There a hump acting as a leaf-spring ends at the metatarsal break, with an inwardly curved toe extremity. These curvatures contribute to increased medio-lateral control at heel-strike and propulsion for weight transfer and push-off. Results from finite-element modelling indicate that the asymmetrically shaped keel is at least twice as active in storing energy compared with a completely symmetrical one. A preliminary gait study is carried out for a 24-year-old below-knee amputee fitted with the new design, the SPACE foot and a dynamic elastic response foot with a symmetrical keel. With the SPACE foot, there is a 14% increase in walking speed combined with a reduction in the phasic asymmetries. The absolute difference between the initial and terminal double support is 1.4% for the asymmetrical keel design compared with 4.4% for the symmetrical keel foot prosthesis. The peak ankle power generation burst indicates that the SPACE foot behaves as a dynamic elastic response foot.
Allard
P
P
Laboratorie d'Etude du Mouvement, Hôpital Sainte-Justine, Côte Ste-Catherine, Montréal, PQ, Canada.
Trudeau
F
F
Prince
F
F
Dansereau
J
J
Labelle
H
H
Duhaime
M
M
D001696:Biomechanical Phenomena; D005528:Foot / Q000502:physiology*; D005684:Gait; D006801:Humans; D008954:Models, Biological; D019736:Prostheses and Implants; D011474:Prosthesis Design