| abstract |
The present invention relates to a prosthetic foot including an integral spring portion providing motion in the foot, particularly a unitary foot structure providing a selectable degree of plantar flexion and a stiff structure for toe off. The present invention has found that an integrally formed c-shaped spring portion having an anterior gap, joining a connection platform and the heel and forefoot portions can provide a controlled range of natural mobility in a prosthetic foot as an economical design. The c-shaped spring can deflect, angling the connection platform rearwardly to a partially opened position against the bias of the spring, and angling the connection platform forwardly until the stop abuts the top surface of the forefoot in a closed position. The stop is positioned a selected distance above the top surface to obtain the desired angle of dorsiflexion. The plantar flexion against the bias of the spring is relatively stiff and provides a variable limit to the range of plantar flexion depending on the force exerted. In contrast, the deflection closing the c-shaped spring is relatively compliant but provides an angular range specifically defined by the position of the stop. In addition, the anterior gap also deflects to permit more limited inversion and eversion before the deflection is stabilized by contact between the stop and the top surface. Additional flexibility is obtained using an integral spring element having a substantially S-shape. The posterior facing c-shaped aperture in the S-shaped spring element provides additional deflection for plantar flexion. |