Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Leg – Foot
Reexamination Certificate
1999-05-26
2001-07-17
Snow, Bruce (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Leg
Foot
Reexamination Certificate
active
06261324
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to foot prostheses and, more particularly, to foot prostheses configured to duplicate the dynamic performance characteristics of the human foot and ankle.
Significant advancements in the field of foot prostheses have been made in recent years, due largely to the development of composite materials technology. Foot prostheses incorporating fiberglass/epoxy and carbon fiber/epoxy composite materials have been developed, which closely duplicate the dynamic performance characteristics of the human foot and ankle.
One such foot prosthesis is disclosed in U.S. Pat. No. 4,959,073 issued to Merlette. The Merlette prosthesis incorporates an elongated composite main member having a leg section and a forwardly extending foot section, and it further incorporates a heel member projecting rearwardly from the underside of the main member's foot section. A high-density polyurethane elastomer is disposed between the heel member and the main member's foot section, to permanently attach the two members together and to provide limited cushioning. The upper end of the main member's leg section supports an amputation socket for receiving the amputee's residual limb, and a crepe sole can be attached to the underside of the heel member. A foam foot shell or cosmesis can be placed over the composite members, to provide the prosthesis with an appearance of a normal human foot.
The Merlette foot prosthesis described briefly above has enjoyed substantial commercial success. Nevertheless, it is believed that the Merlette prosthesis can be improved upon by simplifying its manufacture, thus reducing both material and labor costs, and by minimizing the possibility of component failure.
Users of foot prostheses of this kind typically will desire to use the prosthesis while wearing a variety of shoes having heels of different heights. One drawback to prior foot prostheses is that they typically have been configured to have a fixed heel height. They typically have not been configured to provide for a convenient adjustment of their heel height, to allow the user to use the prosthesis with a variety of shoes.
Users of foot prostheses of this kind typically also will desire to use the prosthesis in a variety of physical activities. Some of these activities will be best engaged in using a prosthesis having relatively high stiffness, while others will be best engaged in using a prosthesis having relatively low stiffness, or high compliance. Despite this desire, foot prostheses generally have not been configured to provide for a convenient adjustment of their stiffnesses.
It should therefore be appreciated that there exists a need for a foot prosthesis that can be manufactured more economically and that is configured to facilitate a convenient adjustment of its heel height and its stiffness. The present invention fulfills this need and provides further related advantages.
SUMMARY OF THE INVENTION
The present invention is embodied in an improved foot prosthesis, and in a method for making it, which can be manufactured more economically and which is configured to facilitate a convenient adjustment of its heel height and/or its stiffness. The foot prosthesis includes an elongated monolithic composite member having a forwardly extending forefoot section, and further includes a high-density elastomeric sole molded to the underside of the forefoot section of the monolithic composite member, the elastomeric sole including a heel section projecting rearwardly from the forefoot section, to define a heel, and further including lateral and medial sections projecting laterally from the forefoot section. An elastomeric cosmesis having the general shape of a human foot can conformably envelope the elastomeric sole.
In more detailed features of the invention, the elongated monolithic composite member has a substantially uniform width, and it is formed of a carbon fiber composite material. In addition, the elastomeric sole has a peripheral shape similar to that of a normal human foot, and it preferably is formed of a high-density polyurethane. The elastomeric sole preferably incorporates lateral and medial sections having a maximum transverse width about three times greater than the substantially uniform width of the composite member. In some embodiments, the monolithic composite member incorporates a generally vertically oriented pylon section that projects above a rearward portion of its forefoot section. An elastomeric coating can be disposed on this pylon section, to facilitate mechanical coupling to an amputation socket.
In a separate and independent feature of the invention, the foot prosthesis further includes a sole plate configured to have a peripheral shape substantially the same as the peripheral shape of the elastomeric sole and further configured to be releasably securable to the underside of the elastomeric sole, so as to modify a predetermined parameter (e.g., stiffness and/or heel height) of the foot prosthesis' physical characteristic.
In one embodiment, the sole plate includes an elongated monolithic composite member extending along substantially the entire length of the sole plate, and further includes a high-density elastomeric material molded under or around the elongated monolithic composite member. In this embodiment, the sole plate, when attached to the underside of the elastomeric sole, adjusts the stiffness of the foot prosthesis. In another embodiment, the sole plate is thicker in its rearward portion than in its forward portion, so as to adjust the foot prosthesis' heel height.
The sole plate can be releasably attached to the elastomeric sole by configuring the upper side of the sole plate and the underside of the elastomeric sole to incorporate complementary relief patterns. This relief pattern is configured to prevent relative movement or shifting between the two components, either medial to lateral or anterior to posterior. One suitable pattern is a waffle pattern.
In another separate and independent feature of the invention, the foot prosthesis is made by 1) forming a laminate of high-strength composite material, 2) making a series of parallel cuts through the laminate, to form a plurality of elongated, monolithic strips of composite material having substantially uniform widths, and 3) molding a high-density elastomeric sole to the underside of each elongated strip of composite material. Each such elastomeric sole includes a heel section projecting rearwardly from the composite member, and it further includes lateral and medial sections projecting laterally from the composite member. Finally, a low-density foam cosmesis having the general shape of a human foot is conformably placed or molded around each of the elastomeric soles, to produce a plurality of foot prostheses.
In more detailed features of the invention, the laminate of high-strength composite material has a thickness that varies from one edge to an opposite edge. In addition, it is molded into a predetermined shape, such that each of the plurality of elongated strips of composite material will have a generally vertically oriented pylon section and a generally horizontally oriented forefoot section. The composite strips are thickest in the ankle section, where the pylon section transitions to the forefoot section.
Other features and advantages of the present invention should become apparent from the following description of the preferred embodiments, taken in conjunction with the exemplary drawings, which illustrate the principles of the invention.
REFERENCES:
patent: 4822363 (1989-04-01), Phillips
patent: 4959073 (1990-09-01), Merlette
patent: 5219365 (1993-06-01), Sabolich
patent: 5486209 (1996-01-01), Phillips
patent: 5593456 (1997-01-01), Merlette
patent: 5728171 (1998-03-01), Bryant, Jr. et al.
patent: 5888239 (1999-11-01), Wellershaus et al.
patent: 5993487 (1999-11-01), Skardoutos et al.
Brueggemann James R.
CRP, Inc.
Sheppard Mullin Richter & Hampton LLP
Snow Bruce
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