Lower leg prosthesis

Abstract

An improved lower leg prosthesis is disclosed that, during use, provides an improved dynamic feel at heel strike and that provides improved inversion/eversion compliance. The prosthesis includes an elongated pylon having an upper, generally vertical section and a lower, forwardly oriented foot section, and it further includes a generally horizontally oriented foot plate disposed beneath the pylon and including a heel section projecting a substantial distance rearwardly of a vertical pylon axis. An elastomeric layer is interposed between the pylon and the foot plate, extending along substantially the entire length of the heel section of the foot plate, for attaching the pylon and foot plate together. During use of the prosthesis, at heel strike, upward deflection of the foot plate's heel section is limited in substantial part both by the stiffness of the heel section, itself, and by compression of the portion of the elastomeric layer disposed rearwardly of the vertical pylon axis.

I claim:  
     
         1 . A lower leg prosthesis comprising: 
 an elongated pylon having an upper, generally vertical section and a lower, forwardly oriented forefoot section, wherein the upper section defines a vertical pylon axis;    a generally horizontally oriented foot plate disposed beneath the pylon and including a heel section projecting a substantial distance rearwardly of the vertical pylon axis;    wherein the pylon and the foot plate both are formed of a high-strength composite material; and    an elastomeric layer interposed between, and attaching together, the pylon and the foot plate, wherein the elastomeric layer extends along substantially the entire length of the heel section of the foot plate;    wherein during use of the prosthesis, at heel strike, upward deflection of the heel section of the foot plate is limited in substantial part both by the stiffness of the heel section, itself, and by compression of the portion of the elastomeric layer disposed rearwardly of the vertical pylon axis.    
     
     
         2 . A lower leg prosthesis as defined in  claim 1 , wherein: 
 the forward tip of the foot plate is disposed substantially beneath the forward tip of the pylon's forefoot section; and    the elastomeric layer extends along substantially the entire length of the foot plate, from its forward tip to the rearward tip.    
     
     
         3 . A lower leg prosthesis as defined in  claim 2 , wherein the elastomeric layer has a width that tapers from a minimum at the foot plate's forward tip to a maximum at a mid-portion of the foot plate to a minimum at the foot plate's rearward tip.  
     
     
         4 . A lower leg prosthesis as defined in  claim 3 , wherein the pylon's forefoot section has a width that tapers from a maximum at a location substantially aligned with the maximum width of the elastomeric layer to a minimum at the forefoot section's forward tip.  
     
     
         5 . A lower leg prosthesis as defined in  claim 4 , wherein the points of maximum width of the pylon's forefoot section and the elastomeric layer are located forward of the vertical pylon axis.  
     
     
         6 . A lower leg prosthesis as defined in  claim 2 , wherein the portion of the elastomeric layer disposed on the heel section of the foot plate has a concave upper surface.  
     
     
         7 . A lower leg prosthesis as defined in  claim 6 , wherein the concave upper surface of the portion of the elastomeric layer disposed on the heel section of the foot plate is a circular arc, substantially tangent both to the pylon's upper, vertical section and to the foot plate's rearward tip.  
     
     
         8 . A lower leg prosthesis as defined in  claim 1 , wherein the pylon and the foot plate each are of unitary construction.  
     
     
         9 . A lower leg prosthesis as defined in  claim 8 , wherein: 
 the unitary pylon and the unitary foot plate each are formed of an epoxy/carbon fiber composite material;    the elastomeric layer is formed of a high-density polyurethane material; and    the elastomeric layer non-removably attaches the foot plate to the pylon.    
     
     
         10 . A lower leg prosthesis as defined in  claim 1 , wherein the portion of the elastomeric layer disposed rearwardly of the vertical pylon axis provides at least about one-third of the total resistance to upward deflection of the foot plate's heel section at heel strike.  
     
     
         11 . A lower leg prosthesis as defined in  claim 1 , wherein the elastomeric layer has a thickness of at least about one-half centimeter along substantially its entire length.