Differential porosity prosthetic hip system

Abstract

A prosthetic femoral implant for use in a hip joint, as a ball and socket type joint, is disclosed. The implant includes a modular neck having a variety of adjustable positions to adjust the lateral offset and version angle of the femoral implant in relation to the femur. The implant further includes a broad, full collar for providing a compression force increasing the interdigitation between the interface of the bone, implant and cement. The implant also includes a stem having a depression having a roughened porous surface for resisting the increased torsional loads placed on the implant due to the increased lateral offset and version angle. The stem further comprises three distinct zones, each zone having its own roughened surface creating a tripartite differential porosity.

1 - 112 . (canceled)  
     
     
         113 . A prosthetic device for implantation into a bone comprising: 
 a head portion configured to articulate with an articulation surface of a ball and socket joint;    a stem portion having a proximal region, and a distal region, the proximal region having a top surface with a cavity formed therein, said cavity being defined by a wall, said stem portion configured for securing the prosthetic device to the bone;    a plurality of modular neck portions, each of the neck portions comprising an indexable portion, an anteverted portion, and a proximal end and a distal end separated by a shaft, the shaft of each of the modular neck portions is provided with a length differing from the other modular neck portions, wherein a surgeon selects one of the modular neck portions for insertion into the cavity of said stem portion such that the selected modular neck portion laterally offsets the head portion from the stem portion to thereby aid in restoring the natural biomechanics of the ball and socket joint; and    a means for attaching the selected modular neck portion to the stem portion;    wherein said indexable portion permits the modular neck portion to be positioned in a plurality of orientations; and    wherein said anteverted portion is configured to provide differing version angles through varying the orientation of the modular neck portion for further alteration of the stress points between the prosthetic device and the fixation material.    
     
     
         114 - 131 . (canceled)  
     
     
         132 . A method of implanting a prosthetic device into a bone comprising the steps of: 
 resecting a portion of a femoral bone exposing the medullary canal;    reaming a canal in the femoral bone;    interposing an amount of bone cement into the canal;    implanting a stem portion of the prosthetic device into the canal, said stem portion having top portion and a cavity formed in the top portion thereof; and    attaching a modular neck portion to the cavity of the stem portion using an indexable portion located on a distal end of the modular neck portion to interact with the cavity and for altering stress points on an interface between the stem portion and the bone cement, the modular neck portion having an anteverted portion for further altering the stress points.    
     
     
         133 - 143 . (canceled)  
     
     
         144 . A prosthetic device for implantation into a bone, said device comprising: 
 a stem having a cavity formed therein;    a modular neck portion comprising an anteverted section and a means for attaching the modular neck portion to the stem, wherein said means for attaching comprises a double tapered section and further comprises an indexable portion providing a plurality of selectable, predetermined indexable positions of the neck portion relative to the stem, such that said neck portion produces a plurality of selectable angles of anteversion corresponding to said plurality of selectable, predetermined indexable positions.    
     
     
         145 . The prosthetic device of  claim 145 , wherein the double tapered section comprises an inner portion and an outer portion, and where said inner portion has a length that is about one to about ten times a length of the outer portion, wherein the inner portion is configured and dimensioned so as to avoid bottoming out in the recess thereby allowing friction fit to occur.  
     
     
         146 . The prosthetic device of  claim 145 , wherein the length of the inner portion is about three to about four times the length of the outer portion.  
     
     
         147 . The prosthetic device of  claim 145 , wherein the outer portion comprises a diameter and the inner portion comprises a diameter, wherein the diameter of the outer portion is greater than the diameter of the inner portion.  
     
     
         148 . The prosthetic device of  claim 145 , wherein the outer portion and the inner portion both taper at an angle relative to a longitudinal reference axis of the modular neck portion, the angle being within a range of self-locking taper angles.  
     
     
         149 . The prosthetic device of  claim 148 , wherein the cavity of the stem comprises a recess formed by at least a first and second sidewall, and wherein said first and second sidewalls both taper at an angle relative to a neck axis, the angle being within a range of taper angles of the self-locking type, such that the inner tapered sidewall and the second sidewall form a primary self-locking taper fit, and the outer tapered sidewall and the first sidewall form a secondary self-locking taper fit that serves as an emergency backup to thereby support a primary self-locking taper.  
     
     
         150 . A prosthetic device for implantation into a bone, said device comprising: 
 a stem having a cavity formed therein;    a plurality of modular neck portions, each modular neck portion comprising an anteverted section and a double tapered section, wherein each neck portion has a different length than the other modular neck portions such that each neck portion thereby produces a different lateral offset when attached to the stem than the other neck portions would produce.