Bone prosthesis and method of implantation

Abstract

A bone prosthesis for implantation at a joint includes a stem having a tip generally at one end thereof. The stem is sized and shaped for reception in a bone at the joint such that the tip of the stem is exposed to locations outside of the bone. The stem has a passageway extending from a first location on the bone prosthesis to a second location on the bone prosthesis.

What is claimed is:  
     
         1 . A bone prosthesis for implantation at a joint, the prosthesis comprising a stem sized and shaped for implantation in a bone at the joint such that at least a portion of the stem is received in the bone and a portion is exposed to locations outside the bone, the stem having a passageway arranged to vent fluid pressure from a first location which is subject to elevated fluid pressures when the joint is in use after implantation of the prosthesis to a second location for venting fluid from the first location to the second location thereby to inhibit fluid pressure build up between bone located at the joint and the prosthesis.  
     
     
         2 . A bone prosthesis as set forth in  claim 1  wherein the passageway is arranged to vent joint wear debris from the first location which is subject to high concentrations of joint wear debris after implantation of the prosthesis to the second location for venting joint wear debris from the first location to the second location thereby to inhibit wear debris build up between bone located at the joint and the prosthesis.  
     
     
         3 . A bone prosthesis as set forth in  claim 1  wherein the stem includes a tip adapted to be received through the bone upon implantation of the prosthesis, the tip being disposed generally at the second location and the passageway having an aperture generally at the tip.  
     
     
         4 . A bone prosthesis as set forth in  claim 3  wherein the passageway extends within the stem.  
     
     
         5 . A bone prosthesis as set forth in  claim 4  wherein the passageway includes a primary channel extending generally longitudinally of the stem and secondary channels extending from multiple, spaced apart openings on the exterior of the stem to the primary channel.  
     
     
         6 . A bone prosthesis as set forth in  claim 5  wherein the stem has side surfaces, the secondary channel openings being located in the side surfaces so that the secondary channels and the primary channel are in fluid communication with a prosthesis-bone interface, the secondary channels extending inwardly from the openings at angles oblique to the side surfaces.  
     
     
         7 . A bone prosthesis as set forth in  claim 6  wherein the stem is sized for transosseous implantation in which the stem extends through the bone and the tip of the stem is exposed outside of the bone.  
     
     
         8 . A bone prosthesis as set forth in  claim 7  wherein the primary channel opens at the aperture in the tip of the stem, the aperture and primary channel being sized and shaped to receive an infusion element for infusing fluid into the channel when the bone prosthesis is installed in the bone, the fluid passing from the primary channel to the secondary channels and the prosthesis-bone interface.  
     
     
         9 . A bone prosthesis as set forth in  claim 4  for implantation in a femur at a hip joint, the prosthesis further comprising a collar on an end of the stem opposite the tip, a neck mounted on the collar and a ball mounted on the neck, the passageway in the stem opening at the first location disposed on an upper surface of the collar.  
     
     
         10 . A bone prosthesis as set forth in  claim 9  wherein the passageway constitutes a first passageway, and wherein the stem has a second passageway in the stem opening on an upper surface of the collar and extending to the second location.  
     
     
         11 . A bone prosthesis as set forth in  claim 10  wherein the second passageway is sized and shaped to receive an instrument therethrough to provide access to the first location.  
     
     
         12 . A bone prosthesis as set forth in  claim 11  wherein the second passageway has no connection to the first passageway.  
     
     
         13 . The bone prosthesis of  claim 12  wherein the first and second passageways extend through the stem to separate apertures at the stem tip.  
     
     
         14 . A bone prosthesis for implantation at a joint, the prosthesis comprising a stem having: 
 a tip generally at one end thereof, and    a collar on an end of the stem opposite the tip,    the stem being sized and shaped for reception in a bone at the joint such that the tip of the stem is exposed to locations outside of the bone,    the stem having a passageway therein extending from a first location on the bone prosthesis to a second location on the bone prosthesis.    
     
     
         15 . A bone prosthesis as set forth in  claim 14  in combination with an infusion element, wherein the passageway of the bone prosthesis has an aperture at the second location, the aperture and passageway being sized and shaped to receive an infusion element for infusing fluid into the passageway when the bone prosthesis is installed in the bone.  
     
     
         16 . A bone prosthesis as set forth in  claim 15  wherein the passageway comprises a primary channel extending from the aperture at the second location and secondary channels extending from the primary channel to openings in the bone prosthesis, the infused fluid being capable of passing from the primary channel to the secondary channels and thence out of the secondary channel openings.  
     
     
         17 . A bone prosthesis as set forth in  claim 16  wherein the infusion element has threads formed thereon, and wherein the primary channel has threads at the aperture adapted to engage the threads of the infusion element for securing the infusion element in the aperture.  
     
     
         18 . A bone prosthesis as set forth in  claim 17  wherein the tip of the stem is generally at the second location and the primary channel aperture is located generally at the tip.  
     
     
         19 . A bone prosthesis as set forth in  claim 15  further in combination with an infusion port in fluid communication with the infusion element, the infusion port being adapted for implantation under the skin for use in repeated infusion of fluid into the passageway.  
     
     
         20 . A method of implanting a femoral head-neck prosthesis in a femur without the use of cement, the femur having a shaft and a neck at the upper end of the shaft at the medial side of the femur, the prosthesis having a longitudinal passageway for venting fluid pressure from a first location which is subject to elevated fluid pressures when the joint is in use after implantation of the prosthesis to a second location for venting fluid from the first location to the second location thereby to inhibit fluid pressure build up between bone located at the joint and the prosthesis, the method comprising the steps of: 
 cutting the neck of the femur to form a seat on the femur neck;  
 drilling a passage along a line through the shaft of the femur; and  
 inserting the stem of the prosthesis in the passage of the femur such that the longitudinal passageway for venting fluid is not occluded.  
 
     
     
         21 . A method as set forth in  claim 20  wherein the step of inserting the stem comprises driving the stem through the passage until a distal end of the stem protrudes from the lateral side of the femur.  
     
     
         22 . A method as set forth in  claim 21  further comprising, prior to said step of inserting the stem, the step of attaching a removable guide on the distal end of the stem to inhibit occlusion of the longitudinal passageway of the stem during said step of inserting the stem.