Modular hip implant with shock absorption system

Abstract

A modular hip implant that can be custom fit to an individual patient, including a shock absorption system that absorbs compressive stresses that are imparted to the implant. The size of the femoral ball member, size of the femoral stem, femoral neck length, and tension in the shock absorption system are all individually adjustable parameters, depending on the particular patient. A unique coupling member houses a modular spring mechanism that serves as the shock absorber. The coupling member is received into the ball member to an adjustable depth, the adjustment of which varies the length of the femoral neck. The length of the femoral neck can be adjusted during surgery without requiring additional parts.

What is claimed is:  
     
         1 . A modular hip prosthesis, comprising a ball member having an outer surface adapted to cooperate with an acetabular socket and further comprising a threaded bore to fit into a coupling member. 
 A femoral stem having a shank adapted to be inserted and secured into a medullary cavity of a femur bone, said femoral stem having a neck at the proximal end comprising a threaded bore thereof, said neck connected to a coupling member via a spring mechanism attached to the said bore in the neck.    A spring mechanism disposed intermediate said coupling member and said neck member, said spring mechanism providing cushioning movement and shock absorption between said acetabular socket and said ball member via the coupling member.    Said spring mechanism detachably connected to said neck member and to the coupling member, thereof said coupling member detachably connected to the ball member.    
     
     
         2 . The modular hip prosthesis of    claim 1   , further comprising: 
 a coupling member housing said spring mechanism, the connection of said ball member to said spring mechanism being through said coupling member, said coupling member received in said threaded bore of the ball member to an adjustable depth, adjustment of said depth causing corresponding adjustment of the distance said neck extends from said ball member.    
     
     
         3 . The modular hip prosthesis of    claim 2   , wherein said threaded bore in the ball member and the coupling member comprise corresponding threads, said coupling member being threadingly received in said threaded bore.  
     
     
         4 . The modular hip prosthesis of    claim 2   , wherein said spring mechanism includes a first connector at a first end thereof connecting said neck member to said spring mechanism. The first connector threadingly connected to said neck member.  
     
     
         5 . The modular hip prosthesis of    claim 4   , wherein said spring mechanism includes a second connector at a second end thereof connecting said spring mechanism to said coupling member.  
     
     
         6 . The modular hip prosthesis of    claim 3   , wherein said coupling member and said bore in the ball member include corresponding threads, said coupling member threadingly received into said bore to an adjustable depth, adjustment of said depth causing corresponding adjustment of the distance said neck extends from said ball member.  
     
     
         7 . The modular hip prosthesis of    claim 6   , wherein said coupling member comprises a substantially hollow insert having a substantially smooth inner-surface, said neck member slidingly engages said inner smooth surface during said cushion movement and shock absorption to prevent stress and strain in the hip joint and in the prosthesis.  
     
     
         8 . The modular hip prosthesis of    claim 5   , wherein said spring mechanism is threadingly connected to said coupling member wherein both components are detachable and attachable by the surgeon should it become necessary during a surgical procedure.  
     
     
         9 . The modular hip prosthesis of    claim 8   , wherein said spring mechanism is threadingly connected to to said neck member wherein both components are detachable and attachable by the surgeon should it become necessary during a surgical procedure.  
     
     
         10 . A method of custom-fitting the modular hip prosthesis comprising the following steps: 
 Selecting a femoral component with a threaded opening formed in the femoral neck member.    Attaching the neck of the femoral component to a coupling member by means of a spring mechanism, which is detachabale if desired by the surgeon during a surgical procedure for any modifications necessary.    Selecting a ball member comprising a threaded bore and afixing the ball member over the coupling member by using threaded means by screwing method by the surgeons hands, to a determined depth to adjust neck length. Both components are detachable and attachable by the surgeon during a surgical procedure for any modifications, should it become necessary.    
     
     
         11 . The modular hip prosthesis of    claim 10   , further comprising installing a versatile spring mechanism to allow a coupling member attached to the ball member to slide over the neck member.  
     
     
         12 . The modular hip prosthesis of    claim 11   , further comprising selecting the spring mechanism having spring elements of different stiffnesses, lengths, removable and reattachable to custom fit a prosthesis between a coupling member and a neck member.  
     
     
         13 . The modular hip prosthesis of    claim 1   , wherein the ball member, the coupling member, the femoral stem and the neck, the spring mechanism are fabricated from selected materials from titanium alloys, vitallium, stainless steel, nylon, plastic, ceramic or other suitable combination thereof, suitable for human implantation.