Method of resecting a femoral head for implantation of a femoral neck fixation prosthesis

Abstract

A femoral neck fixation prosthesis and method of using same which reduces bone loss and the avoids the other shortcomings of the prior art by allowing the fixation of a stable femoral head replacement while reducing the amount of the femur which must be reamed for the insertion of the prosthesis. The preferred embodiment provides that the femoral head is attached to a fixation prosthesis, which extends coaxially through the canal of the femoral neck, into the femur, and is then attached to the opposite lateral wall of the femur. In this manner, the prosthesis serves to imitate the original structure of the femoral neck. No other support members, either crosspins or arms extending into the length of the femur, are required.

1 . A method of resecting a femoral head from a femur having a femoral neck, the method comprising the steps of:
 positioning a locator shaft adjacent an exterior surface of the femoral head and substantially parallel to a longitudinal axis of the femoral neck;   positioning a pin locator guide having at least two holes along the locator shaft;   inserting a pin through each of the at least two of the holes in the pin locator guide and into the femoral head; and   resecting the femoral head by aligning a cutting guide relative to the pins in the femoral head.   
   
   
       2 . A method according to  claim 1 , wherein a locator plane formed by the pins is parallel to a cutting plane at which the femoral head is resected. 
   
   
       3 . A method according to  claim 1 , wherein:
 a locator plane formed by the pins is parallel to a cutting plane at which the femoral head is resected; and   the cutting plane is perpendicular to the longitudinal axis of the femoral neck.   
   
   
       4 . A method according to  claim 1 , wherein the step of positioning a locator shaft further comprises the steps of:
 providing a femoral neck clamp having a superior clamping member, an inferior clamping member, and a locator shaft guide member connected to at least one of the superior clamping member and the inferior clamping member; and   clamping the femoral neck clamp around the femoral neck at an isthmus of the femoral neck such that the superior clamping member is adjacent a superior region of the femoral neck, the inferior clamping member is adjacent an inferior region of the femoral neck, and a longitudinal axis of the locator shaft guide member is substantially parallel to the longitudinal axis of the femoral neck.   
   
   
       5 . A method of resecting a femoral head from a femur having a femoral neck, the method comprising the steps of:
 locating an isthmus plane at an isthmus of the femoral neck;   fixing the orientation of a cutting plane based on the isthmus plane; and   resecting the femoral head at the cutting plane.   
   
   
       6 . A method according to  claim 5 , wherein the step of fixing the orientation of the cutting plane further comprises the steps of:
 inserting at least two pins into the femoral head.   
   
   
       7 . A method according to  claim 6 , wherein the pins are positioned along a line parallel to the isthmus plane. 
   
   
       8 . A femoral neck clamp for locating a cutting plane on a femur for resecting a femoral head of the femur, the femoral neck clamp comprising:
 a superior clamping member;   an inferior clamping member adjustably connected to the superior clamping member;   a locator shaft guide hole connected to at least one of the superior clamping member and the inferior clamping member; and   wherein the locator shaft guide hole is oriented substantially parallel to a longitudinal axis of the femoral neck when the femoral neck clamp is positioned at an isthmus of the femoral neck such that the superior clamping member is adjacent a superior region of the femoral neck and the inferior clamping member is adjacent an inferior region of the femoral neck.   
   
   
       9 . A femoral neck clamp according to  claim 8 , wherein the superior clamping member includes an arcuate region to contact an antero-superior ridge on the femoral neck. 
   
   
       10 . A femoral neck clamp according to  claim 8 , wherein the inferior clamping member is V-shaped to cradle the inferior region of the femoral neck. 
   
   
       11 . A femoral neck clamp according to  claim 8 , wherein:
 the superior clamping member includes an arcuate region to contact an antero-superior femoral neck; and   the inferior clamping member is V-shaped to cradle the inferior region of the femoral neck.   
   
   
       12 . A femoral neck clamp according to  claim 8 , wherein the inferior clamping member further comprises:
 a proximal clasp aligned with the superior clamping member; and   a distal clasp rotatably connected to the proximal clasp.   
   
   
       13 . A femoral neck clamp according to  claim 12 , wherein the distal clasp provides anti-rotational stability for the femoral neck clamp when secured around the femoral neck. 
   
   
       14 . A femoral neck clamp according to  claim 12 , wherein a connecting member is used to rotatably connect the proximal clasp to the distal clasp. 
   
   
       15 . A femoral neck clamp according to  claim 12 , further comprising:
 a connecting member pivotally connected to the proximal clasp and rigidly connected to the distal clasp; and   a torsion spring operably connected to the connecting member and the proximal clasp to bias the distal clasp toward the femoral neck.   
   
   
       16 . A femoral neck clamp according to  claim 12 , further comprising:
 a connecting member rigidly connected to the proximal clasp and rigidly connected to the distal clasp; and   wherein the connecting member is made from a flexible material to bias the distal clasp toward the femoral neck.   
   
   
       17 . A femoral neck clamp according to  claim 16 , wherein the connecting member is made from spring steel. 
   
   
       18 . A femoral neck clamp according to  claim 12 , further comprising:
 a connecting member pivotally connected to the proximal clasp and rigidly connected to the distal clasp; and   a fastener connected between the connecting member and the proximal clasp to lock a rotational position of the distal clasp relative to the proximal clasp.