Trialing System and Method for Modular Hip Joint Replacement System

Abstract

A system and method for trialing a modular hip replacement system ( 10 ) permits evaluation and replication of the anatomic anteversion rotational angle of the femur. A distal stem component ( 18 ) of the hip replacement system ( 10 ) includes a proximal portion ( 34 ) having a locator feature ( 35 ) that is externally accessible when the stem component is mounted within the femur. A proximal trial body assembly ( 60 ) is mounted on the proximal portion ( 34 ) of the distal stem component ( 18 ) to permit rotation of a trial neck component ( 62 ). The trial neck component ( 62 ) also includes a locator feature ( 126 ) that can be externally referenced to determine the anteversion angle.

1 . A method for trialing a modular hip joint replacement system to determine the anteversion rotational angle of the femoral component, comprising the steps of:
 disposing a distal stem component within a prepared bore in the femur, the distal stem component configured for fixation within the prepared bore and having a proximal portion, the proximal portion defining a stem locator feature;   temporarily mounting a proximal trial assembly on the proximal portion of the distal stem component, the trial assembly defining a bore therethrough for accessing the locator recess in the distal stem component, the proximal trial assembly having a first component rotatable relative to the distal stem component about a longitudinal axis of the proximal portion of the distal stem component, the first component defining a trial locator feature independent of the stem locator feature, the first component including a portion configured as a trial neck;   rotating the first component of the proximal trial assembly relative to the distal stem component, while the stem component maintains its rotational position within the femur, until the trial neck portion is oriented at an acceptable anteversion rotational angle relative to the femur; and   using an instrument to reference the anteversion orientation of the trial neck portion relative to the femur.   
     
     
         2 . The method for trialing a modular hip joint replacement system according to  claim 1 , further comprising the step of using the instrument referenced to the anteversion orientation to position a proximal neck component of the joint replacement system at the anteversion orientation relative to the femur, wherein the neck component configured for substantially permanent mounting on the distal stem component within the femur. 
     
     
         3 . The method for trialing a modular hip joint replacement system according to  claim 1 , further comprising the step of temporarily locking the first component relative to the distal stem component prior to the step of using an instrument to reference the anteversion orientation. 
     
     
         4 . The method for trialing a modular hip joint replacement system of  claim 1 , wherein the step of disposing the distal stem component within the prepared bore includes substantially permanently implanting the distal stem component within the bore. 
     
     
         5 . The method for trialing a modular hip joint replacement system of  claim 1 , further comprising the step, prior to the step of temporarily mounting a proximal trial assembly, of disposing a sleeve component of the joint replacement system within the prepared bore such that the proximal end of the distal stem component extends through the sleeve, the sleeve configured for substantially permanent fixation within the prepared bore in the femur. 
     
     
         6 . The method for trialing a modular hip joint replacement system of  claim 5 , wherein said proximal trial assembly includes a second component rotatable relative to the first component, and the step of temporarily mounting the proximal trial assembly includes rotationally indexing the second component relative to the sleeve component.