System for establishing the orientation of a modular implant
This invention provides apparatus and a method for assembling a modular hip implant where the desired orientation of the neck component is uniquely determined during the trialing phase of the operation, and that same desired orientation is accurately reproduced during the implantation phase of the actual hip implant device.
1. A method for determining and recording the orientation of a modular hip implant neck, the method comprising:
providing an assembly comprising:
a trial implant comprising:
a trial body having (i) a bore and (ii) an opening for attachment to a recording instrument; and
a trial neck having (i) a shaft which is adapted for insertion into the bore of the trial body and (ii) a portion for attachment to the recording instrument; and
the recording instrument comprises an elongated body having a distal end and a proximal end, wherein the proximal end comprises (i) a first member for attachment to the trial neck and (ii) a second member coaxial with the first member for attachment to the trial body;
adjusting the trial neck relative to the trial body so as to assume a desired orientation between the trial neck and the trial body, wherein the desired orientation is determined by orienting the trial neck in relation to a first anatomical reference and orienting the trial body in relation to a second anatomical reference;
attaching the first member to the trial neck and the second member to the trial body so as to record the orientation of the trial neck and the trial body;
providing a modular hip implant comprising a neck component and a body component;
assembling the neck component and the body component in the recorded orientation; and
inserting the assembled modular implant into a patient's femur.
2. The method of claim 1 wherein the recording of the orientation of the trial neck comprises making a mechanical recording of the orientation.
3. The method of claim 1 wherein one of the anatomical references is a cavity prepared in the femur for the assembled modular implant.
4. The method of claim 1 wherein one of the anatomical references is an anatomic landmark on the femur.
5. The method of claim 1 wherein one of the anatomical references is a knee joint.
6. The method of claim 1 wherein one of the anatomical references is the posterior condyle of a patient's knee.
7. The method of claim 1 wherein one of the anatomical references is a long axis of a patient's tibia.