Hip replacement navigation systems and methods

Abstract

Hip joint navigation systems and methods are provided. In some embodiments, the systems and methods described herein determine a table reference plane that approximates the Anterior Pelvic Plane. In some embodiments, the systems and methods described herein measure a pre-operative and post-operative point. In some embodiments, the comparison of the pre-operative and post-operative point corresponds to changes in leg length and joint offset. In some embodiments, the systems and methods described herein determine an Adjusted Plane. In some embodiments, the Adjusted Plane adjusts for tilt by rotating the Anterior Pelvic Plane about the inter-ASIS line. In some embodiments, the Adjusted Plane improves correlation between navigated cup angles and post-operative images.

1 .- 65 . (canceled) 
     
     
         66 . A method of positioning a medical prosthesis comprising:
 securing a fixation base to a pelvis of a patient;   securing a target to a femur of the patient;   recording an initial orientation of the femur relative to the pelvis before positioning an acetabular cup;   positioning the acetabular cup; and   returning the femur to the initial orientation after positioning the acetabular cup.   
     
     
         67 . The method of  claim 66 , further comprising recording an orientation of a point. 
     
     
         68 . The method of  claim 66 , further comprising recording an orientation of a point before and after positioning the acetabular cup. 
     
     
         69 . The method of  claim 66 , further comprising determining a change in leg length. 
     
     
         70 . The method of  claim 66 , further comprising determining a change in joint offset. 
     
     
         71 . The method of  claim 66 , further comprising registering gravitational zero. 
     
     
         72 . A method of positioning a medical prosthesis comprising:
 positioning a probe to contact a point;   registering the point before positioning an acetabular cup;   positioning the acetabular cup;   positioning a femur such that the femur is in the same position before positioning the acetabular cup and after positioning the acetabular cup; and   positioning the probe to contact the point after positioning the acetabular cup to determine a change in leg length or joint offset.   
     
     
         73 . The method of  claim 72 , wherein the point is located on a fixture. 
     
     
         74 . The method of  claim 72 , wherein the point is located in a divot in the femur. 
     
     
         75 . The method of  claim 72 , wherein the point is an anatomical landmark. 
     
     
         76 . The method of  claim 72 , wherein a change in the point along a vertical plane indicates a change in leg length. 
     
     
         77 . The method of  claim 72 , wherein a change in the point along a horizontal plane indicates a change in joint offset. 
     
     
         78 . A method of positioning a medical prosthesis comprising:
 recording a position of a first anatomical landmark;   recording a position of a second anatomical landmark, wherein a landmark-based reference plane contains the position of first anatomical landmark and the position of second anatomical landmark; and   establishing an adjusted plane by rotating the landmark-based reference plane containing the position of first anatomical landmark and the position of second anatomical landmark relative to the direction of gravity.   
     
     
         79 . The method of  claim 78 , wherein the adjusted plane provides an abduction angle corresponding to a post-operative image. 
     
     
         80 . The method of  claim 78 , wherein the adjusted plane provides an anteversion angle corresponding to a post-operative image. 
     
     
         81 . The method of  claim 78 , wherein the first anatomical landmark comprises an ipsilateral ASIS. 
     
     
         82 . The method of  claim 78 , wherein the second anatomical landmark comprises a contralateral ASIS. 
     
     
         83 . The method of  claim 78 , wherein the landmark-based reference plane contains an inter-ASIS line. 
     
     
         84 . The method of  claim 78 , wherein the position of the first anatomical landmark is recorded while the patient is in a supine position. 
     
     
         85 . The method of  claim 84 , wherein the position of the second anatomical landmark is recorded while the patient is in the supine position.