Customized acetabular cup positioning guide and system and method of generating and employing such a guide

Abstract

Implementations described and claimed herein provide an arthroplasty system positioning an acetabular cup implant. In one implementation, the system includes a shape-match hip guide having a patient specific mating region that is a negative of the surface contour of the inside surface of the patient's acetabular cup, and a directional rod that extends generally along the axis of the patient's femoral head and femoral neck. They system can additionally include an outrigger or silo device to aid in the alignment of surgical tools for preparing and implanting of the prosthetic acetabular cup in the patient's acetabular cup. Related methods are also disclosed herein for generating a shape-match guide and implanting an acetabular cup with the guide.

What is claimed is: 
     
         1 . A method of manufacturing a custom acetabular cup positioning guide for use in an arthroplasty procedure on a portion of a hip region of a patient's body, wherein the portion of the hip region includes a patient's acetabular cup, the method of manufacturing comprising:
 generating a plurality of two dimensional medical images of the portion of the hip region of the patient's body to undergo the arthroplasty procedure;   identifying landmarks on bone boundaries in the two dimensional medical images;   identifying a hip axis line by triangulating a plurality of the landmarks in the two dimensional medical images;   using a computer processor to generate a three dimensional bone model of the portion of the hip region of the patient's body to undergo the arthroplasty procedure from the plurality of two dimensional medical images, wherein the three dimensional bone model includes a three dimensional model of the patient's acetabular cup;   shape-matching an inside surface of the three dimensional model of the patient's acetabular cup relative to the hip axis line;   generating the custom acetabular positioning guide based upon the identification of the hip axis line and a negative contour of the inside surface of the three dimensional model of the patient's acetabular cup.   
     
     
         2 . The method of  claim 1 , wherein the custom positioning guide comprises a directional rod that extends generally along the hip axis line when the custom positioning guide matingly interdigitates with an inside surface of the patient's acetabular cup. 
     
     
         3 . The method of  claim 1 , further comprising generating a three dimensional acetabular cup positioning guide model from the three dimensional bone model. 
     
     
         4 . The method of  claim 1 , wherein the plurality of medical images are generated from MRI slices or CT slices. 
     
     
         5 . The method of  claim 1 , wherein identifying landmarks on bone boundaries include a user at a user interface employing at least one of a mouse, keyboard, pen-and-tablet system, touch screen system, or spatial input device to place landmark points. 
     
     
         6 . The method of  claim 1 , wherein the landmarks identified on the bone boundaries in the two dimensional images comprise a left teardrop and a right teardrop of a pelvis, a right anterior-superior ilium symphysis (“ASIS-R”), a left anterior-superior ilium symphysis (“ASIS-L”), and a pubic symphysis. 
     
     
         7 . The method of  claim 6 , wherein the landmarks are identified in a coronal image slice. 
     
     
         8 . The method of  claim 6  or  7 , wherein the plurality of landmarks used in triangulation in the two dimensional images include the ASIS-R, the ASIS-L, and the pubic symphysis. 
     
     
         9 . The method of  claim 8 , wherein identifying the hip axis line further comprises identifying a pelvic axis line in the two dimensional images that extends through the left teardrop and the right teardrop of the pelvis. 
     
     
         10 . The method of  claim 9 , further comprising determining an acute first angle between the pelvic axis line and a first line that extends through the pubic symphysis and either the ASIS-R or ASIS-L, wherein the first line will extend through the ASIS-R if a right hip region is to undergo the arthroplasty procedure and the first line will extend through the ASIS-L if a left hip region is to undergo the arthroplasty procedure. 
     
     
         11 . The method of  claim 10 , further comprising identifying a second angle by increasing the first angle by a surgically prescribed degree, rotated downward from the first line, wherein the second angle is coextensive with a hip axis angle, whereby the hip axis angle is defined between the first line and the hip axis line. 
     
     
         12 . The method of  claim 11 , wherein the surgically prescribed degree is about forty-five degrees. 
     
     
         13 . A custom acetabular cup positioning guide for use in an arthroplasty procedure on a portion of a hip region of a patient's body, wherein the portion of the hip region includes a patient's acetabular cup, femoral head and femoral neck, the guide comprising: a directional rod extending from a semi-hemispherical mold, wherein the mold includes a hemispherical surface that is generally a surface negative of a surface contour of an inside surface of the patient's acetabular cup, whereby when the mold interdigitates with the surface contour of the inside surface of the patient's acetabular cup the directional rod extends along a hip axis line, wherein the hip axis line generally extends along an axis collinear with a preoperative orientation of the femoral head and the femoral neck. 
     
     
         14 . The custom guide of  claim 13 , further comprising an outrigger positioning device, the outrigger positioning device comprising a first and a second coupler, the first coupler configured to couple with a portion of the directional rod, the second coupler configured to couple with the first coupler and couple with a portion of a reference rod, the reference rod configured to imbed or anchor in a portion of a superior hip region of a patient's body. 
     
     
         15 . The custom guide of  claim 14 , wherein the reference rod extends generally parallel with the directional rod, thereby providing a correlating reference to the hip axis line. 
     
     
         16 . The custom guide of  claim 14 , wherein the directional rod extends through a portion of the first coupler and wherein the reference rod extends through a portion of the second coupler. 
     
     
         17 . The custom guide of  claim 16 , wherein the first coupler matingly interdigitates with the second coupler. 
     
     
         18 . The custom guide of  claim 17 , wherein the first and the second coupler matingly interdigitate along corresponding planar surfaces. 
     
     
         19 . The custom guide of  claim 16 , wherein the first coupler is configured for the removal of the directional rod while maintaining orientation relative to the hip axis line, thereby allowing a shaft of a surgical tool to be received in the first coupler such that the shaft is generally collinear with the hip axis line. 
     
     
         20 . The custom guide of  claim 19 , wherein the first coupler is configured to allow translational movement of the shaft of the surgical tool generally along the hip axis line. 
     
     
         21 . A method of manufacturing a custom acetabular cup positioning guide for use in an arthroplasty procedure involving a hip region of a patient's body, wherein the hip region includes the patient's femoral head, femoral neck and acetabular cup, the guide including a mating region configured to matingly receive a portion of the patient's acetabular cup, the mating region including a surface contour that is generally a negative of a surface contour of the patient's acetabular cup, the surface contour of the mating region being configured to mate with the surface contour of the patient's acetabular cup in a generally matching or interdigitating manner when the patient's acetabular cup is matingly received by the mating region, the method of manufacture comprising:
 a) generating medical imaging slices of the portion of the patient bone;   b) identifying landmarks on bone boundaries in the medical imaging slices;   c) identifying a hip axis line, the hip axis line being generally collinear with an axis of the patient's femoral head and femoral neck in a preoperative state;   d) using a computer processor to generate a three dimensional bone model of the patient's acetabular cup;   e) shape-matching an inner surface of the three dimensional bone model of the patient's acetabular cup relative to the bone axis line;   f) using data associated with the inner surface of the three dimensional model of the patient's acetabular cup to manufacture the custom acetabular cup positioning guide.   
     
     
         22 . The method of  claim 21 , wherein the identifying a hip axis line further comprises triangulating landmarks on the bone boundaries in the medical imaging slices. 
     
     
         23 . The method of  claim 21 , wherein the medical imaging slices are generated from MRI slices or CT slices. 
     
     
         24 . The method of  claim 22 , wherein the landmarks identified on the bone boundaries in the medical imaging slices include a left teardrop and a right teardrop of a pelvis, a right anterior-superior ilium symphysis (“ASIS-R”), a left anterior-superior ilium symphysis (“ASIS-L”), and a pubic symphysis. 
     
     
         25 . The method of  claim 24 , wherein the landmarks are identified in a coronal image slice. 
     
     
         26 . The method of  claim 24 , wherein the landmarks used in triangulation in the two dimensional images include the ASIS-R, the ASIS-L, and the pubic symphysis. 
     
     
         27 . The method of  claim 26 , wherein identifying the hip axis line further comprises identifying a pelvic axis line in the two dimensional images that extends through the left teardrop and the right teardrop of the pelvis. 
     
     
         28 . The method of  claim 27 , further comprising determining an acute first angle between the pelvic axis line and a first line that extends through the pubic symphysis and either the ASIS-R or ASIS-L, wherein the first line will extend through the ASIS-R if a right hip region is to undergo the arthroplasty procedure and the first line will extend through the ASIS-L if a left hip region is to undergo the arthroplasty procedure. 
     
     
         29 . The method of  claim 28 , further comprising identifying a second angle by increasing the first angle by a surgically prescribed degree, rotated downward from the first line, wherein the second angle is coextensive with a hip axis angle, whereby the hip axis angle is defined between the first line and the hip axis line. 
     
     
         30 . The method of  claim 29 , wherein the surgically prescribed degree is about forty-five degrees. 
     
     
         31 . A method of performing an arthroplasty procedure on a hip region of a patient's body, the arthroplasty procedure involving implanting a prosthetic acetabular cup into a patient's acetabular cup, the method comprising:
 preparing the hip region of a patient's body to undergo the arthroplasty procedure, wherein preparing the hip region includes accessing the patient's acetabular cup;   matingly interdigitating a shape-match hip guide with the patient's acetabular cup, the shape-match hip guide comprising a directional rod and a mating head with a mating surface that is generally a surface negative of a surface contour of the patient's acetabular cup;   identifying a hip axis line that is generally collinear with a longitudinal axis defined along the directional rod when the mating surface of the mating head matingly interdigitates with the patient's acetabular cup, the hip axis line extending generally collinear with an axis of the patient's femoral head and femoral neck in a preoperative state;   preparing of the patient's acetabular cup to receive the prosthetic acetabular cup; and   implanting the prosthetic acetabular cup into the patient's acetabular cup along the hip axis line in order to replicate the preoperative state.   
     
     
         32 . The method of  claim 31 , wherein preparing of the patient's acetabular cup comprises reaming. 
     
     
         33 . The method of  claim 31 , further comprising removing of the shape-match hip guide from the patient's acetabular cup before the preparing of the patient's acetabular cup to receive the prosthetic acetabular cup. 
     
     
         34 . The method of  claim 31 , wherein implanting the prosthetic cup comprises driving of the prosthetic acetabular cup into the patient's acetabular cup. 
     
     
         35 . The method of  claim 31 , further comprising:
 coupling the shape-match hip guide to a reference rod, the reference rod being generally parallel to the directional rod and configured to imbed in the hip region of a patient's body;   decoupling the shape-match hip guide from the reference rod;   removing the shape-match hip guide from the patient's acetabular cup;   slideably coupling an impactor rod to the reference rod, wherein the impactor rod is configured to impact and seat the prosthetic acetabular cup into the patient's acetabular cup;   driving of the prosthetic acetabular cup into the patient's acetabular cup along the hip axis line; and   removing the impactor rod and the reference rod from the hip region of the patient's body.   
     
     
         36 . The method of  claim 35 , wherein coupling to the reference rod occurs via a pair of couplers. 
     
     
         37 . The method of  claim 36 , further comprising:
 slideably coupling a reamer to the reference rod;   reaming the patient's acetabular cup along the hip axis line; and   decoupling and removing the reamer from the reference rod.