Abstract:
Instrumentation and method for determining the orientation of the pelvic bone during hip-replacement surgery. Instrumentation includes a pelvis frame and a pelvis level. The pelvis frame is used for performing an operation which provides preliminary information for determining the position of the pelvic bone, and includes pads which are specifically contoured for contact with the pelvic bone. The pelvis level is used in combination with the pelvis frame to determine the exact position of the patient&#39;s pelvic bone, and includes a ball level which is capable of withstanding steam sterilization.

Description:
BACKGROUND OF INVENTION  
       [0001]     The present invention relates to surgery. More specifically, the invention relates to hip-replacement surgery. Such surgery is frequently performed as a treatment for arthritis of the hip. Sometimes, the hip ball can, after the operation, slip out of the hip socket. Such an occurrence is technically and medically referred to as a dislocation. A common cause of such dislocation is improper positioning of the acetabular component (hip socket) in the patient&#39;s pelvic bone. There are generally accepted angles for placement of the acetabular component that an orthopedic surgeon attempts to attain while performing the surgery. To do so, the surgeon must know or determine the orientation of the patient&#39;s pelvic bone. Herein lies the problem. The patient is covered with sterile surgical drapes, and only a small portion of the bone is visible. The patient may be leaning forward or backward, and there is no accurate method to assess his or her exact position or orientation. The present invention provides a solution to this problem.  
       SUMMARY OF INVENTION  
       [0002]     In general, the present invention provides instrumentation and method for determining the orientation of the pelvic bone during hip-replacement surgery.  
         [0003]     The instrumentation comprises a pelvis frame and a pelvis level.  
         [0004]     The pelvis frame comprises (a) a first rigid elongated member; (b) a second rigid elongated member mounted on the first rigid member in a perpendicular relationship thereto; (c) first and second pads attached to the first rigid elongated member in a perpendicular configuration; (d) a third pad attached to the second rigid elongated member in a perpendicular configuration; and (e) means for varying the position of the first, second, and third pads, and for fixating said position as required, for effecting orientation-determining contact of the first, second, and third pads with the pelvic bone of a patient undergoing hip-replacement surgery. The first, second, and third pads are contoured to conform to portions of the pelvic bone which said pads contact.  
         [0005]     The pelvis level comprises a housing which includes first and second parallel straight-line openings extending therethrough, for insertion therein of first and second wires used to effect temporary connection of the housing to the pelvic bone of a patient undergoing hip-replacement surgery. The pelvis level further comprises a level, disposed in the housing under a transparent cover, for determination of a level position of the housing.  
         [0006]     The method comprises (a) providing a pelvis frame comprising a first rigid elongated member; a second rigid elongated member mounted perpendicularly on the first rigid elongated member; first and second pads attached perpendicularly to the first rigid elongated member; a third pad attached perpendicularly to the second rigid elongated member; and means for varying the position of the first, second, and third pads, and for fixating said position as required, for effecting orientation-determining contact of the first, second, and third pads with a patient undergoing hip-replacement surgery; (b) providing a pelvis level including a level disposed in a housing which includes first and second parallel straight-line openings extending therethrough; (c) adjusting the pelvis frame so that the first and second pads rest on the anterior superior iliac spines of the patient undergoing the hip-replacement surgery; (d) adjusting the pelvis frame so that the third pad rests on the pubic symphysis of the pelvic bone of the patient undergoing the surgery; (e) drilling first and second wires into the anterior superior iliac spine through first and second openings in the first or second pad contacting the anterior superior iliac spine on the side on which the surgery is to be performed; (f) removing the pelvis frame from contact with the patient; (g) turning the patient from back contact to side contact with an operating-room bed; (h) beginning the hip-replacement surgery; (i) at a point during the surgery that the acetabular component of the pelvic bone is to be replaced, sliding the pelvis level over the first and second wires through the first and second holes in the pelvis level; (j) adjusting position of the operating-room bed as required until the pelvis level indicates level position; and (k) replacing the acetabular component of the pelvic bone. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0007]      FIG. 1A  is a plan view of a pelvis frame for hip-replacement surgery, made in accordance with the principles of the present invention.  
         [0008]      FIG. 1B  is a front elevation of the pelvis frame shown in  FIG. 1A .  
         [0009]      FIG. 1C  is a side elevation of the pelvis frame shown in  FIG. 1A .  
         [0010]      FIG. 2  is a schematic representation of a portion of the body of a patient undergoing hip-replacement surgery, lying on his/her back, with the pelvis frame of  FIGS. 1A-1C  resting thereon.  
         [0011]      FIG. 3A  is an isometric view of a bubble level for hip-replacement surgery, made in accordance with the principles of the present invention.  
         [0012]      FIG. 3B  is a plan view of the bubble level shown in  FIG. 3A .  
         [0013]      FIG. 3C  is a side view of the bubble level shown in  FIGS. 3A and 3B .  
         [0014]      FIG. 4A  is an isometric view of a ball level for hip-replacement surgery, made in accordance with the principles of the present invention.  
         [0015]      FIG. 4B  is a plan view of the ball level shown in  FIG. 4A .  
         [0016]      FIG. 4C  is a side view of the ball level shown in  FIGS. 4A and 4B .  
         [0017]      FIG. 5A  is a schematic representation of the side of the body of a patient lying on his/her side, with two wires in the pelvis, and the bubble or ball level inserted over the wires.  
         [0018]      FIG. 5B  is a schematic representation of the front of the body of a patient lying on his/her side, with two wires in the pelvis, and the bubble or ball level inserted over the wires. 
     
    
     DETAILED DESCRIPTION  
       [0019]     More specifically, reference is made to  FIGS. 1A-1C , in which is shown a pelvis frame for hip-replacement surgery, made in accordance with the principles of the present invention, and generally designated by the numeral  2 .  
         [0020]     The pelvis frame  2  comprises a first rigid elongated member  4 ; a second rigid elongated member  6  mounted on the first rigid elongated member  4  in a perpendicular relationship thereto; first and second pads  8   a  and  8   b  attached to the first rigid elongated member  4  in a perpendicular configuration; a third pad  10  attached to the second rigid elongated member  6  in a perpendicular configuration; and screw-down knobs  12   a ,  12   b , and  12   c . The screw-down knobs  12   a ,  12   b , and  12   c provide the means for varying the position of the first, second, and third pads  8   a ,  8   b , and  10 , and for fixating said position as required, for effecting orientation-determining contact of the first, second, and third pads  8   a ,  8   b , and  10  with the pelvic bone of a patient undergoing hip-replacement surgery.  
         [0021]     As seen best in  FIG. 1B  and  FIG. 1C , the first, second, and third pads  8   a ,  8   b , and  10  are contoured to conform to portions of the pelvic bone which said pads contact. More specifically, pads  8   a  and  8   b  are cylindrical, with a contact surface  8   c  which is concave. By concave is meant that the surface  8   c  is concave as viewed in  FIG. 1B . The third pad  10  is cylindrical, with a contact surface  10   a  which is saddle-shaped. By saddle-shaped is meant that the surface  10   a  is saddle-shaped as viewed in  FIG. 1C . The first and second pads  8   a  and  8   b  include guide openings  8   d  for insertion of wires used to determine the orientation of the patient undergoing surgery. The width of the guide openings  8   d  is preferably about two millimeters. Disposition of the guide openings  8   d  is defined in  FIG. 1A . Intersection of a line  8   e  drawn perpendicular to the first rigid elongated member  4  with a line  8   f  drawn between and connecting the guide openings  8   d  to one another defines an angle  8   g  of from about twenty degrees to about thirty degrees. Preferably, the angle  8   g  has a magnitude of from about twenty-four degrees to about twenty-six degrees. Most preferably, the magnitude of the angle  8   g  is about twenty-five degrees.  
         [0022]     Reference is now made to  FIG. 2 , in which is represented a portion of the anatomy of a patient undergoing hip-replacement surgery, with the pelvis frame  2  resting on the patient&#39;s abdomen. More specifically, the first and second pads  8   a  and  8   b  contact the patient&#39;s anterior superior iliac spines  14 , while the third pad  10  rests on the pubic symphysis  16  of the patient&#39;s pelvic bone  17 .  
         [0023]     Reference is now made to  FIGS. 3A-3C , in which is shown a bubble level for hip-replacement surgery, made in accordance with the principles of the present invention, and generally designated by the numeral  18 . The bubble level  18  comprises a housing  20  which includes first and second parallel straight-line openings  20   a  and  20   b  extending therethrough, for insertion therein of first and second wires  22   a  and  22   b . The wires  22   a  and  22   b  are used to effect temporary connection of the housing  20  to the pelvic bone  17  of the patient undergoing the hip-replacement surgery. The bubble level  18  further comprises a liquid  24  including a bubble  24   a , disposed under a convex transparent cover  26 . By convex is meant convex as viewed in  FIGS. 3A-3C .  
         [0024]     Reference is now made to  FIGS. 4A-4C , in which is shown a ball level for hip-replacement surgery, made in accordance with the principles of the present invention, and generally designated by the numeral  28 . The ball level  28  comprises a housing  30  which includes first and second parallel straight-line openings  30   a  and  30   b  extending therethrough, for insertion therein of the first and second wires  22   a  and  22   b . As for the bubble level  18 , the wires  22   a  and  22   b  are used for the temporary connection of the housing  30  to the pelvic bone  17  of the patient undergoing the surgery. The ball level  28  further comprises a ball  33  disposed on a concave surface  35  between a transparent cover  36  and the concave surface  35 . By concave is meant concave as viewed in  FIGS. 4A-4C . The ball level  28  is beneficially made of materials that can withstand steam sterilization. Thus, the ball  33  and the housing  30  are preferably made of metal, polytetrafluoroethylene, a heat-resistant plastic, a ceramic, or other heat-resistant material. The transparent cover  36  is preferably made of Pyrex® glass or any other transparent heat-resistant material.  
         [0025]     For a description of the surgical method of the present invention, reference is again made to  FIGS. 2-5B .  
         [0026]     As shown in  FIG. 2 , after anesthesia has been administered to the patient, the pelvis frame  2  is placed on the front of the patient&#39;s lower abdominal area, with the patient lying on his or her back on an operating room bed  19 . The pelvis frame  2  is adjusted so that the first and second pads  8   a  and  8   b  rest on the anterior superior iliac spines  14 , and the third pad  10  rests on the public symphysis  16  of the patient&#39;s pelvic bone  17 . On the side that the hip replacement is to be performed, the two wires  22   a  and  22   b  are drilled into the anterior superior iliac spine  14  through the openings  8   d  in the first or second pad  8   a  or  8   b . The pelvis frame  2  is then removed, leaving the wires  22   a  and  22   b  in the pelvis.  
         [0027]     As shown in  FIG. 5A and 5B , the patient is then turned side-ways on the operating room bed  19 , and the hip surgery is begun.  FIG. 5A  depicts a patient having a right hip surgery. The wires  22   a  and  22   b  are perpendicular to the coronal plane  15  of the pelvis. At the point during the surgery that the acetabular component  17   a  of the pelvic bone  17  is to be replaced, the pelvis level  18  ( FIGS. 3A-3C ) or  28  ( FIGS. 4A-4C ) is slid over the wires  22   a  and  22   b  through the openings  20   a  and  20   b  ( FIGS. 3A-3C ) or  30   a  and  30   b  ( FIGS. 4A-4C ) in the housing  20  ( FIGS. 3A-3C ) or  30  ( FIGS. 4A-4C ). The operating room bed  19  is then adjusted with its built-in controls until the bubble  24   a  ( FIGS. 3A-3C ) or the ball  33  ( FIGS. 4A-4C ) is centered, indicating that the pelvis is perpendicular to the floor of the operating room, and providing the surgeon with the necessary information to insert the acetabular component  17   a  at the correct angle. Crosshairs  27   a  ( FIGS. 3A and 3B ) or  37   a  ( FIGS. 4A and 4B ) on the pelvis level  18  ( FIGS. 3A-3C ) or  28  ( FIGS. 4A-4C ) are parallel to the coronal plane  15  of the pelvis as depicted in  FIG. 5A . The crosshairs  27   a  ( FIGS. 3A and 3B ) and  37   a  ( FIGS. 4A and 4B ) therefore provide additional information about pelvic position which is not accounted for by centering the bubble or the ball. At the end of the operation, the alignment wires  22   a  and  22   b  are removed from the patient&#39;s pelvis.  
         [0028]     While certain embodiments and details have been described to illustrate the present invention, it will be apparent to those skilled in the art that many modifications are possible and can be made without departing from the spirit, basic principles, and scope of the invention.