System and method of hip replacement

Abstract

A cup for a hip replacement is disposed in a first relationship in an operating room with an object providing a sighting for the cup rotation in a first plane. The cup is thereafter rotated in the first plane through a first angle (e.g., 20°-30°). The cup is then disposed in a planar relationship in the operating room with another object providing a sighting for the cup rotation in a second plane transverse (e.g. perpendicular) to the first plane. The cup is subsequently rotated through a second angle (e.g. 40°-45°) in the second plane. In this way, the cup is properly positioned in the acetabulum socket. The length of the leg receiving the hip rotation is then adjusted so that the leg length matches the length of the patient's other leg. This adjustment is provided without affecting the offset position of the center of the ball on the femur.

1 . A system for matching the length of a patient's leg receiving a hip replacement to the length of the other leg of the patient,
 a microprocessor, and   a mechanism operatively coupled to the microprocessor and constructed to be disposed in a fixed relationship to a selective position on the patient's femur and including a plurality of transmitters displaced relative to one another at the selective position for transmitting signals to the microprocessor,   the microprocessor being responsive to the transmitted signals for processing the signals to indicate whether the selective position provides a match in the length of the patient's leg receiving the hip replacement to the length of the patient's other leg.   
     
     
         2 . The system as set forth in  claim 1  wherein
 the first mechanism includes a plurality of position-defining members for transmitting signals indicating the positions of the members and wherein 
 the microprocessor is constructed to respond to the signals from the position-defining members to indicate the length of the leg receiving the hip replacement relative to the length of the other leg. 
 
     
     
         3 . The system as set forth in  claim 1  wherein
 the first mechanism includes three (3) position-defining members for transmitting signals indicating the position of the members and wherein 
 the microprocessor is constructed to respond to the signals from the position-defining members to indicate the length of the patient's leg receiving the hip replacement relative to the length of the patient's other leg. 
 
     
     
         4 . The system as set forth in  claim 3  wherein
 a monitor is responsive to the indications from the microprocessor to indicate the positioning at each instant of the femur relative to the acetabulum. 
 
     
     
         5 . The system as set forth in  claim 1  wherein
 a monitor is responsive to the indications from the microprocessor to indicate the positioning at each instant of femur relative to the acetabulum. 
 
     
     
         6 . The system as set forth in  claim 3  wherein
 a monitor is responsive to the indications from the microprocessor to indicate the positioning at each instant of the femur relative to the acetabulum. 
 
     
     
         7 . A system for matching the length of a patient's leg receiving a hip replacement to the length of the other leg of the patient,
 a first mechanism constructed to be disposed on the patient's leg receiving the hip replacement for providing signals indicating the length of the leg,   a second mechanism constructed to be disposed on the patient's acetabulum for providing signals indicating the displacement of the patient's body from a reference position, and   a microprocessor responsive to the signals from the first and second mechanisms for eliminating any effects resulting from the displacement of the patient's body and for indicating only any difference between the length of the patient's leg receiving the hip replacement and the length of the patient's other leg.   
     
     
         8 . The system as set forth in  claim 7  wherein
 the microprocessor is responsive to the signals from the first and second mechanisms for indicating an offset of the patient's leg receiving the hip replacement. 
 
     
     
         9 . The system as set forth in  claim 7  wherein
 the first mechanism includes a first plurality of transmitters for transmitting first signals to the microprocessor to indicate the length of the patient's leg receiving the hip replacement and wherein 
 the second mechanism includes a second plurality of transmitters for transmitting second signals to the microprocessor to indicate any displacements of the patient's body from a reference position and wherein 
 the microprocessor processes the first and second signals to indicate the length of the patient's leg receiving the hip replacement. 
 
     
     
         10 . The system as set forth in  claim 7   wherein the first mechanism includes three (3) transmitters displaced from one another in the direction of the length of the femur for transmitting first signals to the microprocessor to obtain in the microprocessor the production of signals indicating the length of the patient's leg receiving the hip replacement and wherein   the second mechanism includes three (3) additional transmitters displaced from one another in the direction of the length of the leg for transmitting second signals to the microprocessor to eliminate any effects of body displacement on the indications provided by the first mechanism.   
     
     
         11 . The system as set forth in  claim 9  wherein
 the transmitters in the first mechanism are disposed on the femur and the transmitters in the second mechanism are disposed on the pelvis. 
 
     
     
         12 . The system as set forth in  claim 10  wherein
 the microprocessor is responsive to the signals from the first and second mechanisms for indicating an offset of the patient's leg receiving the hip replacement and wherein 
 the transmitters in the first mechanism are disposed on the femur and the transmitters in the second plurality are disposed on the pelvis. 
 
     
     
         13 . A method of matching the length of a leg receiving a hip replacement to the length of the other leg of the patient including the steps of:
 disposing a reference member on the patient's femur,   supporting a plurality of spaced transmitters on the reference member,   transmitting signals from the transmitters to a microprocessor, and   processing at the microprocessor the signals from the transmitters to determine any displacement of the reference member from a desired position.   
     
     
         14 . A method as set forth in  claim 13  wherein
 the length of the patient's leg receiving the hip replacement matches the length of the patient's other leg when the processing of the transmitter signals indicates that the reference member is at the desired position. 
 
     
     
         15 . A method as set forth in  claim 13  wherein
 there are three (3) transmitters displaced from one another in the direction of the length of the femur and wherein 
 the microprocessor processes the signals from the transmitter to determine any displacement of the reference member from a desired position in the direction of the length of the femur. 
 
     
     
         16 . A method as set forth in  claim 13  wherein
 the reference member is screwed into the client's femur and has a hollow interior and wherein 
 the transmitters are retained by a member extending into the hollow interior of the reference member. 
 
     
     
         17 . A method as set forth in  claim 13  wherein
 the length of the femur in the leg receiving the hip replacement is adjusted to produce a match between the lengths of the legs of the patient when the processing at the microprocessor of the signals from the transmitters indicate a displacement of the reference member from the desired position. 
 
     
     
         18 . A method as set forth in  claim 14  wherein
 there are three (3) transmitters displaced from one another in the direction of the length of the femur and wherein 
 the microprocessor processes the signals from the transmitters to determiner any displacement of the reference member from a desired position in the direction of the length of the femur and wherein 
 the reference member is screwed into the client's femur and has a hollow interior and wherein 
 the transmitters are retained by a member disposed within the hollow interior of the reference member and wherein 
 the length of the femur in the leg receiving the hip replacement is adjusted to produce a match between the lengths of the legs of the patient when the processing at the microprocessor of the signals from the transmitters indicates a displacement of the reference member form the desired position. 
 
     
     
         19 . A method of matching the length of a leg receiving a hip replacement to the length of the other leg of the patient, including the steps of:
 disposing a plurality of first transmitters on a patient's femur of the leg receiving the hip replacement,   transmitting signals from the first transmitters to a microprocessor,   disposing a plurality of second transmitters to a microprocessor,   disposing a plurality of second transmitters on the patient's pelvis on the side of the body wherein the leg receiving the hip replacement is located,   transmitting signals from the second transmitters to the microprocessor, and   processing the signals from the first and second transmitters at the microprocessor to recover the signals indicating whether the length of the user's leg receiving the hip replacement is the same as, or different from, the length of the patient's other leg and to discard the signals resulting from the movements of the patient's body.   
     
     
         20 . A method as set forth in  claim 19  wherein
 the first transmitter are displaced from one another on the femur in the direction of the length of the femur and wherein 
 the second transmitters are displaced from one another on the pelvis in the direction of the length of the femur. 
 
     
     
         21 . A method as set forth in  claim 19  wherein
 the length of the leg receiving the hip replacement is adjusted when the processing at the microprocessor of the signals from the transmitter indicates that the length of the leg receiving the hip replacement does not match the length of the other leg of the patient. 
 
     
     
         22 . A method as set forth in  claim 20  wherein
 the femur has a ball at the end of the femur adjacent to the acetabulum and wherein the ball has an extension and wherein the ball and the extension are replaced by a ball with a different extension which is attached to the femur when the processing at the microprocessor of the signals from the first transmitters indicates that the length of the leg does not match the length of the other leg of the patient. 
 
     
     
         23 . A method as set forth in  claim 22  wherein
 the offset of the center of the ball is adjusted when the ball with the different extension is disposed on the femur. 
 
     
     
         24 . A method as set forth in  claim 20  wherein
 the length of the leg receiving the hip replacement is adjusted when the processing at the microprocessor of the signals from the transmitter indicates that the length of the leg receiving the hip replacement does not match the length of the other leg of the patient, 
 the femur has a ball at the end of the femur adjacent to the acetabulum and wherein the ball has an extension and wherein the ball and the extension are replaced by a ball with a different extension which is attached to the femur when the processing at the microprocessor of the signals from the first transmitters indicates that the length of the leg does not match the length of the other leg of the patient.