Computer assisted insertion of an artificial hip joint

• US 20040147926A1
• Filed: 03/18/2004
• Published: 07/29/2004
• Est. Priority Date: 04/06/2001
• Status: Active Grant

• Current Assignee: Om Surgical (UK) Limited
• Original Assignee: Orthometer A/S
• Inventors: Iversen, Bjorn Franc
• Granted Patent: US 6,991,655 B2
• Time in Patent Office: Days
• US Class Current: 606/53
• CPC Class Codes: A61B 17/1746 for the acetabulum
• CPC Class Codes: A61B 2034/102 Modelling of surgical devices, implants or prosthesis
• CPC Class Codes: A61B 2034/107 Visualisation of planned trajectories or target regions
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2034/2072 Reference field transducer attached to an instrument or patient
• CPC Class Codes: A61B 2090/061 for measuring dimensions, e.g. length
• CPC Class Codes: A61B 2090/067 for measuring angles
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 34/25 User interfaces for surgical systems
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/4603 for insertion or extraction of endoprosthetic joints or of accessories thereof
• CPC Class Codes: A61F 2/4607 of hip femoral endoprostheses
• CPC Class Codes: A61F 2/4609 of acetabular cups
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 : Necks
• CPC Class Codes: A61F 2002/4631 : the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2002/4632 : using computer-controlled surgery, e.g. robotic surgery
• CPC Class Codes: A61F 2002/4658 : for measuring dimensions, e.g. length
• CPC Class Codes: A61F 2002/4668 : for measuring angles
• CPC Class Codes: B23Q 15/02 : according to the instantaneous size and the required size of the workpiece acted upon B23Q15/06 takes precedence
• CPC Class Codes: G05B 2219/45172 : Prosthesis

Abstract

A system and a method for ensuring correct insertion of the components of a femoral prosthesis, i.e. a prosthesis stem with a ball head and a cup with recess for receipt of the ball head, is described. The system comprises a tool for controlling the mutual angle between the prosthesis stem and the cup in addition to a positioning system for definition of a reference system and for determination and adjustment of the offset and length of the leg.

Claims

1. A system of ensuring the desired mutual positioning of the main components of an artificial hip joint prosthesis, the prosthesis including a prosthesis stem with a ball head and a cap with a recess for receipt of the ball head, the system comprising:

a positioning tool configured to interact with a neck of the prosthesis stem and the cup, wherein an angle between the prosthesis stem and the cup can be controlled;

at least one sensor placed at the positioning tool;

a position determination instrument in operative communication with said at lease one sensor, said position determination instrument configured to read a position and an orientation within a room.

2. The system of claim 1 wherein said position determination instrument comprises a sensor fastened to a pelvis.

3. The system of claim 1 wherein said position determination instrument comprises a conversion unit configured to convert the position of said at least one sensor to said angle between the prosthesis stem and the cup.

4. The system of claim 1 wherein said position determination instrument comprises an additional sensor, said additional sensor configured to be fastened to a femur, said additional sensor configured to measure at least one of a spatial angle, an offset and a length of said femur.

5. The system of claim 1 wherein said position determination instrument comprises a source for a magnetic field, at least one sensor, a calculation unit and a display unit for presentation of the position of said at least one sensor.

6. The system of claim 1 wherein said position determination instrument comprises a conversion unit, configured to convert the spatial position of said at least one sensor to a predetermined angle.

7. A method for computer assisted insertion of an artificial hip joint comprising:

making the anatomy of a hip available for insertion of parts of a prosthesis, wherein said parts of said prosthesis comprise a prosthesis stem and a cup;

preparing for insertion of said parts of said prosthesis;

inserting temporarily said prosthesis stem into a femur;

inserting temporarily said cup into a pelvis;

inserting a positioning tool between said prosthesis stem and said cup, said positioning tool configured to control an angle between said parts of the prosthesis;

assembling the artificial hip joint;

stretching said hip and a knee associated with said hip;

placing a foot associated with said hip and said knee in a position configured with the toes pointing forward relative to a body associated with said foot;

measuring the position of said parts of the prosthesis with a position determination instrument;

luxating the hip joint;

removing said parts of the prosthesis from said femur and said pelvis;

inserting said cup into said pelvis into a predetermined position, said predetermined position being equal to a position measured by said position determination instrument;

controlling said insertion of said cup with said position determination instrument;

fixing said cup into said predetermined position;

fixing said prosthesis stem to said femur; and

reassembling said hip joint.

8. The method of claim 7 wherein said position determination instrument comprises at least one sensor and a conversion unit configured to calculate the placement and spatial position of an at least one first sensor.

9. The method of claim 8 further comprising:

placing said at least one first sensor on said positioning tool; and

moving said at least one first sensor to an insertion instrument for the insertion of said cup.

10. The method of claim 8 further comprising:

fastening a second sensor to said pelvis after the anatomy is made available;

correcting. for any movement of said pelvis during the method for computer assisted insertion of the artificial hip joint with said second sensor.

11. The method of claim 10 further comprising:

fastening a third sensor to said femur, said third sensor is configured for use in the determination of the position of the femur;

measuring a preoperative offset and a length of a limb of said femur subsequent to said hip joint assembly and prior to luxation of said hip joint assembly, wherein said measuring comprises measuring a distance between said second sensor and said third sensor.

12. The method of claim 11 further comprising:

measuring said predetermined position before fixing said prosthesis stem to said femur; and

correcting said predetermined position before fixing said prosthesis stem to said femur.

17. The method of claim 10 further comprising:

fastening a third sensor to said femur, said third sensor is configured for use in the determination of the position of the femur;

measuring a preoperative offset and a preoperative length of a said femur subsequent to said hip joint assembly and prior to luxation of said hip joint assembly, wherein said measuring comprises measuring a distance between said second sensor and said third sensor.

18. The method of claim 17 further comprising:

controlling a predetermined preoperative offset determined from said measurement;

controlling a predetermined preoperative femur length determined from said measurement;

adjusting said predetermined preoperative offset during inserting said prosthesis stem into said femur; and

adjusting said predetermined preoperative femur length during inserting said prosthesis stem into said femur.

13. A method for computer assisted insertion of an artificial hip joint comprising:

making the anatomy of a hip available for insertion of parts of a prosthesis, wherein said parts of a prosthesis comprise a prosthesis stem and a cup;

preparing for insertion of said parts of a prosthesis;

inserting temporarily said prosthesis stem into a femur;

inserting temporarily said cup into a pelvis;

inserting a positioning tool between said prosthesis stem and said cup, said positioning tool configured to control an angle between said parts of the prosthesis;

assembling the artificial hip joint;

stretching said hip and a knee associated with said hip;

placing a foot associated with said hip and said knee in a position configured with the toes pointing forward relative to a body associated with said foot;

measuring the position of said parts of the prosthesis with a position determination instrument;

luxating the hip joint;

removing said parts of the prosthesis from said femur and said pelvis;

inserting said prosthesis stem into said femur in a predetermined position, said predetermined position being equal to a position measured by said position determination instrument;

controlling said insertion of said prosthesis stem with said position determination instrument wherein said femur is placed into said predetermined position;

fixing said prosthesis stem to said femur in said predetermined position;

inserting said cup into said pelvis into a predetermined position, said predetermined position being equal to a position measured by said position determination instrument;

controlling said insertion of said cup with said position determination instrument;

fixing said cup into said pelvis in said predetermined position; and

reassembling said hip joint.

14. The method of claim 13 wherein said position determination instrument comprises at least one sensor and a conversion unit configured to calculate the placement and spatial position of an at least one first sensor.

15. The method of claim 14 further comprising:

placing said at least one first sensor on said positioning tool; and

moving said at least one first sensor to an insertion instrument for the insertion of said cup.

16. The method of claim 15 further comprising:

fastening a second sensor to said pelvis after the anatomy is made available;

correcting for any movement of said pelvis during the method for computer assisted insertion of the artificial hip joint with said second sensor.