Method and device for determining the position of a knee-joint endoprosthesis
First Claim
1. Method for determining the position of the tibial part and/or the femoral part of a knee-joint endoprosthesis in relation to the proximal tibial head or to the distal femur in which the position of the femur and of the tibia are monitored by means of a navigation system, in which the distal femur and the proximal tibial head are laterally and medially displaced with a defined force into a spread position by means of a distraction appliance when the knee is straightened and bent, and the relative positions of the femur and the tibia, and consequently the size of the gap between the femur and the tibia, are thereby respectively determined, in which various virtual relative positions of the femur and the tibia are calculated according to geometrical data of the knee-joint endoprosthesis and to different assumed positions of the tibial part on the tibia and/or of the femoral part on the femur when the knee is straightened and bent, and in which an assumed position in which the virtual relative position of the femur and the tibia when the knee is straightened and bent differs from the spread position in a specified manner is determined as a selected position.
1 Assignment
0 Petitions
Accused Products
Abstract
To be able to determine the insertion position of the parts of an artificial knee joint without changing the original knee joint, a method is proposed for determining the position of the tibial part and/or the femoral part of a knee-joint endoprosthesis in relation to the proximal tibial head or to the distal femur in which the position of the femur and of the tibia are monitored by means of a navigation system, in which the distal femur and the proximal tibial head are laterally and medially displaced with a defined force into a spread position by means of a distraction appliance when the knee is straightened and bent, and the relative positions of the femur and the tibia, and consequently the size of the gap between the femur and the tibia, are thereby respectively determined, in which various virtual relative positions of the femur and the tibia are calculated according to geometrical data of the knee-joint endoprosthesis and to different assumed positions of the tibial part on the tibia and/or of the femoral part on the femur when the knee is straightened and bent, and in which an assumed position in which the virtual relative position of the femur and the tibia when the knee is straightened and bent differs from the spread position in a specified manner is determined as a selected position.
-
Citations
27 Claims
- 1. Method for determining the position of the tibial part and/or the femoral part of a knee-joint endoprosthesis in relation to the proximal tibial head or to the distal femur in which the position of the femur and of the tibia are monitored by means of a navigation system, in which the distal femur and the proximal tibial head are laterally and medially displaced with a defined force into a spread position by means of a distraction appliance when the knee is straightened and bent, and the relative positions of the femur and the tibia, and consequently the size of the gap between the femur and the tibia, are thereby respectively determined, in which various virtual relative positions of the femur and the tibia are calculated according to geometrical data of the knee-joint endoprosthesis and to different assumed positions of the tibial part on the tibia and/or of the femoral part on the femur when the knee is straightened and bent, and in which an assumed position in which the virtual relative position of the femur and the tibia when the knee is straightened and bent differs from the spread position in a specified manner is determined as a selected position.
- 20. System for determining the position of the tibial part and/or the femoral part of a knee-joint endoprosthesis in relation to the proximal tibial head or to the distal femur with a navigation system for monitoring the position of the femur and the tibia by means of marking elements which can be fixed on the femur and tibia, with a distraction appliance, which displaces the distal femur and the proximal tibial head laterally and medially with a defined force into a spread position when the knee is straightened and bent, with a data processing system, which determines the relative position of the femur and the tibia during the distraction, and consequently the size of the gap between the femur and the tibia, and calculates various virtual relative positions of the femur and the tibia according to geometrical data of the knee-joint endoprosthesis and different assumed positions of the tibial part on the tibia and/or of the femoral part on the femur when the knee is straightened and bent.
Specification