Determining the Positional Information of Characteristic Points of a Leg for Osteotomy

A navigation system for computer-assisted surgery comprising a computer having a processor configured to execute a computer-implemented method for determining a positional information of characteristic points of a leg, the method comprising executing, on the processor of the computer, steps of:

• a) acquiring, at the processor, by detecting via a hand-held device, a position of a stationary reference and epicondylar contacting devices or detecting a position of a tip of a pointer device to which the hand-held device or a hand-held camera is attached, the tip being placed on one of the femoral epicondyles, at least four different positions of the femur, wherein the pelvis within which the femur can turn is stationary with respect to the position of the stationary reference and the femur is in a different position each time a positional information value of the femur is acquired;
• b) determining, by the processor, from the at least four different acquired positional information values of the femur the position of the center of rotation of the femoral head in relation to the position of a femur reference;
• c) acquiring, at the processor, a femur information by detecting via the hand-held device the position of the femur reference, and the position of the tip of the pointer device to which the hand-held device or hand-held camera is attached in relation to the femur reference, the tip being placed on one of the femoral epicondyles;
• d) determining, by the processor, from the femur information and the position of the tip of the pointer device acquired in step c) the distal end point of the femur axis and the proximal end point of the tibia axis at least in relation to the position of the femur reference;
• and
• e) determining, by the processor, the distal end point of the tibia axis by acquiring via the hand-held device the positional information of an ankle reference being at the distal end point of the tibia axis.

A non-transitory computer-readable program storage medium storing a program which, when executed by a processor of a computer, causes the processor to execute a computer-implemented method for determining the positional information of characteristic points of a leg, the method comprising executing, on the processor of the computer, steps of:

• a) acquiring, at the processor, by detecting via a hand-held device, a position of a stationary reference and epicondylar contacting devices or detecting a position of a tip of a pointer device to which the hand-held device or a hand-held camera is attached, the tip being placed on one of the femoral epicondyles, at least four different positions of the femur, wherein the pelvis within which the femur can turn is stationary with respect to the position of the stationary reference and the femur is in a different position each time a positional information value of the femur is acquired;
• b) determining, by the processor, from the at least four different acquired positional information values of the femur the position of the center of rotation of the femoral head in relation to the position of a femur reference;
• c) acquiring, at the processor, a femur information by detecting via the hand-held device the position of the femur reference, and the position of the tip of the pointer device to which the hand-held device or hand-held camera is attached in relation to the femur reference, the tip being placed on one of the femoral epicondyles;
• d) determining, by the processor, from the femur information and the position of the tip of the pointer device acquired in step c) the distal end point of the femur axis and the proximal end point of the tibia axis at least in relation to the position of the femur reference;
• and
• e) determining, by the processor, the distal end point of the tibia axis by acquiring via a hand-held device the positional information of an ankle reference being at the distal end point of the tibia axis.

A computer-implemented method for determining the positional information of characteristic points of a leg, the method comprising executing, on a processor of a computer, steps of:

• a) acquiring, at the processor, by detecting via a hand-held device, a position of a stationary reference and epicondylar contacting devices or detecting a position of a tip of a pointer device to which the hand-held device or a hand-held camera is attached, the tip being placed on one of the femoral epicondyles, at least four different positions of the femur, wherein the pelvis within which the femur can turn is stationary with respect to the position of the stationary reference and the femur is in a different position each time a positional information value of the femur is acquired;
• b) determining, by the processor, from the at least four different acquired positional information values of the femur the position of the center of rotation of the femoral head in relation to the position of a femur reference;
• c) acquiring, at the processor, a femur information by detecting via the hand-held device the position of the femur reference, and the position of the tip of the pointer device to which the hand-held device or hand-held camera is attached in relation to the femur reference, the tip being placed on one of the femoral epicondyles;
• d) determining, by the processor, from the femur information and the position of the tip of the pointer device acquired in step c) the distal end point of the femur axis and the proximal end point of the tibia axis at least in relation to the position of the femur reference (R1);
• and
• e) determining, by the processor, the distal end point of the tibia axis by acquiring via the hand-held device the positional information of an ankle reference (R2) being at the distal end point of the tibia axis.