Femoral medial condyle spherical center tracking

1. A femoral medial condyle spherical center tracking method comprising:

identifying, using an arm of a robotic surgical device, a plurality of tibial-femoral contact points between a femur and a tibia;

digitizing a femoral medial condyle based on the plurality of tibial-femoral contact points;

intraoperatively identifying coordinates of a spherical center of the femoral medial condyle at a processor of the robotic surgical device based on the digitized femoral medial condyle, wherein identifying the coordinates of the spherical center includes:

inserting a pin in a femoral intramedullary canal;

applying a line down a center of a surface of the femoral medial condyle;

securing a spherical center guide to the pin; and

rotating the spherical center guide based on the applied line to identify a spherical center external location and a spherical center depth; and

executing a surgical procedure relative to the spherical center.

2. The method of claim 1 , wherein identifying the spherical center includes:

determining a joint line distance from the femoral medial condyle to a distal and posterior joint line; and

determining a posterior aspect radius of the femoral medial condyle, wherein identifying the coordinates of the spherical center is based on the posterior aspect radius.

3. The method of claim 1 , wherein identifying the coordinates of the spherical center includes immobilizing the femur based on a femur fixation device.

4. The method of claim 3 , wherein determining the spherical center includes:

fitting a virtual sphere to the digitized points; and

locating the center of the virtual sphere.

5. The method of claim 3 , wherein determining the spherical center includes:

locating a mid-line of the femoral medial condyle;

determining a mid-line plane using mechanical axis information; and

fitting a circle to the digitized points on the mid-line plane.

6. The method of claim 1 , wherein identifying the spherical center includes identifying a femoral head location of a femur.

7. The method of claim 1 , wherein identifying the spherical center includes identifying a femoral head location of the femur by registering the femoral head location using a tracking device when the tibia and the femur are in full extension.

8. The method of claim 7 , further comprising:

fixing a femoral reference instrument to a femoral distal end; and

transferring the femoral head location to a femoral head-tracking device.

9. A robotic surgical device for tracking a femoral medial condyle spherical center comprising:

a robotic controller to autonomously manipulate a robotic arm to identify a plurality of tibial-femoral contact points between a femur and a tibia; and

a processor to:

digitize a femoral medial condyle based on the plurality of tibial-femoral contact points;

intraoperatively identify coordinates of a spherical center of the femoral medial condyle at a processor of the robotic surgical device based on the digitized femoral medial condyle; and

control the robotic arm to cause a portion of a surgical procedure to be executed relative to the spherical center;

wherein to identify the coordinates of the spherical center, the processor is further to:

digitize a series of points on the femoral medial condyle;

determine the spherical center of the femoral medial condyle based on the series of points;

transform coordinates of the spherical center of the femoral medial condyle to a coordinate system based on a femoral reference instrument location and orientation fixed on the distal end of the femur; and

track the center of the femoral head.

10. The robotic surgical device of claim 9 , wherein to identify the coordinates of the spherical center, the processor is further to:

fit a virtual sphere to the digitized series of points; and

locate the center of the virtual sphere.

11. The robotic surgical device of claim 9 , wherein to identify the coordinates of the spherical center, the processor is further to:

locate a mid-line of the medial femoral medial condyle;

determine a mid-line plane using mechanical axis information; and

fit a circle to the digitized points on the mid-line plane.

12. The robotic surgical device of claim 9 , wherein to identify the coordinates of the spherical center, the processor is further to:

determine a tibial flexion-extension axis;

determine a plurality of tibial tracking points within a virtual coordinate system throughout a tibial adjustment based on a tracking device fixed to a head of the tibia proximate a femoral head;

digitize a tibial plateau; and

identify the plurality of tibial-femoral contact points between the femur and the tibia based on the tibial plateau and the plurality of tibial tracking points.

13. The robotic surgical device of claim 9 , wherein to identify the coordinates of the spherical center, the processor is further to:

identify a femoral head location of a femur;

register the femoral head location while the tibia and the femur are fixed in full extension; and

transfer the femoral head location to a femoral head tracking device based on a femoral reference instrument fixed to a femoral distal end.

14. A femoral medial condyle spherical center tracking method comprising:

immobilizing a femur based on a femur fixation device;

fixing a tracking device to a head of a tibia proximate a femoral head of the femur;

adjusting the tibia in flexion and extension;

determining a tibial flexion-extension axis;

determining a plurality of tibial tracking points within a virtual coordinate system throughout tibial adjustment;

digitizing a tibial plateau;

identifying a plurality of tibial-femoral contact points between the femur and the tibia based on the tibial plateau and the plurality of tibial tracking points;

digitizing a femoral medial condyle of the femur based on the plurality of tibial-femoral contact points;

intraoperatively identifying coordinates of a spherical center of the femoral medial condyle at a processor of a robotic surgical device based on the digitized femoral medial condyle; and

outputting the coordinates of a spherical center for use in a surgical procedure.

15. The method of claim 14 , wherein intraoperatively identifying coordinates of the spherical center includes identifying the femoral head location of the femur by registering the femoral head location using a tracking device when the tibia and the femur are in full extension.

16. The method of claim 15 , further comprising:

fixing a femoral reference instrument to a femoral distal end; and

transferring the femoral head location to a femoral head-tracking device.

17. A robotic surgical device for tracking a femoral medial condyle spherical center comprising:

a robotic controller to autonomously manipulate a robotic arm to identify a plurality of tibial-femoral contact points between a femur and a tibia; and

a processor to:

digitize a femoral medial condyle based on the plurality of tibial-femoral contact points; and

intraoperatively identify coordinates of a spherical center of the femoral medial condyle at a processor of the robotic surgical device based on the digitized femoral medial condyle;

wherein to identify the coordinates of the spherical center, the robotic arm is controlled by the robotic controller to:

insert a pin in a femoral intramedullary canal;

secure a spherical center guide to the pin; and

rotate the spherical center guide based on a line down a center of a surface of the femoral medial condyle to identify a spherical center external location and a spherical center depth; and

control the robotic arm to cause a portion of a surgical procedure to be executed relative to the spherical center.

18. The robotic surgical device of claim 17 , wherein to identify the coordinates of the spherical center, the processor is further to:

determine a joint line distance from the femoral medial condyle to a distal and posterior joint line; and

determine a posterior aspect radius of the femoral medial condyle, wherein identifying coordinates of the spherical center is based on the posterior aspect radius.