Method and system for planning/guiding alterations to a bone
A computer-assisted surgery system for guiding alterations to a bone, comprises a trackable member secured to the bone. The trackable member has a first inertial sensor unit producing orientation-based data. A positioning block is secured to the bone, and is adjustable once the positioning block is secured to the bone to be used to guide tools in altering the bone. The positioning block has a second inertial sensor unit producing orientation-based data. A processing system providing an orientation reference associating the bone to the trackable member comprises a signal interpreter for determining an orientation of the trackable member and of the positioning block. A parameter calculator calculates alteration parameters related to an actual orientation of the positioning block with respect to the bone.
1. A method for planning/guiding alterations to a bone comprising:
obtaining, using one or more processors of a computer-assisted surgery system, orientation-based data for at least two degrees of freedom in orientation from a positioning block secured to the bone, the positioning block having an inertial sensor unit moving therewith, an orientation of the positioning block being adjustable with respect to the bone by movement;
determining, using the one or more processors of the computer-assisted surgery system, an orientation reference of the bone, from the orientation-based data of the positioning block; and
calculating and outputting, using the one or more processors of the computer-assisted surgery system, bone alteration parameters from the orientation-based data of the positioning block with respect to the orientation reference of the bone.
2. The method according to claim 1 , wherein determining an orientation reference of the bone comprises digitizing a coordinate system aligned with a mechanical axis of the bone.
3. The method according to claim 2 , wherein the bone is a tibia and digitizing a plane incorporating the mechanical axis comprises tracking an orientation of a tool on the tibia with respect to an orientation of the positioning block.
4. The method according to claim 2 , wherein the bone is a femur and digitizing the mechanical axis comprises tracking an orientation of a tool secured to an entry point of the mechanical axis with respect to at least an orientation of the positioning block.
5. The method according to claim 1 , wherein calculating and outputting bone alteration parameters comprises calculating and outputting at least one of a varus-valgus and flexion-extension and rotation of planes of the bone.
6. The method according to claim 1 , wherein the positioning block is aligned with an anterior-posterior axis of the bone, and wherein calculating bone alteration parameters comprises calculating and outputting at least one of a varus-valgus and flexion-extension and rotation of planes of the bone.
7. The method according to claim 1 , further comprising calculating and outputting an orientation of cut planes with an orientation of the positioning block and an instrument having an inertial sensor unit, laid on cut surfaces of the bone as a function of the orientation reference.
8. The method according to claim 1 , further comprising adjusting an orientation of the positioning block as a function of a tracking of the positioning block and of the orientation reference.
9. The method according to claim 8 , wherein adjusting an orientation comprises adjusting at least one of a varus-valgus orientation and a flexion-extension orientation and rotation of the positioning block with respect to the bone.
10. The method according to claim 1 , further comprising calculating and outputting an orientation of cut planes with an orientation of the positioning block as a function of the orientation reference.
11. The method according to claim 1 , wherein calculating and outputting the bone alteration parameters includes displaying data associated with the bone alteration parameters, using the one or more processors of the computer-assisted surgery system, at the inertial sensor unit.