Devices and methods for knee arthroplasty
The present invention provides, in certain embodiments, a device for positioning and orienting the femoral cutting block. The present invention also provides a device for setting rotation of sagittal resection for unicompartmental knee arthroplasty. The present invention further provides methods for setting the rotation of the tibial implant by kinematic measurements.
1. A method for setting tibial implant rotation, comprising: coupling at least one inertial sensor with at least one of a tibia and a femur of a leg of a patient; positioning an implant on a resected surface of the tibia of the patient; moving the leg to position the tibia in a plurality of positions differing in flexion, axial rotation, and/or varus-valgus relative to the femur; comparing values based on output of the at least one inertial sensor indicative of tibio-femoral kinematics with tibio-femoral kinematic target values for one or more of flexion, axial rotation, and/or varus-valgus; and quantitatively comparing the varus and valgus laxity.
2. The method of claim 1 , wherein comparing values further comprises comparing values based on output of the at least one inertial sensor with target values for a healthy knee.
3. The method of claim 1 , wherein comparing values further comprises comparing values based on output of the at least one inertial sensor with one or more patient-specific values.
4. The method of claim 3 , further comprising recording patient-specific values of tibio-femoral kinematics of the knee prior to resecting the tibia.
5. The method of claim 3 , further comprising recording patient-specific values of tibio-femoral kinematics of a contralateral knee prior to resecting the tibia.
6. The method of claim 1 , further comprising adjusting the rotation of the knee and repeating the moving step and the comparing step.
7. The method of claim 1 , further comprising balancing the varus and valgus laxity by soft tissue releases.
8. The method of claim 1 , wherein coupling the at least one inertial sensor comprises coupling a first device with the femur and a second device with the tibia.
9. The method of claim 1 , wherein quantitatively comparing the varus and valgus laxity comprises applying alternating varus and valgus torque in order to gauge the tibio-femoral rotation allowed in each direction.
10. A method for setting tibial implant rotation, comprising: coupling at least one inertial sensor with at least one of a tibia and a femur of a leg of a patient; positioning an implant between the tibia and the femur; moving the leg to gather a measurement from the at least one inertial sensor; comparing information based on the measurement with a target value of tibio-femoral kinematics; and quantitatively comparing the varus and valgus laxity.
11. The method of claim 10 , wherein comparing information further comprises comparing information based on output of the at least one inertial sensor with target values for a healthy knee.
12. The method of claim 10 , wherein comparing information further comprises comparing information based on output of the at least one inertial sensor with one or more patient-specific values.
13. The method of claim 10 , further comprising balancing the varus and valgus laxity by soft tissue releases.
14. The method of claim 10 , wherein coupling the at least one inertial sensor comprises coupling a first device with the femur and a second device with the tibia.
15. The method of claim 10 , wherein quantitatively comparing the varus and valgus laxity comprises applying alternating varus and valgus torque in order to gauge the tibio-femoral rotation allowed in each direction.
16. The method of claim 10 , further comprising performing calculations to convert the measurements from the at least one inertial sensor to tibio-femoral kinematic information, wherein comparing information based on the measurement comprises comparing the tibio-femoral kinematic information to the target values of tibio-femoral kinematics.
17. A method for setting tibial implant rotation, comprising: coupling at least one inertial sensor with at least one of a tibia and a femur of a leg of a patient; moving the leg to gather one or more measurements from the at least one inertial sensor in one or more positions differing in flexion, axial rotation, and/or varus-valgus relative to the femur; comparing a value based on the one or more measurements indicative of tibio-femoral kinematics with a tibio-femoral kinematic target value for one or more of flexion, axial rotation, and/or varus-valgus; and quantitatively comparing the varus and valgus laxity.
18. The method of claim 17 , further comprising positioning an implant between the tibia and the femur.
19. The method of claim 17 , wherein quantitatively comparing the varus and valgus laxity comprises applying alternating varus and valgus torque in order to gauge the tibio-femoral rotation allowed in each direction.