Quantitative assessment of implant bone preparation
A system and method for quantitatively assessing, during bone preparation, an estimation of future a press fit value (and provide a mechanism to evaluate optimal quantitative values) of any implant/bone interface regardless the variables involved including bone site preparation, material properties of bone and implant, implant geometry and coefficient of friction of the implant-bone interface without requiring a visual positional assessment of a depth of insertion. The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements.
1. An apparatus for preparing a portion of bone for an insertion of a prosthesis, comprising:
a bone preparation device providing a bone preparation force to the portion of bone using a bone preparation implement engaging the portion of bone, said preparation force operating over a period, said period including an initial preparation act with said preparation device and a subsequent preparation act with said preparation device; and
a system physically coupled to said preparation device configured to provide a real-time parametric estimation, during said period, of a pressfit fixation of the prosthesis to be installed into the portion of bone, said parametric evaluation including an evaluation of a set of factors of the implement with respect to the portion of bone, said set of factors including one or more of a rigidity factor, an elasticity factor, and a combination of said rigidity factor and said elasticity factor.
2. The apparatus of claim 1 wherein said rigidity factor includes a quantitative assessment of a relative motion of the implement with respect to the portion of bone.
3. The apparatus of claim 2 wherein said elasticity factor includes a quantitative assessment of a time-derivative of said relative motion.
4. The apparatus of claim 2 wherein said preparation force includes a first application of a first preparation force (F 1 ) to the implement and a first determination of a first assessed force response of the implement with respect to the portion of bone.
5. The apparatus of claim 4 and wherein said quantitative assessment includes a first comparison of said first preparation force to said first assessed force response.
6. The apparatus of claim 4 wherein said preparation force includes a second application of said first preparation force to the implement subsequent to said first application of said first preparation force and a second determination of a second assessed force response of the implement with respect to the portion of bone and wherein said quantitative assessment includes a first comparison of said first assessed force response to said second assessed force response.
7. The apparatus of claim 6 wherein said assessed force responses include one or more of a tool-response force (F 2 ), an interface-response force (F 3 ), a bone-response force (F 5 ), and combinations thereof.
8. The apparatus of claim 4 wherein said first assessed force response includes one or more of a tool-response force (F 2 ), an interface-response force (F 3 ), a bone-response force (F 5 ), and combinations thereof.
9. The apparatus of claim 8 wherein said elasticity factor includes a predetermined relationship between particular ones of said forces.
10. The apparatus of claim 9 wherein said predetermined relationship includes one or more comparisons selected from the group consisting of how fast F 2 approaches F 1 , how fast delta F 2 approaches 0, how fast F 5 approaches F 1 , how fast delta F 5 approaches 0, how fast F 3 approaches F 1 , how fast delta F 3 approaches 0 when distal collision becomes elastic (F 1 about equal to F 2 about equal to F 3 about equal to F 5 ), and combinations thereof.
11. The apparatus of claim 10 wherein said rigidity factor includes a predetermined relationship between particular ones of said forces.
12. The apparatus of claim 11 wherein said predetermined relationship includes one or more comparisons selected from the group consisting of when F 2 approaches F 1 , when delta F 2 approaches 0, when F 5 approaches F 1 , when delta F 5 approaches 0, when F 3 approaches F 1 , when delta F 3 approaches 0 when distal collision becomes elastic (F 1 about equal to F 2 about equal to F 3 about equal to F 5 , and combinations thereof).
13. The apparatus of claim 8 wherein said rigidity factor includes a predetermined relationship between particular ones of said forces.
14. The apparatus of claim 13 wherein said predetermined relationship includes one or more comparisons selected from the group consisting of when F 2 approaches F 1 , when delta F 2 approaches 0, when F 5 approaches F 1 , when delta F 5 approaches 0, when F 3 approaches F 1 , when delta F 3 approaches 0 when distal collision becomes elastic (F 1 about equal to F 2 about equal to F 3 about equal to F 5 , and combinations thereof).
15. The apparatus of claim 8 further comprising, for each combination of forces, a set of corresponding sensors including one or more of an F 1 sensor, an F 2 sensor, an optional F 3 sensor, and an optional F 5 sensor, said set of corresponding sensors configured for said real-time production of said corresponding force(s) during said period.
16. The apparatus of claim 1 wherein said elasticity factor includes a quantitative assessment of a time-derivative of a relative motion of the implement with respect to the portion of bone.
17. The apparatus of claim 1 wherein said bone preparation implement includes a broach.
18. The apparatus of claim 1 wherein said bone preparation implement includes a reamer.
19. An apparatus for preparing a portion of bone using a bone preparation implement for installing a prosthesis into the portion of a bone, comprising:
a force applicator operating a bone preparation force configured for a preparation of the portion of bone;
a force transfer structure, coupled to said force applicator and to the implement, for conveying an application force F 1 to the implement, said application force F 1 derived from said preparation force;
a force sensing system determining a force response of the implement at an interface of the implement and the portion of bone, said force response responsive to said application force F 1 and a force response component F 2 ; and
a controller, coupled to force applicator and to said force sensing system, said controller setting an operational parameter for said preparation force, said operational parameter establishing said application force F 1 , said controller responsive to said force response to establish a set of parameters including one or more of a rigidity metric, an elasticity metric, and combinations thereof;
further including an F 1 sensor and an F 2 sensor, both sensors disposed between said force applicator and the implement;
wherein said application force F 1 is measured in real-time by said F 1 sensor;
wherein said force response component is measured in real-time by said F 2 sensor.
20. The apparatus of claim 19 wherein the implement includes a broach.
21. The apparatus of claim 19 wherein the implement includes a reamer.
22. An apparatus for preparing a portion of bone using a bone preparation implement for installing a prosthesis into the portion of a bone, comprising:
means for applying a bone preparation force to the implement, said preparation force operating over a period, said period including an initial preparation act with a bone preparation device and a subsequent preparation act with said bone preparation device; and
means, physically coupled to said bone preparation device, for estimating a pressfit fixation of the prosthesis once installed into the portion of bone after preparation during said period, said estimation including an evaluation of a set of factors of the implement with respect to the portion of bone, said set of factors including one or more of a rigidity factor, an elasticity factor, and a combination of said rigidity factor and said elasticity factor.
23. The apparatus of claim 22 wherein said set of factors includes both said elasticity factor and said rigidity factor, further comprising:
means, responsive to said factors, for modifying periodically said preparation force to automatically prepare the portion of bone to provide a cavity for the prosthesis that when the prosthesis is installed within said cavity it may be installed at a best fixation short of fracture.
24. The apparatus of claim 22 wherein the implement includes a broach.
25. The apparatus of claim 22 wherein the implement includes a reamer.