Reaming instrument with adjustable profile
A planing instrument, in accordance with one embodiment, includes a rotatable cutting head and a cutting face on a distal end of the cutting head. At least one radially displaceable cutting element has a cutting edge projecting in a distal direction from the cutting face. An adjustment element is operable to displace the cutting element toward a fully retracted state, or toward a fully expanded state. In another embodiment, a method of modifying a bone surface includes displacing at least one cutting element on a planing instrument to a fully retracted state, inserting the instrument into a human or animal, operating an adjustment element to displace the cutting element toward an expanded state, and activating the cutting head to begin planing the bone.
1. A surgical planing instrument with an adjustable profile, the planing instrument comprising:
a rotatable cutting head comprising a proximal end, a distal end and an axis of rotation about which the cutting head is rotatable;
a cutting face positioned on the distal end of the cutting head, the cutting face conforming to a plane extending generally perpendicular to the axis of rotation;
at least one radially displaceable cutting element having a cutting edge, the cutting edge projecting in a distal direction from the cutting face;
a generally cylindrical collar located substantially adjacent to the at least one radially displaceable cutting element, the collar located in the center of the cutting face and defining a centering mechanism; and
an adjustment element operably engaged with the at least one radially displaceable cutting element,
the adjustment element being operable in a first operation to displace the at least one radially displaceable cutting element radially inwardly with respect to the axis of rotation, and toward a fully retracted state in which the cutting head has a minimum cutting head profile, the adjustment element also being operable in a second operation to displace the at least one radially displaceable cutting element radially outwardly with respect to the axis of rotation, and toward a fully expanded state in which the cutting head has a maximum cutting head profile.
2. The planing instrument of claim 1 , wherein the adjustment element comprises a first engagement surface, and the at least one radially displaceable cutting element comprises a second engagement surface.
3. The planing instrument of claim 2 , wherein the first engagement surface is in direct contact with the second engagement surface.
4. The planing instrument of claim 1 , wherein the adjustment element comprises a gear wheel having a first plurality of gear teeth.
5. The planing instrument of claim 4 , wherein the gear wheel defines a central bore having a bore axis.
6. The planing instrument of claim 5 , wherein the central bore is substantially parallel to and substantially coaxial with the axis of rotation of the cutting head.
7. The planing instrument of claim 5 , wherein the central bore defines an inner wall, the inner wall having a hexagonal profile to form a hexagonal socket inside the gear wheel.
8. The planing instrument of claim 5 , wherein the at least one radially displaceable cutting element comprises a second plurality of gear teeth configured to mate with the first plurality of gear teeth on the gear wheel.
9. The planing instrument of claim 8 , wherein the at least one radially displaceable cutting element comprises a rack, and the rack comprises the second plurality of gear teeth.
10. The planing instrument of claim 9 , wherein the at least one radially displaceable cutting element has an L-shaped body defining a first leg and a second leg extending in a direction generally perpendicular to the first leg.
11. The planing instrument of claim 10 , wherein the rack extends along the second leg.
12. The planing instrument of claim 10 , wherein the cutting edge of the at least one radially displaceable cutting element projects from the first leg.
13. The planing instrument of claim 1 , wherein the cutting face comprises a plurality of cutting elements projecting in the distal direction from the cutting face, the at least one radially displaceable cutting element being one of the plurality of cutting elements.
14. The planing instrument of claim 13 , wherein the cutting face comprises one or more surface depressions for collecting bone fragments and material, and conveying the bone fragments and material away from the cutting elements.
15. The planing instrument of claim 13 , wherein the one or more surface depressions comprises one or more U-shaped channels that extend outwardly toward an outer edge of the cutting head.
16. The planing instrument of claim 15 , wherein the one or more U-shaped channels are each positioned adjacent to one of the plurality of cutting elements.
17. The planing instrument of claim 16 , wherein the one or more U-shaped channels each extend substantially parallel to one of the plurality of cutting elements.
18. The planing instrument of claim 1 , wherein at least a portion of the cutting edge of the at least one radially displaceable cutting element projects radially outwardly from a perimeter edge of the cutting face when the at least one radially displaceable cutting element is in the fully expanded state.
19. The planing instrument of claim 1 , wherein the cutting edge of the at least one radially displaceable cutting element extends, in its entirety, inside a perimeter edge of the cutting face when the at least one radially displaceable cutting element is in the fully retracted state.
20. The planing instrument of claim 1 , wherein the at least one radially displaceable cutting element comprises a first radially displaceable cutting element having a first cutting edge, and a second radially displaceable cutting element having a second cutting edge.
21. The planing instrument of claim 20 , wherein the first radially displaceable cutting element is movable in a first radial direction toward the fully expanded state, and the second radially displaceable cutting element is movable in a second radial direction toward the fully expanded state, the second radial direction being opposite the first radial direction.
22. The planing instrument of claim 20 , wherein the at least one radially displaceable cutting element further comprises a third radially displaceable cutting element having a third cutting edge, and a fourth radially displaceable cutting element having a fourth cutting edge.
23. The planing instrument of claim 22 , wherein the third radially displaceable cutting element is movable in a third radial direction toward the fully expanded state, and the fourth radially displaceable cutting element is movable in a fourth radial direction toward the fully expanded state, the fourth radial direction being opposite the third radial direction.
24. The planing instrument of claim 1 , wherein the centering mechanism comprises a bore defined in the collar, the bore sized to fit over a trunnion on a femoral broach.