Fixation mechanism for an implant
An ankle prosthesis has a tibial component configured for attachment to a tibia of a person, and a talar component. The talar component has a first surface configured for facing the tibial component and a second surface configured for facing a talus of the person. The second surface has first and second arms attached to it, for pivoting or flexing outwardly in medial and lateral directions, respectively, to engage side surfaces of a previously formed slot in the talus.
1. An ankle prosthesis, comprising:
a tibial component configured for attachment to a tibia of a person; and
a talar component having a first surface configured for facing the tibial component and a second surface configured for facing a talus of the person, the second surface having first and second arms attached thereto, for pivoting or flexing outwardly in medial and lateral directions, respectively, to engage side surfaces of a previously formed slot in the talus; and
a separator comprising at least one of a cone and a wedge, the separator being positioned between the first and second arms and attached to a threaded member for moving the separator in an anterior-posterior direction, the separator configured to be advanced towards an end of each of the first and second arms attached to the second surface, for causing the first and second arms to pivot or flex outwardly.
2. The ankle prosthesis of claim 1 , wherein the slot has undercut side surfaces, and the arms have a medial-lateral dimension that increases from a proximal side of each arm adjacent the second surface to a distal side of each arm configured to face the talus.
3. The ankle prosthesis of claim 1 , wherein the slot has undercut side surfaces, and each of the arms have approximately trapezoidal cross sections.
4. The ankle prosthesis of claim 1 , wherein each of the arms is attached to the second surface of the talar component by a pin.
5. The ankle prosthesis of claim 1 , wherein each of the arms is fixedly attached at one end to the second surface of the talar component by a unitary post joining each respective arm to the second surface.
6. The ankle prosthesis of claim 1 , wherein the second surface is included in a plate having first and second guide slots, and each of the arms has a pin extending therefrom, the pin movable within the guide slot during pivoting or flexing of the arms.
7. The ankle prosthesis of claim 1 , wherein the talar component includes:
a proximal portion having the first surface, the first surface being an articulating surface, and
a distal plate portion having the second surface, the distal plate portion joined to the proximal portion,
wherein the tibial component has an articulating surface configured to face the articulating surface of the talar component.
8. The ankle prosthesis of claim 7 , wherein the proximal portion and the distal plate portion are made of different materials from each other.
9. The ankle prosthesis of claim 1 , wherein each of the arms has a plurality of barbs on an outer edge thereof.
10. An ankle prosthesis, comprising:
a first component configured for attachment to a first bone of a person, the first component having an articulating surface; and
a second component having an articulating surface configured for facing the articulating surface of the first component, the second component having a second surface configured for facing a second bone of the person, the second surface having first and second arms attached thereto, for pivoting or flexing outwardly in medial and lateral directions, respectively, to engage side surfaces of a previously formed slot in the second bone; and
a separator positioned between the first and second arms, the separator configured to be advanced towards an end of each of the first and second arms attached to the second surface, for causing the first and second arms to pivot or flex outwardly, and the separator is attached to a threaded member for moving the separator in an anterior-posterior direction,
wherein the slot has undercut side surfaces, and the arms have a medial-lateral dimension that increases from a proximal side of each arm adjacent the second surface to a distal side of each arm opposite the proximal side thereof,
each of the arms has a plurality of teeth on an outer edge of the distal side thereof, and
each of the arms is pivotally attached to the second surface of the second component by a pin.
11. The ankle prosthesis of claim 10 , wherein the pivoting or flexing is in a plane parallel to the second surface.