Radial head implant apparatuses and methods
Radial head implant apparatuses and methods are provided in accordance with the subject matter disclosed herein wherein a shaft and a head portion can be axially movable within a stem portion. In one embodiment, a radial head implant can include a head portion for articular engagement with a humerus bone, a stem portion for engagement with a radius bone, and a shaft for engagement with the stem portion. The head portion can include an upper surface for engaging the humerus bone. The stem portion can have an axial opening for receiving at least a portion of the shaft, and a collar can be disposed around the stem portion at a proximal end thereof. An upper portion of the shaft can be configured for engaging the head portion, while a lower portion of the shaft can be elongated and cylindrical for axially fitting into and moving within the axial opening of the stem portion. Other embodiments are also disclosed for axial movement for a radial head implant. Various structures are disclosed for locking the shaft in position within the stem portion.
1. An implant for engaging a radius bone and a humerus bone, the implant comprising:
(a) a head portion comprising an upper surface for articular engagement with a capitulum of a humerus bone and a lower surface;
(b) a stem portion for engagement with a radius bone and defining an axial opening;
(c) a shaft having an upper shaft portion for engagement within an area of engagement in the lower surface of the head portion, the shaft having a lower, elongated shaft portion for slidable engagement with the stem portion by the elongated shaft portion fitting into the axial opening of the stem portion whereby the elongated shaft portion is axially movable within the axial opening of the stem portion;
(d) a collar at a proximal end of the stem portion defining an opening with an axis at least generally perpendicular to an axis of the axial opening of the stem portion, the opening of the collar being configured to receive a screw for preventing the shaft from sliding within the axial opening of the stem portion; and
(e) wherein the head portion comprises an outer shell and an inner insert, and wherein the area of the head portion for engagement with the upper shaft portion is a recessed area within the inner insert.
2. The implant of claim 1 wherein the insert is removably positioned within the outer shell.
3. An implant for engaging a radius bone and a humerus bone, the implant comprising:
(a) a head portion comprising an upper surface for articular engagement with a capitulum of a humerus bone and a lower surface;
(b) a stem portion for engagement with a radius bone and defining an axial opening;
(c) a shaft having an upper shaft portion for engagement with the lower surface of the head portion, the shaft having a lower, elongated shaft portion for slidable engagement with the stem portion by the elongated shaft portion fitting into the axial opening of the stem portion whereby the elongated shaft portion is axially movable within the axial opening of the stem portion; and
(d) a collar at a proximal end of the stem portion defines an opening with an axis at least generally perpendicular to an axis of the axial opening of the stem portion, the opening of the collar comprises an at least partially threaded, distal wall portion and a smooth, tapered, proximate wall portion connecting with an outer surface of the collar.
4. A radial head implant for engaging a radius bone and a humerus bone, the radial head implant comprising:
(a) a head portion comprising an outer shell and an inner insert fitted into the outer shell, the outer shell having an upper surface for articular engagement with a capitulum of a humerus bone, and the inner insert having a recessed area on a lower surface of the inner insert;
(b) a stem portion for engagement with a radius bone, the stem portion comprising a collar at a proximal end of the stem portion and comprising an elongated portion below the collar, the stem portion defining an axial opening though a central axis of the stem portion;
(c) a shaft having an upper shaft portion with an upper end for fitting at least partially into the recessed area of the inner insert, and the shaft having a lower, elongated shaft portion for slidable engagement within the axial opening of the stem portion by the elongated shaft portion fitting into the axial opening of the stem portion whereby the elongated shaft portion is axially movable within the axial opening; and
(d) the collar at the proximal end of the stem portion defining an opening with an axis at least generally perpendicular to the central axis of the axial opening of the stem portion, the opening of the collar being configured to receive a screw that prevents the shaft from sliding within the axial opening of the stem portion.
5. The implant of claim 4 wherein the head portion and the shaft are integral.