Modular prosthesis for at least partial replacement of a tubular bone adjoining a joint
Modular endoprosthesis for at least partial replacement of a tubular bone, including, as module components, a stem for insertion into a bone cavity of the tubular bone, and an end piece including a support body with a neck part arranged on the medial aspect thereof. The module components being able to be coupled to each other and released from each other along a longitudinal axis of the shaft. The end piece has at least two different surface configurations on its support body, namely a closed surface ( 6 ′) on a medial aspect, and a porous configuration of the surface on the opposite, lateral aspect. The latter permits and positions the adhesion of muscle tissue, specifically without suturing. The muscle trauma caused by suturing, and the peak loads that occur at the respective suture points, can thus be avoided by virtue of the invention.
1 . A modular endoprosthesis for at least partial replacement of a long bone, comprising as module components:
a stem for insertion into a bone cavity of the long bone,
an end piece comprising a supporting body with an anterior side, a posterior side, a medial side and a lateral side, and a neck part arranged on the medial side having a receptacle for a prosthetic joint component, wherein a lower region of the end piece extends completely around a circumference of the end piece, wherein the lower region is tapered, and
at least one cylindrical intermediate piece, wherein the stem is sized and configured to couple and detach from the at least one intermediate piece at one end thereof, and wherein the end piece is sized and configured to connect and detach from the at least one intermediate piece at an opposite end thereof,
characterized in that
the end piece has at least two differently designed surface formations on its supporting body: a closed, non-porous surface on the medial side, and a porous formation on the lateral side, wherein the porous formation ends in a region of a transition to the taper,
wherein the medial side of the end piece and the tapered lower region of the end piece are devoid of the porous formation,
wherein the porous formation is designed as an open-cell porous lattice structure that extends from the lateral side to the anterior side and to the posterior side.
2 . The modular endoprosthesis of claim 1 , wherein the open-cell lattice structure comprises unit cells, wherein the unit cells are an assembled structure and each consist of an interior space and a plurality of interconnected bars surrounding the interior space.
3 . The modular endoprosthesis of claim 1 , wherein the porous formation of the surface is designed as a unit with the supporting body.
4 . The modular endoprosthesis of claim 1 , wherein the porous formation is provided with a coating which promotes growth.
5 . The modular endoprosthesis of claim 4 , wherein the coating comprises calcium phosphate.
6 . The modular endoprosthesis of claim 4 , wherein the coating comprises tantalum.
7 . The modular endoprosthesis of claim 1 , wherein the porous formation comprises a circumferential angle of about 120° to about 210° relative to a central axis of the end piece.
8 . The modular endoprosthesis of claim 1 , wherein a transition between the lateral side and one or both of the anterior side and the posterior side comprises a rounding with a lateral flattening.
9 . The modular endoprosthesis of claim 8 , wherein the rounding has a radius of curvature (r) which is at most a quarter of a distance (d) from the anterior side to the posterior side of the supporting body.
10 . The modular endoprosthesis of claim 8 , wherein the lateral flattening has a minimum radius of curvature (R) of twice a distance (d) from the anterior side to the posterior side of the supporting body.
11 . The modular endoprosthesis of claim 8 , wherein lateral flattening is configured as a contact and growth surface.
12 . The modular endoprosthesis of claim 1 , wherein the porous formation further extends to an upper side of the supporting body, in the lateral side.
13 . The modular endoprosthesis of claim 1 , further comprising a one or more passage holes in the lateral side, wherein the passage holes extend from the anterior side to the posterior side of the supporting body.
14 . The modular endoprosthesis of claim 13 , wherein the one or more passage holes open into a region having the porous formation, and each of their openings is provided with a non-porous border.
15 . The modular endoprosthesis of claim 14 , wherein the porous formation has pores with a width in the range between 0.4 and 2 mm.
16 . The modular endoprosthesis of claim 13 , wherein the one or more passage holes extend transversely to a central axis of the end piece.
17 . The modular endoprosthesis of claim 1 , wherein the module components can be connected by means of matching connections.
18 . The modular endoprosthesis of claim 1 , wherein the lower region of the end piece comprises a lower third of the end piece.