US-20260124038-A1 - MODULAR PROSTHESIS FOR AT LEAST PARTIAL REPLACEMENT OF A TUBULAR BONE ADJOINING A JOINT

US20260124038A1US 20260124038 A1US20260124038 A1US 20260124038A1US-20260124038-A1

Abstract

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.

Inventors

Helmut D. Link
Sebastian Spath

Assignees

WALDEMAR LINK GMBH & CO.

Dates

Publication Date: 20260507
Application Date: 20251222
Priority Date: 20190918

Claims (20)

1 . A modular endoprosthesis for at least partial replacement of a long bone, comprising as module components: 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, and at plurality of intermediate pieces, wherein the end piece is sized and configured to couple and detach from a proximal intermediate piece of the plurality of intermediate pieces, and wherein a second intermediate piece of the plurality of intermediate pieces is sized and configured to connect and detach from the proximal 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 wherein the porous formation ends in a region of a transition to the taper.
2 . The modular endoprosthesis of claim 1 , wherein the at least two differently designed surface formations comprise a closed, non-porous surface on the medial side, and a porous formation on the lateral side, wherein the porous formation of the surface is designed as an open-cell porous lattice structure.
3 . The modular endoprosthesis of claim 2 , 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.
4 . The modular endoprosthesis of claim 2 , wherein the porous formation of the surface is designed as a unit with the supporting body.
5 . The modular endoprosthesis of claim 1 , wherein the modular endoprosthesis further comprises a stem, wherein the stem comprises a coupling portion that is configured to connect the stem to the end piece.
6 . The modular endoprosthesis of claim 1 , wherein the porous formation extends from the lateral side to the anterior side and to the posterior side and comprises a circumferential angle of about 120° to about 210° relative to a central axis of the end piece.
7 . 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.
8 . The modular endoprosthesis of claim 7 , 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.
9 . The modular endoprosthesis of claim 7 , 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.
10 . The modular endoprosthesis of claim 1 , wherein the porous formation extends to an upper side of the supporting body, in the lateral side.
11 . The modular endoprosthesis of claim 1 , wherein the lower region of the end piece does not have the porous formation.
12 . 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.
13 . The modular endoprosthesis of claim 12 , wherein the one or more passage holes open into the region having the porous formation, and each of their openings is provided with a non-porous border.
14 . The modular endoprosthesis of claim 13 , wherein the porous formation has pores with a width in the range between 0.4 and 2 mm.
15 . The modular endoprosthesis of claim 1 , wherein modular components can be connected by means of matching connections, and has an exchangeable end piece (3*) (6*).
16 . The modular endoprosthesis of claim 11 , wherein the lower region of the end piece comprises a lower third of the end piece.
17 . The modular endoprosthesis of claim 12 , wherein the one or more passage holes extend transversely to a central axis of the end piece.
18 . The modular endoprosthesis of claim 5 , wherein the coating comprises calcium phosphate.
19 . The modular endoprosthesis of claim 5 , wherein the coating comprises tantalum.
20 . The modular endoprosthesis of claim 1 , wherein the porous formation extends from the lateral side to the anterior side and to the posterior side.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a Continuation of prior-filed U.S. Ser. No. 17/753,877 , filed Mar. 16, 2022, which is a national stage of International Patent Application Serial No. PCT/EP2020/075845, filed Sep. 16, 2020, which claims priority to European Patent Application No. 19198089.5, filed Sep. 18, 2019, the disclosures of both are incorporated herein by reference in their entirety. FIELD The invention relates to 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, and an end piece comprising a supporting body and a neck part, the latter having a receptacle for a joint device and being arranged on the medial side. BACKGROUND Various types of endoprostheses are known for replacing diseased or defective bones and joints. In particular, these include pure joint endoprostheses, and also others that partially or completely replace the adjacent long bones. They have a stem that extends over the length of the long bone to be replaced. The stem replaces or reinforces the diseased or missing area of bone. It is often connected to a joint unit that replaces an adjacent joint (for example, a knee or hip). The dimensions of the prosthesis socket must therefore be chosen according to the given anatomy and pathology of the patient. Modular endoprosthesis systems for the purpose of adapting to individual needs are known. They include a stem, optionally several intermediate pieces, and an end piece, which usually also forms a joint component. Such a system is known, for example, from DE 20 2004 019 264 U1. Also known from prior use is a modular system from DePuy, Inc. (USA) called the Orthopedic Salvage System, in which the end piece has a porous coating all around it. It has been shown that satisfactory growth behavior can be achieved with the system on portions of bone that are still present. With regard to the connection to soft tissues, such as muscles in particular, there is a need for improvement. Experiments with a coating containing tantalum have shown that it can only stimulate the adhesion of connective tissue, but not the muscle attachment that is actually desired. The invention is based on the object of creating a modular endoprosthesis of the type mentioned at the outset which exhibits better behavior with regard to muscle adhesion. The solution according to the invention lies in the features of the independent claim. Advantageous refinements are the subject matter of the dependent claims. In a modular endoprosthesis for the at least partial replacement of a long bone, comprising as module components a stem for insertion into a bone cavity of the long bone, and an end piece comprising a supporting body with an anterior, posterior, lateral and medial side and comprising a neck part which is arranged on the medial side and which has a receptacle for a joint device, and at least one intermediate piece, wherein the module components can be coupled to and detached from each other along a longitudinal axis of the stem, for example via plug-in connections or other types of connection, according to the invention, the end piece has at least two differently designed surface formations on its supporting body—a closed surface on a medial side facing the neck part, and a porous formation of the surface on the lateral side facing away from the neck part. The terms lateral, medial, anterior and posterior are common anatomical terms for directions. In this case, “lateral” means towards the outside, “medial” means towards the center (of the body), anterior means towards the front, and posterior means towards the back. The invention is based on the idea of making the surface porous, which is favorable for the adhesion of muscle tissue, in a targeted manner at a specific point—and specifically only at that point and not all around. This particular location is the lateral side, that is, the side that faces laterally outward when implanted. On the one hand, the porous formation creates a basis for the reliable adhesion of soft tissue, including muscle tissue, and on the other hand, the precise positioning of the porous formation and its concentration at the specific point (and only there, i.e., not all around) achieves a favorable adhesion behavior of the muscle in a targeted and specific manner. The muscle should attach at this specific point resulting in a favorable power transmission to the prosthesis (and thus to the corresponding extremity). In the case of an endoprosthesis for the proximal femur, the muscle that is offered a location-specific adhesion point according to the invention is the so-called “gluteus medius.” The invention has recognized that with such a design, a location-specific growth of the muscle can be achieved in such a way that the muscle is directly attached. The suturing that is conventionally required to connect the muscle to the end piece of the endoprosthesis