Assembly Formed By A Bone Anchoring Base Belonging to a Prosthetic Joint and by at Least One Screw Fastening This Base to a Bone

Abstract

An assembly has a bone anchoring base and a screw. The bone anchoring base has at least one protrusion configured to be inserted in a hole arranged in the cancellous portion of a bone. The screw has a thread suitable for engaging with the cancellous portion of the bone. The protrusion is inwardly hollow and comprises an orifice at its distal free end, the screw being configured to be engaged through the protrusion and screwed in the cancellous portion of the bone through the orifice. The orifice is tapped at the pitch of the thread of the screw and the thickness of a distal wall is such that it is possible to arrange more than half of a turn of the threading therein, suitable for receiving the thread of the screw, such that, during the placement of the screw, the thread of this screw engages with said distal wall.

Claims

1. An assembly comprising: a bone anchoring base of a prosthetic joint comprising at least one protrusion configured to be inserted in a hole arranged in the cancellous portion of a bone; and at least one screw configured to fasten the base to the bone, wherein the screw has a thread configured to engage in the cancellous portion of the bone, wherein the protrusion is inwardly hollow and comprises an orifice at its distal free end, wherein the screw is configured to pass through the hollow protrusion, and be screwed in the cancellous portion of the bone through said orifice until a head of the screw comes into contact with a distal wall of the protrusion defined by a free end of the protrusion, wherein said orifice is tapped at the pitch of the thread of the screw and wherein the thickness of said distal wall is such that more than half of a turn of the threading suitable for receiving the thread of the screw is formed therein such that, during the placement of the screw, the thread of the screw engages with said distal wall.

2. The assembly according to claim 1, wherein the thickness of the distal wall is such that at least one complete threading turn suitable for receiving the thread of the screw is formed therein.

3. The assembly according to claim 1, wherein the bone anchoring base comprises a plate.

4. The assembly according to claim 3, wherein the at least one protrusion extends from the plate.

5. The assembly according to claim 3, wherein said bone anchoring base is a prosthetic shoulder glenoid base

6. The assembly according to claim 5, wherein said protrusion is an anchoring stud arranged coaxially to the plate formed by the bone anchoring base.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The foregoing and other aspects of the present invention are best understood from the following detailed description when read in connection with the accompanying drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments that are presently preferred, it being understood, however, that the invention is not limited to the specific instrumentalities disclosed. Included in the drawings are the following Figures:

[0018] FIG. 1 is a perspective view of a prosthetic shoulder glenoid base and a screw intended to be screwed into the cancellous bone inserted through an anchoring protrusion comprised by the glenoid base;

[0019] FIG. 2 is an axial view of the glenoid base on the proximal side;

[0020] FIG. 3 is a view of the glenoid base from the side, in sectional view along the axis of this base, a detail being circled at the distal end of said anchoring protrusion;

[0021] FIG. 4 is an enlarged view of the detail circled in FIG. 3;

[0022] FIG. 5 is a view of the glenoid base similar to FIG. 3, during the placement of the screw; and

[0023] FIG. 6 is a view of the base and the screw similar to FIG. 5 once the screw is completely screwed in.

DETAILED DESCRIPTION

[0024] The figures show a glenoid base 1 of a prosthetic shoulder and a screw 2 intended to be screwed into the cancellous bone of a scapula in order to guarantee perfect anchoring of the base 1 to said scapula.

[0025] The base 1 comprises a plate 5 intended to receive an articular part (not shown) and a protrusion 6 of a piece with this plate, intended to be inserted tightly into a hole previously arranged in the cancellous bone of the scapula.

[0026] The plate 5 forms a proximal receiving housing 7, by force or with clipping, for said articular part, which may in particular be made from high-density polyethylene to guarantee sliding with the conjugated articular head of the part affixed to the end of the humerus.

[0027] In the illustrated example, the plate 5 comprises four holes 8 for receiving bone anchoring screws arranged through it, surrounding the protrusion 6. These holes 8 may be of the type described in French patent application No. FR 1,154,791 (U.S. Pat. No. 2,975,888), which is herein incorporated by reference in its entirety, having radial notches that guarantee a specific orientation of anchoring screws during the placement of these screws.

[0028] Furthermore, the plate 5 is inwardly etched with an inscription making it possible to identify the portion of this plate having to be placed at an angle against the upper position of the scapula, namely UP in the illustrated example.

[0029] The protrusion 6 is secured to the central portion of the plate 5. It is inwardly hollow and emerges at the center of the plate 5. It has outer reliefs allowing a certain axial retention relative to the cancellous bone of the scapula into which it is inserted. Inwardly, as particularly visible in FIG. 3, it has a proximal mechanical threading 9 allowing its connection to the corresponding threaded end of the shaft of a tool (not shown) for grasping, manipulating and impacting the base 1, well known in itself. At its distal end, as particularly visible in FIG. 4, the protrusion 6 has a distal wall 6d with a thickness greater than the peripheral wall 6p of this protrusion, this distal wall 6d being pierced by an orifice 10. This orifice 10 allows the passage of the screw 2, as shown by FIGS. 5 and 6.

[0030] The orifice 10 is tapped at the pitch of the thread of the screw 2, and FIG. 4 shows that the thickness of the wall 6d is such that it is possible to arrange a complete threading turn 11 therein suitable for receiving the thread of the screw 2. Thus, during the placement of the screw 2, the thread of this screw engages by screwing with the wall 6d.

[0031] The screw 2 in turn is of the traditional type, having an outwardly smooth a cylindrical head with a diameter that is slightly smaller than the inner diameter of the protrusion 6.

[0032] As is understood, the tapping of the orifice 10 makes it possible for the screw 2, during placement thereof, to engage by screwing with the part of the wall 6d defining the orifice 10, which makes it possible not only to guide the screw 2 perfectly in a manner coaxial to the protrusion 6, but also to advance the screw 2 in the cancellous bone while this screw is being screwed in and to block the rotation of the screw 2 when the head of the screw encounters said wall 6d at the end of screwing.

[0033] The disclosed embodiments thus provide an assembly with the decisive advantage of resolving the aforementioned drawbacks of the homologous assemblies according to the prior art.

[0034] The disclosed embodiments have been described in reference to a glenoid base 1; it must, however, be understood that it is applicable to other types of bone anchoring bases belonging to a prosthetic joint, in particular to a tibial base of a prosthetic knee.

[0035] The elements of the figures are not exclusive. Other embodiments may be derived in accordance with the principles of the invention to accomplish the same objectives. Although this invention has been described with reference to particular embodiments, it is to be understood that the embodiments and variations shown and described herein are for illustration purposes only. Modifications to the current design may be implemented by those skilled in the art, without departing from the scope of the invention.