humeral anchoring element of shoulder prosthesis

Abstract

The invention relates to a humeral anchoring element (2) of a humeral joint component (4, 4') of a shoulder prosthesis, the humeral anchoring element (2) being characterized in that it comprises: - a main body (8) for insertion into a humerus (16) from a resected metaphyseal surface (10), and - a proximal flange (12) forming a proximal end of the humeral anchoring element (2) and positioned at one end of the main body (8), a proximal face (14) of the proximal flange (12) extending into the humerus (16) and below the resected metaphyseal surface (10). Figure for the abstract: Figure 1

Description

Title of the invention: humeral anchoring element for shoulder prosthesis

[0001] The present invention relates to a humeral anchoring element allowing the anchoring to a humerus of a humeral articular part of a shoulder prosthesis.

[0002] It is well known to anchor a humeral articular component by means of a tapered medullary stem incorporated within the component. The medullary stem has a flared proximal portion, designed to be positioned at the level of the bone metaphysis, and a tapered distal portion designed to be inserted into the medullary canal as far as the diaphysis. However, such an articular component with a medullary stem can be difficult to implant when the bone is not of good quality, particularly in cases of osteoporosis in an elderly patient. The same applies when revising a previously implanted prosthesis, as this prior implantation may have already resulted in more or less significant bone resorption. In either case, the fixation of the articular component to the bone may not be perfect and may not fully withstand the repeated stresses experienced by the prosthesis over time.

[0003] In another scenario, for a patient with healthy bone (for example, a younger patient) but a joint worn down by repeated stress (for example, from work or sports) and / or for whom surgery on the rotator cuff muscles is not or is no longer possible, improvements in the long-term stability of prostheses allow for prosthesis implantation using an anchoring element without a spinal cord stem. This is because it is possible to stabilize the prosthesis without having to locate a low anchoring point in the diaphysis of the humerus, as the epiphysis and metaphysis are in good condition. The anchoring element then extends into the metaphysis of the bone, after resection of the humeral head.

[0004] In both scenarios, the stacking of the elements forming the humeral articular component can lead to a displacement of the center of rotation of the joint from the humerus towards the glenoid fossa. This is not optimal because, without a prosthesis, the center of rotation of the anatomical joint is located at the humerus and not the glenoid fossa. Implanting a prosthesis can therefore lead to a displacement of the center of rotation of the joint, creating a situation that does not reproduce the anatomical joint position.

[0005] The present invention aims in particular to remedy this drawback by providing a humeral anchoring element that allows for maintaining a position of the center of rotation of the joint as close as possible to an anatomical reality of the joint.

[0006] To this end, the invention relates to a humeral anchoring element for a humeral joint component of a shoulder prosthesis, the humeral anchoring element comprising: - a main body intended to be inserted into a humerus from a resected metaphyseal surface, and - a proximal collar forming a proximal end of the humeral anchoring element and placed at one end of the main body, a proximal face of the proximal collar extending into the humerus and below the resected metaphyseal surface.

[0007] Thus, the anchoring element is placed entirely within the humerus and below the resected metaphyseal surface. This allows the entire humeral articular component to be moved towards the humerus, whether the prosthesis is an anatomical prosthesis (an anchoring element designed to receive a replacement humeral head) or a reverse shoulder prosthesis (an anchoring element designed to receive a cup). This displacement of the joint towards the humerus allows, when this is not the case for a prosthesis according to the prior art, a displacement of the center of rotation of the joint towards the humerus so as to reproduce an anatomical situation in which the center of rotation of the joint is located at the level of the humerus and not at the level of the glenoid.

[0008] Depending on other optional features of the humeral anchoring element taken alone or in combination: - The proximal collar is designed to extend substantially parallel to a plane in which the resected metaphyseal surface extends, - the proximal face of the proximal collar is intended to extend into the humerus at a distance of between 1 and 10 millimeters below the resected metaphyseal surface, preferably between 1 and 5 millimeters below the resected metaphyseal surface, - the main body is intended to extend only into a metaphyseal portion of the humerus, the main body comprising a peripheral retention system formed by several peripheral anchoring plates separated from each other and intended to extend from the proximal collar towards a distal portion of the humerus, two adjacent peripheral anchoring plates extending in planes that are not parallel to each other, - the peripheral anchoring plates extend in a direction substantially perpendicular to a plane in which the proximal face of the proximal collar extends, - the peripheral anchor plates are of irregular width along their direction of extension, - the main body includes at least one stabilizing pad intended to extend from the proximal collar to a distal part of the humerus, - the stabilizing pad extends in a direction substantially perpendicular to a plane in which the proximal face of the proximal collar extends, - the stabilizing block includes retention grooves extending substantially parallel to a longitudinal axis of the stabilizing block, - The stabilizing block is a hollow body open at its distal end and includes a plurality of through-holes formed in its wall, - the stabilizing block is a hollow, tubular-shaped body open at its proximal end and includes a threaded hole formed on an internal surface of the stabilizing block, and - the stabilizing block includes at least one lateral ring extending from an external face of the stabilizing block in a direction substantially perpendicular to a longitudinal axis of the stabilizing block.

[0009] The invention also relates to a humeral joint part of a shoulder prosthesis comprising a humeral anchoring element according to the invention.

[0010] The humeral articular piece may include a replacement humeral head, and advantageously a spacer placed between the humeral anchoring element and the replacement humeral head.

[0011] Alternatively, the humeral articular piece may include a receiving cup for a glenosphere.

[0012] The invention also relates to a shoulder prosthesis comprising a humeral articular piece according to the invention.

[0013] The shoulder prosthesis can be an anatomical prosthesis or a reverse prosthesis. Brief description of the figures

[0014] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which:

[0015] [Fig-1] is a first perspective view of a humeral anchoring element according to the invention,

[0016] [Fig.2] is a second perspective view of a humeral anchoring element according to the invention,

[0017] [Fig.3] is a side view of a humeral anchoring element according to the invention,

[0018] [Fig.4] is a longitudinal cross-sectional view of a humeral anchoring element according to the invention,

[0019] [Fig.5] is an exploded and perspective view of a humeral articular component according to a first embodiment of the invention,

[0020] [Fig.6] is an assembled and side view of the humeral articular piece according to the first embodiment of the invention,

[0021] [Fig.7] is an exploded and perspective view of a humeral articular component according to a second embodiment of the invention,

[0022] [Fig.8] is an exploded and perspective view of a reverse shoulder prosthesis according to the invention,

[0023] [Fig.9] is an assembled side view of a reverse shoulder prosthesis according to the invention,

[0024] [Fig. 10] is a side view of a humeral articular piece according to the second embodiment of the invention implanted in a humerus. Detailed description

[0025] Reference is now made to Figures 1 to 4 illustrating a humeral anchoring element 2 of a humeral articular component 4 or 4' (see Figures 5 to 9) of a shoulder prosthesis (see Figures 8 and 9: exploded and assembled views of a reverse shoulder prosthesis). A humeral anchoring element is defined as a portion of a humeral articular component intended to be implanted in a cavity formed in the proximal end of a humerus, whether the humeral articular component is that of an anatomical or reverse shoulder prosthesis. The humeral anchoring element 2 may be made from a biocompatible metal such as a titanium alloy or stainless steel.

[0026] The humeral anchoring element 2 comprises a main body 8 intended to be inserted into the humerus from a resected metaphyseal surface 10 (see [Fig. 10]). It also comprises a proximal collar 12 located at a proximal end of the main body 8 and which may be intended to extend substantially parallel to the resected metaphyseal surface 10.

[0027] A proximal face 14 of the proximal collar 12 extends into the humerus and below the resected metaphyseal surface 10. This means that the proximal end of the humeral anchoring element 2, intended to be placed as close as possible to the proximal end of the humerus, is located inside the humerus and below the plane formed by the resected metaphyseal surface 10. This allows, as explained above, the humeral anchoring element 2 to be "buried" in the humerus and thus to move the humeral articular piece and consequently the shoulder prosthesis towards the humerus, thus allowing the center of rotation of the joint to be placed as close as possible to the humerus.

[0028] The proximal face 14 of the proximal collar 12 can for example extend into the humerus at a distance of between 1 and 10 millimeters below the resected metaphyseal surface 10, preferably between 1 and 5 millimeters below the resected metaphyseal surface.

[0029] The proximal collar 12 has a diameter between 30 and 48 millimeters.

[0030] Advantageously, the main body 8 extends only in a part humeral metaphysis 16. This means that anchoring element 2 lacks a medullary anchoring stem. This is particularly advantageous, as explained above, for patients with a healthy humeral metaphysis that can serve as an anchoring base for humeral anchoring element 2, which can then be placed against the calcaneus of the humeral head, which is advantageously preserved during bone resection.

[0031] The main body 8 may include a peripheral anchoring system formed by several peripheral anchoring plates 18 separated from one another, five in the example shown in the figures, intended to extend from the proximal collar 12 to a distal portion of the humerus 16. In the illustrated example, these extend from the proximal collar 12 substantially perpendicularly to a plane in which the proximal face 14 of the proximal collar 12 extends, with two adjacent peripheral anchoring plates 18 extending in planes that are not parallel to each other. The advantage of using a peripheral anchor is that said anchoring is achieved in the cortical part of the humerus, which is the densest part of the bone. Thus, the anchoring of the humeral anchoring element 2 in the humerus 16 is optimized by interaction with the hardest part of the humerus 16.The placement of peripheral anchoring plates 18 with adjacent plates not extending in parallel planes between them prevents rotation of the anchoring element 2 in the humerus 16.

[0032] Advantageously, the peripheral anchoring plates 18 can be of irregular width along their extension direction. This can be seen in the figures, in which recesses 20 are present on either side of the peripheral extension plates 18 on their sides. These irregularities ensure good anchoring of the humeral anchoring element 2 in the bone.

[0033] Preferably, one or more portions of the sides of the peripheral anchoring plates extend in a direction parallel to an extension direction of the proximal face 14 of the proximal collar 12. This is visible in the figures, in which each side of each peripheral anchoring plate 18 comprises three portions extending in such a direction. This further facilitates the anchoring of the anchoring element 2 in the humerus 16.

[0034] The length of the peripheral anchor plates 18 is advantageously between 12 and 20 millimeters.

[0035] The main body 8 may include a stabilizing stud 22, placed in a central position in the example of the figures, intended to extend from the proximal collar 12 towards a distal part of the humerus 16. In the illustrated example, the latter extends from the proximal collar 12 substantially perpendicularly to a plane in which the proximal face 14 of the proximal collar 12 extends. This stabilizing stud 22 is intended to prevent the anchoring element 2, and therefore the articular piece 4 or 4', from overturning in the humerus 16.

[0036] The length of the stabilizing block is advantageously between 14 and 30 millimeters.

[0037] The stabilizing block 22 may advantageously include retention grooves 24 extending substantially parallel to a longitudinal axis of the stabilizing block 22. These grooves optimize the anti-tipping function of the stabilizing block 22.

[0038] The stabilizing block 22 may further be a hollow body open at its distal end (potentially at its proximal and distal ends) and include through-holes 26 formed in its wall. These through-holes connect the interior of the stabilizing block 22 to its exterior. This allows for bone colonization and vascularization of the portion of bone located inside the stabilizing block 22. This vascularization helps maintain consistent bone within the stabilizing block 22, which optimizes the stabilization of the humeral anchoring element 2 in the humerus 16 by allowing anchoring through the interior of the stabilizing block 22.

[0039] The stabilizing block 22 can further be a hollow body open at its proximal end (potentially at its proximal and distal ends) and include a thread 27 provided on an internal surface of the stabilizing block 22. This thread 27 allows the removal of the humeral anchoring element 2 of the humerus 16 if necessary and by screwing in a tool for extracting the humeral anchoring element 2. It would be possible to use a fixing system other than a thread, such as a system of notches or notches.

[0040] The stabilizing block may further include at least one lateral ring 25 (two in the figures) extending from an outer face of the stabilizing block 22 in a direction substantially perpendicular to a longitudinal axis of the stabilizing block 22. It also optimizes the anchoring of the humeral anchoring element 2 in the bone. The lateral ring 25 may further include notches aligned with the retention grooves 24 in order to maintain the function of the latter. The retention grooves are generally not continuous, in order to to have bone positioned between the portions of retention striations 24 in order to further prevent rotation of the humeral anchoring element 2.

[0041] The humeral anchoring element 2 may further include a recess 28 which can form a conical fixing system intended to receive another part of a humeral articular piece 4 or 4' (cup or spacer) as will be described later.

[0042] The proximal collar 12 may further include suture holes 46 (illustrated in figures 1 to 4) allowing the soft parts of the bone to be reattached to the humeral anchoring element 2.

[0043] Figure 5 illustrates a humeral joint component 4 according to a first embodiment of the invention and in the case where the shoulder prosthesis is an anatomical prosthesis, that is to say, reproducing the shape of the anatomical joint. The humeral joint component 4 comprises, in addition to the humeral anchoring element 2, a spacer 30 intended to be positioned in the recess 28. The spacer 30 includes a fixing stud 32 intended to receive a replacement humeral head 34.

[0044] Figure 6 illustrates a humeral articular component 4 according to the first embodiment of the invention, where the shoulder prosthesis is an anatomical prosthesis, and the humeral articular component 4 is assembled. The spacer 30 is placed in the recess 28 and the receiving block 32 is inserted into a fixing hole provided in the replacement humeral head 34.

[0045] Figure 7 illustrates a humeral articular component 4' according to a second embodiment of the invention. In this embodiment, the humeral articular component 4' is that of a reverse shoulder prosthesis 6 visible in Figure 8. A cup 36 is intended to be mounted on the humeral anchoring element 2. This cup 36 comprises, at its end facing the glenoid, a concave surface intended to receive a glenosphere 40 (visible in Figures 8 and 9). Cups of different heights can be used with the same humeral anchoring element 2.

[0046] In this embodiment, a base 38 of the cup 36 is intended to be placed in the recess 27. The base 38 can be conical in shape and quite wide, with for example a diameter at the gauge plane between 15 and 30 millimeters.

[0047] The cupule 36 is advantageously as wide as possible in order to provide the deepest possible concave surface. This allows for a polyethylene layer in the concave surface, for example 4 millimeters thick, against which the glenosphere 40 is placed, while allowing the glenosphere 40 to be positioned as deeply as possible in the concave surface.

[0048] Figures 8 and 9 illustrate a reverse shoulder prosthesis 6, respectively in exploded view ([Fig.8]) and assembled view ([Fig.9]). It includes the articular piece humeral 4', and a glenoid articular piece comprising in the illustrated example the glenosphere 40, a metaglena 42 intended to be fixed in the glenoid and on which the glenosphere 40 is fixed. Several anchoring screws 44 are intended to be used to fix the metaglena 42 in the glenoid.

[0049] Figure 10 illustrates, as described above, a proximal portion of a humerus 16 having a resected metaphyseal surface 10 and a humeral articular piece 4' according to the second embodiment of the invention. As can be seen in the figure, the entire anchoring element 2 is disposed within the humerus 16, the proximal face 14 of the proximal collar 12 extends below a plane in which the resected metaphyseal surface 10 extends. List of references

[0050] 2: humeral anchoring element

[0051] 4, 4': humeral articular piece

[0052] 6: reverse shoulder prosthesis

[0053] 8: main body

[0054] 10: resected metaphyseal surface

[0055] 12: proximal collar

[0056] 14: proximal face

[0057] 16: humerus

[0058] 18: peripheral anchoring plates

[0059] 20: recesses

[0060] 22: stabilizing block

[0061] 24: retention grooves

[0062] 25: lateral crowns

[0063] 26: through holes

[0064] 27: tapping

[0065] 28: recess

[0066] 30: spacer

[0067] 32: Fixation stud

[0068] 34: Replacement humeral head

[0069] 36: Cup

[0070] 38: Base

[0071] 40: Glenosphere

[0072] 42: Metaglene

[0073] 44: Anchor screw

[0074] 46: Suture holes

Claims

Demands

1. Humeral anchoring element (2) of a humeral joint component (4, 4') of a shoulder prosthesis, the humeral anchoring element (2) comprising: - a main body (8) intended to be inserted into a humerus (16) from a resected metaphyseal surface (10), and - a proximal flange (12) forming a proximal end of the humeral anchoring element (2) and positioned at one end of the main body (8), a proximal face (14) of the proximal flange (12) extending into the humerus (16) and below the resected metaphyseal surface (10), the main body (8) being intended to extend only into a metaphyseal portion of the humerus (16), the main body (8) comprising a peripheral anchoring system formed by several peripheral anchoring plates (18) separated by one from the other and intended to extend from the proximal collar (12) towards a distal part of the humerus (16),two adjacent peripheral anchor plates (18) extending in planes that are not parallel to each other, characterized in that the peripheral anchor plates (18) are of irregular width along their direction of extension.

2. Humeral anchoring element (2) according to claim 1, wherein the main body comprises at least one stabilizing stud (22) intended to extend from the proximal collar (12) to a distal part of the humerus (16).

3. Humeral anchoring element (2) according to claim 2, wherein the stabilizing pad (22) comprises retention grooves (24) extending substantially parallel to a longitudinal axis of the stabilizing pad (22).

4. Humeral anchoring element (2) according to any one of claims 2 or 3, wherein the stabilizing block (22) is a hollow body open at its distal end and comprises a plurality of through holes (26) formed in its wall.

5. Humeral anchoring element (2) according to any one of claims 2 to 4, wherein the stabilizing block (22) is a hollow body of tubular shape open at its proximal end and includes a thread (27) formed on an internal surface of the stabilizing block (22).

6. Humeral anchoring element (2) according to any one of claims 2 to 5, wherein the stabilizing pad (22) comprises at least one lateral ring (25) extending from an external face of the stabilizing pad (22) in a direction substantially perpendicular to a longitudinal axis of the stabilizing pad (22).

7. Humeral articular piece (4, 4') comprising a humeral anchoring element (2) according to any one of the preceding claims.

8. Shoulder prosthesis comprising a humeral articular piece according to claim 7.