Subtalar implant for arthroereisis of the talocalcaneal joint

Abstract

A subtalar implant for arthroereisis of the talocalcaneal joint. The implant is intended to be inserted into the talocalcaneal joint via its lateral orifice and has an oblong shape that extends longitudinally along an axis of insertion of the implant. The implant includes: a head with the shape of a cone of revolution centred on the axis of insertion; an anchoring thread; and a rod having the shape of a cylinder of revolution. The rod has, on its surface, the anchoring thread and being configured to be inserted up to the axis of rotation of the talocalcaneal joint. The head has, on its radially outer surface, a retaining element for retaining the implant in rotation about the axis of insertion, the retaining element exerting retention against a colonising tissue.

Claims

1. A subtalar implant for arthroereisis of the talocalcaneal joint, the implant configured to be inserted into the talocalcaneal joint via its lateral orifice, the implant being one-piece and comprising: an oblong shape that extends longitudinally along an axis of insertion of the implant; a head having a shape of a cone of revolution centred on the axis of insertion; an anchoring thread; a rod having a shape of a cylinder of revolution centred on the axis of insertion, the rod having, on its surface, the anchoring thread and being arranged to be inserted up to the axis of rotation of the talocalcaneal joint, the head flaring out from the rod and being located upstream of the head along the axis of insertion of the implant, the head having, on its radially outer surface, retaining elements for retaining the implant in rotation about the axis of insertion, the retaining elements being arranged to exert retention against a colonising tissue, wherein the retaining elements comprise: a plurality of depressions with respect to the shape of the cone of revolution of the head; at least one recess located inside each of the depressions, the at least one recess communicating with the at least one recess of at least one other of the plurality of depressions inside the head in order to create at least one annular cavity to be colonised by colonising tissue, each of the plurality of recesses having a bottom, which is flat, wherein, in a transverse cross-section perpendicular to the axis of insertion: the head is inscribed inside a first polygon, wherein sides of which extend at the depressions; for each of the at least one annular cavity, the bottoms of the recesses of that annular cavity joined end to end have a shape of a second polygon such that the annular cavity has a polygonal shape, suitable for allowing inscription of a fibrous integration polygon inside the head.

2. The implant according to claim 1, wherein the retaining elements comprise at least one edge extending lengthwise on the radially outer surface of the head in a manner substantially overlapping with or parallel to a generatrix of the radially outer surface, creating a stop zone to cooperate with the colonising tissue.

3. The implant according to claim 2, wherein the retaining elements comprise a plurality of edges angularly offset with respect to one another.

4. The implant according to claim 3, wherein each depression is defined by two edges.

5. The implant according to claim 4, wherein in a transverse cross-section perpendicular to the axis of insertion, the corners of the first polygon are formed near the edges.

6. The implant according to claim 1, wherein the first polygon is regular.

7. The implant according to claim 1, wherein each depression has a plurality of recesses.

8. The implant according to claim 7, wherein the implant further comprises a succession of annular cavities located along the axis of insertion inside the head, the recesses located at a same height along the axis of insertion communicating with each other inside the head in order to create one of the at least one annular cavity.

9. The implant according to claim 1, wherein the depressions: are regularly distributed over the radially outer surface of the head; extend lengthwise in a manner substantially parallel to a generatrix of the radially outer surface of the head, over at least 70% of a length of the head.

10. The implant according to claim 9, wherein the depressions extend lengthwise over substantially the entire length of the head.

11. The implant according to claim 10, wherein the implant has a central cannula for guiding on a pin, the at least one annular cavity being independent of the central guide cannula.

12. The implant according to claim 1, wherein the annular cavity defines an annular volume that has, in the transverse cross-section perpendicular to the axis of insertion, an inner perimeter and an outer perimeter that both have a polygonal shape, the inner perimeter being formed by the bottoms of the recesses.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of one or more embodiments of the disclosure will be clearer upon reading the following description of various exemplary embodiments of the disclosure, given as illustrative and non-limiting examples, and the appended drawings among which:

(2) FIG. 1 is a representation of a subtalar implant according to an exemplary embodiment, inserted into the talocalcaneal joint via its lateral orifice;

(3) FIGS. 2a and 2b are schematic views of a first embodiment of the implant, in a lateral view and a longitudinal cross-section passing through the axis of insertion;

(4) FIG. 3 is a perspective view of a second embodiment of the disclosure;

(5) FIG. 4 is a schematic view of a third embodiment of the disclosure, in a lateral view;

(6) FIG. 5 is a schematic side view of the implant according to a fourth embodiment;

(7) FIG. 6 is a schematic perspective view of a portion of the head of the implant of FIG. 5;

(8) FIG. 7 is a cross-sectional view of FIG. 6.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(9) In reference to FIGS. 1 to 5, an aspect of the present disclosure relates to a subtalar implant 1.

(10) In reference to FIG. 1, the subtalar implant according to an exemplary embodiment is designed for the arthroereisis of the talocalcaneal joint. The implant is intended to be inserted into the talocalcaneal joint via its lateral orifice.

(11) In reference to FIGS. 2a, 2b, 3, 4 and 5, the subtalar implant 1 according to an exemplary embodiment has an oblong shape that extends longitudinally along an axis of insertion X of the implant into the talocalcaneal joint.

(12) Such an implant is extra-osseous.

(13) According to FIGS. 2a, 2b, 3, 4 and 5, the implant 1 comprises: a head 2; a rod 3.

(14) In reference to 2a, 2b, 3, 4 and 5, the head 2 has the shape of a cone of revolution centred on the axis of insertion X. More precisely, the head 2 has the shape of a frustum.

(15) The rod 3 has the shape of a cylinder of revolution centred on the axis of insertion.

(16) The head flares out from the rod while being located upstream of the head along the axis of insertion X of the implant.

(17) In other words, along the axis of insertion, the rod is located in front of the head, the head having the shape of a cone that flares out from the rod.

(18) As illustrated by FIG. 5 and as mentioned above, the head 2 has, more precisely, the shape of a frustum from which the rod 3 extends. The rod 3 is inscribed inside the projection P.sub.c of the shape of a cone of revolution of the head, from the head and in the direction of the top of the cone.

(19) Again according to FIGS. 2a to 5, the implant 1 comprises: an anchoring thread 4; retaining elements 5 for retaining the implant in rotation about the axis of insertion.

(20) The anchoring thread 4 is presented by the rod on its surface. The rod, with the anchoring thread on its surface, is intended to be inserted up to the axis of rotation of the talocalcaneal joint.

(21) The head has, on its radially outer surface, the retaining elements 5 for retaining in rotation.

(22) The retaining elements 5 for retaining in rotation are intended to exert retention against colonising tissue.

(23) In reference to FIGS. 2a, 4 and 6 and 7, the retaining elements 5 for retaining in rotation comprise at least one edge 50.

(24) The edge 50 extends lengthwise over the radially outer surface 20 of the head 2 in a manner that substantially overlaps with or is parallel to a generatrix of the radially outer surface of the head. The edge 50 creates a stop zone intended to cooperate with the colonising tissue.

(25) Indeed, an edge is formed at the intersection of two planes. The edge thus creates a stop zone (or surface presented by the surface of the head), which does not correspond to the shape of a cone of revolution in which said head is inscribed. This surface, after the colonisation of the soft tissue, thus forms a stop that cooperates with the colonising tissue in order to exert retention against the rotation of the implant about its axis of insertion.

(26) The edge, by extending lengthwise on the radially outer surface of the head in a manner that substantially overlaps with or is parallel to a generatrix of the radially outer surface of the head, cannot be equated with the anchoring thread located on the rod.

(27) In reference to FIG. 7, the retaining elements 5 for retaining in rotation comprise a plurality of edges 50 offset angularly with respect to one another.

(28) The retaining elements 5 for retaining in rotation also comprise depressions 51 with respect to the shape of a cone of revolution of the head. These depressions correspond more precisely to an offset of the outer surface of the head with respect to theoretical shape of a cone of revolution in which the head is inscribed.

(29) According to the embodiment illustrated by FIGS. 2a and 2b, the depressions 51 take the shape of longitudinal grooves that substantially overlap with or are parallel to a generatrix of the radially outer surface of the head.

(30) According to the embodiment illustrated by FIG. 3 and by the embodiments illustrated by FIGS. 4, 5, 6 and 7, the depressions 51 take the shape of flat sections.

(31) In reference to FIGS. 6 and 7, each depression 51 (taking the shape of flat sections) is defined by two edges 50.

(32) In this case, said edges are formed during the creation of the flat sections and correspond to the intersection of the lateral edges of the flat section with the surface of the cone.

(33) In reference to FIGS. 2a, 4, 5, 6 and 7, the head 2 has, on its radially outer surface, continuous smooth portions 20 between each end of the head. These continuous smooth portions correspond to the radially outer surface 20 of the head that is inscribed in the cone of revolution.

(34) These continuous smooth portions are regularly distributed around the head. They thus allow a continuity of the cone of revolution to be formed.

(35) As illustrated by these drawings, each depression is located between two continuous smooth portions.

(36) In reference to FIG. 7, in a transverse cross-section perpendicular to the axis of insertion, the retaining elements for retaining in rotation have six depressions.

(37) Again in the transverse cross-section perpendicular to the axis of insertion, the head is inscribed in a polygon P, the sides of which extend at the depressions and the corners of which are formed near the edges.

(38) According to the present embodiment, the polygon P is regular.

(39) The capacity of the head to be inscribed in a polygon allows its anchoring inside a fibrous integration polygon.

(40) With this embodiment, the colonising soft tissue can trap the cone at a depth and block the axial rotation.

(41) The depressions can also be put in contact with certain osseous surfaces during the implantation. A possible rotation can thus be blocked in a much more efficient manner.

(42) In reference to FIGS. 2a to 7, the retaining elements 5 for retaining in rotation can also comprise recesses 52 located inside the depressions 51.

(43) In reference to FIGS. 2a, 2b, 3 and 4, the recesses 52 are blind.

(44) In reference to the embodiment illustrated by FIGS. 4, 5 and 6, the recesses 52 take the shape of a transverse groove perpendicular or substantially perpendicular to a generatrix of the radially outer surface of the head.

(45) According to the embodiments illustrated by FIGS. 5 to 7, the recesses 52 communicate with each other inside the head 2. The recesses thus communicate to create one or more annular cavities 6 (illustrated by FIGS. 6 and 7) that are intended to be colonised by colonising tissue.

(46) This or these annular cavities take the shape of a polygon, or have a polygonal shape. More precisely, the annular cavity or cavities have a hexagonal shape.

(47) Indeed, in reference to FIGS. 6 and 7, each recess 52 is formed by a peripheral wall 520 and by a bottom 521, the peripheral wall extending from the bottom 521 to the surface of the head 2 of the implant 1. The bottom 521 of each recess is thus formed according to the depth of the recess 52. These bottoms 521 are flat.

(48) As illustrated by these drawings, the bottoms 521, joined end to end have the shape of a polygon (or a polygonal cross-section), in particular the shape of a regular polygon, and even more precisely a hexagonal shape.

(49) The annular cavities 6 are thus created due to the formation of communication passages 63 between the recesses 52 that are adjacent to each other. The communication passages 63 are in this case formed by the junction of the peripheral walls 520.

(50) In other words and in reference to FIG. 7, the annular cavities 6 define an annular volume that has, in a transverse cross-section perpendicular to the axis of insertion, an inner perimeter 61 and an outer perimeter 60 (the inner perimeter 61 being more precisely formed by the bottom 521 of the recesses 52) that both have the shape of a polygon, in particular the shape of a regular polygon, and more precisely the shape of a hexagon.

(51) According to the present embodiment illustrated by FIGS. 6 and 7, the recesses located at the same height along the axis of insertion communicate with each other to create an annular cavity. The annular cavity created is independent of those created by recesses located at a different height along the axis of insertion.

(52) According to a non-illustrated embodiment, recesses directly adjacent and located at at least two different heights can create the same annular cavity.

(53) As illustrated by FIG. 5, the implant comprises a succession of annular cavities located along the axis of insertion inside the head 2.

(54) These annular cavities 6 contribute to the maximisation of the space intended for fibrous integration located inside the head.

(55) In reference to FIGS. 2b, 6 and 7, the implant 1 has a central cannula 7 for guiding on a pin. As illustrated by FIGS. 6 and 7, the annular cavities 6 are independent of the central guide cannula.

(56) According to FIGS. 2b and 3, the head 2 of the implant 1 also comprises a drive element 8. The drive element 8 of the implant is in the shape of a rear cavity having six sides.

(57) In reference to FIG. 2b, the drive element 8 communicates with the central guide cannula 7. This central guide cannula 7 has an inner thread 9 inside the cannula. This inner thread allows the coupling of the implant with a threaded rod intended to allow the removal of the implant to be facilitated.

(58) The implant according to an exemplary embodiment can be made from titanium, from an alloy of titanium, from poly ethylene, from PEEK (polyetheretherketone), or from a resorbable biopolymer (PLLA ((L)-lactic acid), PLA (polylactic acid), PGA (polyglycolic acid) or a hybrid).

(59) As illustrated by the drawings, the implant according to an exemplary embodiment is in one piece. That is to say, the implant is made from a single part.

(60) Such an implant according to an exemplary embodiment can be manufactured via turning/machining. It thus has a lower manufacturing cost than modes of manufacturing via addition of material.

(61) For information: the diameter at the rear of the head can be between from 5 to 20 mm; the total length of the implant is between from 10 to 20 mm; the length of the head is between from 5 to 16 mm.

(62) In an exemplary embodiment, the total length of the implant is between 13.5 to 18 mm and the length of the head is between 6.9 to 15.4 mm.

(63) An exemplary embodiment of the present application overcomes the disadvantages of the prior art.

(64) An exemplary embodiment proposes a subtalar implant, for arthroereisis of the talocalcaneal joint, that is extra-osseous and that does not tend at all or at the very most only slightly tends to move backwards once it has been inserted and the colonisation of the fibrous tissue has taken place, under the effect of micromovements related to walking.

(65) An exemplary embodiment proposes such a subtalar implant that does not tend to irritate the surrounding tissue and osseous structures.

(66) An exemplary embodiment proposes such a subtalar implant that does not have a complicated and costly implementation.

(67) Although the present disclosure has been described with reference to one or more examples, workers skilled in the art will recognize that changes may be made in form and detail without departing from the scope of the disclosure and/or the appended claims.