Plate for osteosynthesis

Abstract

A T-shaped plate for osteosynthesis, has at least three first attachment holes (124) and second attachment holes (113) including a curved linkage area (13). The epiphysis portion has a recess (34) with a curved profile from one end to the other of the T-bar when viewed from the top, and a curved profile when viewed from the side, and the diaphysis portion is straight and rigid. The plate is non-deformable at normal temperatures. The leg of the T has a rounded inner surface (56). The linkage area (13) has an S-shaped longitudinal cross-section, the ends (132, 133) of which that are adjoined with the bar and leg of the T, respectively, are substantially parallel to one another.

Claims

1. An osteosynthesis T-shaped plate comprising: an epiphysis portion that forms a bar of the T and is provided with at least three first fixation holes for first anchoring screws; and a diaphysis portion that forms a leg of the T and is provided with second fixation holes for second anchoring screws, wherein said epiphysis portion and said diaphysis portion are connected by a curved joining area, wherein the epiphysis portion is concave, with a curved profile from one end to the other of the bar of the T, said concavity of said epiphysis portion of said plate being along an inner surface of said plate, said epiphysis portion also having a curved profile when viewed from a side, wherein the diaphysis portion is straight and rigid, wherein said plate is titanium, and symmetrical with respect to a longitudinal axis, and wherein said diaphysis portion is convex along said inner surface said convex inner surface of said diaphysis portion having a camber that, when viewed in a plan orthogonal to said longitudinal axis, is convex from a first longitudinal edge of the leg to a second longitudinal edge of the leg, said convex inner surface of said diaphysis portion being directed toward a bone, and wherein said curved joining area has an S-shaped longitudinal cross section, such that ends of said curved joining area join respectively to the epiphysis portion and to the diaphysis portion of the T-shaped place in a manner substantially parallel to each other.

2. The osteosynthesis plate as claimed in claim 1, wherein the concave inner surface of the epiphysis portion is in the shape of a portion of an ellipsoid of revolution about an axis of revolution situated in a plane of symmetry of the longitudinal axis.

3. The plate as claimed in claim 2, wherein the ellipsoid is a sphere of radius R1.

4. The plate as claimed in claim 3, wherein the axis of revolution of said inner surface of the epiphysis portion forms, with the leg of the T of the diaphysis portion, a re-entrant angle of between 5 and 45.

5. The plate as claimed in claim 2, wherein the axis of revolution of an inner surface of the epiphysis portion forms, with the leg of the T of the diaphysis portion, a re-entrant angle of between 5 and 45.

6. The plate as claimed in claim 1, wherein the curved profile of the concave inner surface of the epiphysis portion, in a side view, is of constant radius.

7. The plate as claimed in claim 6, wherein the radius is between 20 mm and 40 mm.

8. The plate as claimed in claim 7, wherein the radius is equal to 32 mm, in order to form an addition plate.

9. The plate as claimed in claim 7, wherein the radius is equal to 22.5 mm, in order to form a subtraction plate.

10. The plate as claimed in claim 1, wherein the curved joining area has, in longitudinal cross section, a radius of curvature of between 15 mm and 40 mm in its concave part.

11. The plate as claimed in claim 10, wherein the radius of curvature is equal to 20 mm, in order to form an addition plate.

12. The plate as claimed in claim 10, wherein the radius of curvature is equal to 22.5 mm, in order to form a subtraction plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features and advantages of the invention will become clearer from reading the following description of embodiments of the invention, which are given as illustrative and non-limiting examples and with reference to the accompanying drawings, in which:

(2) FIG. 1 is a front view of an osteosynthesis plate according to one embodiment of the invention.

(3) FIG. 2 is a cross-sectional side view along A-A of the plate from FIG. 1.

(4) FIG. 3 is a top view of the plate from FIG. 1.

(5) FIGS. 4A and 4B are perspective views of the plate from FIG. 1, in two positions serving to illustrate an embodiment of the shape of the concavity of the head of the plate according to the invention.

(6) FIG. 5 is a perspective view of a device with a plate according to one embodiment of the invention.

(7) FIG. 6 is a cross-sectional view along VI-VI of the foot of the plate from FIG. 5.

(8) FIGS. 7 and 8 are side views illustrating the positioning of a plate according to the invention when used as a subtraction plate (FIG. 7) and as an addition plate (FIG. 8).

(9) FIG. 9 is a schematic cross-sectional view along IX-IX of the plate from FIG. 8.

(10) FIG. 10 is a schematic view showing the plate in several positions permitting optimized adjustment thereof.

DETAILED DESCRIPTION

(11) As has been indicated above, one of the principles of the invention is to make available an osteosynthesis plate which is non-deformable at ambient temperature and which has a foot intended to be connected to the diaphysis of a bone and has a head intended to be connected to an epiphysis of the same bone, such that the head has a continuously curved profile, when viewed from above and also when viewed from the side, while permitting easy adjustment by virtue of the other features described hereinbelow.

(12) Referring to FIG. 1, a plate 1 according to the invention is shown in front of a bone 2, on which it is intended to be fixed.

(13) The bone 2 illustrated is a long bone, shown in part here, specifically in the area of one of its epiphyses 21 and as far as its diaphysis 22.

(14) The plate 1 is rigid and non-deformable at ambient temperature. Thus, during an operation performed by a surgeon, it is connected to the bone 2 without undergoing deformation.

(15) The plate 1 is made, for example, of a material comprising titanium, or of any other material allowing a good compromise between mechanical performance, ease of shaping, and cost.

(16) In order to be non-deformable, such a plate 1 has a thickness of at least 2 mm. Intended for the field of osteosynthesis, it is characterized by a maximum thickness of the order of 4.5 mm.

(17) In FIG. 1, the plate 1 is shown in a view from the front. It has the general shape of a T.

(18) This view illustrates more precisely that the plate 1 is formed, in the lower part, by a foot 11 in the shape of a substantially rectangular blade with a thickness of 2 mm and with a plane surface 111, for example flat and with softening lateral bevels 112, its other surface (situated toward the bone) being convex, as will be described with reference to FIG. 6.

(19) The plate has a head 12 located in the upper part and connected to the lower part by an S-shaped area 13, such that the plate 1 is symmetrical with respect to the longitudinal median plane of said foot, and it has a top 121 substantially parallel to the plane surface 111.

(20) In the preferred embodiment illustrated, the plate has a T shape. Its head 12 is intended to be connected to the epiphysis 21, while its foot 11 is intended to be connected to the diaphysis 22.

(21) The head 12, which surmounts the foot, comprises an upper surface 121 provided with two flat end recesses 122 and with a plane upper central part 123 in the continuation of the upper surface of the foot 11 and of that 131 of the joining area 13. The head comprises three threaded orifices 124 able to cooperate with fixation means, such as fixation screws or rods in particular (not shown).

(22) More precisely, it comprises a first distal end 125 and a second distal end 126, between which the three orifices 124 are uniformly distributed, respectively on the flat areas 122 and the central part 123.

(23) The plate 1 is thus intended more particularly to be connected to the epiphysis 21 by at least one screw passing through the head 12 and, preferably, by three screws passing through these orifices 124.

(24) The foot 11 is provided with three threaded orifices 113 able to cooperate with fixation means similar to those indicated above. It extends between a rounded distal end 114, at the lower part, and an upper part 115 connecting it to the head 12.

(25) The three orifices 113 are uniformly distributed, starting from the distal end 114 of the foot as far as, for example, the half-way point of the length of the foot. The plate 1 is intended to be connected to the diaphysis 22 by at least one screw passing through the foot 11 and, preferably, by three screws passing through these orifices 113 and self-locking in the threaded orifices.

(26) Thus, the head 12 comprises at least one orifice 124 intended to be passed through by a screw in order to connect the plate to said epiphysis 21, and said foot 11 comprises at least one orifice 113 intended to be passed through by a screw in order to connect the plate to said diaphysis.

(27) The ends 125 and 126 of the head 12 and the end 114 of the foot 11 can thus constitute bearing points of the plate 1 on the bone 2. These three points being eccentric to the maximum extent, they thereby guarantee a high degree of stability of the plate on the bone.

(28) In FIG. 2, the plate 1 is shown in a side view, while in FIG. 3 its head 12 is shown in a top view, with reference to the front view illustrated in FIG. 1.

(29) FIG. 3 shows that the head 12 has, in a top view, a profile that is continuously curved from its first distal end 125 to its second distal end 126.

(30) This profile is characterized by a radius of curvature R3 which varies, such that the profile is substantially elliptic, but which could equally well also be constant, such that the segment shown has a circular shape.

(31) Similarly, FIG. 2 illustrates the fact that the plate 1 has, in a side view and at least in a cross section passing through said foot 11, a profile that is continuously curved along the full extent of the head 12.

(32) This continuously curved profile of the head 12, as viewed from the side, has a radius of curvature R1 which is constant.

(33) The value of the radius of curvature R1 is between 20 mm and 40 mm.

(34) According to a preferred embodiment of what is called an addition plate, this value is 32 mm. According to another preferred embodiment (not shown), of what is called a subtraction plate, this value is 22.5 mm.

(35) In the same way, it will be noted that the head 12 of the plate 1 has a continuously curved profile along the full extent of the head, with a constant radius of curvature, in other cross-sectional views not passing through the foot 11.

(36) In particular, the profile of the head 12 has the same radius of curvature R1 on the other vertical cross sections made between the two distal ends of the head (other cross sections not shown).

(37) Thus, the head 12 has an ovoid shape, even a spherical shape, particularly suitable for allowing its adjustment on the epiphysis 21 of the bone for which it is intended.

(38) FIG. 2 also illustrates that said upper part of said foot 11 belonging to the area of joining 13 to said head 12 has, in a side view and in a cross section passing through said foot 11, a continuously curved profile.

(39) The radius of curvature R2 of said continuously curved profile of said upper joining portion 115, seen from the side, has a value of between 15 mm and 40 mm.

(40) According to a preferred embodiment of what is called an addition plate, R2 has a value of 20 mm.

(41) According to another preferred embodiment (not shown), of what is called a subtraction plate, R2 has a value of 22.5 mm.

(42) By extension, the foot 11 has a curved profile with radius of curvature R2 across the entire width of the foot, in other words in all cross sections of the foot made parallel to the one shown in FIG. 2.

(43) Thus, the plate 1 is congruent to the bone 2, from the epiphysis 21 to the diaphysis 22.

(44) As can be seen from FIG. 2, the joining area has an S shape, of which the ends 132, 133 have plane or substantially plane longitudinal surfaces 132, 133 (hence also their longitudinal sections) which are substantially parallel or form an angle toward the inside, i.e. toward the bones, of between 0 and 5, for example between 0 and 2, for example 1.

(45) FIGS. 4A and 4B show a plate 30 according to one embodiment of the invention, comprising a curved head 31 and a straight foot 32 which are joined together by an S-shaped joining area 33.

(46) The inner surface 34 of the cavity is in the shape of a portion of a sphere 35 of revolution about an axis of revolution 36 situated in the plane P of symmetry of the longitudinal axis 37 of the plate 30.

(47) The axis of revolution 36 forms an angle of >0 with the longitudinal axis (or more generally the leg of the T), for example of 30, such that the concavity of the inner surface 34 is directed toward the foot (downward).

(48) In this embodiment, each hole 38 has, on its inner face, lips 39 in the upper part of the hole (cf. FIG. 4A) in the shape of a half or third of a crown, with a thickness of the order of 1 mm permitting better screwing (width of fixation), contact which if need be will be able to be inscribed in part on the meridians 40, 41, 42 of the sphere of diameter 43, for example.

(49) FIG. 5 shows a device 44 comprising a plate 45 according to another embodiment of the invention, provided with a head 46 with three holes 47 provided with a seat in the form of a partial crown, for example in the form of a similar crescent of small thickness 47, and three screws 48, 48, 48 which are threaded along only part of their length near the screw head, for example on only a portion of their length, for example a third.

(50) Once they have been screwed in, the screws 48 and 48, being lateral screws, form a first angle with the tangent 49, 49, 49 to the inner surface 50, and the central screw 48 forms a second angle , the difference between and being 3, for example.

(51) The plate 45 comprises a foot 51 provided with four uniformly distributed holes 52 and with at least two corresponding screws 53 threaded along substantially their entire length.

(52) Referring to FIG. 6, the foot has a substantially trapezoidal cross section with a flat upper face 54 and two lateral sides 55 in the form of rounded bevels, and a bone contact face 56 of convex shape, with a maximum thickness d of between 0.1 and 0.5 mm, for example of 0.2 mm.

(53) This feature allows better adjustment of the plate on the diaphysis and epiphysis, allowing a slight pivoting (arrow 57) of the plate along the crest line 58 of the convex surface 56 during adjustment, and making it possible to ensure precision in the positioning of the point of contact with the foot (without interface of the rest of the foot).

(54) FIGS. 7, 8, 9 and 10 show the function of a plate 60 of the type described with reference to FIG. 1.

(55) FIG. 7 shows the plate 60 in the case where it is used as a subtraction plate.

(56) In this case, it is in contact on at least two end points 61 and 62 (cf. FIG. 9) in the epiphysis portion 63 and on one point 64 of the diaphysis portion, quite a large space e (several mm) being able to exist between the rest of the foot of the plate and the bone.

(57) FIG. 8 shows the same non-deformable plate 60 still in contact on the points 61 and 62 of the epiphysis portion, but by contrast in contact differently on one or two points 64, 65 of the diaphysis portion, with an almost zero space e this time existing between the rest of the foot of the plate and the bone.

(58) The use of a plate according to the invention will now be described with reference in particular to FIG. 10.

(59) The surgeon who decides to apply a plate in order to repair a fracture 69 on a bone 70 comprising an epiphysis portion 71 and a diaphysis portion 72 frees this fractured part of the flesh and tendons and/or muscles around it, and he then prepares the operation by spreading the bone parts away from each other and sliding a wedge in between them, or, by contrast, bringing them together after having removed a slice of bone for example.

(60) In order to reduce this fracture 69 and/or to fix it in position, he then applies the T-shaped plate 73 according to the type described with reference to the preceding figures.

(61) The plate, being symmetrical with respect to its axis 74 and convex, will be able to be adjusted by slight lateral pivoting and is furthermore positioned, for optimization of its position, by sliding it between the positions 75, 76, 77 indicated in FIG. 10.

(62) To do this, the surgeon moves the plate by sliding it in order to find the axial congruence between the plate and the bone along the curves 78, 79 in dot-and-dash lines in the figure.

(63) He does this such that two contact points 80, 81 at least are obtained opposite the first end holes of the bar on the fractured epiphysis portion 71, and one point at least is obtained on the end of the leg of the T with the diaphysis portion.

(64) Once the position of congruence has been obtained by contact with these two points, he fixes the bar of the T at these ends on these two points by carrying out screwing and locking, in a manner known per se, in the two corresponding first holes.

(65) Since the plate is non-deformable, the part which had slid along the diaphysis portion is also fixed simultaneously and/or progressively and alternately with the screwing of the first screws, by way of at least one contact point 82 of the convex part, by screwing a screw into the second hole nearest the contact or centered on the contact point 82.

(66) The plate is thus screwed without compression at three points of the bone to be repaired, making it possible to obtain excellent and lasting fixation.

(67) Other embodiments, based on the principle of an osteosynthesis plate as has just been described, are of course conceivable without departing from the scope of the invention.