Screw for osteosynthesis plate

Abstract

V is for osteosynthesis plate. The invention relates to a screw (1) for osteosynthesis plate comprising a screw head (6) including a screw head thread (18), the thread (18) being interrupted by at least one groove (26a) obtained by means of a grooving tool configured to form a V-groove, and a shank (8) extending from the screw head (6) and including a shank thread (54). Figure for the abstract: Fig. 1.

Description

Title of the invention: Screw for osteosynthesis plate Technical field

[0001] The present invention relates to a screw for an osteosynthesis plate, as well as to an assembly comprising said screw and an osteosynthesis plate. Prior art

[0002] Osteosynthesis screw / plate assemblies are commonly used in cases of scheduled orthopedic surgery or in the context of trauma emergency treatment. Depending on the needs, a practitioner can either insert “non-locking” type screws into an osteosynthesis plate in order to generate pressure from the osteosynthesis plate against one or more bone fragments, or insert “locking” type screws into the osteosynthesis plate in order to hold the bone fragment(s) in position by locking into the osteosynthesis plate.

[0003] “Non-locking” type screws can generally be inserted in a multitude of directions into the osteosynthesis plate; these are called polyaxial insertions, whereas “locking” type screws can generally only be inserted in a single direction in which the axis of the screw coincides with the axis of an opening made in the plate and intended to receive the screw; these are called monoaxial insertions.

[0004] However, there are variants of "locked" type screws that are configured to allow polyaxial insertion into the osteosynthesis plate. These screws are commonly called polyaxial locking screws. This type of screw allows insertion and / or locking in a multitude of directions in the osteosynthesis plate, making it possible, for example, to avoid a necrotic area or one with lower bone density, or to avoid conflicts, for example by avoiding healthy joint surfaces.

[0005] In order to lock the polyaxial locking screw in the osteosynthesis plate in any desired direction, screws for osteosynthesis plates are known from the prior art, configured so that one of the two threads of the screw or of the osteosynthesis plate is machined when the screw is locked in the osteosynthesis plate. The machining of a thread corresponds to a removal of material from the thread. This embodiment has the disadvantage of providing a mechanical strength of the assembly which is not uniform depending on the direction and / or the direction of stress of the screw.

[0006] There is nevertheless a need to provide a screw, for example a polyaxial locking screw, which offers improved mechanical resistance when inserted and / or locked into the osteosynthesis plate. Statement of the invention

[0007] The invention aims in particular to solve this problem. The invention aims to provide a screw for an osteosynthesis plate which offers improved mechanical resistance when it is inserted and / or locked into the osteosynthesis plate and relates, according to a first aspect, to a screw for an osteosynthesis plate comprising a screw head comprising a screw head thread, the thread being interrupted by at least one groove and a shank extending from the screw head and comprising a shank thread.

[0008] For example, said at least one groove may be obtained by means of a grooving tool configured to form a V-groove.

[0009] For example, said at least one groove may be a V-shaped groove, for example V-shaped.

[0010] In the present disclosure, said at least one groove may be formed by means of the grooving tool configured to form a V-shaped groove so as to interrupt the thread of the head of the screw, i.e. so as to form an interruption in the thread of the head of the screw. The groove may also be likened to a furrow.

[0011] The particular shape of the groove obtained by means of the tool configured to form a V-shaped groove makes it possible to improve the positioning of the screw, for example when it is inserted and locked into an osteosynthesis plate.

[0012] The advantage associated with the shape of the groove obtained according to the present invention, unlike grooves having other geometric shapes, is to allow interruptions in the thread to be made which are short enough so as not to have to trim the thread of the screw head more than necessary and would compromise the performance of the anchoring in the plate. The contact surface between the thread of the screw head and that of the osteosynthesis plate is thus increased when the screw is locked in the osteosynthesis plate, which makes it possible to offer improved mechanical resistance.

[0013] Furthermore, the particular shape of the groove allows the thread of the screw head to be deformed so as to conform to the thread of an osteosynthesis plate, without machining or milling the thread of the screw or the plate.

[0014] According to one feature, the thread of the screw head is configured to deform plastically when the screw is inserted into an osteosynthesis plate. For example, the thread of the screw head is configured to undergo plastic deformation when the screw is inserted into an osteosynthesis plate.

[0015] By plastic deformation is meant a permanent deformation, for example an irreversible deformation.

[0016] Machining or milling means removing material, for example from the thread of the screw head or plate.

[0017] According to other characteristics of the invention, the screw of the invention comprises one or more of the following optional characteristics considered alone or in all possible combinations.

[0018] Said at least one groove is formed by two surfaces of the screw head, the two surfaces extending relative to each other so as to form an angle of between 30° and 70°, preferably an angle of 50°.

[0019] One of the two surfaces extends from an outer surface portion of the screw head toward a central portion of the screw head.

[0020] The screw head comprises an upper end comprising for example a top and a lower end, said at least one groove being arranged at a distance from the upper end of the screw head.

[0021] Said at least one groove is arranged at a distance of at least 0.1 mm from the upper end of the screw head.

[0022] The screw head comprises a section decreasing from an upper end to a lower end and in which said at least one groove is formed by means of the grooving tool so as to follow an inclination of the screw head.

[0023] The thread of the screw head is configured to deform plastically when the screw is inserted into an osteosynthesis plate.

[0024] The thread of the screw head is interrupted by six grooves obtained by means of the grooving tool configured to form a V-groove.

[0025] According to another aspect, the invention relates to an assembly comprising a screw as previously described, and an osteosynthesis plate in which at least one through hole is provided, adapted to receive the screw, said at least one through hole being delimited by a peripheral wall comprising a thread.

[0026] According to one characteristic, the thread of the screw head has a thread pitch different from the thread pitch of the thread of the wall delimiting said at least one through hole of the plate.

[0027] According to one characteristic, the thread of the screw head is a double-thread thread and the thread of the wall delimiting said at least one through hole of the plate is a double-thread thread. Brief description of the drawings

[0028] [Fig.l] [Fig.l] represents a screw for an osteosynthesis plate according to one embodiment of the invention.

[0029] [Fig.2] [Fig.2] is an enlarged view of a head of the screw and a portion of the shank of the screw shown in [Fig.l].

[0030] [Fig.3] [Fig.3] shows a longitudinal sectional view of the screw head.

[0031] [Fig.4] [Fig.4] shows a view from below of the screw.

[0032] [Fig.5] [Fig.5] represents an osteosynthesis plate according to a method of realization of the invention.

[0033] [Fig.6] [Fig.6] represents a sectional view along line VLVI of [Fig.5].

[0034] [Fig.7] [Fig.7] shows a sectional view of an assembly comprising a screw inserted and locked into an osteosynthesis plate in a first position.

[0035] [Fig.8] [Fig.8] represents a sectional view of the assembly in which the screw is inserted and locked in the osteosynthesis plate in a second position, different from the position illustrated in [Fig.7].

[0036] [Fig.9] [Fig.9] illustrates a grooving tool, configured to form grooves in V-shaped, according to one embodiment.

[0037] [Fig. 10] [Fig. 10] illustrates a deformation of a thread of the screw head when the screw is inserted into the osteosynthesis plate.

[0038] [Fig. 11] [Fig. 11] illustrates the thread of the screw head before insertion and locking of the screw in the osteosynthesis plate.

[0039] [Fig. 12] [Fig. 12] illustrates the deformed screw head thread after insertion and locking of the screw in the osteosynthesis plate in polyaxial configuration.

[0040] [Fig. 13] [Fig. 13] illustrates an angulation cone obtained by the polyaxial locking screw mechanism. Description of the embodiments

[0041] In the description and the claims, the expressions "upper", "above", and "lower", "below", and their derivatives will be used without limitation in reference to the upper part, and to the lower part, respectively, of figures 1 to 8 and 10 to 12.

[0042] In the remainder of the description of the screw, the osteosynthesis plate and the assembly comprising the plate and the osteosynthesis screw according to the invention, the same numerical references designate the same elements.

[0043] [Fig. 1] illustrates a screw according to the invention. The screw 1 extends along a longitudinal axis “X”.

[0044] The screw 1 may be a bone screw, for example a screw for an osteosynthesis plate.

[0045] The screw 1 can be configured to be inserted and locked into a plate 2 osteosynthesis.

[0046] For this purpose, at least one through hole 4a intended to receive a screw 1 according to the present invention can be provided in the osteosynthesis plate 2 ([Fig.5]).

[0047] For example, several through holes may be provided in the osteosynthesis plate 2. Each through hole may, for example, have a cylindrical shape. Each through hole is intended to receive a screw 1 according to the present invention. In [Fig. 5], four through holes 4a, 4b, 4c, 4d are visible. Each through hole 4a, 4b, 4c, 4d may define a through hole axis “X'” passing through the through hole ([Fig. 6]).

[0048] The through hole axis "X'" may extend from one side of the through hole to the other side of the through hole. The through hole axis "X'" may pass through the through hole. For example, the through hole axis "X'" connects two spaces extending on either side of the osteosynthesis plate and passes through the through hole. The through hole axis "X'" is, for example, a radial axis of the through hole.

[0049] In the present disclosure, the screw 1 may be a polyaxial locking screw.

[0050] By polyaxial locking screw, it is meant that the screw 1 can be inserted and / or locked into the plate, for example by rotating the screw 1 in a through hole 4a, 4b, 4c, 4d of the plate, in a multitude of directions, for example with an angulation of plus or minus 10°.

[0051] Such a polyaxial locking screw therefore allows an angulation cone of 20°. Such an angulation cone is shown in [Fig. 13].

[0052] [Fig. 7] illustrates a first configuration in which the screw is inserted and / or locked into the plate so that the longitudinal axis “X” of the screw and the through hole axis “X'” are coaxial. For example, the longitudinal axis “X” of the screw 1 coincides with the through hole axis “X'” ([Fig. 7]) when the screw 1 is inserted and / or locked into the osteosynthesis plate. This configuration illustrates a position of the screw in the plate generally called the coaxial position or monoaxial position.

[0053] [Fig. 8] illustrates a second configuration in which the screw is inserted and / or locked into the plate such that the longitudinal axis “X” of the screw and the through-hole axis “X'” are not coaxial. For example, the longitudinal axis “X” of the screw 1 has an angular offset “y”, for example of plus or minus 10°, relative to the through-hole axis “X'” of the through-hole 4a when the screw 1 is inserted and / or locked into the osteosynthesis plate 2. This configuration illustrates a position of the screw in the plate generally referred to as the non-coaxial position or polyaxial position.

[0054] As illustrated in [Fig.l], the screw 1 comprises a head 6, called the screw head, and a rod 8, called the screw rod, extending from the screw head 6.

[0055] The head 6 comprises an upper end 10 comprising a top 12 of the head and a lower end 14 from which the rod 8 can extend.

[0056] The top 12 of the screw head may comprise a flat surface ([Fig.2]).

[0057] The screw head 6 comprises a thread 18. The thread 18 can extend between the upper end 10 and the lower end 14 of the screw head 6.

[0058] For example, the thread 18 may extend from the upper end 10 to a lower end portion comprising the lower end 14 of the screw head 6.

[0059] As illustrated in [Fig. 3], the screw head 6 may comprise a screw head body 20 around which the thread 18 extends circumferentially. The thread 18 may extend circumferentially on an external surface of the screw head body 20. The body 20 and the thread 18 are formed in a single piece, i.e. in a single piece.

[0060] In the present disclosure, the thread 18 is a helical thread.

[0061] In the present disclosure, the thread 18 is a double-thread thread, for example a triangular thread. A double thread is a thread comprising two threads forming, for example, an angle of 180° to each other.

[0062] The double-thread thread has the advantage of multiplying the number of attachment points of the screw with the osteosynthesis plate while further improving the deformation capacity of the thread of the screw head. Such deformation capacity of the thread of the screw head will be described later. Furthermore, the feed rate of a double-thread screw is greater than that of a single-thread screw for one rotation of the screw.

[0063] The invention is not limited to this type of thread shape and may for example have other shapes such as a round thread or a trapezoidal thread.

[0064] The thread 18 may further comprise a thread root 22 and a thread crest 24.

[0065] The body 20 of the screw head 6 may further comprise a decreasing section from the upper end 10 to the lower end 14. The screw head 6 may further comprise a flared section from the lower end 14 to the upper end 10. The thread roots 22 may be arranged such that a truncated cone connecting the thread roots 22 has a decreasing section from the upper end 10 to the lower end 14, and / or the thread crests 24 may be arranged such that a truncated cone connecting the thread crests 24 has a decreasing section from the upper end 10 to the lower end 14. As illustrated in [Fig. 2], an external surface of the screw head defined for example by the thread 18, may be inclined by an angle “a” of for example between 5 and 15°, preferably 10° relative to a longitudinal axis “X” of the screw.

[0066] For example, the screw head may be conical. For example, the screw head has a conical external geometry.

[0067] The invention is not limited to this shape and the screw head 6 may for example have other shapes such as a spherical shape.

[0068] Furthermore, as illustrated in [Fig. 3], a blind hole 16 or imprint may be provided in the center of the screw head 6 and opens out at the top 12 of the head. The blind hole 16 is intended to receive a tool configured to direct the screw 1, for example by rotation, during insertion and / or locking of the screw in an osteosynthesis plate 2.

[0069] As illustrated in Figures 1, 2 and 4, the thread 18 is interrupted by at least one groove 26a.

[0070] In the present disclosure, said at least one groove 26a is for example obtained, that is to say formed by means of a grooving tool, configured to form a V-shaped groove, for example V-shaped. Thus the groove 26a may be a V-shaped groove, for example V-shaped.

[0071] For example, said groove 26a can be obtained following the passage of such a tool in the thread 18 of the screw head 6.

[0072] The use of such a tool makes it possible to obtain a groove of a particular shape.

[0073] An example of a grooving tool 28 is illustrated in [Fig.9].

[0074] The tool 28 may further comprise at least one cutting element 30a comprising a shape configured to dig or remove material in the screw head 6 so as to form a V-shaped groove in the screw head. For example, said at least one cutting element 30a may comprise a cone or conical shape. Thanks to the cone or conical shape of the cutting element 30a, the groove 26a formed following the passage of the cutting element 30a in the screw head, for example in the thread 18 of the screw head 6, may have a shape corresponding to that of the cutting element of the tool, for example a conical shape, for example a V-shape.

[0075] According to an example illustrated in [Fig.9], the tool 28 may comprise a disc 32 arranged at one end of an arm 34.

[0076] The disc 32 may comprise, for example, a plurality of cutting elements, for example, eight cutting elements 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, each having a shape intended to form a V-shaped groove in the head of the screw. For example, each cutting element 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h may comprise a cone-shaped or conical portion.

[0077] The tool 28 is intended to carry out two types of movements:

[0078] A cutting movement, for example a rotational movement, allowing the tool 28 to cut, dig, generate the V-shaped groove in the head of the screw, for example by means of the cutting elements.

[0079] A feed movement, for example a translation movement, allowing the tool to move along the head of the screw, for example from a lower end portion comprising the lower end 14 towards an upper end portion comprising the upper end 10.

[0080] For example, the tool 28 may be a reverse cone conical cutter.

[0081] The groove can be obtained by other possible means. For example, the groove can be formed by two different tools having different but complementary specificities, making it possible to obtain the shape of the groove at the end of their passage in the thread.

[0082] According to yet another embodiment, the groove could be obtained by electroerosion for example.

[0083] Said at least one groove 26a obtained by means of the grooving tool is illustrated in [Fig.4] which is a view from below of the screw 1 which makes it possible to appreciate the shape of the grooves due to the conical shape of the screw head.

[0084] In [Fig.4], the screw has six grooves 26a, 26b, 26c, 26d, 26e, 26f.

[0085] Each groove 26a, 26b, 26c, 26d, 26e, 26f can be formed or delimited by two surfaces 36, 38 of the screw head 6.

[0086] The two surfaces 36, 38 may for example correspond to internal walls of the screw head, obtained for example following the passage of the grooving tool. It is understood that the internal walls of the screw head may result from a passage of the grooving tool 28 in the thread of the screw head. Said internal walls may for example comprise a part of the thread 18 or a part of the thread 18 and a part of the body 20 of the screw head.

[0087] The two surfaces 36, 38 delimit said at least one groove 26a in the head of the screw, for example in the thread of the head of the screw.

[0088] The two surfaces 36, 38 are arranged relative to each other so as to form a V, for example in section along a plane orthogonal to the central axis of the screw head and / or the longitudinal axis “X”. For example, each leg of the V is formed by one of the two surfaces 36, 38 of the screw head 6.

[0089] For example, the two surfaces 36, 38 are arranged relative to each other so as to comprise a common vertex 40, for example of a common edge, corresponding for example to the point of intersection between the two surfaces 36, 38, the edge being for example formed by all such points of intersection of the same groove, and corresponding for example to the point of intersection of the two legs of the V. The common edge is for example coplanar with the central axis of the screw head and / or the longitudinal axis “X”.

[0090] The arrangement of the two surfaces 36, 38 makes it possible to delimit a groove having, for example in section along a plane orthogonal to the central axis of the screw head and / or the longitudinal axis “X”, the shape of a V, for example in the shape of a triangle of which the first side and the second side of the triangle are for example defined by the two surfaces 36, 38 and the third side of the triangle is defined by an imaginary line connecting the ends of the surfaces, opposite the vertex 40.

[0091] According to the present disclosure, the thread may be interrupted by at least one V-shaped or, for example, triangular-shaped groove.

[0092] The particular shape of the groove according to the present invention, for example triangular and narrow, makes it possible to trim, for example, between 5 and 10% of the thread 18 of the screw head when other shapes, for example cylindrical, would trim more, for example on average 30%. The contact surface of the thread of the screw head with a thread 42 of an osteosynthesis plate (illustrated in [Fig.6]) is thus increased, which makes it possible to offer improved mechanical resistance.

[0093] In the present disclosure, one of the two surfaces 36, called the first surface, may extend from a portion of the external surface 44 of the head, towards a central portion 46 of the top of the screw head. It is understood that one of the two surfaces 36, called the first surface, may extend from a portion of the external surface 44 of the head, towards the center of the screw head, for example towards the central axis of the screw head, for example along a plane passing through the central axis of the screw head and / or the longitudinal axis “X”. One of the two surfaces 36, 38, for example the surface 36, may be coplanar with the central axis of the screw head and / or the longitudinal axis “X”.

[0094] The central axis of the screw head can be confused with the longitudinal axis “X”.

[0095] The outer surface portion 44 can be defined as an end portion of the screw head, for example comprising the screw head thread, proximal to a central portion of the screw head. The other surface 38 may extend with an angular offset relative to the first surface 36.

[0096] The two surfaces 36, 38 of the screw head, which delimit said at least one groove, can extend relative to each other, for example from the vertex 40 corresponding to their junction so as to form an angle “e” of between 30° and 70°, preferably 50°. The angle “e” between the two surfaces 38, 38 is for example fixed, for a given groove or for all the grooves. This configuration makes it possible to offer optimal mechanical resistance. For example, an angle of 90° would present less satisfactory resistance because it would trim more thread.

[0097] A tight angle "e" allows both to maintain an adequate thread surface while giving the screw head thread an optimal deformation capacity. Such a deformation capacity of the screw head thread will be described later.

[0098] As illustrated in [Fig.l], 2, 11 and 12 said at least one groove 26a can extend between the upper end 10 and the lower end 14 of the head 6 of the screw.

[0099] For example, said at least one groove 26a may extend vertically between the upper end 10 and the lower end 14 of the head 6 of the screw.

[0100] For example, said at least one groove may extend substantially perpendicularly, for example to within 10°, to the top 24 of the thread of the screw head 6.

[0101] When the head of the screw is flared between the lower end 14 and the upper end 10, for example when the screw head 12 is conical, said at least one groove 26a can be provided or formed in the thread 18 so as to follow the inclination of the screw head 6.

[0102] For example, said at least one groove may be formed by a passage of the tool 28 during an advance movement of the tool 28, following a trajectory corresponding to the inclination of the head of the screw, for example the inclination of the external surface of the head of the screw.

[0103] In the present disclosure, as illustrated in [Fig.2], said at least one groove 26a is arranged at a distance from the upper end 10 of the head of the screw.

[0104] For example, said at least one groove 26a is arranged at a distance of at least 0.1 mm from the upper end 10. For example, said at least one groove 26a is arranged at a distance of between 0.1 mm and 0.3 mm from the upper end 10.

[0105] In this configuration, said at least one groove does not open onto the top 12 of the screw head 6.

[0106] This configuration makes it possible not to generate areas with brittle geometry on the top 12 of the head of the screw which could form points of attachment with soft tissues. The top 12 of the head of the screw has a completely flat surface, for example smooth, for example flat, outside the imprint 16. This configuration makes it possible to avoid forming areas of attachment of the screw 1 with the soft tissues.

[0107] When the thread 18 of the screw head 6 is interrupted by a plurality of grooves, each of the grooves is arranged at a distance from the upper end 10 of the screw head.

[0108] For example, said at least one groove 26a can be obtained by passing the tool 28 through the screw head 6 along a first part of trajectory “Tl” in in which the tool digs the groove in the thread of the screw head, for example by removing material, and a second part of trajectory "T2", called the exit trajectory in which the tool is withdrawn from the thread of the screw head ([Fig.3]).

[0109] The first part of trajectory “Tl”, for example rectilinear, can be defined between the lower end 14 and the upper end 10 of the head of the screw, for example from the lower end portion comprising the lower end 14 in the direction of the upper end portion comprising the upper end 10.

[0110] The second part of trajectory “T2”, for example curved, can be defined at the level of the part proximal to the upper end portion comprising the upper end 10.

[0111] The second part of trajectory “T2” may have a radius of curvature “r” of between 0.5 and 4 mm, preferably 2 mm.

[0112] In the present disclosure, as illustrated in [Fig.4] six grooves 26a, 26b, 26c, 26d, 26e, 26f as previously described may interrupt the thread.

[0113] The grooves may be equidistantly distributed around the circumference of the screw head 6.

[0114] The invention is not limited to this number of grooves, and may comprise fewer or more grooves, for example two, three, four, five, seven, eight grooves.

[0115] The screw configuration with six grooves offers the best compromise in terms of mechanical resistance of the interface and deformability of the thread.

[0116] The rod 8 of the screw is described below.

[0117] In the present disclosure, the rod 8 of the screw may comprise a first portion end portion 48 proximal to the head of the screw and a second end portion 50, distal to the head of the screw.

[0118] The second end portion 50 may be tapered and may comprise, for example, a groove 52, for example a self-piercing one.

[0119] In the present disclosure, the head 6 of the screw and the shank 8 of the screw are formed in a single piece.

[0120] The screw rod 8 may comprise a thread 54, for example helical, which extends between the first end portion 48 and the second end portion 50 of the rod.

[0121] For example, the thread 54 of the rod 8 is a single thread.

[0122] In the present disclosure, the pitch of the thread 54 of the rod 8 may be different from the pitch of the 18 thread of head 6 of the screw.

[0123] For example, the pitch of the thread 18 of the screw head can be 1.6 mm and the pitch of the thread 54 of the rod 8 can be 1.5 mm.

[0124] The osteosynthesis plate 2 according to the invention is more particularly described below.

[0125] In the present disclosure, each through hole 4a, 4b, 4c, 4d of the plate is delimited by a peripheral wall 56 comprising a thread 58, for example helical, which extends between an upper end portion of the wall, for example proximal to a first face 60 of the plate, and a lower end portion of the wall, for example proximal to a second face 62 of the plate, the first face 60 of the plate being for example opposite the second face 62 of the plate.

[0126] For example, thread 58 is a double-threaded thread or triangular thread.

[0127] For example, the pitch of the thread 58 of the plate, for example of the thread 58 of the walls delimiting each through hole 4a, 4b, 4c, 4d of the plate 2 is different from the pitch of the thread 18 of the screw head 6.

[0128] For example, the pitch of the thread 58 of the plate, for example of the thread 58 of the walls 56 delimiting each through hole 4a, 4b, 4c, 4d of the plate 2 is less than the pitch of the thread 18 of the screw head 6.

[0129] The difference in pitch between the thread 18 of the screw head 6 and the thread 58 of the wall 56 delimiting each through hole 4a, 4b, 4c, 4d of the plate may be of the order of 0.1 mm.

[0130] For example, the pitch of the screw head thread may be 1.6 mm and the pitch of the thread of the wall delimiting the through hole of the plate may be 1.5 mm.

[0131] This makes it possible to ensure that the screw is kept locked in the osteosynthesis plate, and in particular to prevent the screw from passing through the osteosynthesis plate, in particular when the screw is in a monoaxial position.

[0132] According to another embodiment, the pitch of the thread of the wall delimiting each through hole formed in the plate is identical to the pitch of the thread of the screw rod, with a tolerance of plus or minus 2%.

[0133] As illustrated in [Fig.6], the plate may comprise for each through hole, a first counterbore 64, called the upper counterbore, arranged above an upper end portion of the thread of the plate, and / or a second counterbore 66, called the lower counterbore, arranged below a lower end portion of the thread of the plate.

[0134] The upper counterbore 64 is configured to allow the screw head 6, for example at the top 12 of the screw head 6, to be flush with the first face 60 of the osteosynthesis plate when the screw is inserted in the monoaxial position ([Fig.7]). This makes it possible to prevent the upper end 10 of the screw head 6 from being in contact with the soft tissues when the screw is inserted and / or locked in the osteosynthesis plate.

[0135] The lower counterbore 66 may have an inclined circumference 660. For example, the wall delimiting the lower counterbore 66 may be inclined. For example, the inclination is of the order of 10° relative to the axis of the through hole “X'” of the plate. This configuration makes it easier to insert the screw from several directions into the plate.

[0136] For example, the thread 58 of the walls delimiting each through hole formed in the plate 2 is arranged between the lower counterbore 66 and the upper counterbore 64.

[0137] In the present disclosure, the screw may be a polyaxial locking screw configured to insert and lock into a through hole formed in an osteosynthesis plate in both a monoaxial position and a polyaxial position.

[0138] In the monoaxial position ([Fig.7]), the conicity of the screw head allows a jamming between the screw head and the through hole of the plate at a junction 600 located between the upper counterbore 64 of the plate and the thread 58 thus allowing the screw to be locked in the plate.

[0139] In the polyaxial position ([Fig.8]) the deformation capacity of the screw head thread allows the screw head to lock into the plate.

[0140] In the present disclosure, said at least one groove 26a formed in the thread 18 of the screw head 6 allows the thread 18 of the screw head to deform, for example during insertion of the screw into the osteosynthesis plate, so as to conform to the shape of the thread 58 of the wall delimiting each through hole of the osteosynthesis plate ([Fig. 10]). The configuration of the screw allows the thread 18 of the screw to deform so as to conform to the thread 58 of the wall delimiting the through hole of the osteosynthesis plate, without machining or milling the thread of the wall delimiting the through hole of the osteosynthesis plate ([Fig. 10]).

[0141] The presence of the grooves 26a, 26b, 26c, 26d, 26e, 26f according to the invention provides a deformation capacity to the thread 18 of the screw head 6 so that each portion of the thread of the screw head is opposite a portion of the thread 58 of the wall delimiting the through hole of the osteosynthesis plate 2, for example when the screw 1 is inserted into the osteosynthesis plate.

[0142] For example, the thread of the head of the screw ([Fig. 11]), for example the thread crest 24, can become irreversibly deformed ([Fig. 12]), for example when the screw is inserted into the osteosynthesis plate.

[0143] For example, the thread 18 of the screw head is configured to deform plastically, i.e., to undergo plastic deformation when the screw is inserted into the plate.

[0144] For example, the screw and the osteosynthesis plate can be formed from an identical material, that is to say in the same material.

[0145] For example, the screw and / or the osteosynthesis plate is / are made of metallic material, for example, the screw and / or the osteosynthesis plate is / are made of metal.

[0146] The invention is not limited to this type of material, for example the screw / or the osteosynthesis plate may be made of composite material or plastic material such as for example polyetheretherketone (PEEK).

[0147] Figures 7, 8 and 10 illustrate an assembly 70 comprising a screw 1 and an osteosynthesis plate 2 as previously described.

[0148] A method of manufacturing a screw according to the invention is described.

[0149] The method comprises a step in which at least one groove 26a is formed in the thread 18 of the screw head 6 at least one grooving tool configured to form V-shaped grooves so as to interrupt the thread.

[0150] The method may comprise a step in which said at least one groove is formed by passing the tool 28 through the thread of the screw head between the lower end 14 and the upper end of the screw head.

[0151] For example, the method comprises a step in which the tool 28 follows a first part of the trajectory, for example rectilinear, defined from the lower end portion comprising the lower end 14 in the direction of the upper end portion comprising the upper end 10.

[0152] For example, the tool 28 can follow a second part of the trajectory, for example a curved part can be defined at the level of the part proximal to the upper end portion comprising the upper end 10.

[0153] The second part of the trajectory may have a radius of curvature “r” of between 0.5 and 4 mm, preferably 2 mm.

[0154] For example, the method comprises a step in which said at least one groove 26a is formed so as to follow an inclination of the head of the screw.

[0155] For example, the method comprises a step in which the thread 18 of the screw head 6 can be interrupted by six grooves 26a, 26b, 26c, 26d, 26e, 26f. This configuration has demonstrated the best compromise in terms of mechanical strength and deformability of the thread.

[0156] For example, the method may comprise a step in which the grooves 26a, 26b, 26c, 26d, 26e, 26f are formed so as to be distributed equidistantly around the circumference of the head of the screw.

Claims

Claims

1. A screw (1) for an osteosynthesis plate comprising: - a screw head (6) comprising a screw head thread (18), the thread (18) being interrupted by at least one groove (26a) obtained by means of a grooving tool configured to form a V-shaped groove, - a shank (8) extending from the screw head (6) and comprising a shank thread (54), wherein said at least one groove (26a) is formed by two surfaces (36, 38) of the screw head (6), the two surfaces (36, 38) extending relative to each other so as to form an angle of between 30° and 70°, preferably an angle of 50°.

2. A screw (1) according to claim 1 wherein one of the two surfaces (36) extends from an outer surface portion (44) of the screw head (6) towards a central portion (46) of the screw head (6).

3. Screw (1) according to any one of the preceding claims wherein the screw head comprises an upper end (10) comprising for example a top (12) and a lower end (14), said at least one groove (26a) being arranged at a distance from the upper end (10) of the screw head (6).

4. Screw (1) according to claim 3 wherein said at least one groove (26a) is arranged at a distance of at least 0.1 mm from the upper end (10) of the screw head (6).

5. Screw (1) according to any one of the preceding claims wherein the screw head (6) comprises a section decreasing from an upper end (10) to a lower end (14) and wherein said at least one groove (26a) is formed by means of the grooving tool so as to follow an inclination of the screw head (6).

6. A screw (1) according to any preceding claim wherein the thread (18) of the screw head is configured to plastically deform when the screw (18) is inserted into an osteosynthesis plate.

7. A screw (1) according to any preceding claim wherein the thread of the screw head (6) is interrupted by six grooves (26a, 26b, 26c, 26d, 26e, 26f) obtained by means of the grooving tool configured to form a V-groove.

8. Assembly (70) comprising: - a screw (1) according to any one of the preceding claims, - an osteosynthesis plate (2) in which at least one through hole (4a) is provided, adapted to receive the screw (1), said at least one through hole (4a) being delimited by a peripheral wall (56) comprising a thread (58).

9. Assembly (70) according to claim 8 in which the thread (18) of the screw head (6) has a thread pitch different from the thread pitch of the thread (58) of the wall (56) delimiting said at least one through hole (4a) of the plate.

10. Assembly (70) according to any one of claims 8 or 9 in which the thread (18) of the screw head (6) is a double thread and the thread (58) of the wall (56) delimiting said at least one through hole (4a) of the plate is a double thread.

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