Osteosynthesis device including at least one fixation pin

Abstract

The present invention relates to an osteosynthesis device (1) comprising at least one fixation pin (2) suitable for embedding in bone material (R) so as to ensure at least partial reduction of a fracture, the osteosynthesis device (1) comprising locking means (3) designed to lock in place the fixation pin (2) embedded in the bone material (R), the locking means (3) comprising (a) a support structure (4) provided with means (41) by which the support structure (4) can be fixed on the bone material (R) and comprising a locking opening (42) suitable for the fixation pin (2) to pass through, and (b) a fastening means (5) fitted in the locking opening (42) and designed to abut against a portion of the fixation pin (2) to ensure the locking of the fixation pin (2) in place.

Description

[Technical Field]

[0001] The present invention relates to the general field of surgical instruments for bone fixing techniques.

[0002] The invention more particularly relates to an osteosynthesis device including one or more fixation pins suitable for reducing a bone fracture. [Background technology]

[0003] Fracture reduction and stabilization is generally performed using fixation screws and / or pins embedded in the bone material, possibly in association with a bone plate.

[0004] The fixation pins used are in the form of plain or threaded metal rods, at least one end of which is generally pointed or tapered so that it can be driven into the bone material using a surgical motor. Fixation pins are generally used to stabilize small bone fragments.

[0005] However, after actuation, these pins may move in either direction depending on the stresses within the receiving bone material.

[0006] This potential for movement can cause problems with the stability of the reduction and can damage surrounding tissue.

[0007] To try to limit the possibility of this displacement, after positioning the pin, the surgeon may fold its protruding end against the bone material or against the associated osteosynthesis plate. Summary of the Invention [Problem to be solved by the invention]

[0008] However, such folding or bending operations are not easy to perform and, moreover, only prevent pin movement in one direction. [Means for solving the problem]

[0009] In order to remedy this drawback of the state of the art, the present invention proposes an osteosynthesis device comprising at least one fixation pin suitable for embedding in bone material so as to ensure at least partial reduction of the fracture, said osteosynthesis device comprising locking means designed to lock in place said at least one fixation pin embedded in said bone material.

[0010] More particularly, the locking means of the osteosynthesis device according to the invention comprises: (a) a support structure provided with means for fixation to bone material, said support structure including a locking aperture through its thickness, said locking aperture being centered on an aperture axis and bounded by an aperture contour, said locking aperture adapted to receive said at least one associated fixation pin therethrough; (b) a fastening means fitted into the locking opening and designed to abut against a portion of the at least one locking pin to securely lock the at least one locking pin in place.

[0011] According to a preferred embodiment, at least a part of the opening contour of the locking opening is provided with an opening thread; the fastening means comprises a locking nut centered on a nut shank, the locking nut being bounded by an upper nut portion provided with a recess adapted to be turned using a suitable tool, a lower nut portion located opposite the upper nut portion, an outer peripheral envelope including a nut thread adapted to cooperate with the opening thread of the locking opening in the support structure, and an internal shape delimiting an axial hole adapted for passage of the at least one fixation pin; The locking nut further includes a deformable fastening structure adapted to deform and abut against a portion of the at least one fixation pin housed within the axial bore when the locking nut is threaded into the open threads.

[0012] Other non-limiting advantageous features of the osteosynthesis device according to the invention, taken individually or in all technically possible combinations, are: the fastening structure includes at least one fastening tab disposed on the lower nut portion; the at least one fastening tab is deformable by bending about a bending axis perpendicular to the nut axis; the fastening structure includes a plurality of fastening tabs regularly distributed around the circumference of the lower nut part, each of said fastening tabs being deformable by bending about a bending axis perpendicular to said nut axis, the different bending axes of said fastening tabs lying in the same plane perpendicular to said nut axis; The fastening structure includes two to four, preferably three, fastening tabs; the fastening structure includes a plurality of fastening tabs spaced apart by slots extending in a radial plane relative to the nut shank; the outer shape of the locking opening of the support structure is generally a truncated cone, and the angle of the truncated cone relative to the opening axis of the locking opening is between 9° and 11°; the outer envelope of the locking nut forming the fastening means has a generally frusto-conical shape, the angle of said truncated cone relative to the nut axis of the locking nut being between 7° and 9°; the means capable of fixing the support structure to the bone material consist of at least one fixation opening arranged on said support structure, which cooperates with a fixation screw; The support structure is in the form of a bone plate that includes (a) a plurality of fixation apertures and (b) a plurality of locking apertures, at least some of which are adapted to receive fixation pins.

[0013] Preferably, the fixation apertures and locking apertures of the bone plate are identical so that each will receive either a fixation screw or a fixation pin.

[0014] Obviously, different features, alternatives and embodiments of the invention can be associated with one another in various combinations, unless they are mutually exclusive or incompatible with one another.

[0015] Moreover, various other features of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, which illustrate non-limiting embodiments of the invention. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view of an osteosynthesis device according to the invention before the locking nut is threaded into its receiving opening in the support structure to lock the fixation pin in place; FIG. [Figure 2] 2 is a schematic cross-sectional view similar to FIG. 1 showing the osteosynthesis device according to the present invention in an activated position after the locking nut has been screwed and tightened into its receiving opening in the support structure to lock the fixation pin in place. [Figure 3] 1 is a perspective view of the locking nut of the osteosynthesis device according to the invention, seen from the upper nut part side, separated; FIG. [Figure 4] 4 is a perspective view of the locking nut of FIG. 3 as viewed from the lower nut portion side. [Figure 5] FIG. 5 is a first side view of the locking nut illustrated in FIGS. 3 and 4. [Figure 6] FIG. 5 is a second side view of the locking nut illustrated in FIGS. 3 and 4. [Figure 7] FIG. 7 is a plan view of the locking screw illustrated in FIGS. [Figure 8] 1 is a perspective view from the lower nut side showing the locking nut of the osteosynthesis device according to the invention, with the fixation pin extending through the central hole of the locking nut; FIG. [Figure 9] 9 is a view similar to FIG. 8 illustrating the locking nut and securing pin in relation to a perspective view from the upper nut portion side. [Figure 10] 1 is a perspective view illustrating an osteosynthesis device according to the invention, the support structure of which is in the form of an osteosynthesis plate positioned on the bone material to be received; FIG. [Figure 11] FIG. 11 is an enlarged view of a portion of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The osteosynthesis device 1 illustrated in Figures 1 and 2 comprises a fixation pin 2 adapted to be embedded in bone material R so as to ensure reduction of at least part of the fracture, and the osteosynthesis device 1 also comprises locking means 3 arranged to lock the fixation pin 2 in place.

[0018] The fixing pin 2 is made of a metal, such as stainless steel, titanium, or cobalt-chromium, and is in the form of a plain rod having at least one pointed end 21, a length of which may be between 20 and 200 mm, and a diameter of which may be constant and between 0.8 and 4 mm.

[0019] The locking means 3 is (a) a support structure 4 provided with means 41 for fixing the support structure 4 to bone material R, the support structure 4 including a locking opening 42 passing through its thickness, the locking opening 42 being centered on an opening axis 43 and delimited by an opening contour 44, the locking opening 42 being adapted to allow a fixation pin 2 to pass through; (b) fastening means 5 fitted into said locking opening 42 and designed to abut against a portion of said fixing pin 2 to securely lock said fixing pin 2 in place;

[0020] The opening contour 44 includes an opening thread 45 and the fastening means 5 comprises a locking nut 5 centered on a nut shaft 51 .

[0021] The support structure 4 is here in the form of an osteosynthesis support plate a few millimeters thick and is delimited by a lower surface 4a intended to be in contact with the bone material R to be received, and an opposite upper surface 4b.

[0022] In addition to the above-mentioned locking openings 42 of the locking means 3, adapted to receive the fixation pins 2 and the fastening means 5, the support structure 4 is provided with at least one opening 411, passing through its thickness between its lower surface 4a and its upper surface 4b, which opening 411 is intended for the passage of a fixation member 412 (in particular in the form of a fixation screw shown diagrammatically in Figures 1 and 2) for fixing the support structure 4 to the bone material R to be received.

[0023] The openings 411 and the associated fixing members 412 form means 41 for fixing the osteosynthesis plate 4 on the bone material R.

[0024] The opening contour 44 of the locking opening 42 of the support structure 4 has a generally frusto-conical shape, with its tip directed towards the underside 4a of the support structure 4. The angle X of this truncated cone relative to the opening axis 43 is between 5° and 15° (preferably between 8° and 12°, more preferably between 9° and 11°).

[0025] The locking nut 5 is illustrated in isolation in FIGS. 3-7 and in association with the fixing pin 2 in FIGS.

[0026] The locking nut 5 is bounded by an upper nut part 52 including an upper nut end 52a, a lower nut part 53 including a lower nut end 53a located opposite the upper nut part 52, an outer peripheral envelope 54 including a nut thread 55 adapted to cooperate with the opening thread 45 of the locking opening 42, and an inner shape 56 that defines an axial hole 57 adapted for the fixing pin 2 to pass through.

[0027] The upper nut portion 52 is provided with a recess 58 adapted to be rotated using a suitable tool for screwing or unscrewing the locking nut 5 .

[0028] The outer envelope 54 of the locking nut 5 has a generally frustoconical shape, the tip of which is directed towards the lower nut part 53. The angle Y of this frustoconical outer envelope 54 is between 4° and 12° (preferably between 6° and 10°, more preferably between 7° and 9°).

[0029] The locking nut 5 further includes a deformable fastening structure 59 adapted to deform when the locking nut 5 is threaded into the open thread 45 and to abut against a portion of the fixation pin 2 housed within the axial bore 57.

[0030] The fastening structure 59 includes at least one fastening tab 60 , and preferably several fastening tabs 60 , located on the lower nut portion 53 .

[0031] Here, the fastening structure 59 comprises a plurality of fastening tabs 60 regularly distributed around the circumference of the lower nut part 53. These fastening tabs 60 are spaced from one another by slots 61 extending in a radial plane relative to the nut axis 51, and each of these fastening tabs 60 is deformable by bending about a bending axis perpendicular to said nut axis 51.

[0032] The slot 61 extends from the lower nut end 53 a over a portion of the height of the locking nut 5 , here exactly half the height of the locking nut 5 .

[0033] The corresponding bending axes are illustrated in Figure 6 by datums 62. The different bending axes 62 of the fastening tabs 60 lie in the same plane perpendicular to the nut axis 51.

[0034] Preferably, the number of fastening tabs 60 is 2, 3 or 4. In the illustrated embodiment, the fastening structure 59 includes three fastening tabs 60.

[0035] Radial slots 61 created in the lower nut portion 53 define fastening tabs 60, each deformable about a bending axis 62 perpendicular to the nut axis 51. For each fastening tab 60, the bending axis 62 corresponds to a line connecting the bottom to the two radial slots 61 located on either side of it.

[0036] The nut threads 55 extend over the full height, or nearly the full height, of the outer envelope 54 between the upper nut portion 52 and the lower nut portion 53 .

[0037] The fastening tabs 60 are integral with the locking nut 5. Their contour extends over the frustoconical outer envelope 54, and this contour of the fastening tabs 60 includes part of the nut thread 55.

[0038] The shape of the locking aperture 42 is adapted to apply a radial compressive force to the outer shape of the lower portion 53 of the locking nut 5 as the threading of the locking nut 5 on the aperture threads 45 proceeds in such a way as to obtain the desired fastening function, so that the diameter of the lower portion of the locking aperture 42 is smaller than the diameter of the lower end 53 a of the locking nut 5 before threading.

[0039] Before actuating the fastening structure 59, the axial bore 57 of the locking nut 5 allows the fixing pin 2 to pass through. The axial bore 57 may then be in the form of a channel or a cylindrical shape, the diameter of which corresponds with a clearance to the diameter of the fixing pin 2.

[0040] This possibility of passage or sliding is illustrated in FIG. 1, which shows the lock nut 5 prior to tightening into the lock opening 42, by the small space that exists between the inner shape 56 of the lock nut 5 (which defines the axial bore 57) and the cylindrical wall opposite the fixation pin 2.

[0041] 8 and 9, the locking nut 5 is not guided into the locking opening 42 of the support structure 4 and the fixing pin 2 can also slide freely within the axial hole 57 of said locking nut 5.

[0042] Once the support structure 4 is secured to the receiving bone material R, with the locking nut 5 not threaded or not fully threaded into the locking opening 42 (e.g., as illustrated in FIG. 1), the fixation pin 2 may be positioned by the surgeon through the axial bore 57 of the locking nut 5 in a manner to effect the desired reduction of the fracture.

[0043] When the fixation pin 2 is correctly positioned within the bone material R, its positioning may be locked by threading a locking nut 5 onto the threads of the locking opening 42 in the support structure 4 .

[0044] During this screwing, the appropriate shape of the locking hole 42 causes the fastening tabs 60 of the locking nut 5 to deform radially towards the nut shaft 51 and thus towards the fixing pin 2.

[0045] This deformation is achieved by bending the fastening tabs 60 about their respective bending axes 62 until they abut against the fixing pin 2 .

[0046] It will be appreciated that by then threading the locking nut 5, the fastening tabs 60 can apply high pressure to the fixation pin 2, ensuring that the fixation pin 2 is locked in place so that it can no longer slide or move in either direction, as illustrated in FIG. 2.

[0047] The plurality of fastening tabs 60 are regularly distributed around the circumference of the lower nut part 53, so that a uniform fastening of the fixing pin 2 can be achieved.

[0048] The locking nut 5 acts as a kind of locking wedge between the opening profile 44 and the fixing pin 2 .

[0049] The shape of the opening contour 44 of the locking opening 42 (angle X) and the shape of the outer envelope 54 of the locking nut 5 (angle Y), as well as their sizes, are adapted to obtain deformation of the fastening tabs 60 and the desired locking when the locking nut 5 is screwed into the locking opening 42.

[0050] In the illustrated embodiment, the opening contour 44 of the locking opening 42 and the outer peripheral envelope 54 of the locking nut 5 both have a generally frusto-conical shape but with different tip angles; in an alternative embodiment, the outer peripheral envelope of the locking nut may be generally cylindrical and the opening contour of the locking opening of the support structure has a generally frusto-conical shape.

[0051] As another alternative, means other than a locking screw may be used to block the fixing pin against the support structure 4. For example, a conical crown may be provided that includes at least a flexible portion that can be impacted between the opening contour 44 and the fixing pin 2, thus forming a kind of locking wedge.

[0052] As illustrated in Figures 10 and 11, the support structure 4 can be in the form of a bone plate including a plurality of fixation openings 411 for fixing it on the bone material R, and a plurality of locking openings 42 each adapted to receive a fixation pin 2.

[0053] In a particular embodiment, the fixation openings for fixing the bone plate 4 onto the bone material R and the locking openings for receiving the fixation pins 2 are identically designed to accommodate either the fixation screws 412 or the fixation pins 2, respectively.

[0054] It will be appreciated that the surgeon can reduce the fracture using one or more fixation pins 2 in a conventional manner and lock each of these fixation pins into place once the surgeon deems their position correct.

[0055] The fixation pin 2 may be temporarily or permanently fixed in the receiving bone material.

[0056] After temporary fixation, the surgeon unscrews the locking nut 5 and the fixation pin 2 then regains its ability to slide within the axial bore 57 of the locking nut 5 for its removal.

[0057] For durable fixation, the surgeon cuts the fixation pin 2 flush with the support plate to avoid the presence of protrusions.

Claims

1. 1. An osteosynthesis device comprising a support structure (4), means (41) for fixing said support structure (4) to bone material (R), at least one fixation pin (2) suitable for embedding in the bone material (R) so as to ensure reduction of at least a part of the fracture, and locking means (3) designed to lock in place said at least one fixation pin (2) embedded in the bone material (R), said support structure (4) including a locking aperture (42) through its thickness, said locking aperture (42) being centered on an aperture axis (43) and delimited by an aperture contour (44), said locking aperture (42) being adapted to receive said at least one associated fixation pin (2); the locking means (3) of the osteosynthesis device comprises fastening means (5) that are fitted into the locking openings (42) and are designed to abut against a portion of the at least one fixation pin (2) to secure the locking of the at least one fixation pin (2) in place, At least a portion of the opening contour (44) is provided with an opening thread (45); the fastening means (5) consists of a locking nut (5) centered on a nut shank (51), the locking nut (5) being bounded by an upper nut part (52) provided with a recess (58) adapted to be turned with a suitable tool for screwing or unscrewing it, a lower nut part (53) located opposite the upper nut part (52), an outer circumferential envelope (54) including a nut thread (55) adapted to cooperate with the opening thread (45) of the locking opening (42), and an inner shape (56) delimiting an axial hole (57) adapted for passing the at least one fixing pin (2), the nut thread (55) extending over the entire height of the outer circumferential envelope (54), the locking nut (5) further comprises a deformable fastening structure (59) adapted to deform when the locking nut (5) is threaded into the open thread (45) and to abut against a portion of the at least one fixation pin (2) housed in the axial bore (57); the fastening structure (59) comprises a plurality of fastening tabs (60) regularly spaced around the circumference of the lower nut part (53) and spaced from one another by slots (61) extending in a radial plane relative to the nut axis (51), each of the fastening tabs (60) being deformable by bending about a bending axis (62) perpendicular to the nut axis (51), the different bending axes (62) of the fastening tabs (60) lying in the same plane perpendicular to the nut axis (51); The slot (61) extends from the lower nut end 53a over a portion of the height of the locking nut 5; The opening contour (44) of the locking opening (42) has a generally frusto-conical shape, and the outer circumferential envelope (54) of the locking nut (5) has a generally frusto-conical shape or a generally cylindrical shape, and when the outer circumferential envelope (54) of the locking nut (5) has a generally frusto-conical shape, the opening contour (44) and the outer circumferential envelope (54) have different tip angles. A bone synthesis device characterized by:

2. Osteosynthetic device according to claim 1, characterized in that the fastening structure (59) comprises two to four, preferably three, fastening tabs (60).

3. 3. The osteosynthesis device according to claim 1 or 2, characterized in that the opening contour (44) of the locking opening (42) of the support structure (4) has a generally frusto-conical shape, and the angle (X) of the truncated cone relative to the opening axis (43) of the locking opening (42) is between 9° and 11°.

4. 4. Osteosynthetic device according to any one of claims 1 to 3, characterized in that the outer circumferential envelope (54) of the locking nut (5) forming the fastening means (5) has a generally frusto-conical shape, the truncated cone angle (Y) relative to the nut axis (51) of the locking nut (5) being between 7° and 9°.

5. 5. Osteosynthesis device according to any one of claims 1 to 4, characterized in that the means (41) capable of fixing the support structure (4) to the bone material (R) consist of at least one fixation opening (411) arranged on the support structure (4) which cooperates with a fixation screw (412).

6. 6. The osteosynthesis device according to claim 5, characterized in that the support structure (4) is in the form of a bone plate (4) comprising a plurality of fixation openings (411) and a plurality of locking openings (42), at least some of which are adapted to receive fixation pins (2).

7. 7. The osteosynthesis device according to claim 6, characterized in that the fixation openings (411) and the locking openings (42) of the osteosynthesis plate (4) are identical so as to accommodate either fixation screws (412) or fixation pins (2), respectively.

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