IMPLANT

Description

[0001] The present invention relates to an implant device for osteosynthesis, and in particular for vertebral osteosynthesis.

[0002] More particularly, the present invention relates to an implant for maintaining a distraction or compression element which generally consists of a bar connected to implants through support means, or else of a plate pierced with holes for the passage of the implants.

[0003] Such an implant is for example described in document FR 2880254. It is of the type consisting of a screw comprising a threaded rod, as well as a head provided with an imprint for its maneuvering, and which has a spherical or partially spherical part intended to cooperate with a support part capable of pivoting on said head and being immobilized there, said support part comprising means for fixing and blocking a distraction or compression element.

[0004] There are many variations of these implant devices, which differ primarily in the means of fixation and locking of a distraction or compression bar.

[0005] However, all implant devices have the same disadvantages, namely anchoring that can be unreliable, as well as bone healing that is not fast enough.

[0006] Some have proposed threaded implants which have, in the longitudinal direction, distinct zones, in particular by having different pitches, as in documents US 2013253594 and US 2014012334, with the disadvantage that the part which has a longer pitch accelerates the speed of movement of the implant, so that the pitch of the part which has a shorter pitch tends to drill a hole rather than making a tap, which is detrimental to anchoring.

[0007] Also known from document US 2015196336 is an implant which has two threaded distal and proximal parts, which have equal pitches, with the characteristic, however, that said pitch of the threaded proximal part is a double-thread pitch so that the dreaded drilling effect is not eliminated.

[0008] One of the main problems encountered after implantation of a pedicle implant is the creation of a mobility chamber for the implant in the vertebral pedicle between the screw and the internal part of the pedicle. This mobility is due to cell lysis resulting from the intense pressure on the cell at the time of implantation, between the core of the screw and the cortical bone.

[0009] The aim of the present invention is to propose an implant device making it possible to overcome the various aforementioned drawbacks.

[0010] The implant device according to the invention, used for holding a distraction or compression element which consists of a bar connected to implants through support means, or a plate pierced with holes for the passage of the implants, and of the type comprising a threaded rod, as well as a head provided with an imprint for its maneuvering and which has a spherical or partially spherical part intended to cooperate with a support part capable of pivoting on said head and being immobilized there, said support part comprising means for fixing and blocking a distraction or compression element, and it is essentially characterized in that said threaded part comprises two zones, namely a distal end zone of conical profile and whose thread with wide turns is configured for spongy bone, and a proximal zone of conical profile with a conicity angle less than that of said distal part,and whose thread is fine and configured for the cortex of the bone, namely that it has fine and deep cutting threads, while the core is flat; and in that the two threads are of the same pitch or very close pitch.,

[0011] The configuration of the proximal part, namely its conicity, even slight, and its fine and deep spiral thread associated with a flat core, makes it possible to avoid cell lysis and therefore to improve contact. The internal part of the pedicle is therefore less compressed, which results in better hold in the short, medium and long term.

[0012] This thread aims to provide maximum intra-pedicular bone grip without excessive compression of the bone cell and allows rapid osseointegration. This thread has the particularity of achieving intra-pedicular progression without lateral pressure constraints responsible for pedicle fracture at the end of screwing. This thread is exclusively pedicular.

[0013] According to an additional characteristic of the implant device according to the invention, it comprises a cannula shaped to allow the introduction of a pin equipped with a density sensor.

[0014] According to another additional characteristic of the implant device according to the invention, the proximal zone has a conicity of 1°, while the distal zone has a conicity of 4°.

[0015] According to another additional characteristic of the implant device according to the invention, the thread of the proximal zone has a pitch smaller than that of the distal zone.

[0016] According to another additional characteristic of the implant device according to the invention, the difference in step values ​​is less than 20%.

[0017] The distal area has a different thread with round threads and the same depth as the thread of the proximal part. It has a sharp helix at its end. Its taper allows for gradual insertion without constraint. It is equipped with three slots parallel to the slope to achieve a self-tapping function.

[0018] The sharp helix allows the implant to be easily inserted into the bone without presenting a cortical microfracture responsible for the initiation of a pedicle fracture, and it performs a self-perforation function.

[0019] It should be noted that a screw with such characteristics is not easy to produce. The thread is thus produced in two stages: in the first stage, the thread of the distal zone is produced using a whirling tool, then in the second stage, the thread of the proximal zone is produced by turning with a plate, with, between these two operations, a stage of marking the stopping point of the first operation and the starting point of the second operation.

[0020] The advantages and characteristics of the implant device according to the invention will emerge more clearly from the description which follows and which refers to the attached drawing, which represents several non-limiting embodiments.

[0021] In the attached drawing: there figure 1 represents a perspective view of an implant device according to the invention. figure 2 represents a schematic plan view of the same implant device. figure 3 represents a plan view from one end of the same implant device.

[0022] In reference to the figures 1 et 2 , we can see an implant device according to the invention, comprising a threaded rod 1 intended to be associated with a support part, not shown, designed for holding a distraction or compression element consisting of a bar or the like in accordance with document FR 2 880 254.

[0023] The threaded rod 1 comprises a threaded part 10, a head 11 provided with an imprint 12 for its operation, as well as a partially spherical part 13 allowing the pivoting cooperation of the support part, not shown.

[0024] According to the invention, it can be seen that the threaded part 10 comprises two zones, namely a distal zone 2 and a proximal zone 3, extending between the distal zone 2 and the head 11.

[0025] The distal zone 2, which extends over 2 / 5 of the threaded part, has a conical shape, in this case, preferably but not limited to, this conicity is at an angle β of 4° relative to the longitudinal axis XX'.

[0026] The proximal zone 3 is slightly conical in shape, in this case, preferably but not limited to, it has a conicity of an angle α of 1° relative to the longitudinal axis XX'.

[0027] The thread 30 of the proximal zone 3 has, over 3 / 5 of the total length of the implant, fine and deep sharp turns 31 of 0.7 mm, while the bottom 32 is flat. This thread 30 aims to provide maximum intra-pedicular bone grip without excessive compression of the bone cell and allows rapid osseointegration. This thread 30 has the particularity of achieving intra-pedicular progression without lateral pressure constraints responsible for pedicular fracture at the end of screwing. This thread 30 is exclusively pedicular.

[0028] The distal zone 2 has a different thread 20 with round turns 21, of the same depth as the thread 30 of the proximal zone 3, and with a concave bottom 22.

[0029] Preferably, the threads 20 and 30 have identical pitches. However, if the threads 20 and 30 of the zones, respectively distal 2 and proximal 3, are different, they are then of very close values, and the pitch of the thread 30 is then less than that of the thread 30. In this case, in the embodiment shown, the difference between the two values ​​is of the order of 15%.

[0030] The distal zone 2 also has self-tapping notches 23, three in number as can be seen in the figure 3 .

[0031] The free end of the distal zone 2 is shaped into a sharp helix 24, which facilitates introduction into the bone material.

[0032] On the figure 3 , we can also see that the implant 1 comprises an axial cannula 14, which is intended for the introduction of a pin equipped with a density sensor, making it possible to determine the location of the implant.

Claims

1. Implant device configured to retain a distraction or compression element that consists of a bar which is connected to implants (1) by means of support means, or a plate pierced with holes for implants (1) to pass therethrough, and of the type comprising a threaded shank (10), and a head (11) provided with a recess (12) for maneuvering the device and which has a spherical or partially spherical portion (13) for engaging with a support part which is capable of pivoting on said head (11) and being immobilized thereon, said support part including means for fastening and locking a distraction or compression element, said threaded shank (10) including two zones (2, 3), i.e. a distal end zone (2) with a conical profile and a proximal zone (3) with a conical profile of angle (α) with a taper of less than the angle (β) of that of said distal end zone (2), characterized in that said distal end zone (2) includes a screw thread (20) which is configured for cancellous bone, i.e. it has a thread (21) with wider turns than the screw thread (30) of the proximal zone (3) while its base (22) is concave, and said proximal zone (3) includes a screw thread (30) which is configured for cortical bone, i.e. it has a flat core (32) and thinner threads (31) than those (21) of the screw thread (20) of the distal end zone (1), forming sharp turns; and in that the two screw threads (20, 30) are of the same pitch.

2. Implant device configured to retain a distraction or compression element that consists of a bar which is connected to implants (1) by means of support means, or a plate pierced with holes for implants (1) to pass therethrough, and of the type comprising a threaded shank (10), and a head (11) provided with a recess (12) for maneuvering the device and which has a spherical or partially spherical portion (13) for engaging with a support part which is capable of pivoting on said head (11) and being immobilized thereon, said support part including means for fastening and locking a distraction or compression element, said threaded shank (10) including two zones (2, 3), i.e. a distal end zone (2) with a conical profile and a proximal zone (3) with a conical profile of angle (α) with a taper of less than the angle (β) of that of said distal end zone (2), characterized in that said distal end zone (2) includes a screw thread (20) which is configured for cancellous bone, i.e. it has a thread (21) with wider turns than the screw thread (30) of the proximal zone (3) while its base (22) is concave, and said proximal zone (3) includes a screw thread (30) which is configured for cortical bone, i.e. it has a flat core (32) and thinner threads (31) than those (21) of the screw thread (20) of the distal end zone (1), forming sharp turns; and in that the two screw threads (20, 30) have different pitches, the screw thread (30) of the proximal zone (3) having a shorter pitch than that of the distal zone (2), the difference in pitch values being less than 20%.

3. Implant device according to claim 1 or claim 2, characterized in that it includes a cannula (14) which is shaped to allow the insertion of a pin provided with a density sensor.

4. Implant device according to any one of claims 1 to 3, characterized in that the proximal zone (3) has a taper of 1°, while the distal zone (2) has a taper of 4°.

5. Implant device according to any one of claims 1 to 4, characterized in that the screw thread (20) of the distal zone (2) includes threads which are round and of the same depth as that of the screw thread (30) of the proximal part (3).

6. Implant device according to any one of claims 1 to 5, characterized in that the distal region (2) is provided with three self-tapping slots (23).

7. Implant device according to any one of claims 1 to 6, characterized in that the free end thereof includes a sharp helix (24).