Surgical screw

Abstract

The invention relates to a surgical screw (1) having a longitudinal axis (I), comprising a distal portion (2) provided with a distal thread (21) and a proximal portion (3) provided with a proximal thread (31), the proximal thread (31) having a first thread pitch and the distal thread (21) having a second thread pitch different from the first thread pitch, wherein a distal end (22) of the distal portion (2) has at least one cutting tooth (25) having a leading surface (251) inclined relative to the longitudinal axis (I) and an upper surface (252) inclined relative to the longitudinal axis (I), the intersection of the upper surface (252) and the leading surface (251) forming a cutting edge (253),characterized in that the distance (d1) between the longitudinal axis (I) and a thread root (311) of the proximal thread (31) corresponds substantially to the distance (d2) between the longitudinal axis (I) and a thread crest (212) of the distal thread (21). Figure 1,

Description

Title of the invention: Surgical screw

[0001] The present invention relates to a surgical screw, in particular for bone repair, intended to allow the bringing together of two bone fragments or bones.

[0002] Certain pathologies, such as Hallux Valgus or osteotomies, induce a deformation of the toes in the foot: in particular, it happens that two adjacent phalanges of a toe do not maintain their natural alignment and form an angle between them, constantly deforming the toe. When, for example, the deformation occurs in a horizontal plane, the patient suffers from Hallux Valgus: the toe, in particular the big toe, forms a prominence on the outside of the foot.

[0003] These pathologies cause pain in the forefoot, corns, functional discomfort: the patient has difficulty walking correctly, he may also have difficulty putting on shoes.

[0004] To correct, for example, a Hallux Valgus, it is customary to cut the bone of the first metatarsal, then to realign the bone and to carry out osteosynthesis to fix the two fragments of cut bone. Osteosynthesis consists of surgically assembling two bones or two fragments of bone by welding them by bone fusion. The two bones, or fragments, to be assembled are held together by one or more compression screws for the time necessary for bone fusion.

[0005] Traditionally, to implant a compression screw, a practitioner begins by cutting the bone and realigning it. Then, the practitioner inserts a pin into the bone fragments. The practitioner then uses the pin to guide a cannulated drill. The cannulated drill prepares a cavity in the bone fragments to be assembled. The practitioner then screws the screw into the prepared cavity using the drill.

[0006] Using the drill bit can be difficult in hard-to-reach areas. In addition, the drill bit can damage certain fragile bones.

[0007] Consequently, the present invention aims to provide a screw which can be easily implanted while guaranteeing the integrity of the bone elements in which it is implanted.

[0008] The present invention also aims to provide a screw which ensures good anchoring in the bone or bone fragment in which it is implanted, while avoiding creating large cavities in the latter.

[0009] According to a general definition, the invention relates to a surgical screw having a longitudinal axis. The screw comprises a distal portion provided with a distal thread and a proximal portion provided with a proximal thread. The proximal thread has a first thread pitch and the distal thread has a second, different thread pitch. of the first thread pitch. A distal end of the distal portion has at least one cutting tooth having a leading surface inclined relative to the longitudinal axis of the screw and an upper surface inclined relative to the longitudinal axis of the screw, the intersection of the upper surface and the leading surface forming a cutting edge. Furthermore, the distance between the longitudinal axis and a thread root of the proximal thread corresponds substantially to the distance between the longitudinal axis and a thread crest of the distal thread.

[0010] The presence of a tooth at the distal end of the screw allows the screw to be self-drilling. In other words, the screw according to the invention makes it possible to dispense with the use of a drill to prepare the bone cavity. The tooth makes it possible to drill a cavity in bones to be assembled while preserving the integrity of these bones. Thus, the screw according to the invention can be implanted easily while guaranteeing the integrity of the bone elements in which it is implanted. Furthermore, the fact that a thread root of the proximal thread is substantially at the same distance from the longitudinal axis as a thread crest of the distal thread prevents loss of anchoring at the screw head and facilitates insertion of the screw head into the bone or bone fragment. It is thus possible to minimize the diameter of the screw head, while guaranteeing good anchoring of the screw in the bone or bone fragment.The cavities created in the bone or bone fragment are therefore less wide, thus avoiding excessive damage to the latter.

[0011] According to one embodiment, the distances respectively between the longitudinal axis and a thread root of the proximal thread and between the longitudinal axis and a thread crest of the distal thread are between 1.15 mm and 1.20 mm.

[0012] According to another embodiment, the distances respectively between the longitudinal axis and a thread root of the proximal thread and between the longitudinal axis and a thread crest of the distal thread are between 1.35 mm and 1.40 mm.

[0013] According to another embodiment, the distances respectively between the longitudinal axis and a thread root of the proximal thread and between the longitudinal axis and a thread crest of the distal thread are between 1.60 mm and 1.65 mm.

[0014] According to another embodiment, the distances respectively between the longitudinal axis and a thread root of the proximal thread and between the longitudinal axis and a thread crest of the distal thread are between 2.10 mm and 2.15 mm.

[0015] According to another embodiment, the distances respectively between the longitudinal axis and a thread root of the proximal thread and between the longitudinal axis and a thread crest of the distal thread are between 3.25 mm and 3.30 mm.

[0016] According to another embodiment, the proximal portion has a cylindrical region and a conical region.

[0017] According to another embodiment, the thread root of the proximal thread located substantially at the same distance from the longitudinal axis as the thread crest of the thread distal is located in the cylindrical region of the proximal portion.

[0018] According to another embodiment, the cylindrical region of the proximal portion has a longitudinal dimension at least equivalent to twice the first thread pitch.

[0019] According to another embodiment, the screw has at least two cutting teeth separated by a cylindrical opening from the distal end of the surgical screw, the attack surface of one of the cutting teeth being in the extension of the cylindrical opening.

[0020] According to another embodiment, the screw has a hole passing through the screw along its longitudinal axis.

[0021] Other characteristics and advantages of the invention will emerge from the description which follows, with reference to the appended drawings which represent an embodiment of the invention.

[0022] [Fig-1] is a perspective view of a screw according to the invention;

[0023] [Fig.2] is a side view of a screw according to the invention;

[0024] The invention relates to a surgical screw 1 shown in Figures 1 and 2.

[0025] The screw 1 has a longitudinal axis I. The screw 1 comprises a distal portion 2, a proximal portion 3 and an intermediate portion 4 positioned between the distal portion 2 and the proximal portion 3.

[0026] The distal portion 2 is provided with a distal thread 21. The proximal portion 3 is provided with a proximal thread 31. The proximal thread 31 has a first thread pitch and the distal thread 21 has a second thread pitch different from the first thread pitch. In other words, the proximal thread 31 has a thread pitch different from the thread pitch of the distal thread 21. According to the embodiment presented here, the intermediate portion 4 has a substantially smooth cylindrical shape.

[0027] According to the embodiment presented here, a distal end 22 of the distal portion 2 has three cutting teeth 25. According to other embodiments, the distal end 22 could have a different number of cutting teeth 25. Each cutting tooth 25 has a leading surface 251 inclined relative to the longitudinal axis I of the screw 1 and an upper surface 252 inclined relative to the longitudinal axis I of the screw 1. The intersection of the upper surface 252 and the leading surface 251 forms a substantially rectilinear cutting edge 253. The leading surface 251 can be inclined from 1 to 40 degrees relative to the longitudinal axis I of the screw 1. According to one embodiment, the leading surface 251 can be inclined from 2 to 35 degrees relative to the longitudinal axis I of the screw 1. The upper surface 252 can be inclined from 30 to 85 degrees relative to the longitudinal axis I of the screw 1.According to one embodiment, the upper surface 252 can be inclined from 40 to 80 degrees relative to the longitudinal axis I of the screw 1.

[0028] The cutting teeth 25 are separated by cylindrical openings 254 of the distal end 22. The attack surface 251 of each cutting tooth 25 is in the extension of a corresponding cylindrical opening 254.

[0029] According to the embodiment presented here, the distal portion 2 has a substantially cylindrical geometry.

[0030] With reference to Figures 1 and 2, the proximal portion 3 may have a cylindrical region 32 and a conical region 33.

[0031] The cylindrical region 32 may have a longitudinal dimension at least equivalent to twice the first thread pitch.

[0032] The distance dl between the longitudinal axis I and a thread root 311 of the proximal thread 31 corresponds substantially to the distance d2 between the longitudinal axis I and a thread crest 212 of the distal thread 21. These distances dl and d2 may be comprised for example between 1.15 mm and 1.20 mm, or between 1.35 mm and 1.40 mm, or between 1.60 mm and 1.65 mm, or between 2.10 mm and 2.15 mm, or between 3.25 mm and 3.30 mm. The thread root 311 is located in the cylindrical region 32 of the proximal portion 3.

[0033] Furthermore, the screw 1 may advantageously have a central bore passing through the screw along its longitudinal axis I. This bore makes it possible to engage the screw 1 on a guide pin.

[0034] In use condition, a practitioner can engage the screw on a guide pin. Then the practitioner uses the screw 1 to drill the bone cavity necessary for the implantation of the screw 1. Thus, the screw 1 makes it possible to do without the use of a drill. The screw according to the invention can therefore be implanted easily while guaranteeing the integrity of the bone elements in which it is implanted.

[0035] Of course, the invention is not limited to the single embodiment shown above, but on the contrary embraces all embodiments.

Claims

Claims

1. Surgical screw (1) having a longitudinal axis (I), comprising a distal portion (2) provided with a distal thread (21) and a proximal portion (3) provided with a proximal thread (31), the proximal thread (31) having a first thread pitch and the distal thread (21) having a second thread pitch different from the first thread pitch, wherein a distal end (22) of the distal portion (2) has at least one cutting tooth (25) having a leading surface (251) inclined relative to the longitudinal axis (I) and an upper surface (252) inclined relative to the longitudinal axis (I), the intersection of the upper surface (252) and the leading surface (251) forming a cutting edge (253), characterized in that the distance (dl) between the longitudinal axis (I) and a thread root (311) of the proximal thread (31) corresponds substantially to the distance (d2) between the longitudinal axis (I) and a thread crest (212) of the distal thread (21).

2. Surgical screw (1) according to claim 1, characterized in that the distances (dl, d2) respectively between the longitudinal axis (I) and a thread root (311) of the proximal thread (31) and between the longitudinal axis (I) and a thread crest (212) of the distal thread (21) are between 1.15 mm and 1.20 mm.

3. Surgical screw (1) according to claim 1, characterized in that the distances (dl, d2) respectively between the longitudinal axis (I) and a thread root (311) of the proximal thread (31) and between the longitudinal axis (I) and a thread crest (212) of the distal thread (21) are between 1.35 mm and 1.40 mm.

4. Surgical screw (1) according to claim 1, characterized in that the distances (dl, d2) respectively between the longitudinal axis (I) and a thread root (311) of the proximal thread (31) and between the longitudinal axis (I) and a thread crest (212) of the distal thread (21) are between 1.60 mm and 1.65 mm.

5. Surgical screw (1) according to claim 1, characterized in that the distances (dl, d2) respectively between the longitudinal axis (I) and a thread root (311) of the proximal thread (31) and between the longitudinal axis (I) and a thread crest (212) of the distal thread (21) are between 2.10 mm and 2.15 mm.

6. Surgical screw (1) according to claim 1, characterized in that the distances (dl, d2) respectively between the longitudinal axis (I) and a bottom thread (311) of the proximal thread (31) and between the longitudinal axis (I) and a thread crest (212) of the distal thread (21) are between 3.25 mm and 3.30 mm.

7. Surgical screw (1) according to one of claims 1 to 6, characterized in that the proximal portion (3) has a cylindrical region (32) and a conical region (33).

8. Surgical screw (1) according to claim 7, characterized in that the thread root (311) of the proximal thread (31) located substantially at the same distance from the longitudinal axis (I) as the thread crest (212) of the distal thread (21) is located in the cylindrical region (32) of the proximal portion (3).

9. Surgical screw (1) according to claim 7 or claim 8, characterized in that the cylindrical region (32) of the proximal portion (3) has a longitudinal dimension at least equivalent to twice the first thread pitch.

10. Surgical screw (1) according to one of claims 1 to 9, characterized in that the screw (1) has at least two cutting teeth (25) separated by a cylindrical opening (254) from the distal end (22) of the surgical screw (1), the attack surface (251) of one of the cutting teeth (25) being in the extension of the cylindrical opening (254).

11. Surgical screw (1) according to one of claims 1 to 10, characterized in that it has a bore passing through the screw (1) along its longitudinal axis (I).

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