Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
  • A61B17/86—Pins or screws or threaded wires; nuts therefor
  • A61B17/8645—Headless screws, e.g. ligament interference screws
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws or setting implements
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
  • A61B17/86—Pins or screws or threaded wires; nuts therefor
  • A61B17/8625—Shanks, i.e. parts contacting bone tissue
  • A61B17/863—Shanks, i.e. parts contacting bone tissue with thread interrupted or changing its form along shank, other than constant taper

Definitions

• the present invention relates to self-compressive screws, and advantageously self-tapping screws, for joining two portions of bone with a view to carrying out an osteosynthesis between these two portions of bone.
• the screw rod is screwed into a first of the two portions of bone, until it crosses it, then partially penetrates the second portion of bone, and a nut or the like is screwed on the end of the part of the rod which emerges of the first portion of bone.
• the main drawback lies in the fact that, in the case of small bones, it is very difficult if not impossible to retract the part of the screw which emerges with the nut, with the risk of injuring the flesh surrounding the bone portions to reunite.
• the present invention therefore aims to achieve a self-tapping and self-compressive screw to join two portions of bone in order to obtain osteosynthesis between these two portions of bone, which largely overcomes the drawback mentioned above.
• bone screws of the prior art having a relatively simple structure minimizing the number of constituent elements compared to the screws of the prior art, while allowing very good self compression to be obtained.
• the present invention relates to a self-compressive screw for joining two portions of bone in order to achieve osteosynthesis between these two portions of bone, comprising a screw rod defined on an axis of revolution, and two first and second threads made on said screw rod, these two first and second threads being centered on said axis of revolution, characterized in that the first casing in the form of a hollow cylindrical of revolution defined by the first thread between the bottom and the the top of its thread is entirely included in the second envelope in the form of a hollow cylindrical revolution defined by the second thread between the bottom and the top of its thread, and that the pitch of the first thread is smaller than the pitch of the second thread.
• the three figures 1 to 3 are representations in longitudinal half-section according to a conventional representation well known in industrial drawing, of a part of revolution or substantially of revolution,
• FIG. 1 representing the block diagram of a self-compressive screw according to the invention
• FIG. 2 representing a diagram making it possible to understand the operation of the self-compressive screw according to the invention
• FIG. 3 showing, in schematic form, a preferred embodiment of the self-compressive screw according to the invention.
• the screw according to the invention relates to a self-compressive screw for joining two portions of bone O s for the purpose of osteosynthesis between these two portions of bone.
• This screw comprises a screw rod 1 defined on an axis of revolution 2 and two first and second threads 11, 22 produced on the screw rod 1, these two first and second threads being centered on the axis of revolution 2.
• the first casing 15 in the form of a hollow cylindrical of revolution centered on the axis 2 and defined by the first thread 11 between the bottom 12 and the top 13 of its thread 14 is entirely included in the second casing 25 in the form, too, of a hollow cylindrical revolution centered on the axis 2 and defined by the second thread 22 between the bottom 23 and the top 24 of its thread 25.
• the pitch Pu of the first thread 11 is smaller than the pitch P 22 of the second thread 22. It is specified that the two threads 11, 22 produced on the rod 1 can be consecutive without space separating them, but that they can also be followed by being separated for example by a smooth part of the rod.
• the internal diameter of the first envelope 15 is substantially equal to the interior diameter of the second envelope 25.
• the difference between the outside diameter and the inside diameter of the first envelope 15 is substantially equal to half the difference between the outside diameter and the internal diameter of the second casing 25, and the pitch Pu of the first thread 11 is substantially equal to half of the pitch P 22 of the second thread 22.
• the end 16 of the first thread 11 opposite that 17 which faces the second thread 22 it is shaped at the gripping end 18 by a screwing tool.
• This end 16 may comprise, as illustrated, a slot, a polygonal housing, etc., with which a tool such as a screwdriver or the like can cooperate without it having been necessary to produce a shoulder head as for conventional screws.
• a screwdriver is a well-known ancillary in the field of bone repair surgery.
• the screw rod 1 and the two first and second threads 11, 22 are made in one piece from a biocompatible material such as titanium or a titanium alloy.
• FIG. 2 represents the thread 30 obtained in the first portion of os O s after passing the second thread 22.
• the second thread 22 of the screw penetrates into the second portion of bone and, by self-tapping, is also screwed there.
• the first thread 11 is screwed into the thread 30 produced with the second thread in the first portion of bone, as illustrated in FIG. 2.
• the first thread 11 has a pitch smaller than that of the second thread 22
• the movement of recoil of the second portion of bone being of greater amplitude than that of the first portion of bone since, structurally, the step P 2 2 is greater than the step Pu.
• the difference in relative recoil of the two bone portions is in fact proportional to the difference in the values of the two steps Pu and P 22 .
• the screwing of the screw is carried out by the gripping head 18, as mentioned previously.
• the screw according to the invention has other advantages than those mentioned above. In particular, it does not require the screwing of a nut on the end of the screw rod emerging from the first portion of bone. After the screw has been screwed into the two bone portions and the compression force has been carried out by the practitioner, this emerging part of the screw rod 1 can be cut flush with the first portion of bone, without a portion dangerously protruding into the surrounding flesh.
• the screw according to the invention may advantageously include screwing-unscrewing means so that it can easily undergo a screwing extra after its emerging end has been cut or unscrewed after being implanted.
• These screw-unscrewing means to obtain the above-mentioned goals can be constituted by at least one longitudinal flat parallel to the axis of the screw rod produced on the first thread 11, this flat being able to serve as a grip for a clamp. or the like to drive the screw in rotation in one direction or the other as required.

Landscapes

• Health & Medical Sciences (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Surgery (AREA)
• Life Sciences & Earth Sciences (AREA)
• Heart & Thoracic Surgery (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Neurology (AREA)
• Medical Informatics (AREA)
• Molecular Biology (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Surgical Instruments (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2003
  • 2003-05-30 FR FR0306559A patent/FR2855391B1/fr not_active Expired - Lifetime
• 2004
  • 2004-05-17 US US10/558,646 patent/US20080015595A1/en not_active Abandoned
  • 2004-05-17 EP EP04742753A patent/EP1631208A2/de not_active Withdrawn
  • 2004-05-17 WO PCT/FR2004/001205 patent/WO2004107999A2/fr not_active Ceased
  • 2004-05-17 JP JP2006508339A patent/JP2006525844A/ja active Pending

Non-Patent Citations (1)

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