Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • 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, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/683—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin comprising bone transfixation elements, e.g. bolt with a distal cooperating element such as a nut

Definitions

• the invention relates to a device for the fixation of bones or bone fragments, according to the preamble of patent claim 1.
• a bone screw which can be fixed in the bone by means of a nut resting on the bone surface opposite the screw head, is known from US 3,489,143 HALLORAN.
• This known bone screw has the disadvantage that the nut has a fixed support that is orthogonal to the longitudinal axis of the bone screw, so that angulations of the bone surface with respect to the longitudinal axis lead to a one-sided or even point-shaped support of the nut.
• the invention seeks to remedy this.
• the invention has for its object to provide a bone screw with locking means which have a variable angle with respect to the longitudinal axis of the bone screw support.
• the invention solves this problem with a device for the fixation of bones or bone fragments, which has the features of claim 1.
• the locking means can be screwed onto the external thread of the bone screw, whereby the number of necessary parts can be reduced to a minimum.
• the surface defines a surface that can be adjusted relative to the longitudinal axis of the bone screw within an angular range ⁇ in the range from 80 ° to 100 °, preferably from 85 ° to 95 °, so that the surface is in contact with the geometry of the bone is customizable.
• the locking means comprise at least one spring element that is elastically deformable parallel to the longitudinal axis.
• a plate spring is possible as a spring element.
• the spring element can also be designed as a spring ring, which has at least one radial slot with respect to the longitudinal axis. By designing the spring element as a spring ring, a maximum contact zone distributed over the circumference between the spring element and the bone surface can be achieved.
• the spring element is designed with a central bore having an internal thread, the internal thread being screwable via the external thread of the bone screw.
• the locking means comprise a nut and a spring element.
• FIG. 1 shows a view of an embodiment of the device according to the invention with a bone screw inserted into a bone
• FIG. 2 shows a section through the unloaded locking means of the embodiment of the device according to the invention shown in FIG. 1;
• FIGS. 1 and 2 shows a section through the loaded locking means of the embodiment of the device according to the invention shown in FIGS. 1 and 2;
• FIG. 4 is a view of another embodiment of the device according to the invention with a bone screw inserted into a bone;
• FIG. 5 shows a section through a further embodiment of the device according to the invention.
• FIG. 6 shows a section through the spring element of an embodiment of the device according to the invention.
• Fig. 7 is a plan view of the spring element shown in Fig. 6;
• FIG. 1 an embodiment of the device according to the invention is shown, which essentially comprises a bone screw 1 with a longitudinal axis 2, a screw head 21 at the rear end 5 and an external thread 3, and as a locking means 6 a coaxial to the longitudinal axis 2 from the front end 4 of the bone screw 1 on the external thread 3 screwable disc spring 8 comprises.
• the bone screw 1 can be used, for example, for the fixation of two bone fragments 22; 23, the screw head 21 resting on the outer bone surface 18 of the first bone fragment 22 and the support 7 of the fixing means 6 being able to be brought into contact with the outer bone surface 17 of the second bone fragment 23 ,
• the plate spring 8 has a central bore 9 with an internal thread 10 matching the external thread 3. As shown in FIGS.
• the plate spring 8 comprises an inner flat segment 15 concentric with the longitudinal axis 2 and an outer segment 15 surrounding the inner segment 15 with the longitudinal axis 2 Concentric hollow truncated cone-shaped segment 16.
• half the cone angle ⁇ of the outer segment 16 is between 45-90 °. Due to the hollow truncated cone-shaped configuration of the outer segment 16, this lies only on its outer circumference on the bone surface 17, so that the plate spring 8 receives a linear contact with the bone surface 17.
• the plate spring 8 consists of a spring metal, so that the outer segment 16 is elastically deformable parallel to the longitudinal axis 2.
• a case as shown in Fig. 3 obliquely i.e. Bone surface 17 not perpendicular to the longitudinal axis 2 can adapt to the outer segment 16 due to its elastic deformability, so that it rests on the entire circumference of the plate spring 8 despite the inclined bone surface 17.
• the plate spring 8 expediently has an outside diameter in the range from 3 to 25 mm, preferably from 5 to 20 mm.
• the embodiment of the device according to the invention shown in Fig. 4 differs from the embodiment shown in Figs. 1 to 3 only in that the locking means 6 between the bone surface 17 and the front end 4 of the bone screw 1 in succession a disc spring 12 for contacting the Bone surface 17 and a nut 11 screwable onto the external thread 3 of the bone screw 1.
• the plate spring 12 has a central bore 14 without an internal thread and is displaceable on the bone screw 1 parallel to the longitudinal axis 2.
• FIG. 5 shows an embodiment of the device according to the invention, which comprises only one nut 11 as the fixing means 6.
• the nut 11 has a central bore 24 with an internal thread 13, the internal thread 13 having only a single thread. Furthermore, there is play between the internal thread 13 and the external thread 3 of the bone screw 1, so that the nut 11 can be screwed obliquely over the external thread 3.
• the locking means 6 designed as a nut 11
• a face 7 is formed by the end face 25 of the nut 11 adjoining the bone surface 17, which defines a circular surface 19.
• the angle ⁇ between the end face 25 of the nut 11 lying against the bone surface 17 and the longitudinal axis 2 of the bone screw 1 is variable within an angular range of 80 ° ⁇ ⁇ 100 °. As a result, a support 7 of the nut 11 can be produced on the entire circumference of the nut 11.
• the play between bone screw 1 and nut 11 can be controlled by various parameters.
• the pitch of the internal thread 13 and the external thread 3 should expediently have the same pitch, while the flank angle, the core and thread groove diameter of the two threads can be changed within suitable limits.
• the spring ring 26 comprises a planar circular disk-shaped central part 31 with a central bore 30 which is coaxial with the longitudinal axis 2 of the bone screw (FIG. 1) and four tongues 28 which are angled at an angle ⁇ with respect to the longitudinal axis 2 and which are separated by radial slots 27.
• the angle ⁇ can be between 45 ° and 90 ° be.
• the tongues 28 are elastically deformable parallel to the longitudinal axis 2 and each have an edge 32 at their free ends 29.
• FIG. 8 shows a further embodiment, in which the fixing means 6 comprise a bone plate 35 with a lower surface 36, which can be brought into contact with the bone surface 17, and an upper surface 37 and a nut 11.
• the nut 11 can be screwed onto the external thread 3 of the bone screw 1 and serves to fix the bone plate 35 to the bone.
• the bone plate 35 comprises a central bore 38 which extends from the lower surface 36 to the upper surface 37 and widens towards the upper surface 37 with a spherical cavity 40 which is concentric with the longitudinal axis 2.
• the nut 11 has a spherically convex curvature 39 which is complementary to the cavity 40.
• the bone plate 35 can be rotated about the center of the spherically convex bulge 39 relative to the bone screw 1 before the nut 11 is tightened with respect to two axes orthogonal to one another and perpendicular to the longitudinal axis 2, so that the lower surface 36 of the bone plate 35 unites with the longitudinal axis 2 Angle ß ⁇ 90 °.
• FIG. 9 again shows a further embodiment, in which the fixing means 6 comprise a bone plate 35 with a spherical cavity 40, in which a radially elastically deformable insert 45 can be moved polyaxially, and a nut 11, by means of which the insert 45 can be expanded.
• the bone plate 35 has an upper surface 37, a lower surface 36 serving to abut the surface of a bone and has a central bore 38 penetrating the bone plate 35 from the upper surface 37 to the lower surface 36 and having the spherically concave cavity opening into the upper surface 37 40 on.
• the insert 45 is toroidal and is radially elastically deformable with respect to the longitudinal axis 2.
• This radial deformability is produced here, for example, by four slots 47 distributed over the circumference.
• the slots 47 run parallel to the longitudinal axis 2 and penetrate from the end face to a depth T in Insert 45 a.
• the insert 45 has a central bore 46, which is coaxial with the longitudinal axis 2, conical and tapers against the lower surface 36 of the bone plate 35.
• the nut 11 can be screwed onto the external thread 3 of the bone screw 1 and has an external cone 48 which is complementary to the conical central bore 46 of the insert 45. By tightening the nut 11, the outer cone 48 is pressed into the conical central bore 46 in the insert 45, as a result of which the latter is radially expanded and jammed in the cavity 40.

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)
• Connection Of Plates (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

Family

ID=33102855

Family Applications (1)

Country Status (5)

Cited By (1)

Citations (4)

• 2003
  • 2003-04-02 AU AU2003212181A patent/AU2003212181A1/en not_active Abandoned
  • 2003-04-02 WO PCT/CH2003/000215 patent/WO2004086989A1/de not_active Application Discontinuation
• 2004
  • 2004-03-12 TW TW093106676A patent/TW200507798A/zh unknown
  • 2004-03-29 AR ARP040101035A patent/AR043948A1/es unknown
  • 2004-03-30 CL CL200400672A patent/CL2004000672A1/es unknown

Patent Citations (4)

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