A system for fixation of fractures comprising an elastic chassis

SWEDEN (12) PATENTS (13) C2 (11) 522 202

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(19) SE (si)

International class ⁷

A61B 17/68, 17/56

PATENT AND REGISTRATION (45) (41) (22) (24) (62) (86) (86) (83)

Patent issued 2004-01-20

Application widely available 2003-04-30 The patent application was filed on 10/21/2001

Running day 2001-10-29

Tribal application number

International filing day

Filing date for European patent application

Deposit of microorganism (21) Patent Application Number 0103575-7

Application received as:

Swedish patent application completed international patent application with number □ converted European patent application with number (30) Priority information (73) (72) (74) (54) (56)

PATENT HOLDER General Orthopedics International AB, Box 16500 200 25 Malmö SE (57)

INVENTOR Carl-Göran Hagert, Bjärred SEE OMBUD Ström &amp; Gulliksson IPC AB

NAME Fracture fixation system PUBLICATIONS:

SE C2 509 703 (A61B 17/86), US A US A 603 713 (355/128), US A 954 US B 6 290 703 (A61B 17/70)

462 547 (24/192), 722 (177/52),

SUMMARY: ...

The present invention relates to a system for fixing fractures. The system comprises a chassis (1) and one or more fixing elements in the form of screws (2, 3) and / or pins (4). Each fixing element is received in the chassis in such a way that it is locked by friction with respect to movement in axial, rotational and angular directions. The friction is preferably given that the material of the chassis (1) has an elasticity which gives a locking effect by means of friction on the fixing elements (2, 3, 4).

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The numbers in brackets indicate international identification code, INID code. The letter within the clamp indicates the international document code.

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SUMMARY

The present invention relates to a system for fixing fractures. The system comprises a chassis (1) and one or more fixing elements in the form of screws (2, 3) and / or pins (4). Each fixing element is received in the chassis in such a way that it is locked by friction with respect to movement in axial, rotational and angular directions. The friction is preferably given that the material of the chassis (1) has an elasticity which gives a locking effect by means of friction on the fixing elements (2, 3, 4).

To be published with Fig. 1.

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Technical area

The present invention relates to a system for fixing fractures. The system is mainly intended for external fixation, but it can also be used for internal fixation. It can be used on any broken bone in humans and animals.

Previous technology

Bones with fractures are normally fixed using various internal fixings, external fixings or a plaster joint. All different fixing methods have both disadvantages and advantages.

Existing fixing systems often utilize metal plates that have pre-drilled, free holes, in which screws are received. The screws are pulled down against the metal plate, the underlying bone structure having to adapt to the hard, rigid metal plate. This can risk both deformation and dislocation of the bone structure. Because the known plates rest on the bone, blood circulation is disturbed. It is known to have plates with openings to reduce these problems.

The invention

It is an object of the present invention to provide a fixation system which avoids the problems of a rigid plate pressed against a bone structure.

A further object is to provide a fixation system which can be easily adapted to the position and shape of the actual fracture. It is also an object to provide an easy-to-use fixing system which has a relatively low cost.

The above objects are met by a system for fixing fractures comprising a chassis and one or more fixing devices. The fixing devices are screws and / or pins. Each fixing element must be received in

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The PAT.DOC chassis in such a way that it is locked by friction for movement in axial, rotational and angular directions.

Preferably, the chassis is made of a material that locks the fixing devices by friction.

The present invention will not cause any stress on the bone structure caused by the fixing force. It can be said that the invention extends the cortex to enable the fixing devices to be inserted. The chassis is placed at any distance from the bone structure. By the present invention, it is possible to transfer internal fixation to simpler external fixation.

The chassis is preferably made of a polymer and can be formed after the anatomy at the fracture area. The shape and thickness, etc., are much easier to vary in polymeric materials compared to details made of a metal. The system of the present invention can be manufactured at a much lower cost than metal products.

The system of the present invention is much more convenient for a patient to wear compared to, for example, a plaster dressing or any of the existing external fixings. The system can be used without locking a joint during healing if required and without exerting any force on the joint. The risk of having complications regarding a rigid joint after the fracture has healed is thus avoided.

The present fixation system can be used for any bone regardless of size and shape. The system has many benefits such as lesser requirements for rehabilitation, better healing and more comfortable wearing for the patient. The fixation system is normally in place for 5 to 6 weeks.

Further objects and advantages will become apparent to those skilled in the art upon reading the detailed description below of a preferred embodiment.

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PAT. DOC

Brief description of the drawings

The invention will be further explained below by way of example and with reference to the accompanying drawings. In the drawings:

Fig. 1 is a perspective view of a system for fixing according to a first embodiment of the present invention; Fig. 2 is a cross-sectional view of the system of Fig. 1; Fig. 3 is a perspective view of a second embodiment of the present invention; third embodiment of the present invention.

Detailed description of preferred embodiments

The system includes a chassis 1, one or more screws 2, 3 and one or more pins 4. In some embodiments, the chassis 1 is received in a stiffener 6.

The chassis 1 is made of a material that locks the inserted screws 2, 3 and / or the pins 4 by means of friction. All screws 2, 3 and pins 4 are locked for rotation, axial and angular movements. One material that can be used for chassis 1 is UHMWPE (ultra high molecular weight polyethylene). UHMWPE is generally approved for medical use both externally and internally and is also transparent to X-rays. Other materials having the same properties can also be used, for example different types of plastics.

The shape of the chassis 1 can be adapted to the size of the bone and the anatomical shape at the position of the fracture (s) to be fixed. Thus, there will be a wide range of different designs of the chassis 1 in terms of both size and shape.

The screws 2, 3 used will be of standard type. Screws 2, 3 of the same size can be used for the same chassis 1. The pins 4 used are also of a standard type. For small fracture parts and bones, pin 4 is preferably used, since a screw 2, 3 would cause additional

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fragmentation. As an example, pins 4 with a diameter of 2 mm have been inserted into channels with a diameter of 1 mm in the chassis 1. The channels will control the insertion of the pins 4 in the desired direction and, due to its smaller diameter, will lock.

When the fracture has been reduced satisfactorily, the chassis 1 is placed over the fracture area. Then holes are pre-drilled through the chassis 1, the skin and the bone structure 5. The chassis 1 can be provided with a number of holes in manufacture, which can be used if appropriate. In some embodiments, the chassis 1 will not be provided with holes in manufacture. A screw 2, 3 or pin 4 is then screwed into any desired pre-drilled hole. The chassis 1 is kept at any selected distance from the leg during and after fixation. The screws 2, 3 have the same pitch, which means that the chassis 1 will not move during fixation. Thus, there is always a distance between the body and the chassis 1. The chassis 1 will not be in direct contact with the underlying bone structure 5 or the skin.

Screws 2, 3 are screwed in synchronously, ie. the screws 2, 3 move equidistantly in the leg structure 5 and the chassis 1. Thus no forces are generated in the axial direction of the screws 2, 3 and a force-neutral fixation of the chassis 1 and the end structure 5 will be achieved. Pin 4 and additional screws 2, 3 are applied in the same manner at any position as desired by the surgeon. When the chassis 1 is fixed to the bone structure 5 on both sides of the fracture area, a bridge span is formed between the bone fragments. This bridge span will now ensure that the bone fragments are fixed and in a rigid state relative to each other. The formed bridge span can be described as a parallel movement of the cortex of the bone structure 5 to the outside, whereby it is possible to transfer internal fixation to external fixation when the system of the present invention is used. This transfer is much sought after by the number of surgical procedures

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The surgeon is free to position the screws 2, 3 and the pins 4 optimally, since he himself decides exactly where the holes are and thus the screws 2, 3 and the pins 4 should be placed during the actual operation. Previously known fixing devices or plates normally have openings, the location of which is given during manufacture. Thus, the surgeon must compromise on the placement of the prior art fixing elements. With the present invention, the surgeon in flight can determine where the optimum positions are for screws 2, 3 and pins 4.

The material in the chassis 1 provides a frictional force on the screws 2, 3 or the pins 4 sufficiently large to ensure that they are not unscrewed or unloaded in any other way. This is a problem with previous metal-made plates that have free holes.

The chassis 1 material is selected to provide sufficient bending stiffness to allow the fracture to heal. This bending stiffness eliminates the risk of breakage, which is a well-known complication for plates made of steel etc.

Figures 3 and 4 show two embodiments where the chassis 1, 7, 8 has been placed in a stiffener 6. The function of the guide 6, preferably made of steel, is to increase the bending stiffness.

The only difference between the embodiments of Figures 1, 2 and 3 is the stiffening.

In the embodiment of Fig. 4, the chassis 1 has been divided into two chassis parts 7, 8. A gap is formed between the chassis parts 7, 8 and the chassis parts 7, 8 can move in an axial direction towards and away from each other. The purpose of the two chassis parts 7, 8 is that in some cases it may be desirable to have a compression or distraction force at. fracture. Whereby the chassis sections 7, 8 are to be moved against

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away from each other after fixation at the bone structure 5 with the fracture. In all other respects, this embodiment corresponds to the other embodiments.

Although the present invention is described in connection with external fixation, one skilled in the art will recognize that it can also be used for internal fixation.

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NEW PATENT CLAIMS