WO2007098631A2

WO2007098631A2 - External fixing element

Info

Publication number: WO2007098631A2
Application number: PCT/CH2007/000105
Authority: WO
Inventors: Oskar E. Illi
Original assignee: Illi Oskar E
Priority date: 2006-03-03
Filing date: 2007-03-01
Publication date: 2007-09-07
Also published as: EP1991142A2; WO2007098631A3; CH714281B1

Abstract

The invention relates to an external fixing element which comprises a fixing bar (3) onto which two fixing units (2) are fixed in relation to each other in any position. Said fixing units (2) comprise a clamping part (5) in which Schanz screws are held in a clamped manner, and a runner-part (6) which comprises a housing (7) in which a ball (8) is mounted. The Schanz screws (4) are fixed to the clamping part (5) by means of a clamping screw (22) whilst a stop screw (14) presses onto the ball (8), thus allowing the position of the Schanz screws (4) to be fixed in relation to the fixing bar (3) both in the transversal direction aswell as in each angular position in relation to said fixing bar (3). All parts are suitable for mass production, where they can be produced as plastic or metal pressure parts thus providing an exceptionally economical external fixing element which is both suitable for use as a disposable item and which can be easily used by the operator.

Description

External fixator

The present invention relates to a fixator for external repositioning and stabilization of bone fragments, comprising a fixator rod, a clamping unit for clamping support of two Schanz 'see screws or nails, wherein the clamping unit is connected to a rider member which is displaceable on the fixator and around the Fixateurstablangsach.se is pivotable.

External Fixteure of the aforementioned type are known in various embodiments. Typical examples of this type are shown, for example, in WO 2004/045451 (Amei Technologies Inc.), German Patent Application DE-A-3614305 or EP-AO '695' 538. Finally, EP-A-0'630 '214 also shows a external fixator of the type mentioned. Of the documents mentioned, with the exception of DE-A-3614305, all documents show external fixators which are suitable for use in hand or foot surgery. A basic problem for external fixators in this area of application is on the one hand the required smallness of the Construction and on the other hand, the X-ray permeability to control the reduction and retention. In addition, the majority of known constructions is extremely complicated and contains a large number of different components. This variety of components requires a costly disassembly after use or before sterilization and then again a correspondingly complex assembly of the individual components. The complexity of these constructions also makes it impossible to use the fixatives as disposable solutions. The multiplicity of individual parts, however, increases the risk that some of these parts will be lost, and then the entire external fixator will be unusable accordingly. Since the assembly takes place practically only at the operating table, it is extremely unpleasant when it is determined only during assembly that parts are no longer available. Accordingly, physicians tend to dispose of such external fixators after use contrary to the concept. In addition, removal of the external fixator is often performed by another physician and not at the site where the fixator has been placed externally. In any case, reuse is illusory anyway. In particular, a family doctor will take as far as possible no hand-surgical measures and thus has no need for an external fixator for hand or foot surgery. Based on these considerations, the object of the present invention is to provide an external fixator for the hand or foot surgery, which has a particularly simple structure, is correspondingly inexpensive to produce and thus can be used for the realistically required disposable use.

Another object of the present invention is to disclose a solution which is also suitable for being configured with a fixator rod made of X-ray permeable material.

In addition, it is particularly desirable to design the construction in such a way that it is ensured that the disposable external fixator designed for single use can certainly not be used for multiple use.

The first main task of a simple and inexpensive construction solves the invention by means of an external fixator, which has the features of the preamble of claim 1 and is characterized in that the fixator rod has a non-round cross section and the rider part comprises a housing by a ball stored is, which is penetrated by the fixator rod and wherein the clamping unit consists of an integrally connected to the rider part.

This solution provides a simple design principle in which two otherwise separate and relative to each other via a or multiple joints connected parts are assembled into a simple component. Further advantageous embodiments of the subject invention will become apparent from the dependent claims and their meaning and operation is described in detail in the appended description with reference to a preferred embodiment shown in the accompanying drawings. It shows:

FIG. 1 shows an external fixator consisting of a fixator rod and two fixation units;

FIG. 2 shows a plan view of a fixing unit according to FIG. 1, while FIG

Figure 3 illustrates such a fixing unit in the side view, wherein the viewing direction is parallel to the longitudinal axis of the fixator rod. Finally, the shows

Figure 4 shows a central cross section through a

Fixation unit parallel to the longitudinal axis of the fixator rod.

The external fixator according to the invention, which has been developed in particular for hand and foot surgery, is denoted overall by 1. It includes on the one hand

Fixator bar 3, on which at least two fixation units 2 are held displaceable and fixable. Each fixing unit 2 comprises in each case a clamping part 5 and a rider part 6. The rider part 6 has a housing 7 which, however, by no means necessarily has an external annular shape, in particular a circular-cylindrical annular shape and whose inner surface is spherically curved to receive a ball 8 Ball 8 is penetrated by a diametrically this piercing opening 10. The diametrical opening 10 is designed in cross section corresponding to the cross section of the fixator rod 3. In order to prevent a rotary movement of the fixator rod 3 in the diametrical opening 10, it is advantageous to give the cross section of the diametrical opening 10 a non-round shape. In the present example, this diametrical opening 10 is provided with a rectangular cross section and, accordingly, the fixator rod 3 is provided with such a cross section.

The ball 8 in the housing 7 of the rider portion 6 is preferably formed of two hemispheres 8 'and 8''. Accordingly, a separating gap 9 remains between the two hemispheres. The inner region of the separating gap 9, which extends over the diametrical opening, is widened so that here a deformation space 11 is created. The housing 7 of the rider part 6 has a threaded hole 13, which is arranged in the assembled state of the external fixator so that this runs with its central axis perpendicular to the plane passing through the separating gap 9 of the two Hemisphere 8 'and 8''is defined. In threaded hole 13 a locking screw 14 is mounted, which is provided here with a hexagon socket. If you pull the locking screw 14, so this presses on the hemisphere 8 ', at the same time the reaction force leads to a slight deformation of the housing 7 of the rider part, so that on the one hand by the locking screw 14, the two hemispheres 8' and 8 '' are compressed and This thus secure the fixator 3 against a transverse displacement, while at the same time by the deformation of the housing 7, a rotation of the ball 8 in the rider part 6 is impossible. The deformation space 11 simultaneously increases the deformability of the ball 8 and increases the specific surface pressure between the two hemispheres 8 'and 8''. If one loosens the locking screw 14, the housing 6 and the two hemispheres 8 'and 8''elastically deformed back and the fixator rod 3 can be translationally move in the diametrical opening 10, while at the same time the entire fixing unit 2 in all directions or can twist or swivel to the fixator 3. Here, the system is designed so that even with not tightened locking screw 14, the two hemispheres 8 'and 8''with a small bias to each other and press on the fixator rod, so that these parts are indeed relative to each other displaced or rotated or pivoted However, these movements are all self-locking and only at Application of a certain force to be applied by the surgeon relative to each other are movable.

Thus, the threaded hole 13 has a sufficient length to apply a high force by means of the locking screw 14 on the underlying hemisphere 8 ', the annular housing 7 of the rider portion 6 in the region of the threaded hole 13 has a housing thickening 15.

On the annular housing 7 of the rider part 6, viewed from the housing thickening 15, offset by 90 ° to the side, a clamping part 5 is formed on the rider portion 6. This clamping member 5 has a plate-like shape and is practically tangentially integrally formed on the annular housing 7 of the rider portion 6. The thickness of the plate 16 is one and a half to twice as thick as the largest diameter of the usable Schanz 'see screws or nails. The maximum diameter of such Schanz screws or nails is 2 - 2.4 mm, while the thinnest to be used screws are approximately between 1 - 1.5 mm. In particular, these areas will vary depending on whether the external fixator is for hand or foot surgery, or whether the patient is a child or an adult patient. The plate 16 of the clamping member 5 has a longitudinal orientation which is perpendicular to the central diametrical plane of the annular housing 7 of the rider portion 6. The length of this plate 16 of Clamping part 5 is greater than the width of the annular housing 7 of the rider part. In this way, a greater relative distance between the two Schanz 'see screws allows, namely in particular a size of, for example, 10 - 15 mm, although the width of the annular housing 7 of the rider portion only has a width of about 5 - 8 mm. Over the plate 16 of the clamping member 5, a clamping cap 18 is slipped. This clamping cap 18 has substantially the shape of a U-profile, wherein the two side legs 19 rest against the lateral longitudinal edges of the plate 16. These two legs 19 can be slightly spread apart, so that the cap 18 can be easily put on and press so far on the plate 16 until the legs 19 laterally clamped. In the side legs 19 conical receiving slots 21 are formed, which extend from the top surface 20 of the terminal cap 18 to its lower ends conically. This conical extension of the receiving slots 21 serves to clamp Schanz 'see screws with different diameters. Accordingly, the conical receiving slots 21 are designed so that they are in their narrowest area near the top surface 20 smaller than the smallest diameter of the male Schanz 'see screws or nails, while the lowest widest opening is larger than the largest male Schanz' see screws or nails. A centric hole in the clamping cap 18 allows a clamping screw 22 through the clamping cap 18th through which opens into a threaded hole in the plate 16. The clamping screw 22 is used solely for the clamping of the Schanz 'see screws 4 or nails in a desired relative position on the fixing unit. 2

In principle, the entire external fixator 1 with the exception of the two screws 14 and 22 and the Schanz 'see screws 4 or nails can be made entirely of plastic. Preferably, however, the one-piece manufactured clamping and riding parts 5 and 6 are made of metal. This allows higher powers to be transmitted. In addition, in turn, the entire external fixator can be made smaller in turn. In particular, the clamping part and the rider part 5 or 6 can be made as a metal casting or metal diecasting. This allows a very reasonably priced production. However, if one manufactures clamp part and rider part together from plastic, it is preferable to use a high-strength plastic possibly reinforced with glass fibers. However, in this case too, it will be preferable to manufacture the clamping cap 18 from metal.

Thanks to the configuration of the external fixator shown here, it is possible to produce the fixator rod 3 from a radiolucent material. Preferably, one will use a carbon rod. When using Fixateurstäben of carbon fiber material is advantageously used a fixator rod with a rectangular cross-section. Here, the longer edge of the cross section should be aligned parallel to the direction of Schanz 'see screws or nails. Thus, the larger cross-section is used to accommodate the flexion and extension movements of the hand, as these movements are exerted with greater force and accordingly blocked due to the larger diameter accordingly. The abduction and adduction movements exerted with substantially smaller forces are then absorbed by the fixator rod in the direction of the smaller diameter. If this small movements can take place anyway, this is not only unproblematic but almost desirable because this micro-movements in the fracture area can occur, which are known to promote the healing process.

The press-on clamping cap should never be made of plastic. For the manufacture of the supernateable, compressible terminal cap is particularly suitable a solution of metal, in which case a medical steel in particular comes into question. But the terminal cap can also be made of a relatively hard aluminum. If in such a clamping cap made of an aluminum alloy

Unscrewing a remaining deformation occurs, so this is by no means problematic, since the entire external Fixator according to the invention is designed as a disposable solution. The solution shown here can be produced practically less than one third of the production costs of known external fixatives. Thanks to this cost saving, assembly, sterilization and reassembly are no longer worthwhile. Disposable use will definitely be much cheaper, even if you compare this with a multiple use of a conventional fixator. In addition, wearing comfort is much more pleasant because the total weight of the solution is reduced by more than 50% compared to a conventional all-steel solution. In addition, the individual components are smaller overall, which again weight savings take place.

Another advantage of the inventive fixator is the extremely simple application. The surgeon can practically use the fixing unit 2 directly before placing on the fixator 3 as a jig, he can monitor the repositioning of the fracture parts during setting of the external fixator by means of an X-ray machine, without him while the fixator rod is in the way. If the surgeon has drilled the holes for setting the Schanz screws, he screws in the Schanz screws, puts the fixation unit on top with the already used fixator rod. He is still completely free to perform all pivoting and shifting movements. As soon as the external fixator 1 is put on, it pulls

- li - by means of the clamping screw 22, the terminal cap 18 and as soon as the desired position of the fixing unit 2 is set relative to the Schanz 'see screws or to the fixator 3, the locking screw 4 is tightened in one of the two riding parts 6. Now, the surgeon can still move the second fixation unit on the fixator rod 3 relative to the fixation unit 2 already fixed in position to or away from it, thus adjusting a tensile or compressive force in the region of the fracture according to his wishes, whereupon he then only at the second fixing unit whose locking screw 14 also has to tighten. This extremely user-friendly use reduces the time of surgery and thus the traumatic influences on the patient.

List of reference numbers:

1 external fixator

2 Fixing unit 3 Fixator bar

4 Schanz's screw or nail

5 clamping part

6 rider part

7 housing of the riding part 8 ball in the riding part housing of two hemispheres 8 'and 8' '

9 separating gap

10 diametrical opening

11 deformation space

12 fixator rod axis 13 threaded hole

14 locking screw

15 housing thickening

16 plate

17 receiving hole for Schanz 'see screw 18 clamping cap

19 side legs

20 top surface of the clamping cap

21 conical receiving slots

22 clamping screw 28 flat surfaces of the ball

Claims

claims

1. Fixator (1) for external repositioning and stabilization of bone fragments comprising a fixator rod (3) and at least two fixing units (2) with a clamping part (5) for clamping support of two Schanz 'see screws (4) or nails, said Clamping part (5) is connected to a rider part (6) which is displaceable on the fixator rod (3) and pivotable about the fixator rod longitudinal axis (12), characterized in that the rider part (6) comprises a housing (7) in which a Ball (8) is mounted, which is penetrated by the fixator rod (3), and wherein the fixing units (2) consists of a one-piece with the rider part (6) connected to the clamping part (5).

2. Fixator according to claim 1, characterized in that the fixator rod is made of X-ray permeable material.

3. Fixator according to claim 2, characterized in that the fixator rod is made of carbon fiber material.

4. Fixator according to claim 1, characterized in that the fixator rod has a non-round cross-section.

5. Fixator according to claim 1, characterized in that the fixator rod has a rectangular cross section, wherein the longer edges of the cross section can be aligned parallel to the direction of the Schanz 'see screws or nails.

6. Fixator according to claim 1, characterized in that the ball is separated by a diametrical parting plane into two hemispheres.

7. Fixator according to claims 5 and 6, characterized in that for receiving the fixator rod, the ball crossing opening extends so that the longer side surfaces of the fixator bar perpendicular and the shorter side surfaces of the fixator bar parallel to the diametric separation plane.

8. Fixator according to claim 1, characterized in that the rider part has the form of an annular housing having a spherically shaped inner surface, in which the ball is positively receiving.

9. Fixator according to claim 8, characterized in that the outer shape of the housing of the rider portion is a cylindrical ring and the integrally formed thereon clamping part a virtually tangential on the ring molded plate-shaped shape, wherein its length is greater than the width of the ring.

10. Fixator according to claim 1, characterized in that the clamping part comprises a überstülpbare, compressible clamping cap.

11. Fixator according to claim 10, characterized in that in the outer ends of the plate-shaped clamping part two parallel bores are present, which are larger than the maximum diameter of the Schanz 'to use therein screws or nails.

12. Fixator according to claim 10, characterized in that the slipped over the plate-shaped clamping part compressible clamping cap has a U-shaped configuration with a top surface which corresponds to the size of the plate-shaped clamping unit, and two side legs which run apart from the top surface with low inclination and thus by clamping on the clamping unit can be pressed.

13. Fixator according to claim 11, characterized in that in the side limbs of the clamping cap in the areas that come to lie in the two parallel holes, on both sides depending on a conical receiving slot is present, the largest width of the maximum diameter of Schanz 'see screws or Corresponds to nails and its

- is - smallest width is less than or equal to the minimum diameter of the Schanz 'to use screws or nails.

14. Fixator according to claim 1, characterized in that the combined housing of the rider and clamping part consists of an aluminum die-cast part.

15. Fixator according to claim I _7, characterized in that the combined housing of the rider and clamping part of

Plastic is made.

16. Fixator according to claim 13, characterized in that the clamping cap is made of medical steel.

17. A fixator according to claim 10, characterized in that in the annular housing of the rider portion offset by 90 ° to the plate of the clamping part a threaded hole is formed, in which a locking screw is inserted, which presses on the ball and the relative position of the rider part to the ball and through Traction secures the ball to the fixator bar.

18. Fixator according to claim 16, characterized in that the housing of the rider part in the region of the threaded hole has a thickening.