WO1990011055A1

WO1990011055A1 - External fixation

Info

Publication number: WO1990011055A1
Application number: PCT/HU1990/000019
Authority: WO
Inventors: Péter TATÁR; László ÖRDÖGH; István KÁDAS; Péter FRÖHLICH; István Szigeti
Original assignee: Tatar Peter; Oerdoegh Laszlo; Kadas Istvan; Froehlich Peter; Szigeti Istvan
Priority date: 1989-03-14
Filing date: 1990-03-14
Publication date: 1990-10-04
Also published as: HUT62777A; HU209061B; AU5287490A

Abstract

In a known fixateur externe for osteosynthesis and for healing of bone fractures, implantations driven into the bones to be fixed and guiding rods as well as fixing elements connecting the implantations and the guiding rods to each other are comprised. According to the invention, the fixing elements have tension jaws (2, 3) fixing the implantations and the guiding rod (29, 30) to each other by detachable connection and being parts of a ball joint as well as means for stiffening the ball joint in a desired position.

Description

EXTERNAL FIXATION

Field of the Invention

This invention relates to a fixateur externe for osteosyπthesis and for healing of bone fractures comprising implantations drawn into the bones to be fixed and guiding rods as well as fixing elements connecting the implantations and the guiding rods to each other.

Background of the Invention

As is well known in this field of the art, the broken ends of a bone in case of a fracture have to be fitted together. In simpler cases, this is carried out by the conventional plaster-bandage, in more complicated cases, however, an operative bone reunion is necessary.

But in some cases, neither the plaster-bandage, nor the operative bone reunion can be used. For example, if injuries of soft parts complicated with bone fracture do not allow the application of the plaster-bandage because of the injury of the soft parts, nor the simple operative bone reunion because of the increased danger of infection, the so called fixateur externe will find application. With this, the broken bone parts are provisionally fixed from outside the human body and the load carrying function of the broken bone is taken over by an outer frame.

In the case of all of the known fixateur externe, implanta¬ tions such as Schanz screws or Steinmaπn nails made of tissue-friendly material are drawn into the healthy bone parts by boring holes into them and screwing or striking the implantations in. The implantations are than connected to each other by guiding rods outside the body. After the implantations and, with this, the broken bone parts being positioned, the implantations and the guiding rods are fixed to each other by fixing elements.

In one of the conventional fixateur externe, each fixing element has a vice and a joint. It is advantageous in this system that quite few parts are necessary but only in simple cases. More complicated montage can be built only with difficulties and with the application of numerous parts. Therefore, these montages are weighty and not stable enough. Furthermore, only the contraction and distraction can be carried out as corrections of the fixture and only with special tools.

The weight of the montage is lessened in another solution, wherein tubes are used instead of guiding rods. The fixing elements, however, are basically not different, thus, repositioning the fractures is not possible, neither the torsion can be corrected.

In another fixing element, more than one implantations or guiding rods can be clamped and their position can be varied. However, only contraction and distraction are possible herein, too and only with the interconnection of a special part. It has been also suggested to use curved guiding rods, but their load carrying capacity proved to be insufficient.

In summary, the conventional fixateur externe have numerous problems. When one or more vices get loose, the bone pieces can get unconveniently displaced since the loose elements can move on the guiding rods practically uπlimitedly. Further¬ more, the movement being necessary to tighten the vices falls in the same direction as one possible direction of adjustment of the montage. Thus, the arrangement can be moved out of the justified position when fixing the vices. When loosening the central screw of the vices, the pressure force of the loosening movement results sometimes in collapse of the entire assembly.

A provisional assembly of the elements of the known fixateur externe is not possible, too. With this, however, a pre- assembled montage could be provided for the surgeon and in the operative area, only final justification would be necessary .

It is also negative, that in the known systems, auxiliary vices can not be applied in between existing vices of assembled montages, only after total decomposition.

It is a grave disadvantage that the spatial inaccuracy of the positions of the implantations resulting from the hand-made bores in the bones can not be equalized with the known systems. This causes harmful additional inner tensions of the montage.

The practice has shown that further and new needs should be solved by a fixateur externe. First of all, correction of bone parts during the therapy is necessary not only in the axle direction of the bone (contraction and distraction) but also in angle positions of the extremity in forward and backward as well as in inside and outside directions, and its torsional displacement, too. Furthermore, the dynamization in form of a unilateral motion should be provided for all bones. Essence of the Invention

The main object of the invention is to eliminate the above mentioned deficiencies of the conventional assembles as well as to solve the newly emerged requirements and to provide a fixateur externe for osteosyπthesis and for healing of bone fractures which has very few components and, nevertheless, a greater flexibility than the previous solutions, and which can easily be used in all operative situations.

According to the improvement of the known fixateur externe in this invention, the fixing elements have tension jaws fixing the implantations and the guiding rods to each other by detachable connection and being parts of a ball joint as well as means for stiffening the ball joint in a desired position.

In a preferred embodiment of the fixateur externe in this invention, the tension jaws have a U-like groove for accommodating the implantations or the guiding rods and opposite to the U-like groove, a spherical surface, and the fixing elements have holding plates each having a spherical groove for supporting the spherical surface of the tension jaws. The U-like grooves can have dimensions for accommo¬ dating the implantations or the guiding rods, respectively, with tight fit or the U-like groove can be tighter at its outer opening than elsewhere for snap-in of the implantations or guiding rods. For dynamization purposes, the U-like groove of the tension jaws accommodating the guiding rods can be wider by at least 0,05 mm than the diameter of the guiding rods.

The embodiment of the invention is also preferred, wherein the spherical grooves of each holding plate has a bore at its middle part and the bore is provided with an inner thread, and each tension jaw has an extension at a middle part of the spherical surface comprising a head portion provided with an outer thread fitting into the inner thread of the bore as well as a neck portion between the head portion and the spherical surface having a smaller diameter than that of the bore.

It is also preferred according to the invention, when the holding plates are attached to each other by braces pivotally jointed to opposite sides of the holding plates, and a length of at least one of the braces is variable. In this case, it is preferable when the pivotal joints between the holding plates and the braces are made for having a loose fit providing a spatial backlash between the parts connected to each other by the joints.

In a preferred embodiment of the fixateur externe in this invention, the brace with variable length is formed as a screw and a nut attached to each other, and the screw is pivotally jointed with loose fit in one of the holding plates and the nut is attached to the other holding plate by detachable connection. In this case, the embodiment of the invention is also preferred, wherein the nut of the brace with variable length has a head portion connected to the holding plate and a neck portion attached to the head portion, and the head portion has a spherical surface at the connection of the neck portion and the holding plate has a seat with a spherical hollow having a hole in its middle for letting through the neck portion of the nut.

It is also preferred, when a slit starting from the hole is provided in the holding plate in a plane of rotation of the brace with variable length, and the slit is at least as bright as the hole. In a preferred embodiment, the head portion of the nut has an orifice or at least on a part of the nut a hexagon outer surface is provided for connection of a tightening tool.

In a preferred embodiment of the fixateur externe in this invention, the braces have impact surfaces at the pivotal joints for providing a uπiplanar arrangement of all parts of the fixing element in its open position.

It is finally preferred, when the screw has a further impact surface cooperating with the holding plate at their pivotal joint for determining a perpendicular position of the brace to the holding plate.

Brief Description of the Drawing

Further objects and details of the invention will be de¬ scribed hereinafter on the basis of preferred examples with reference to the accompanying drawing, in which:

Fig. 1 shows a portion of a preferred embodiment of the fixateur externe in this invention: the fixing element in dismounted position,

Fig. 2 is the same portion: the fixing element in mounted position and in perspective view,

Fig. 3 is the same portion but in cross section,

Fig. 4 illustrates the fixateur externe in this invention in an application situations. Detailed Description of the Preferred Embodiment

Fig. 1 shows a fixing element 1 in dismounted situation. Two tension jaws 2, 3 are taken out of their seats formed in holding plates 4, 5. One tension jaw 2 is formed for accommodating an implantation, the other tension jaw 3 for hosting a guiding rod. The difference between the tension jaws 2, 3 is in the dimensions of U-like grooves 6 , 1 provided in the tension jaws 2, 3, respectively.

In the rule, U-like grooves 6, 7 have the same width as the implantations or the guiding rod with a great accuracy. In the most convenient case, the orifice of the U-like grooves 6, 7 defined by the outer ends of the legs of the U-form is narrower by e. g. 0,05 mm than the other parts of U-like grooves 6, 7. With -this, the implantations or the guiding rod can be snapped into U-like grooves 6, 7 and the guiding rod or the implantation will not fall out accideπtly.

Tension jaws 2, 3 have cylindrical mantels 8 the diameter of which is preferably the same for tension jaw 2 as for tension jaw 3. Into one of the base plates of the cylinder, the U- like grooves 6, 7 are worked in. Oppositely to U-like grooves 6, 7, a spherical surface 9 and means for attaching tension jaws 2, 3 to holding plates 4, 5 are provided. Spherical surface 9 and the attaching means are the same for all tension jaws 2, 3 providing the iπterchaπgeability of these elements .

In this embodiment, the attaching means has an extension 10 in the middle of spherical surface 9 comprising a head portion 11 provided with an outer thread as well as a neck portion 12 between head portion 10 and the spherical surface 9. Neck portion 12 has a smaller diameter than that of the outer thread of head portion 10.

In operational position as shown in Figs. 2 and 3, tension jaw 2 is attached to holding plate 4 and tension jaw 3 to holding plate 5. Each of holding plates 4, 5 has a spherical seat 13 (fig. 1) having the same shape as spherical surfaces 9 of tension jaws 2, 3 and supporting them. In the middle, let's say, at the lowest point of spherical seat 13, a bore 14 is made with an inner thread. The outer thread of extension 10 of tension jaws 2, 3 fits into the inner thread of bore 14 of holding plates 4, 5.

Holding plates 4, 5 are attached to each other by braces 15, 16 pivotally jointed in opposite sides of holding plates 4, 5. In this example, the length of brace 16 is variable and brace 15 is a fix element. Holding plates 4, 5 and braces 15, 16 are connected to each other by these pivotal joints like members of a chain with a certain backlash allowing certain "wobble" of the pieces. The backlash is of course very precisely determined and it remains the same for all fixing elements 1.

The pivotal joints are formed as follows. A bore 31 is made perpendicularly to braces 15, 16 in holding plates 4, 5 as well as in braces 15, 16, respectively, but in braces 15, 16, the bores 31 have a somewhat greater diameter than in holding plates 4, 5. At the middle of the bores 31 in holding plates 4, 5, a slot 32 is formed for accommodating ends of braces 15, 16 cooperating with holding plates 4, 5 in the pivotal joints. The width of slots 32 is greater than the thickness of said ends of braces 15, 16. Through these bores, a bolt 17 (Fig. 2) is driven fitting tightly into bores 31 of holding plates 4, 5. With this, a well defined spatial backslash of the pivotal joints is provided. Braces 15, 16 have impact surfaces at the pivotal joints for providing a uπiplanar arrangement of all parts of fixing element 1 in its open position. The very ends of braces 15, 16 lie against the bottom of the slots 32. Furthermore, screw 18 of brace 16 has a further impact surface cooperating with the bottom of the slot 32 of holding plate 5 at their pivotal joint for determining a perpendicular position of brace 16 in respect to holding plate 5.

In this embodiment, both ends of stable brace 15 are pivotally jointed to holding plates 4, 5 whilst variable brace 16 is pivoted only at its one end. At the other end, a detachable connection is provided as it will be described hereinafter.

Brace 16 with variable length is formed as a screw IB and nut 20 assembly. Screw IB is pivoted at bolt 17 in holding plate 5 as described above. Nut 20, in turn, has a neck 20 and a head 21 on it. Neck 20 has a smaller diameter than head 21 or other parts of nut 20. At the junction of neck 20, head 21 has a spherical surface 22 similarly to spherical surface 9 of tension jaws 2, 3. Accordingly, a spherical seat 23 is formed in holding plate 4 at the connection of brace 16 with a hole 24 in its middle letting neck 20 through. Thus, the diameter of the hole 24 is smaller than that of head 21 but greater than that of neck 20. Hole 24 is cut up outwards, i. e. a slit 25 starting at hole 24 is formed in holding plate 4 in a plane of rotation of brace 16. Slit 25 is at least as wide as hole 24.

Nut 20 has to means for connecting a tightening tool. In head 21, an orifice such as a hexagonal orifice 33 for bolt wrench or a slot for screw driver can be provided. At the same time, at least on a part of nut 20, a hexagon outer surface can be formed for a fork wrench.

The embodiment of fixing element 1 is shown in assembled position in Fig. 2 (perspective view) and in Fig. 3 (cross section). The outer thread of neck portion 12 of tension jaws 2, 3 are driven through the inner thread of bores 14 of holding plates 4, 5. After leaving outer thread the inner thread, neck 20 with smaller diameter is at the inner thread of tension jaws 2, 3, thus, tension jaws 2, 3 settle themselves by the cooperation of spherical surface 9 and seat 13.

Neck 20 of nut 20 of brace 16 is pushed through slit 25 and spherical surface 22 of head 21 sits in seat 23. With tightening the nut 20 and screw 18 assembly, tension jaw 2 is pressed against tension jaw 3, and during the above said spatial adjustment, tension jaws 2, 3 and holding plates 4, 5 cooperate as a ball joint. If an implantation is in U-like groove 6 and a guiding rod in U-like groove 7, they can be adjusted in all directions of the space. After final adjustment, screw 18 is more tightened until the ball joint is stiffened and neither tension jaws 2, 3 nor the implantations nor the guiding rod can further be moved. Now, the assembly can be loaded.

In the application example of Fig. 4, Steinmann nails 27, 28 are fixed on both sides of a fracture in the bone as usually. Firstly, Steinmann nails 28 being more apart from the fracture are arranged. A guiding rod 29 is connected to Steinmann nails 28 with four fixing elements 1. For this, Steinmann nail 28 is snapped-in into U-like groove 7 of tension jaw 3 and by holding plate 5, the whole assembly is rotated around neck portion 12 of tension jaw 3 for choosing - li ¬

the most convenient position of fixing element 1. In this, fixing element 1 is closed by turning holding plate 4 with tension jaw 2 onto tension jaw 3 and pushing head 21 of nut 20 of brace 16 through slit 25 into seat 23 of holding plate 4. Thereafter, first guiding rod 29 is pushed into and through U-like groove 6 of tension jaw 2. In the desired position, screw 18 is lightly tightened which allows the adjustment of the parts but holds them in their position. If a guiding rod 29 is already applied, U-like groove 6 will also be snapped on guiding rod 29 and the assembly tightened. ;Now the montage is self-holding but not loadable. The holes for further Steinmann nails 27 can be bored through further fixing element 1 arranged on guiding rod 29. When all parts are finally positioned, screws 18 will finally tightened and the montage becomes stiff and carries the loads until the fracture is healed.

For the sphenoid fracture of the tibia, a unilateral duplex montage can be applied as shown in Fig. 4. As implantations, Schanz screws can of course be used instead of Steinmann nails 27, 28. Parallelly to guiding rod 29, a second guiding rod 30 is mounted with fixing elements 1 in this assembly .Of course, the implantations need not to be so parallel to each other as in the figure, since fixing elements 1 are able to compensate these inaccuracies. By moving the implantations, the broken bone parts can be repositioned as required. After reaching the final position, fixing element 1 are stiffened and the assembly is a load carrying one. The two guiding rods 29, 30 enlarge the stiffness and the security of the montage.

After three weeks from the implantation of the fixateur externe, dynamization, i. e. displacement in the direction of the axle of the bone is required. The proximal fixing elements 1 above the fracture are opened and tension jaw 2 accommodating guiding rods 29, 30 are interchanged with a tension jaw 2 having a U-like groove 6 which is wider by 0,05 mm than the diameter of the guiding rod 29, 30. After mounting fixing elements 1 once again, the bone ends will axially be loaded but any impact differing from the axle direction is excluded.

Nevertheless, guiding rods 29 and 30 can be arranged on different sides of the extremity to be operated. On the left and right side of the bone, respectively, implantations are •applied which will be interconnected by these rods 29, 30 with the aid of fixing elements 1.

When the bone fracture is more complicated or splintery, the V montage or camp montage is applied. In this spatial assembly, three guiding rods 29 are used around the extremity. In the rule, Steinmann nails 27 are frequently used instead of Schanz screws in these cases. Thanks to the flexible variability of fixing elements 1, the most convenient lay-out of the montage can be found. With this, the bigger splinters near to the fracture can be held on their place, too.

Claims

Claims :

1. Fixateur externe for osteosynthesis and for healing of bone fractures comprising implantations driven into the bones to be fixed and guiding rods as well as fixing elements connecting the implantations and the guiding rods to each other, c h a r a c t e r i z e d in that the fixing elements have tension jaws (2, 3) fixing the implantations and the guiding rod (29, 30) to each other by detachable connection and being parts of a ball joint as well as means for stiffening the ball joint in a desired position.

2. Fixateur externe as claimed in Claim 1, wherein each of the tension jaws (2, 3) has a U-like groove (6, 7) for accommodating the implantations or the guiding rod (29, 30) and opposite to the U-like groove (6, 7), a spherical surface (9), and the fixing elements (1) have holding plates (4, 5) each having a spherical seat (13) for supporting the spherical surfaces (9) of the tension jaws (2, 3).

3. Fixateur externe as claimed in Claim 2, wherein the U- like grooves (6, 7) are dimensioned for accommodating the implantations or the guiding rods (29, 30), respectively, with tight fit.

4. Fixateur externe as claimed in Claim 2 or 3, wherein the U-like groove (6, 7) is tighter at its outer opening than elsewhere for snap-in connection of the implantations or guiding rods (29, 30) .

5. Fixateur externe as claimed in Claim 2, wherein the U- like groove (6, 7) of the tension jaw (2) accommodating the guiding rod (29, 30) is wider by at least 0,05 mm than the diameter of the guiding rod (29, 30).

6. Fixateur externe as claimed in any one of Claims 2 to 5, wherein the spherical seat (13) of each holding plate (4, 5) has a ^*bore (14) at its middle area, and the bore (14) is provided with an inner thread, and each tension jaw (2, 3) has an extension at a middle part of the spherical surface (9) comprising a head portion (11) provided with an outer thread fitting into the inner thread of the bore (14) as well as a neck portion (12) between the head portion (11) and the spherical surface (9) having a smaller diameter than that of the bore (14) .

7. Fixateur externe as claimed in any one of Claims 2 to 6, wherein the holding plates (4, 5) are attached to each other by braces (15, 16) pivotally jointed to opposite edges of the holding plates (4, 5), and a length of at least one of the braces (15, 16) is variable.

8. Fixateur externe as claimed in Claim 7, wherein pivotal joints between the holding plates (4, 5) and the braces (15, 16) are made for having a loose fit providing a spatial backlash between the parts connected to each other by the joints.

9. Fixateur externe as claimed in Claim 7 or 8, wherein the brace (16) with variable length is formed as a screw (18) and a nut (19) attached to each other, and the screw (18) is pivotally jointed with loose fit in one of the holding plates (4, 5) and the nut^* (19) is attached to the other holding plate (4) by detachable connection.

10. Fixateur externe as claimed in Claim 9, wherein the nut (19) of the brace (16) with variable length has a head (21) connected detachably to the holding plate (4) and a neck (20) attached to the head (21), and the head (21) has a spherical surface (22) at the connection of the neck (20) and the holding plate (4) has a seat (23) with a spherical hollow having a hole (24) in its middle for letting through the neck (20) of the nut (19).

11. Fixateur externe as claimed in Claim 10, wherein a slit (25) starting at the hole (24) is provided in the holding plate (4) in a plane of rotation of the brace (16) with variable length, and the slit (25) is at least as bright as the hole (24).

12. Fixateur externe as claimed in Claim 11 or 12, wherein the head (21) of the nut (19) has an orifice (33) for connection of a tightening tool.

13. Fixateur externe as claimed in any one of Claims 9 to

12, wherein at least on a part of the^* nut (19) a hexagon outer surface (26) is provided.

14. Fixateur externe as claimed in any one of Claims 9 to

13, wherein the braces (15, 16) have impact surfaces at the pivotal joints fro- providing a uniplaπar arrangement of all parts of the fixing element (1) in its open position.

15. Fixateur externe as claimed in any one of Claims 9 to

14, wherein the screw (18) has a further impact surface cooperating with the holding plates (4, 5) at their pivotal joint for determining a perpendicular position of the brace to the holding plates (4, 5).