AU718087B2

AU718087B2 - External fixator

Info

Publication number: AU718087B2
Application number: AU20166/97A
Authority: AU
Inventors: Jacques Mata; Marcel Nyfeler; Denis Worek
Original assignee: Jaquet Orthopedie SA
Current assignee: Stryker European Holdings I LLC
Priority date: 1996-05-10
Filing date: 1997-05-09
Publication date: 2000-04-06
Anticipated expiration: 2017-05-09
Also published as: ES2185892T3; ATE228337T1; DE69717343D1; DE69717343T2; AU2016697A; CH691568A5

Abstract

The bone fixing for a long tubular human or animal bone with a fracture close to one end, comprises two sets of pins (3) inserted into the bone on either side of the fracture, clamps (10) to grip the pins, and articulated joints (60) which enable the clamps to be positioned relative to a rigid linking bar. One jaw of each clamp has a cylindrical bar (50) to co-operate with an articulated joint, the bar lying parallel to the plane of the bone pins and perpendicular to the pins' axes. Each clamp has one jaw (30) in a U-shape with holes through its two legs to receive the end of the bar and equipped with a lock to prevent the bar from rotating. The clamp jaws are made from plastic materials reinforced e.g. with carbon fibres.

Description

S F Ref: 378636

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIRCATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Jaquet Orthopedie S.A.

chemin des Aulx CH-1228 Plan-les-Ouates

SWITZERLAND

Jacques Mata, Marcel Nyfeler and Denis Worek Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia External Fixator The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845 External fixator The present invention pertains to the field of orthopaedics and relates more particularly to an external fixator which is intended for the consolidation of a long bone fractured towards its end.

For many years now, development work has been carried out on external fixators whose components are put into place after the pins have been inserted in the optimum position in relation to the bone fragment, which is to be maintained, and to the tissue surrounding it.

Hinge elements provide for the connection between the :.pins and the immobilizing rod or rods, so as to ensure their relative orientation. The Applicant has specifically developed for this purpose the hinge element 15 which is described in European Patent Application No. 0,700,664 and which permits orientation either of a pin and a rod or of two rods. This hinge element includes several pairs of jaws forming grooves which are positioned and disposed in such a way as to present an external opening which allows the cylindrical component to be snapped into place by means of pressing the latter •counter to the elastic means which press the adjacent faces of the jaws one against the other, in order to hold the hinge element in place on the cylindrical components prior to the hinge element being locked.

In some cases it is necessary to use a fixator which includes a single immobilizing rod and not a series of rods forming an immobilizing frame. For this type of fixator, pairs of at least two bone pins are inserted on either side of the fracture and are indirectly fixed to the ends of an immobilizing rod. When a long bone is fractured near a joint, it is preferable to insert the pins in what is called a arrangement, some of the pins being inserted in the epiphysis in a plane perpendicular to the bone, the others being inserted in the central part of the bone, in a plane containing the fractured bone. Each group of pins is held in a vice which can be oriented in relation to the immobilizing rod by means of a hinge or a ball joint.

It is the object of the present invention to substantially overcome or at least ameliorate one or more of the above disadvantages.

Accordingly, in a first aspect, the present invention provides an external fixator for attachment to a fractured bone comprising: two groups of at least two pins having first ends insertable into the bone on either side of the fracture; two vice elements clamped to second ends of each group of pins, each vice element having a first jaw for clamping onto said pins and each vice element further including a cylindrical bar, said bar on said vice element extending in a direction perpendicular to a longitudinal axis. of said pins; an immobilizing rod extendable across the fracture; and S: :a pair of hinge elements, each having two pairs of rotatable clamps for respectively engaging said immobilizing rod and said cylindrical bar; wherein S 15 each vice element includes a second jaw in the shape of a U having branches including two openings which face each other into which ends of said cylindrical bar are "inserted.

In a second aspect, the present invention provides a method for attaching an external fixator as described above to a fractured bone, comprising the steps of: 20 inserting each group of pins into bone fragments on either side of the fracture; :i ~clamping the pins in the vice elements; and fitting the 'hinge elements onto the Cylindrical bar of the vices and onto said a go :"-o:immobilizing rod prior to proceeding to the final adjustment of the position of the bone fragments by positioning the immobilizing rod in relation to the pins.

Preferred embodiments of the invention simplify this type of fitting and reduce the size and weight of the assembly, being more particularly designed for long bones, such as the radius, which have been fractured near their end.

Preferred forms of the present invention will now be described by way of example only with reference to the accompanying drawings, wherein: Figure 1 represents the vice according to the invention, in a front view on the left-hand side of the drawing and in cross-section on the right-hand side.

Figure 2 represents the vice in Figure 1 as seen from the side and shown mounted on a hinge element of the type which is described in detail in European Patent ~Application No. 0,700,664 of the Applicant.

[R:\LIBLL]09150.doc:MFF Figure 3 is a perspective view of the fixator assembly according to the invention.

The vice 10 represented in Figure 1 consists in a conventional manner of an upper jaw 20 and of a lower jaw 30 which are connected by a central locking screw These jaws 20 and 30 include series of parallel grooves 21 and 31 for the bone pins 3.

The upper jaw 20 additionally includes two wings 22 and 23 for relative positioning of the jaws and a central passage 24 through which the locking screw *o o* go ••ooo *o* o [R:\LIBLL09150.doc:MFF 3 passes freely.

The lower jaw 30 has a general shape (upside down in the drawing), the branches 32 and 33 of which are intended to receive a small bar 50 whose ends are inserted in a passage 34 formed in each branch and are secured by means of a small pin 35 intended to prevent any rotation of the small bar. The lower jaw 30 also includes a central passage 36 intended to cooperate with the screw 40. A metal screw socket 37 is preferably interposed between the passage 36 and the screw 40. By design, the small bar 50 is parallel to the plane containing the pins and, as can be seen in the drawing, it is perpendicular to the axis of the bone pins.

*The side view in Figure 2 again shows the jaws 15 and 30 forming the vice 10 for clamping pins 3, the lower jaw 30 presenting the small bar 50 intended for securing :a hinge element 60. The latter includes a first pair of jaws 61 which are clamped on a spacing rod and a second pair of jaws 62 clamped on the small bar 50, it being 20 possible for these pairs of jaws to be oriented in relation to a central axis constituted by the locking screw 63 which constitutes the axis of rotation of the jaws. It is possible to separate the pairs of jaws 61 and 62 by a helical spring 64 which is intended to hold the 25 components in place until the screw 63 has been fully tightened, as is detailed in European Patent Application No. 0,700,664 already mentioned.

The general view in Figure 3 shows a long bone 1 which has been fractured relatively close to the distal end 2 of the radius, an area where more than 20% of limb fractures occur. Each bone fragment 1 and 2 receives at least two pins 3 and 4, respectively, which are preferably disposed in a arrangement. These pins are clamped in two vices 5 and 6 cooperating with hinge elements 7 and 8 between which an immobilizing rod 9 is disposed. The physician will be able to reduce the fracture and return the bone fragments 1 and 2 to their optimum position by virtue of the combination of the rotational movements of: 4 the hinge elements 7 and 8 in relation to the axis of the rod 9, the pairs of jaws of each hinge element 7 or 8 on their clamping axis 63, the hinge elements 7 and 8 in relation to the small bar of each vice 5 or 6.

In the representation in Figure 3, the pins 3 are in a horizontal plane, while the pins 4 are in a vertical plane. It will be noted that the axis of the hinge element 8 is substantially parallel to the pins 4, while the axis of the hinge element 7 is at 450 to the plane containing the pins 3.

In the case of fractures of the wrist, it has been observed that it is of advantage to dispose the pins 3 preferably in a plane at 450 to the horizontal, the axis of the hinge element 7 being substantially aligned .with the central clamping axis of the vice 5. Depending on the region of use of the fixator according to the invention, it is possible to envisage arranging the two groups of pins in substantially parallel planes, and not in the arrangement as is described above, without departing from the scope of the present invention.

The procedure for putting into place the fixator which has been described hereinabove consists in inserting pairs of pins into the bone fragments on either side of the fracture, in clamping the pins in the vices, in fitting the hinge elements on the vices and on an immobilizing rod, before proceeding to the final adjustment of the position of the bone fragments by virtue of the combination of the rotational movements of the hinge elements, or in other words positioning of the immobilizing rod in relation to the pins.

It is also to be noted that it is advantageous to use vices; and even an immobilizing rod, made of radiota-nsparent, composite materials, so that it is easy to check the-relative positioning of the bone fragments when the fixator is being put into place. For example, use will be made of reinforced plastics, preferably ones based on carbon fibres.

5 The small bars 50 and spacing rod 9 preferably have the same diameter, which permits greater freedom of positioning of the components.

*a e S*

Claims

1. An external fixator for attachment to a fractured bone comprising: two groups of at least two pins having first ends insertable into the bone on either side of the fracture; two vice elements clamped to second ends of each group of pins, each vice element having a first jaw for clamping onto said pins and each vice element further including a cylindrical bar, said bar on said vice element extending in a direction perpendicular to a longitudinal axis of said pins; an immobilizing rod extendable across the fracture; and a pair of hinge elements, each having two pairs of rotatable clamps for respectively engaging said immobilizing rod and said cylindrical bar; wherein each vice element includes a second jaw in the shape of a U having branches S: including two openings which face each other into which ends of said cylindrical bar are ooeo S-"inserted. 15

2. The fixator as set forth in claim 1 wherein said opening in said branch oooo ••additionally includes an element for locking the bar against rotation.

3. The fixator as set forth in claim 1 wherein the jaws of the vice are made of reinforced plastic.

4. A method for attaching an extemrnal fixator to a fractured bone according o000 20 to claim 1, comprising the steps of: inserting each group of pins into bone fragments on either side of the fracture; clamping the pins, in the vice elements; and -fitting the hinge elements onto the cylindrical bar of the vices and onto said immobilizing rod prior to proceeding to the final adjustment of the position of the bone fragments by positioning the immobilizing rod in relation to the pins.

The method as set forth in claim 4 wherein the two groups of pins are arranged with one group of pins being inserted in a first plane and the other group of pins being inserted in a plane oriented perpendicularly to said first plane.

6. An external fixator for attachment to a fractured bone, said fixator being substantially as hereinbefore described with reference to the accompanying drawings. [R:\LIBLL]09150.doc:MFF

7. A method for attaching an external fixator to a fractured bone, said method being substantially as hereinbefore described with reference to the accompanying drawings. Dated 27 January, 2000 Jaquet Orthopedie S.A. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON [R:ULBLL]091