WO1991011150A1

WO1991011150A1 - Bone fixation

Info

Publication number: WO1991011150A1
Application number: PCT/GB1991/000134
Authority: WO
Inventors: Albert Edward Oliver
Original assignee: Sheffield City Council
Priority date: 1990-01-30
Filing date: 1991-01-30
Publication date: 1991-08-08
Also published as: GB9002033D0; AU7301891A

Abstract

Figure (1) shows a bone fixator having clamps (10A, 10B) connected by telescoping means (12) provided with releasable securing means (13) for locking the telescoping means in at least partially extended condition for initial setting of a fracture, the securing means (13) being adapted to be released at the appropriate later stage in the healing process for the telescoping means (12) to allow of dynamic distraction of the fracture. The telescoping means (12) can also be used to effect adjustment of the nominal length of the fixator to suit different lengths of fractured bones and/or different locations of fractures.

Description

BONE FIXATION

This invention relates to bone fixation and has as one object the provision, at low cost, of an effective bone fixator capable of being adapted for dynamic distraction of a fracture at the appropriate stage in its healing process.

A secondary object is to provide a bone fixator as aforesaid also capable of providing for adjustment of its length.

According to the present invention, a bone fixator comprises a pair of clamps each having means for clamping at least two bone pins, telescoping means connecting the clamps with each other, and releasable securing means for locking the telescoping means m at least a partially extended condition for initial setting of a fracture, the securing means being adapted to be released at the appropriate later stage m the healing process for the telescoping means to allow of dynamic distration of the fracture.

The releasable securing means may conveniently be a setscrew (or "grubscrew") in a screwthreaded lateral hole in an outer tubular member of the telescoping means and adapted to bear against an inner member of the telescoping means, which inner member may be tubular but is preferably a solid shaft, and which inner member preferably has a longitudinal groove in which the setscrew engages and the inner end of which forms a stop for the setscrew preventing complete withdrawal of the inner telescoping member from the outer.

One or each of the clamps may be connected to the telescoping means by an angular adjustable joint, e.g., a

SUBSTITUTESHEET ball-and-socket joint, provided with means for securing the joint in any angularly adjusted position upon setting a fracture, e.g., one or more setscrewε (or "grubscrews" ) through the socket wall to bear on the ball or (preferably) dig into the ball, or means similar to one disclosed in O89/09031 (PCT/GB89/00309) whereby hardenable filler material can be introduced around projections extending from the ball into a compartment adjoining the socket, which compartment preferably adjoins a closed end within the outer tubular member of the telescoping means, in which case the inner telescoping member is formed integral with one part of the other clamp.

It will be appreciated that the telescoping means connecting the clamps can be used to effect adjustment of the nominal length of the fixator to suit different lengths of fractured bones and/or different locations of fractures.

The components of the fixator may be formed of aluminium or aluminium alloy, but preferably of rigid plastics, with the setscrew or setscrews and clamping screws for the bone pins made of metal, whereby the fixator can be disposable.

An embodiment of the invention and two modifications thereof will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a part-sectional side elevation of a bone fixator in accordance with the invention;

Figure 2 is an end elevation as seen from the right hand end of Figure 1; Figure 3 is a section on the line III-III of Figure 1;

Figure 4 is a section on the line IV-IV of Figure 1;

Figure 5 corresponds to Figure 1 but shows the fixator as disposed and secured for setting of a fracture;

Figure 6 is a section on the line VI-VI of Figure 1 but showing a modification; and

Figure 7 corresponds to Figure 6 but shows a variation of that modification.

In Figures 1 to 5, a bone fixator comprises a pair of clamps 10A, 10B each having means for clamping at least two bone pins 11, telescoping means 12 connecting the clamps with each other, and releasable securing means 13 for locking the telescoping means in at least a partially extended condition for initial setting of a fracture, the securing means being adapted to be released at the appropriate later stage in the healing process for the telescoping means to allow of dynamic distraction of the fracture.

The releasable securing means 13 is a setscrew 14 in a screwthreaded lateral hole 15 in the outer tubular member 16 of the telescoping means and adapted to bear against the inner member 17 of the telescoping means, which inner member is a solid shaft but has a longitudinal groove 18 m which the setscrew engages and the inner end 19 of which forms a stop for the setscrew preventing complete withdrawal of the inner telescoping member 17 from the outer member 16.

The telescoping means 12 connecting the clamps 10A, 10B can be used to effect adjustment of the nominal length of the fixator tc su t different lengths of fractured bones

SUBSTITUTESHEET and/or different locations of fractures.

The clamp 10A is connected to the telescoping means 12 by an angular adjusrable joint 20 which is a ball-and-socket joint, provided with means for securing the joint in any angularly adjusted positon upon setting a fracture.

In Figures 1 to 5 the ball-and-socket joint 20 is shown provided with means similar to one disclosed in WO89/09031 whereby hardenable filler material 21 can be introduced around projections 22 extending from the ball 23 into a compartment 24 adjoining the socket 25, which compartment adjoins a closed end 26 within the outer tubular member 16 of the telescoping means, the inner telescoping member 17 being formed integral with one part of the other clamp 10B.

Alternatively, the ball-and-socket joint 20 can . be releasably secured in angularly adjusted position by means of setscrews 27 in screwthreaded holes 28 in the socket wail 29 to bear on the ball or, as shown in Figure 6, dig into the ball. The components of the fixatorε are indicated as being made of rigid plastics, with the setscrew 14 or setscrews 27 and clamping screws 30 for the bone pins 11 of metal. While it is desirable to use B.S.Whitworth screwthreads to avoid stripping of the plastics screwthreads, an alternative shown in Figure 7 has the socket wall 29 encircled by a metal ring 31 having screwthreaded holes 28A in register with plain holes 28B in the socket wall 29 through which the setscrews 27 pass.

Claims

1. A bone fixator comprising a pair of clamps each having means for clamping at least two bone pins, telescoping means connecting the clamps with each other, and releasable securing means for locking the telescoping means m at leasr a partially extended condition for initial setting of a fracture, the securing means being adapted to be released at the appropriate later stage in the healing process for the telescoping means to allow of dynamic distration of the fracture.

2. A bone fixator as m Claim 1 wherein the releasable securing means is a setscrew in a screwthreaded lateral hole in an outer tubular member of the telescoping means and adapted to bear against an inner member of the telescoping means,

3. A bone fixator as in Claim 1 or 2, wherein the inner member of the telescoping means is a shaft.

4. A bone fixator as in Claim 3, wherein the shaft is tubular.

5. A bone fixator as in any one of Claims 2 to 4, wherein the inner member has has a longitudinal groove in which the setscrew engages and the inner end of which forms a stop for the setscrew preventing complete withdrawal of the inner telescoping member from the outer.

6. A bone fixator as in any preceding Claim wherein one of the clamps is connected to the telescoping means by an angular adjustable joint.

7. A bone fixator as in Claim 6 wherein the angular

SUBSTITUTESHEET adjustable joint is a ball-and-socket joint.

8. A bone fixator as in Claim 6 or Claim 7, wherein the joint is provided with means for securing the joint in any angularly adjusted position upon setting a fracture.

9. A bone fixator as in Claims 7 and 8, in combination wherein the means for securing the joint is provided by one or more setscrews through the socket wall to bear on the ball.

10. A bone fixator as in Claims 7 and 8 in combination wherein the means for securing the joint is provided by means whereby hardenable filler material can be introduced around projections extending from the ball into a compartment adjoining the socket.

11. A bone fixator as in Claim 10, wherein the compartment adjoining the socket adjoins a closed end within the outer tubular member of the telescoping means, in which case the inner telescoping member is formed integral with one part of the other clamp.

12. A bone fixator as in any preceding Claim, wherein the components of the fixator are formed of aluminium or aluminium alloy.

13. A bone fixator as in any of Claims 1 to 10, wherein the components of the fixator are formed of rigid plastics, with the setscrew or setscrews and clamping screws for the bone pins made of metal.

SUBSTITUTESHEET