WO1991011151A1

WO1991011151A1 - Bone fixation

Info

Publication number: WO1991011151A1
Application number: PCT/GB1991/000276
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: AU7305391A; GB9002065D0

Abstract

Figures (1 and 2) show a bone fixator having clamps (10A, 10B) for bone pins (11) connected by means (12) including a ball-and-socket joint (13, 14) having at least one setscrew (15) in the socket wall (17) to dig into the ball (13) for setting up a fracture, but with the intention of being releasable for re-setting of the clamps at a later stage; also having the advantage of being more convenient for use in high ambient temperatures or in poor lighting conditions that previously disclosed fixators using hardenable resin filler to secure the ball joint. Three setscrews (15) in the socket wall (17) are preferred.

Description

BONE FIXATION

This invention relates tc bone fixation and has as its object the provision of a bone fixator having simple effective means for positively securing a pair of spaced bone-pm clamps at an angle to each other, upon setting of a fracture, yet allowing releasing and/or re-setting of the clamps relative to each other at an appropriate stage in the healing process.

According to the present invention, a bone fixator comprises a pair of clamps each having means for clamping at least two bone pins, and connecting means between the clamps incorporating a ball-and-socket joint having at least one setscrew (but preferably three) in a screwtnreaded hole in the socket wall and adapted to dig into the ball.

Thus the ball-and-socket joint allows the clamps to be set at an angle to each other and then to be secured by the setscrew (or each setscrew) being screwed into the screwtnreaded hole in the socket wall until the tip of the setscrew digs into the ball. The (or each) setscrew can be unscrewed when release and/or re-setting of the clamps relative to each other is desirable. However, a major advantage of the present invention is that it provides a more convenient way of securing the clamps relative to each other thar. using resir. as described m WO S9/09GΞ1 in high ambient temperatures or in poor lighting conditions where it would be difficult tc see the holes for introduction and emergence of the resin.

The connecting means may also incoporate telescoping means and releasable securing means 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 m the healing process for the telescoping means to allow of dynamic distraction 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.

It will be appreciated that the telescoping means 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.

The socket wall may be encircled by a metal ring having a screwthreaded hole or holes for a setscrew or setscrews in register with a plain hole or holes in the socket wall through which the or each setscrew passes. The metal ring may be mcroporated m the moulding of the socket wall . but is preferably force-fitted on the socket wall or secured thereon with adhesive after the ball has been snapped into the socket .

An embodiment cf the invention and some modification 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 m accordance with the invention;

Figure 2 is an end elevation as seen from the right hand end of Figure i;

Figure 3 is a section on the line III-III of Figure 1;

Figure 4 corresponds to Figure 3 but shows a preferred feature of the invention; and

Figure 5 corresponds to Figure 4 but shows a modification thereof.

In the embodiment of Figures 1 to 3, a bone fixator comprises a pair of clamps 10A, 10B each having means for clamping at least two bone pins 11, and connecting means 12 between the clamps incorporating a ball-and-socket joint 13, 14 having a setscrew 15 in a screwthreaded hole 16 in the socket wall 17 and adapted to dig into the ball 13.

Thus the ball-and-socket joints 15, 14 allows the clamps iOA. iOB tc be set at an angle to each other ana then tc be secured by the setscrew 15 being screwed into the screwthreaded hole 16 m the socket wall 17 until the tip 15 of the setscrew digs into the ball 13, as shown m Figure 3.

The fixator is indicated as being made of rigid plastics, with the setscrew 15 and clamping screws 19 for the bone pins 11 being made of metal. Therefore, it is preferable to provide three setscrews 15, as shown in Figure 4, to afford a better grip on the ball and ensure that the clamps IOA, 10B are securely held at the required angle to each other.

It has been found desirable to use B.S.Whitworth threads to avoid stripping of the plastic screwthreads, but Figure 5 shows an alternative modifcation in which the socket wall 17 is encircled by a metal ring 20 having screwthreaded holes 16A for the setscrews 15 m register with plain holes 16B in the socket wall through which the setscrews pass. The metal ring 20 may be incorporated in the moulding of the socket wall, but is preferably force-fitted on the socket wall or secured thereon with adhesive after the ball 13 has been snapped into the socket.

The connecting means also incorporate telescoping means 21, 22 and releasable securing means 23 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 23 is shown m Figures I and 2 as consisting of a setscrew 24 in a screwthreaded lateral hole 25 in the outer tubular member 21 of the telescoping means and adapted to bear against the inner member 22 of the telescoping means, which inner member is a solid shaft but has a longitudinal groove 26 in which the setscrew 24 engages and the inner end 27 of which forms a stop for the setscrew preventing complete withdrawal of the inner telescoping member 22 from the outer member 21.

The telescoping means 21, 22 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.

Claims

1. A bone fixator comprising a pair of clamps each having means for clamping at least two bone pins, and connecting means between the clamps incorporating a ball-and- socket joint having at least one setscrew in a screwthreaded hole in the socket wall and adapted to dig into the ball.

2. A bone fixator as in Claim 1, wherein three setscrews are provided.

3. A bone fixator as in Claim 1 or Claim 2, wherein the connecting means incorporates telescoping means and releasable securing means 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.

4. A bone fixator as in Claim 3, 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.

5. A bone fixator as in Claims 3 or , wherein the inner member of the telescoping means is tubular.

6. A bone fixator as in Claim 3 or Claim 4, wherein the inner member of the telescoping means is a solid shaft.

7. A bone fixator as in any one of Claims 4 to 6, wherein the inner member 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.

5. A bone fixator as m any one of Claims 1 tc where in the components of the fixator are formed of aluminium or aluminium alloy.

9. A bone fixator as in any one of Claims 1 to 7, 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, whereby the fixator can be disposable.

10. A bone fixator as in Claim 9, wherein the socket wall is encircled by a metal ring having a screwthreaded hole or holes m register with a plain hole or holes in the socket wall through which the or each setscrew passes.

11. A bone fixator as in Claim 10, wherein the metal ring is incorporated in the moulding of the socket wall.

12. A bone fixator as in Claim 10, wherein the metal ring is force-fitted on the socket wall after the ball has been snapped into the socket.

13. A bone fixator as in Claim 10, wherein the metal ring is secured on the socket wall with adhesive after the ball has been snapped into the socket.