WO2017077489A1

WO2017077489A1 - A fastening device

Info

Publication number: WO2017077489A1
Application number: PCT/IB2016/056638
Authority: WO
Inventors: Hugh Bryan THEUNISSEN
Original assignee: Theunissen Hugh Bryan
Priority date: 2015-11-04
Filing date: 2016-11-04
Publication date: 2017-05-11

Abstract

Herein described is an orthopaedic fastening device comprising a shaft (12) having an engaging head (14) movable from an engaged condition to a retracted condition and a stop (16) being securable along a length of the shaft wherein the shaft includes a series of gripping formations (22) along its length with corresponding engaging formations (30) provided about an opening (28) through the stop (16). A method of setting a fractured bone using the orthopaedic device is also described.

Description

A FASTENING DEVICE

FIELD OF THE INVENTION The invention relates to a fastening device for securing two objects together and, more specifically, to such a device for use in orthopaedic surgery to connect two sides of a fractured bone.

BACKGROUND TO THE INVENTION

To facilitate proper healing of broken or fractured bones, it is often required that fragments of a fractured or broken bone be secured or set together.

Open orthopaedic surgery (reduction) involves the surgical incision of surrounding tissue to expose a fractured bone and subsequent realignment and securement of fragments thereof. Surgical steel fasteners, which may include pins, and screws and bolts with nuts, are typically used to set the fragments in order for the bone to mend.

Such surgery generally requires access to opposite sides of a bone at the fracture or injury site. This can be difficult and/or involves additional cutting of surrounding soft tissue.

There are various reasons why minimising the extent of the incisions required is beneficial. Minimal cutting involves less risk and has reduced soft tissue recovery time and/or scaring of the skin.

There is a need to provide a fastening device, preferably an orthopaedic fastening device that at least ameliorates one of the disadvantages described herein above and/or described in the prior art.

SUMMARY OF THE INVENTION

Broadly, and in accordance with a first aspect of the invention there is provided an orthopaedic fastening device comprising a shaft having an engaging head movable from an engaged condition to a retracted condition and a stop being securable along a length of the shaft, such that in use, the engaging head in the retracted condition may pass through an opening.

The shaft may include a series of gripping formations along its length with corresponding engaging formations provided about an opening through the stop.

The engaging formations of the stop may include a circular arrangement of teeth about the opening located through the stop. The stop may be provided as a circular disk-shaped cap. The engaging head may include a circular arrangement of deformable barbs formed around the shaft.

The barbs may be arranged around a leading end of the shaft. The shaft may include a recess located behind the barbs to accommodate the barbs in the retracted condition. The head may preferably be of substantially or the same end profile as the shaft when in the retracted position.

The gripping formations of the shaft may be provided as annular ribs. Each rib may have a first tapered edge over which the teeth move when the stop is positioned or displaced along a portion of the shaft, and a first locking edge to engage the teeth once the teeth have passed over the first tapered edge.

The teeth may be configured with a corresponding second tapered edge and a corresponding second locking edge, wherein the first and second tapered edges serve to provide cam formations, and wherein the first and second locking edges act to lead the gripping formations into overlapping engagement with the teeth.

There is further provided that at least one of the shaft, the engaging head and the stop may be flexible or may be resiliency deformable and/or may be of a suitable flexible or resiliency deformable material such as, but not limited to, a plastics material. It is to be understood that in certain embodiments of the invention it may be desirable for the shaft to be rigid. In a particular embodiment of the invention, the head may be deformable and resiliency biased into the engaged condition. There is further provided that the head may have a tapered profile. The shaft and head may be moulded from plastics material. When in use, the device may be located within a rigid insertion tube which may provide a guide for placement and fitting of the device which may include a flexible shaft.

In accordance with a second aspect of the invention there is provided a method of setting or securing together at least a first and second portion of a fractured bone, the method comprising the following steps:

providing first and second holes through the first and second sections of the fractured bone;

passing the engaging head of the device, as described in the first aspect of the invention above, with the head in the retracted condition through the first and second holes; allowing the head to move from the retracted position into the engaged position;

displacing the stop of the device along the shaft toward the head;

clamping the first and second sections of the fractured bone together by allowing the stop to abut against a first outer surface of the first section and allowing the barbs to abut against a second outer surface of the second section.

The clamping may be facilitated by the gripping formations of the shaft and the engaging formations of the stop. When in use, as the stop is displaced toward the head the first and second sections of the fractured bone clamped together. The method may further include inserting a rigid insertion tube through the first and second holes which may provide a guide for placement and fitting of the device preferably when the device includes a flexible shaft.

There is provided for a device and/or a method substantially as herein described, illustrated and/or exemplified with reference to any one of the accompanying diagrammatic drawings.

These and other features of the invention are described in more detail below. BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described by way of example only with reference to the accompanying drawings in which:

FIGURE 1 is a side cross-sectional view of an assembled fastening device in accordance with the invention;

FIGURE 2 shows a side cross-sectional view of a stop for the device;

FIGURE 3 is a front end view of the assembled device in Figure 1;

FIGURE 4 shows a rear end view of the stop; and

FIGURE 5 shows a side cross-sectional view of the fastening device in use secured between fragments of a fractured bone.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings an orthopaedic fastening device is shown and generally indicated by reference number 10. The device 10 is for use in orthopaedic surgery.

The device 10 includes a shaft 12 having an integral engaging head 14 and a separate stop 16 which is securable along the length of the shaft 12.

The head 14 includes a circular arrangement of deformable barbs 18 having pointed free ends 18A which are splayed around a leading end of the shaft 12. The head 14 and barbs 18 are movable from an engaged condition, as shown in Figure 1, to a retracted condition wherein the barbs 18 are folded inwardly and/or downwardly toward the shaft 12.

A recess 20 is located behind the barbs 18 along a portion of the shaft 12 in order to accommodate the barbs 18 in the retracted condition. This will allow the head 14 to have substantially the same end profile as the shaft 12 when the barbs 18 are in the retracted condition.

A leading end of the shaft 12 which carries the deformable head 14 is pointed. The pointed shape of the head 14 will aid in the passage of the device 10 (through a drill hole in a bone) for its placement when in use. This is discussed in more detail below. The shaft 12 and head 14 are preferably formed, by moulding integrally, from a resilient plastics material. The material provides for the shaft 12 to be suitably rigid but with a degree of flexibility. Additionally the barbs 18 will also be resiliency deformable and inherently biased to the expanded, engaged condition wherein a major portion of each barb 18 is located substantially away from recess 20.

The barbs 18 may be moved to the retracted condition where they will be located within (or partly within) the recess 20. The barbs 18 will naturally return to the engaged condition when no force is acting against the bias provided by the preformed configuration of the plastics material providing the head 14.

A plurality of gripping formations 22 extend along a length of the shaft 12. The formations 22 preferably extend from adjacent the recess 20 to a rounded, trailing end 24 of the shaft 12.

The stop 16 is provided as a circular disk-shaped cap 26 having a central opening 28 to receive the shaft 12. A plurality of inwardly extending engaging formations 30 are arranged about the opening 28 extending away from the cap 26. The engaging formations 30 provide a circular arrangement of teeth 32, to lock the cap 26 in position along the shaft 12.

The cap 26 is preferably moulded from a resilient plastics material similar to that of the shaft 12 and head 14 and the configuration of the teeth 32 provided to afford the required rigidity for (non-return) secure engagement to the gripping formations 22. The cap 26 is also provided with a domed profile which resists deformation when it is tightened onto the shaft 12 in the manner described below.

Figure 1 shows the cap 26 engaged along the length of the shaft 12. The gripping formations 22 of the shaft 12 are provided as annular ribs 34 and the teeth 32 of the cap 26 are located within grooves between the ribs 34.

Each rib 34 has a first tapered edge 38 over which the teeth 32 can be moved when the cap 16 is positioned along the shaft 12 and a first locking edge 36 to engage the teeth 32 once they have passed over the first tapered edge 38. The teeth 32 are similarly configured with a corresponding second tapered edge 32.1 and a second locking edge 32.2. The first tapered edges 38 and the second tapered edges 32.1 together serve to provide cam formations or ramps which deflect the formations 32. The first and second locking edges 36 and 32.2 act oppositely to lead the formations 22 and 30 into overlapping engagement. The arrangement affords a click, locking fit as the formations 22 and 30 are passed over each other (similar to the mechanism of a cable tie).

The teeth 32 and ribs 34 are accordingly shaped to afford displacement of the cap 16 along the shaft 12 towards the head 14 and locking engagement against movement in the opposite direction.

An object placed between and into contact with each of the cap 26 and head 14 will thus become subject to a clamping force as the cap 26 is pushed along the shaft 12, or stated differently, as the shaft 12 is drawn through the opening 28 of the cap 26. This process amounts to a tensioning of the device.

This tensioning takes place in incremental steps and as the desired clamping force is reached the tensioning of the device 10 is stopped and the cap 26 is locked along the shaft 12. With reference to Figure 5, the device 10 is shown in use fitted in place to repair a fractured bone 40. The bone 40 includes a first section 42 which has fractured from a main section (second section) 43 and is to be secured using the device 10.

The soft tissue on the side "A" of the bone is cut to allow access to the first section 42 for manipulation and alignment. Once the first section 42 is aligned a hole 44 is drilled through the first section 42 and through the bone 40 from side "A" to side "B", which remains covered by soft tissue. Effectively, there is a first aperture 45 on side "A", a second aperture 47 on side "B" and a passage therebetween spanning the first section 42 and the main section 43 of the bone 40.

The hole 44 is preferably of a diameter slightly larger than that of the shaft 12. The device 10 is then threaded or positioned with the pointed end and head 14 through hole 44. As the device 10 is passed through the hole 44 the barbs 18 are pressed downwards by the walls of the hole 44 into the retracted condition. When the head 14 emerges from hole 44 on the side "B", it moves into the engaged condition.

The device 10 is then pulled by the shaft 12 towards the side "A". The barbs 18 abut against the surface of the bone around the second aperture 47 to anchor the head 14 and leading end of the device 10 against withdrawal from the hole 44.

The cap 26 is the fitted over the trailing end 24 of the device 10 by mating engagement of the shaft 12 through the opening 28.

The cap 26 is then displaced (through application of sufficient force and restraining the trailing end 24 of device 10) along the shaft 12 toward the leading end until in abutment with the bone 40 on side "A" around the first aperture 45. A clamping force is then lightly effected across the bone 40 through tension in the shaft 12 between the head 14 and the cap 26. The first section 42 is thus secured to the second main section 43.

The flexible shaft 12 may facilitate fitment under certain conditions but may be replaced with a rigid shaft where this is desired. The device may also be located within a rigid insertion tube when inserted through the drill hole - once the tube is retracted the head will expand and the tube can be withdrawn. Such a tube (which need not be straight) may assist in fitting the device with a flexible shaft.

The invention provides for an alternative approach to reduction surgery which reduces the requirement of cutting to expose opposite sides of a fractured bone.

A person skilled in the art will appreciate that a number of changes can be made to the features described and referred to without departing from the scope of the current invention.

Claims

1. An orthopaedic fastening device comprising a shaft having an engaging head movable from an engaged condition to a retracted condition and a stop being securable along a length of the shaft.

2. The orthopaedic fastening device according to Claim 1, wherein the shaft includes a series of gripping formations along its length with corresponding engaging formations provided about an opening through the stop.

3. The orthopaedic fastening device according to Claim 2, wherein the engaging formations of the stop include a circular arrangement of teeth about the opening located through the stop.

4. The orthopaedic fastening device according to Claim 2 or 3, wherein the stop is provided as a circular disk-shaped cap.

5. The orthopaedic fastening device according to any one of Claims 3 to 4, wherein the head is a circular arrangement of deformable barbs formed around the shaft.

6. The orthopaedic fastening device according to Claim 5, wherein the barbs are arranged around a leading end of the shaft.

7. The orthopaedic fastening device according to Claims 5 or 6, wherein the shaft includes a recess located behind the barbs to accommodate the barbs in the retracted condition.

8. The orthopaedic fastening device according to any one of Claims 3 to 7, wherein the gripping formations of the shaft are provided as annular ribs.

9. The orthopaedic fastening device according to Claim 8, wherein each rib has a first tapered edge over which the teeth move when the stop is positioned along the shaft and a first locking edge to engage the teeth once the teeth have passed over the first tapered edge.

10. The orthopaedic fastening device according to Claim 9, wherein the teeth are configured with a corresponding second tapered edge and a corresponding second locking edge, wherein the first and second tapered edges serve to provide cam formations, and wherein the first and second locking edges act to lead the gripping formations into overlapping engagement with the teeth.

11. The orthopaedic fastening device according to any one of Claims 1 to 10, wherein at least one of the shaft, the engaging head and the stop is flexible.

12. The orthopaedic fastening device according to Claim 10, wherein the head is deformable and resiliently biased into the engaged condition, and wherein the head has a tapered profile.

13. The orthopaedic fastening device according to any one of Claims 1 to 12, wherein the shaft and head are moulded from plastics material.