GB2484178A

GB2484178A - Dynamic finger fixator

Info

Publication number: GB2484178A
Application number: GB1115299.8A
Authority: GB
Inventors: Simon Halsey; Tim Adlam
Original assignee: Bath Institute of Medical Engineering Ltd
Current assignee: Bath Institute of Medical Engineering Ltd
Priority date: 2011-03-30
Filing date: 2011-09-05
Publication date: 2012-04-04
Anticipated expiration: 2031-09-05
Also published as: WO2012131326A3; GB2484178B; GB201105304D0; GB201115299D0; WO2012131326A2; GB2489471A

Abstract

A dynamic finger fixator 10 comprises a two-part elongate strut element 12 and two pin-engagable elements 14 spaced apart on the two-part strut element. The two-part strut element includes spacing-adjustment means 16 for selectively adjusting and setting a spacing between the two pin-engagable elements. A first of these parts includes a strut member 20, and the second part includes a rotatable adjuster 32 forming at least part of the spacing-adjustment means. The adjuster is prefereably rotatably mounted on the strut member . The strut member includes a first of the pin engagable elements 28 and the rotatable adjuster 32 includes the second of the pin engagable elements 34, which is off-centre on a body of the rotatable adjuster 32. A rotation tool (38, fig 2) may be used for rotating the rotatable adjuster.

Description

Dynamic Finger Fixator The present invention relates to a dynamic finger fixator for holding a broken, fractured or damaged finger during the healing process.

A damaged or fractured finger can be treated in various ways including early mobilisation (movement), splintage and stabilisation surgically. The latter can include stabilisation with K wires, screws or screws and plates. For difficult fractures especially comminuted (multi-fragmented) fractures, particularly into a joint, then an external frame may be the only satisfactory solution. The frame is typically fixed to the injured bones proximal and distal to the fracture. Some form of external apparatus acts to distract the K wires, which forces then act against the natural tension forces of the soft tissues. This allows for realignment of the fracture fragments. For intra-articular fractures (into the joint) early movement helps to optimise recovery both of the joint and the soft tissues. At present the distraction force across the fracture is judged by experience. The external frames used at present are either technically demanding to apply or adjust, or bulky; limiting their use especially to border digits.

The present invention seeks to provide a solution to these problems, whereby a separating force can be applied across a damaged area of a finger and the separating force can be easily adjusted as necessity dictates. Joint mobility is maintained during the recovery period due to the arrangement which facilitates dynamic fixation, thereby accelerating a return to a fully-functioning joint.

According to the invention, there is provided a dynamic finger fixator comprising a two-part elongate strut element and two pin engagable elements spaced apart on the two-part elongate strut element, the two-part elongate strut element including spacing-adjustment means for selectively adjusting and setting a spacing between the two pin engagable elements in situ, a first said part of the strut element including a strut member, and a second said part being or including a rotatable adjuster forming at least part of the spacing-adjustment means, the strut member including a first said pin engagable element and the rotatable adjuster including a second said pin engagable element which is off-centre on the rotatable adjuster, so that dynamic fixation is impartable to a patient's finger.

Preferable and/or optional features of the invention are set forth in claims 2 to 18, inclusive.

The invention will now be more particularly described, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 shows a first embodiment of an in use dynamic finger fixator, in accordance with the present invention; and Figure 2 shows a rotation tool being used to angularly adjust a rotatable adjuster of the dynamic finger fixator in situ.

Refening to Figures 1 and 2 of the drawings, there is shown a dynamic finger fixator 10 which comprises a two-part elongate strut element 12, two pin-engagable elements 14, a spacing-adjustment mechanism 16, and first and second resiliently flexible pin elements 18. A first part of the strut element 12, which in this case is formed of moulded plastics or surgical-grade metal, preferably includes a rectilinear planar or substantially planar elongate strut member 20 having a body 22 providing an enlarged head end 24 and a tail end 26 opposite the head end 24. A first one of the pin-engagable elements 14 is provided at or adjacent to the tail end 26 and extends at least partway, and in this case a majority of the way, along a longitudinal extent of the body 22 of the strut member 20.

The first pin-engagable element 14 in this embodiment is a plurality of spaced-apart tail apertures 28 which extend through the body 22. The tail apertures 28 are spread apart laterally, for example, by providing a plurality of adjacent staggered or offset rows, over the body 22 as well as longitudinally from the tail end 26.

An axis of the bore of each tail aperture 28 is preferably normal or substantially normal to the longitudinal extent of the body 22.

The head end 24 of the body 22 is enlarged relative to the tail end 26, and includes a single large head aperture 30, in this case being circular, therethrough. The head aperture 30 is adapted to receive the second part of the strut element 12, being a rotatable adjuster 32. The rotatable adjuster 32 is a circular disk dimensioned to form a tight frictional fit within the head aperture 30. The walls of the head aperture 30 and the rotatable adjuster 32 are cylindrical or substantially cylindrical, but may be tapering to form a Morse taper-fit, for example. Other engagement means may also be considered, for example, by including a circumferentially extending ridge and channel partway along the lateral extents of the walls of the head aperture 30 and the rotatable adjuster 32, whereby a push-fit positive engagement is achievable.

Furthermore, although in this embodiment the walls of the head aperture 30 and the rotatable adjuster 32 are smoothly continuous, they may include indexing means, such as low rise teeth, again to prevent or limit unintentional relative angular displacement.

The low rise teeth are preferably of a height that allows rotation of the rotatable adjuster 32 whilst within the head aperture 30, rather than requiring extraction and re-insertion.

Other modifications are also possible. For example, the head aperture 30 and the rotatable adjuster 32 may be non-circular. In this case, complementarily-shaped lugs may be formed into the walls to enable indexing.

The spacing-adjustment mechanism 16 makes use of the rotatable adjuster 32 and a second one of the pin-engagable elements 14 which includes a plurality of secondary head apertures 34 through the rotatable adjuster 32. The secondary head apertures 34 extend in parallel with the tail apertures 28.

The secondary head apertures 34 are radially spaced from a rotational axis of the rotatable adjuster 32, and in this embodiment, the secondary head apertures 34 are equi-angularly spaced apart from each other. Additionally or alternatively, the secondary head apertures may be equi-radially spaced from a centre of rotation of the adjuster 32, or they may be or include non-uniformly radially spaced secondary head apertures for fine adjustment. For example, there may be more than one aperture aligned in a radial direction of the secondary head aperture.

The tail apertures 28 and the secondary head apertures 34 are dimensioned to receive as a close fit the pin elements 18 mentioned above.

In use, the first pin element 18, typically being Kirschner wire, K-wire or other sterilised sharpened smooth stainless steel, titanium or other biocompatible material pin, is inserted through the patient's finger 36 so that the bone is engaged to one side of the damaged area. The second pin element 18, again typically being Kirschner wire, K-wire or other sterilised sharpened smooth stainless steel, titanium or other biocompatible material pin, is inserted through the patient's finger 36 so that the bone is engaged to the other side of the damaged area. In the case of a damaged phalange or more specifically a damaged phalanx, the first pin element 18 is preferably inserted at or adjacent to the centre of rotation of the interphalangeal joint proximal of the damaged area, and the second pin element 18 is inserted through the phalanx adjacent to and distal of the damaged area.

A first strut element 12 is then located on the first and second pin elements 18 on one side of the finger 36, whereby the first pin element 18 is inserted into an appropriate one of the secondary head apertures 34, and the second pin element 18 is inserted into an appropriate one of the tail apertures 28. Preferably, the first and second pin elements 18, being resiliently flexible, are biased slightly away from each other by the strut element 12 by the engagement with the secondary head aperture 34 and the tail aperture 28.

A second strut element 12 is also located on the first and second pin elements 18 on the other side of the finger, in the same manner as the first strut element 12. The first and second pin elements 18 may be deformed, such as by bending, to lock the strut elements 12 in place to the finger 36, and the two strut elements 12 are interengaged around the finger 36 using surgical tape, plaster or other suitable binding.

A surgical rotation tool 38 is then used to rotate the rotatable adjuster 32 in situ to further bias the first and second resiliently flexible pin elements 18 away from each other. The rotation tool 38 preferably comprises a fixed head 40 and an elongate handle 42. The head 40 includes at least two spaced-apart pins 44 which are receivable in at least two of the unoccupied secondary head apertures 34. The pins 44 extend at or substantially at right angles to the handle 42. By turning the handle 42, the pins 44 cause the rotatable adjuster 32 to turn, thereby dynamically adjusting the tension imparted to the first and second pin elements 18.

Although two spaced-apart pins 44 are suggested, the head 40 of the rotation tool 38 may utilise a single non-circular pin if the secondary head apertures 34 are non-circular, or may utilise openings if engagement pins are provided on the rotatable adjuster 32 instead. More than two spaced-apart pins can also be considered.

Consequently, as the healing process progresses, the rotation tool 38 can be used periodically on the rotatable adjuster 32 of both strut elements 12 to adjust the tension across the damaged area, thereby promoting a more uniform repair and reducing the build up of fracture callus.

The rotatable adjuster may be a domed disk having a convex upper and/or lower surface. The main aperture would therefore preferably have a complementarily shaped wall being concave across the lateral extent to more securely retain the rotatable adjuster in place as a press-fit. Conversely, the domed disk may have a concave upper and/or lower surface with the complementarily shaped wall being convex.

Although the pin elements are bent over at their distal ends to engage with the strut element and the rotatable adjuster, other means for capping or engaging the pin elements with the strut element and the rotatable adjuster may be considered so that interference and rubbing with the neighbouring fingers is avoided or limited.

The rotatable adjuster may also have a harder or tougher core, for example, being metal, which may be covered by a material having a different hardness or toughness, for example, a plastics. This would be beneficial in preventing or limiting creep and wear during use, especially if the rotatable adjuster relies on a frictional fit to prevent or limit angular displacement.

Although a strut element is preferably utilised on each side of the finger, a single strut element may be utilised on only one side. In this case, the pin elements may be screw-threaded fasteners. In any event, modifications to the pin elements may be incorporated in any embodiment, such as screw-threading so that the pin elements do not, for example, have to extend completely through the digit.

It is therefore possible to provide a finger fixator which imparts dynamic fixation due to the resilient flexibility of the pin elements and the adjustability in situ of the strut elements via the rotatable adjuster. This all thereby achieves a reduction in recovery time. The digit can still be used whilst the damaged area is being dynamically biased apart. A longitudinally positively adjustable support via a cam or off-centre adjuster allows the pin elements through a finger to be flexed, thereby providing the damaged area some give whilst maintaining a separating force. It is also far simpler for a surgeon to apply the finger fixator of the present invention without requiring a great deal of skill and practise. It is also feasible to utilise the pin engagable element of the strut element as a drill guide.

The embodiment described above is provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention as defined by the appended claims.

Claims

Claims 1. A dynamic finger fixator comprising a two-part elongate strut element and two pin engagable elements spaced apart on the two-part elongate strut element, the two-part elongate strut element including spacing-adjustment means for selectively adjusting and setting a spacing between the two pin engagable elements in situ, a first said part of the strut element including a strut member, and a second said part being or including a rotatable adjuster forming at least pail of the spacing-adjustment means, the strut member including a first said pin engagable element and the rotatable adjuster including a second said pin engagable element which is off-centre on the rotatable adjuster, so that dynamic fixation is impartable to a patient's finger.
2. A dynamic finger fixator as claimed in claim 1, wherein the rotatable adjuster is rotatably mounted on the strut member.
3. A dynamic finger fixator as claimed in claim 1 or claim 2, wherein the strut member includes an opening at or adjacent to one end thereof, and the rotatable adjuster is complementarily shaped to be rotatably mounted in the opening.
4. A dynamic finger fixator as claimed in claim 3, wherein the rotatable adjuster is a friction fit within the opening of the strut member.
5. A dynamic finger fixator as claimed in any one of the preceding claims, wherein the first pin engagable element on the strut member includes a plurality of first pin-receivable apertures through a body of the strut member.
6. A dynamic finger fixator as claimed in claim 5, wherein the first pin-receivable apertures are spaced apart along at least a portion of the longitudinal extent of the strut member.
7. A dynamic finger fixator as claimed in claim 6, wherein the first pin-engagable apertures are spaced apart along a majority of the longitudinal extent of the strut member.
8. A dynamic finger fixator as claimed in any one of the preceding claims, wherein the second pin engagable element on the rotatable adjuster includes a plurality of second pin-receivable apertures through the body of the rotatable adjuster.
9. A dynamic finger fixator as claimed in claim 8, wherein the second pin-receivable apertures are equi-angularly spaced apart on the body of the rotatable adjuster.
10. A dynamic finger fixator as claimed in any one of the preceding claims, wherein the rotatable adjuster is or is substantially cylindrical.
11. A dynamic finger fixator as claimed in any one of the preceding claims, further comprising indexing means for indexing the rotatable adjuster on the strut member.
12. A dynamic finger fixator as claimed in claim 11, wherein the indexing means includes a plurality of first teeth on the strut member and a plurality of second teeth on the rotatable adjuster, the respective teeth interdigitating to hold an angular position of the rotatable adjuster relative to the strut member.
13. A dynamic finger fixator as claimed in any one of the preceding claims, further comprising a second two-part elongate strut element having further said pin engagable elements, the first and second two-part elongate elements being interconnectable about a patient's finger.
14. A dynamic finger fixator as claimed in claim 13, further comprising first and second pin elements, the first pin element extending from a first said pin engagable element to the opposing pin engagable element, and the second pin element extending from a second said pin engagable element to its opposing pin engagable element.
15. A dynamic finger fixator as claimed in claim 14, wherein the first and second pin elements are resiliently flexible.
16. A dynamic finger fixator as claimed in any one of claims 1 to 12, wherein the two-part elongate strut element is the sole strut element and in use extends along one side of a patient's digit.
17. A dynamic finger fixator as claimed in any one of the preceding claims, further comprising a rotation tool for rotating the rotatable adjuster, the tool including a head and an elongate handle, the head having engagement means for releasably engaging the second pin engagable element.
18. A dynamic finger fixator as claimed in claim 17, wherein the engagement means includes at least two spaced-apart pins receivable in the second pin engagable element.
19. A dynamic finger fixator substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.Amendments to the claims have been filed as follows: Claims 1. A dynamic finger fixator comprising a two-part elongate strut element and two pin engagable elements spaced apart on the two-part elongate strut element, the two-part elongate strut element including spacing-adjustment means for selectively adjusting and setting a spacing between the two pin engagable elements in situ, a first said part of the strut element including a strut member, and a second said part being or including a rotatable adjuster forming at least part of the spacing-adjustment means, the strut member including a first said pin engagable element and the rotatable adjuster including a second said pin engagable element which is off-centre on the rotatable adjuster, wherein the rotatable adjuster is oriented relative to the said second pin engagable element so that the second pin engagable element is movable relative to the first pin engagable element and in the longitudinal direction of the strut member due to rotation of the rotatable adjuster. r(\J 2. A dynamic finger fixator as claimed in claim I, wherein the strut member includes an opening at or adjacent to one end thereof and the rotatable adjuster C'J is complementarily shaped to be rotatably mounted in the opening.3. A dynamic finger fixator as claimed in claim 2, wherein the rotatable adjuster is a friction fit within the opening of the strut member.4. A dynamic finger fixator as claimed in any one of the preceding claims, wherein the first pin engagable element on the strut member includes a plurality of first pin-receivable apertures through a body of the strut member.5. A dynamic finger fixator as claimed in claim 4, wherein the first pin-receivable apertures are spaced apart along at least a portion of the longitudinal extent of the strut member.6. A dynamic finger fixator as claimed in claim 5, wherein the first pin-engagable apertures are spaced apart along a majority of the longitudinal extent of the strut member.7. A dynamic finger fixator as claimed in any one of the preceding claims, wherein the second pin engagable element on the rotatable adjuster includes a plurality of second pin-receivable apertures through the body of the rotatable adjuster.8. A dynamic finger fixator as claimed in claim 7, wherein the second pin-receivable apertures are equi-angularly spaced apart on the body of the rotatable adjuster.9. A dynamic finger fixator as claimed in any one of the preceding claims, wherein the rotatable adjuster is or is substantially cylindrical.10. A dynamic finger fixator as claimed in any one of the preceding claims, further comprising indexing means for indexing the rotatable adjuster on the strut member.11. A dynamic finger fixator as claimed in claim 10, wherein the indexing means includes a plurality of first teeth on the strut member and a plurality of second C\J teeth on the rotatable adjuster, the respective teeth interdigitating to hold an angular position of the rotatable adjuster relative to the strut member. c\JC\J 12. A dynamic finger fixator as claimed in any one of the preceding claims, further comprising a second two-part elongate strut element having further said pin engagable elements, the first and second two-part elongate elements being interconnectable about a patient's finger.13. A dynamic finger fixator as claimed in claim 12, further comprising first and second pin elements, the first pin element extending from a first said pin engagable element to the opposing pin engagable element, and the second pin element extending from a second said pin engagable element to its opposing pin engagable element.14. A dynamic finger fixator as claimed in claim 13, wherein the first and second pin elements are resiliently flexible.15. A dynamic finger fixator as claimed in any one of claims I to 11, wherein the two-part elongate strut element is the sole strut element and in use extends along one side of a patient's digit.16. A dynamic finger fixator as claimed in any one of the preceding claims, further comprising a rotation tool for rotating the rotatable adjuster, the tool including a head and an elongate handle, the head having engagement means for releasably engaging the second pin engagable element.17. A dynamic finger fixator as claimed in claim 16, wherein the engagement means includes at least two spaced-apart pins receivable in the second pin engagable element.18. A dynamic finger fixator substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings. r c\J c\J c\J