WO1998048736A1

WO1998048736A1 - Tendon grafting aid

Info

Publication number: WO1998048736A1
Application number: PCT/GB1998/001200
Authority: WO
Inventors: Hagop Samuel Manushakian; Duncan Angus Mcgrouther
Original assignee: University College London
Priority date: 1997-04-25
Filing date: 1998-04-24
Publication date: 1998-11-05
Also published as: GB2324471A; AU7068998A; GB9708540D0

Abstract

A tendon grafting aid comprises a non-adherent fluid permeable sheet or tube e.g. of silicone material encasing the tendon whilst the graft becomes established. It is removed by cutting and withdrawing it through a small incision under local anaesthetic. Advantages are reduced surgical intervention and earlier physiotherapy.

Description

TENDON GRAFTING AID

This invention relates to a method of tendon grafting, and to a tendon grafting aid. It is primarily but not exclusively applicable to tendons in the hand, but may be indicated also for other tendons in the human body, and may be of use also in veterinary practice, for example in treating injuries to bloodstock.

In hand surgery the current method of tendon grafting is a two-stage technique. In the first stage a solid rod of non-allergenic material such as silicone rubber is implanted in place of the missing tendon so that mesothelial scar tissue will grow around it and form a tunnel to accommodate a replacement tendon. In the second stage, some three to six months later, the rod is removed and the tendon is grafted in place. Both stages involve major operations and moreover the long delay between the stages means that the patient is without full use of his hand for many months; physiotherapy cannot commence until the tendon graft has become established after the second stage.

The present invention at least in its preferred embodiment avoids these disadvantages.

In one aspect the invention provides a method of grafting a tendon comprising enclosing the tendon in non adherent (as defined) material, grafting the tendon in place and subsequently removing the material from around the grafted tendon. In another aspect the invention provides the use of a non adherent material (preferably a material through which interstitial body fluid may pass) in the preparation of a tendon grafting aid for enclosing a tendon during establishment thereof following grafting.

By non-adherent we mean that the material does not become attached to the tendon or to surrounding tissue.

In one form of the invention the tendon is disposed in a tube of said material. In another form the tendon is wrapped in a sheet of said material.

Preferably the tubular member is opened along a longitudinal line of separation to permit removal thereof from the grafted tendon.

In a further aspect the invention provides a prepared tendon grafting aid comprising flexible non-adherent material adapted to enclose a tendon and permitting the passage of interstitial body fluid, the material being such that in use the grafting aid remains separate from the tendon and surrounding tissue and is removable after the tendon is established.

In another aspect the invention provides a tendon grafting aid comprising a tubular member having non-adherent exposed surfaces and a longitudinal line of separation whereby the tubular member can be removed from a grafted-in-place tendon.

Preferably this tubular member also has at least one opening to permit ingress of interstitial body fluid to the tendon.

The material, whether in tube or sheet form may have at least two parallel slits so that upon flexure of the tendon towards the slits a portion of the material between the slits is displaced to permit the passage of interstitial fluid.

The line of separation may be formed by a continuous or discontinuous longitudinal slit in the tubular member.

Alternatively the line of separation may be constituted by overlapping or interlocking edge regions of sheet material formed into said tubular member.

The tubular member may comprise means for maintaining a gap between said edge regions to permit the passage of interstitial fluid. The gap-defining means may be projecting portions on at least one of the edge regions.

In a yet further aspect the invention provides a tendon grafting aid comprising a tubular member having a non-adherent wall permitting the passage of interstitial fluid and separable to permit removal from a grafted-in place tendon.

The tubular member may be made wholly of a non-adherent material such as silicone rubber.

The invention will now be described merely by way of example with reference to the accompanying drawings, wherein

FIGURE 1 shows a first embodiment of a grafting aid of the invention;

FIGURE 2 shows a second embodiment

FIGURE 3 is a cross-section on line 3-3 through the embodiment of figure 2,

FIGURE 4 is a section on line 4-4 of figure 3, and

FIGURES 5 and 6 show a third embodiment.

Referring to figure 1, the tendon grafting aid consists in this embodiment of a flexible thin-walled silicone rubber tube 10, of non-adherent material such as medical grade silicone rubber. Sources of suitable material are Dow Corning, Mentor Meghan Biocell or CUI. It has a wall thickness 0J25 mm and internal diameter to suit the tendon to be grafted, for example 2 mm to 8 mm. The tube is pierced by a series of elongate slots 12 eg 0.5 mm or 1 mm wide, 5 mm long, arranged in lines longitudinally of the tubular member. Some of the slots 14 intersect the ends of the tube 10. The tube is cut to length by the surgeon to suit the graft to be inserted, the lines of slots being staggered so that wherever the tube is cut a slot intersects the ends.

In use the tube 10 is cut to a length approximately equal to that of the tendon graft, the graft is placed within the tube so as to be enclosed thereby and is then implanted by a conventional surgical technique and the wound closed. Before closing the wound, it is ensured that the tube 10 is angularly oriented relative to the graft so that a line of slots is easily accessible when the time comes to remove the tube 10.

The tube 10 is left in place for up to about two months, during which time interstitial fluid is free to pass through the slots 12 to and from the grafted tendon to nourish it and permit it to become established.

When the tendon is established, access is gained to one end of the tube 10 under local anaesthetic via a small incision. It is then withdrawn in stages through the incision, by being cut along lands 16 between successive longitudinally aligned slots, which thus form a line of separation.

It will be appreciated that cutting through a land permits the tube to be withdrawn from around the tendon by the length of the thereby-freed slot. Cutting the next land permits the process to be repeated, and so on until the tube has been completely removed.

The line of separation need not be defined by slots; a series of less elongated holes will suffice, provided it remains practicable for the surgeon to cut between them. Thus a defined line of separation as such is not essential.

An alternative separation line may be a line of closely-spaced perforations or of reduced wall thickness, so that in either case the wall tears easily along the line of weakness, permitting its withdrawal from around the tendon.

If the tube material is resilient yet self supporting, it can be pre-cut along its length to provide a separation line. Then it is removed from the tendon by springing open the cut line to permit the tendon to be passed through the resulting gap.

Figures 2, 3 and 4 show a development of this concept, particularly suitable for large tendons. The tubular member 10 has holes 12 eg of diameter 1 mm to permit passage of interstitial fluid. The size of the holes may vary depending on the size of the tubular member 10. For example a small tube 10 for paediatric use may have holes as small as 0.2 mm in diameter; a large tube 10 may have holes as large as 3 mm in diameter. The tube has a seam 18 formed by overlapping edge portions 20, 22 which in cross-section are shaped as shown in figure 3 so as to engage each other and remain engaged until the time comes to remove the tube from the graft. The material has sufficient stiffness and resilience to achieve this. Viewed in longitudinal section, the edge portions 20, 22 have projections or interdigitations 24 which without prejudicing the inter-engagement of the edge portions 20, 22 maintain them in spaced relationship so that interstitial fluid can pass between them.

The tube is used in the same manner as described for the figure 1 embodiment, except that the tube is removed through the small incision simply by pulling it from one end, the edge portions disengaging to free the tube from the tendon. Care is taken to orient the tube so that the line of separation constituted by the edges 20, 22 is disposed on the side of the tendon away from the skin. Then not only is it most effective in releasing the tube from the tendon, but the space between the edge portions is best positioned to permit the ingress and egress of interstitial fluid.

Alternatively the edges 20, 22 may be provided with interengaging strips having complementary profiles such as are used in resealable plastics bags. A more secure closure may result.

Figures 5 and 6 show a sheet of silicone material 30, 0J25 mm or less in thickness with a series of pairs of parallel slits 32, 34 each 2 mm to 20 mm long and about 1 mm or 2mm apart, in several lines. In use, the sheet (or a portion thereof cut to size) is wrapped around the tendon so as to form a single layer around the majority of the length of the tendon, the edges 36, 38 of the sheet overlapping slightly and being secured by a suitable silicone rubber adhesive. The overlapping adhesive joint 39, figure 6, is positioned so as to be on the outside of the curved tendon if the tendon is subject to flexing (eg during physiotherapy) whilst the grafting aid is still in place. When the tendon is flexed, the portions 42 of material between the slits 32, 34 (especially those on the inside of the curved tendon) will be displaced away from the surface of the tendon permitting interstitial fluid to pass to and from the tendon.

The material is removed from the tendon when the graft is established as already described with reference to figure 1. If the material is particularly thin it may be possible to tear it as it withdrawn; cutting along a line of separation may then not be necessary. The same may be possible for a thin perforated tube as in figure 1.

Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features. The abstract is repeated here as part of the specification.

A tendon grafting aid comprises a non-adherent fluid permeable sheet or tube eg. of silicone material encasing the tendon whilst the graft becomes established. It is removed by cutting and withdrawing it through a small incision under local anaesthetic. Advantages are reduced surgical intervention and earlier physiotherapy.

Claims

1. A method of grafting a tendon comprising enclosing the tendon in non adherent (as defined) material, grafting the tendon in place and subsequently removing the material from around the grafted tendon.

2. A method as claimed in claim 1 comprising disposing the tendon in a tube of said material.

3. A method as claimed in claim 1 comprising wrapping the tendon in a sheet of said material.

4. A method as claimed in any preceding claim comprising opening the enclosing material along a longitudinal line of separation to permit removal thereof from the grafted tendon.

5. A method as claimed in any preceding claim comprising permitting ingress of interstitial body fluid to the tendon via at least one opening in the enclosing material.

6. A prepared tendon grafting aid comprising flexible non-adherent material adapted to enclose a tendon and permitting the passage of interstitial body fluid, the material being such that in use the grafting aid remains separate from the tendon and surrounding tissue and is removable after the tendon is established.

7. A tendon grafting aid as claimed in claim 6 wherein the material is in sheet form.

8. A tendon grafting aid as claimed in claim 6 wherein the material is in tubular form.

9. A tendon grafting aid comprising a tubular member having non adherent exposed surfaces and a longitudinal line of separation whereby the tubular member can be removed from a grafted-in-place tendon.

10. A tendon grafting aid as claimed in claim 9 wherein the material of the tubular member permits the passage of interstitial body fluid to the tendon.

11. A tendon grafting aid as claimed in claim 6 or claim 10 wherein the material has at least one opening to permit said passage of interstitial fluid.

12. A tendon grafting aid as claimed in claim 11 wherein the material has at least two parallel slits so that upon flexure of the tendon towards the slits a portion of the material between the slits is displaced to permit the passage of interstitial fluid.

13. A tendon grafting aid as claimed in claim 9 wherein the line of separation is formed by a continuous or discontinuous longitudinal slit in the tubular member.

14. A tendon grafting aid as claimed in claim 9 wherein the line of separation is formed by overlapping or interlocking edge regions of sheet material formed into said tubular member.

15. A tendon grafting aid as claimed in claim 14 wherein the tubular member comprises means for maintaining a gap between said edges regions to permit the passage of interstitial fluid.

16. A tendon grafting aid as claimed in claim 15 wherein the gap-defining means comprises projecting portions on at least one of the edge regions.

17. A tendon grafting aid comprising a tubular member having non adherent surfaces permitting the passage of interstitial fluid, and separable to permit removal from a grafted-in place tendon.

18. The use of a non adherent material in the preparation of a tendon grafting aid for enclosing a tendon during establishment thereof following grafting.

19. The use of a material as claimed in claim 18 wherein the material permits the passage of interstitial body fluid.

20. A tendon grafting aid as claimed in any of claims 6 to 19 being made of silicone material.

21. A method of grafting, or a tendon grafting aid, or the use of a non-adherent material in the preparation thereof substantially as herein described with reference to the accompanying drawings.