MEDICAL DEVICE

Abstract

The invention concerns a device for use in ligament surgery to locate the best graft attachment site, including parts thereof; a kit of parts for use in ligament surgery; and a method for performing ligament surgery.

Claims

1. A device for use in ligament surgery in a subject comprising: an elongate member having, at a first end, a manipulating member and, at a second end, a locator plate for determining a graft attachment site, wherein said site locator plate comprises a plurality of holes all of which, or a number of which, have attached thereto or associated therewith an elongate indicator that uniquely identifies each hole with respect to the other holes.

2. The device according to claim 1 wherein said elongate indicator is flexible.

3. The device according to claim 1 wherein said elongate indicator comprises at least one thread or suture.

4. The device according to claim 1 wherein said locator plate is adapted to mate with an anatomical area to which a ligament graft is to be located.

5. (canceled)

6. (canceled)

7. The device according to claim 1 wherein said elongate member further comprises an arcuate member or part that is sized and shaped to accommodate, in use, movement of the limb or body part during joint motion.

8. The device according to claim 7 wherein said arcuate member or part is positioned adjacent, or near, from the end of said elongate member.

9. The device according to claim 1 wherein said elongate indicator is adapted to have uni-directional movement towards the locator plate during movement whereby each elongate indicator passes towards the plate under tension by a graded amount but reverse movement is prevented.

10. The device according to claim 9 wherein said elongate indicator comprise a plurality of barbs arranged circumferentially.

11. The device according to claim 10 wherein said barbs are further arranged longitudinally and are spaced with respect to each other along at least of a part of the longitudinal axis.

12. The device according to claim 1 wherein said elongate indicator comprise a plurality of markings and/or indentations.

13. The device according to claim 1 further comprising an arm member for securing the device about a limb to be operated upon wherein said arm member extends from a first end of the elongation member and terminates at a position near or adjacent to the locator plate.

14. The device according to claim 1 wherein said locator plate is releasably attached to said elongate member by an attachment means.

15. A locator plate comprising a plurality of holes all of which, or a number of which, have attached thereto or associated therewith an elongate indicator that uniquely identifies each hole with respect to the other holes, wherein the locator plate is configured to be part of a ligament surgery device, the ligament surgery device comprising an elongate member having, at a first end, a manipulating member and, at a second end, the locator plate, wherein the locator plate is configured to determine a graft attachment site.

16. The locator plate according to claim 15 wherein said elongate indicator is flexible.

17. The locator plate according to claim 15 wherein said elongate indicator comprises at least one thread or suture.

18. The locator plate according to claim 15 wherein said locator plate is adapted to mate with an anatomical area to which a ligament graft is to be located.

19. (canceled)

20. (canceled)

21. The locator plate according to of claim 15 wherein said elongate indicator is adapted to have uni-directional movement towards the locator plate during movement whereby each thread passes towards the plate under tension by a graded amount but reverse movement is prevented.

22. The locator plate according to claim 21 wherein said elongate indicator comprise a plurality of barbs arranged at least partially circumferentially.

23. The locator plate according to claim 22 wherein said barbs are further arranged longitudinally and are spaced with respect to each other along a part of the longitudinal axis.

24. A kit of parts for use in ligament surgery comprising: at least one device comprising an elongate member having, at a first end, a manipulating member and, at a second end, a locator plate for determining a graft attachment site, wherein said site locator plate comprises a plurality of holes all of which, or a number of which, have attached thereto or associated therewith an elongate indicator that uniquely identifies each hole with respect to the other holes, and one or more additional locator plates configured to determine a graft attachment site, each additional locator plate comprising a plurality of holes all of which, or a number of which, have attached thereto or associated therewith an elongate indicator that uniquely identifies each hole with respect to the other holes.

25. The kit according to claim 24 further comprising at least one tension monitor.

26. The kit according to claim 25 wherein said tension monitor is a tube whereby, in use, the elongate indicators are inserted into the tension monitor and the movement of the elongate indicators within said tension monitor during joint movement is used to determine the elongate indicator under least tension.

27. (canceled)

28. (canceled)

Description

[0069] FIG. 1. Shows a perspective view of a medical device in accordance with the invention.

[0070] FIG. 2. Shows (I.h.s.) a side elevation and plan view of a medical device in accordance with the invention and (r.h.s.) a side elevation view of a medical device in accordance with the invention and a plan view of a medical device in accordance with the invention when in an open position.

[0071] FIG. 3. Shows a perspective view of a tip of the medical device in accordance with the invention.

[0072] FIG. 4. Shows diagrammatically how the medical device according to the invention is to be used.

[0073] FIG. 5. Surgical insertion and use of the device according to the invention. In this embodiment, the device is fixed to the femoral condyle using a 5 mm cancellous screw. In alternative arrangements (not shown) the device further comprises an arm to generate a pinching force that will clamp the disc in position;

[0074] FIG. 6. Shows a suture tension device measures tension on threads through a full range of motion. For proof of concept, the tension device was fixed with a 5 mm cancellous screw to the medial malleolus;

[0075] FIG. 7. Shows an example of a tip of a device according the invention with marker holes;

[0076] FIG. 8. Shows a graphical representation of the tension measured for each thread and its corresponding hole reference; in this example 7 would be the best ligament attachment position.

[0077] Table 1. Table showing the tension measured for each thread and its corresponding hole reference.

[0078] Referring now to the figures and, firstly, to FIG. 1 there is shown a perspective view of a medical device in accordance with the invention. It is ideally made from a single moulded or printed material and has a scissor-type handle [1] (although this may vary according to a user's requirements) and originating therefrom is an extension member [2] that terminates in a locator plate [3].

[0079] Extension member [2] is typically, though not exclusively, in the form of a fine rod that arcs or bends towards the end nearest the locator plate [3]. This arcing ensure a surgeon can manipulate a joint when the locator plate is in situ without the rod otherwise obstructing movement. Accordingly, the size and shape of the arc may differ for different applications, e.g. elbow would require a device with a smaller sized arc compared to a device for use with a knee joint. The device also includes an optional arm member [4] that originates from handle [1] and runs parallel with extension member [2] but is shaped or curved in a manner so that it can be placed about a limb to engage with same and so steady the device when in use. This feature is preferred in a device where the locator plate [3] is contiguous with the extension member [2] and so remains attached to same throughout use.

[0080] FIG. 2 shows a printed version of the device described above. In this device, locator plate [3] is fixed or integral with extension member [2] and formed at the end thereof. Arm member [4] is releasably engageable with extension member [2] under the control of handle [1].

[0081] In FIG. 3 there is shown the locator plate [3] and it can be seen that the locator plate includes a series of holes [5], the number and nature of which can be specific to the nature of the joint to be operated upon, e.g. an elbow joint may include a smaller number of smaller holes compared to a locator plate for use with a knee joint. Each one of the holes [5] is threaded with a threadable material [6]. Any type of thread will suffice, however, it is important that each thread distinguishes each threaded hole because the tension in each thread is used to determine which hole represents the best ligament attachment site. Preferably, the thread is resorbable such that, in use, should any thread fragments result from surgery they will be safely absorbable by the body. Any type of indication may be used although it is envisaged that the use of different coloured threads will most easily indicate the hole to be used. This is shown in FIG. 3b, here, each thread is colour coded and, further, provided with a unidirectional movement limiter [7]. Each coloured thread is provided with a number of spaced barbs [7] and in use is inserted in a tension monitor or casing, or tunnel [8] adapted to receive a barbed thread and encase same so that movement is only unidirectional.

[0082] Referring now to FIG. 4a, a tibial tunnel [9] is provided through which the distal aspect of the ACL graft is pulled through, to be attached to the medial wall of the tibia. The device is used to insert the locator plate [3] into the knee joint, it can then be held in place during the subsequent manipulations using handle [1] or attached in place using a surgical screw. The coloured coded threads are then threaded through the tibial tunnel (and in any event externalised) (FIG. 4b). With the locator plate [3] in place the joint is manipulated and as it is moved the tension in each thread is measured using a conventional device. The thread under the least tension identifies the hole that represents the precise site for ligament attachment.

[0083] To determine the tension of each thread in movement, a tension measuring device (the Salter Brecknell Super Samson, a hand-held, light weighing device with overload protection and tare mechanism) was fixed at its distal end through a screw to the medial malleolus. The proximal end of the tension device was connected to each thread coming from the tibial tunnel and measuring the tension elicited through the full range of motion from full flexion to full extension to test suture near isometricity. Tension force data was retrieved from the tension measuring device.

[0084] In one embodiment, the externalised and coloured coded threads are barbed and threaded through a single casing or tension monitor [10] (FIG. 4c). With the locator plate [3] in place, the joint is manipulated and as it is moved the threads are pulled through the casing [10]. The thread that moves the least, and so extends from said casing the furthest, is represent of the thread under least tension and so its corresponding hole represents the precise site for ligament attachment.

[0085] In another embodiment, each one of the externalised and coloured coded threads are barbed and threaded through their own casing [10], or single casing each with its own channel. With the locator plate [3] in place the joint is manipulated and, as it is moved, the threads are pulled through their casings [10]. Due to the presence of the barbs, this movement is unidirectional and so at the end of the joint manipulation one of the threads will have moved the least and so extend from its casing the most, this is representative of the thread under least tension and so of the hole that is the precise site for ligament attachment.

[0086] FIG. 5 shows an image of a locator plate [3] in place i.e. attached to the general location of a ligament attachment site using a surgical screw and its associated threads.

[0087] FIG. 6 shows the device being used on an ankle joint and in combination with a conventional tension measuring device. This shows the distal end of the tension meter, where it is screwed on to the medial malleolus of the ankle joint. The proximal end of the tension meter accepts the sutures that are drawn through the tibial tunnel in the knee

[0088] FIG. 7 shows a view of a locator plate [3], in this image the plate is attached to the medical device, although, as shown in FIG. 5, this is not always the case. The locator plate [3] can be shaped for a user's requirements but is most typically circular or cylindrical. It includes a number of holes each one, in use, is threaded for tension measurement. Though not shown, each hole may be coded in a manner that corresponds to the coding used for its thread, this assists with matching each thread with its hole. In this embodiment it can be seen that an arm member [4] is provided for gripping a limb and aiding in the use of the device.

[0089] FIG. 8 is a graph that measures tension at each of the locator plate hole potential attachment sites, depicted by holes 1-10 of FIG. 7. It can be seen that the tension in thread 7 corresponding to hole 7 is subject to the least tension during the movement of the joint. Accordingly, this represents the best site for ligament attachment.

[0090] Device Designing and 3D Printing

[0091] As proof of concept, a device according to the invention was designed with 10 different positioned holes (FIG. 7) for insertion through the lateral arthroscopic portal and fixed with a clamp to the outer lateral femoral cortex to gain stability while moving the knee from flexion to extension for several cycles.

[0092] Subject

[0093] A disarticulated lower limb human cadaver was used to test a novel mechanical device which was 3D printed. The lower limb cadaver was chosen to be with full range of motion and with the least amount of fat possible to minimize the effects of fatty soft tissue effect on range and ligament tension. The native ACL was severed and a tibial tunnel 9 mm to be drilled in the centre of the tibial footprint of the ACL.

[0094] Surgical Technique

[0095] Before insertion, proline sutures are connected to the holes in which every thread is passed and tied with a knot at the back side (FIG. 3a). The device with the threads was introduced through the lateral arthroscopic portal (FIG. 5a)

[0096] Threads were pulled from a 9-mm tibial tunnel (FIG. 5b) with a suture retrieval handle. In this example, the device was fixed to the femoral condyle via 5 mm cancellous screw to fix it in position (FIG. 5c).

[0097] Results:

[0098] The data from the tension measuring device testing is shown in table 1 and FIG. 8 using a device with 10 holes enumerated from 1-10 (FIG. 7).

[0099] For this study, the assumption was made that we can select a point at which tension in both flexion and extension is the least.

[0100] As we can see there were four holes showing minimal tension (5,6,7 and 8). With least tension at hole 7. This was therefore determined to be the position nearest to isometry, and thus the hole can then be used to drill the femoral tunnel for ACL graft attachment.

[0101] Discussion:

[0102] Anterior cruciate ligament reconstruction is a demanding operation. Tunnel placement is considered one of the crucial determinants in outcome after ACL reconstruction. The aim is to have the graft located at the most isometric point in the position of the original ACL achieving both stability and full range of motion whilst maintaining a length near that of the original ACL. The point of femoral attachment of the graft is crucial and determines graft impingement and whether there will be graft failure.

[0103] We herein disclose a simple yet elegant manual device for measuring the best isometric point for each joint to determine optimum graft attachment position.

TABLE-US-00001 Full flexion Flexion of Full extension 160 degrees 90 Degree No of net tension net tension net tension the hole in gm in gm in gm 1 50 350 150 2 40 400 220 3 90 300 200 4 100 200 150 5 80 150 100 6 50 60 70 7 20 50 10 8 80 100 50 9 150 350 200 10 100 400 250