WO2005110249A1

WO2005110249A1 - Apparatus for use in orthopaedic surgery

Info

Publication number: WO2005110249A1
Application number: PCT/GB2005/001896
Authority: WO
Inventors: Kenneth P. Davis; David L. Mollon; Timothy S. Drew; David W. Paterson; David I. Rowley; Roy Smith
Original assignee: Imp Limited
Priority date: 2004-05-17
Filing date: 2005-05-17
Publication date: 2005-11-24

Abstract

Apparatus for use in orthopaedic surgery includes disposable or partially disposable cutting jigs for use on restructuring the tibia as well as equipment for use in reshaping the patella, thus providing a kit for use in knee surgery.

Description

APPARATUS FOR USE IN ORTHOPAEDIC SURGERY

The present invention relates to apparatus for use in orthopaedic surgery and more particularly to apparatus for use in preparing bones for the fitting of artificial joints. It has become well known to replace worn or damaged human joints by artificial joints and one such joint is the knee. Successful total knee arthroplasty is directly dependent on re-establishment of normal lower extremity alignment, proper orientation of the artificial joint and secure fixation. Instruments and techniques to assist the surgeon in achieving the above factors already exist but are currently made of metal so that they can be sterilised by autoclaving after use. When preparing for total knee arthroplasty, it is necessary to resection both the tibia and the femur. Separate instruments are utilised for resectioning these two bones.

Our co-pending international Patent Application No PCT/GB2005/000901 discloses improved instruments for resectioning the femur. These instruments are designed for single use so as to avoid the need for autoclaving. This has led us to design a new set of instruments for resectioning the tibia so that certain parts can also be single use. Further, the patella is often resectioned and single use tools for this would also be appropriate.

The present invention provides a kit of parts for use in resectioning an end of a bone during orthopaedic surgery comprising an alignment jig and a cutting jig, the alignment jig including means for positioning pins at a preselected location on the bone to be resectioned, and the cutting jig being a block of molded material having apertures for receiving the positioning pins, further apertures for receiving means for fixing the cutting jig to the bone, and at least one slot for receiving a cutting tool for resectioning the end of the bone. In order that the present invention be more readily understood, an embodiment thereof will now be described by way of example only with reference to the accompanying drawings, in which: Fig 1 shows an alignment jig according to the present invention; Fig 2 shows a perspective view of a cutting jig for use with the present invention; Fig 3 shows a tool for use in resectioning the patella; and Fig 4 shows a further tool for use in resectioning the patella. When preparing the tibia for reception of an artificial knee joint, it is necessary to resection the end of the tibia with a cut perpendicular to the mechanical axis of the leg. It is important that the cut be at the correct height and angle to maintain the mechanical axis of the leg. The present embodiment proposes to provide separate alignment and cutting jigs.

Firstly, the alignment jig will be described in relation to Fig 1. The alignment jig consists principally of a main member generally indicated by the reference numeral 1 which comprises a first portion la which telescopically receives a second portion lb so as to enable the length of the main member 1 to be altered to suit the size of the tibia to be resectioned. Near one end of the portion la, is fixed a leg engaging member in the form of a clip 4 which is arranged to hold in position the bottom of the main portion la of the jig near the patient's ankle. An adjustment means in the form of a grub screw arrangement 5 operating on a stem 6 projecting from the clip 4 permits the main portion la to be moved forwards and away from the clip so as to ensure that the main portion la lies parallel to the tibia. The telescopic portion lb of the main member is provided with a stylus 10 that extends transverse to the axis of the portion 2 and is arranged to contact the end of the tibia to be resectioned. The stylus 10 is elongate and the ends are provided with two different sized projections 10a, 10b depending in whether the surgeon wishes to resection based on the highest point of the end of the femur or the lowest point on the femur. Consequently, the stylus 10 is rotatably mounted in the end of the portion lb. The portion lb is also provided with a location plate 12 having two through holes 12a which enable two holes to be drilled in the tibia to permit two threaded, headless pins to be accurately placed in the tibia for the reception and accurate location of the tibial cutting jig. The plate 12 is shown as being positioned to one side of the portion lb which means that the headless locating ins will be off axis. This is because the cutting jigs are either left or right handed to cause the resectioning cut to be at the correct angle. The alignment jig is formed with a separate, adjustable spacer plate 14 so as to ensure that the jig will be set at the correct distance from the tibia. It is rendered adjustable in view of the fact that it is moveable in a slot 15 in the portion lb which permits the correct placement of the plate 14 against the tibia but still permits the overall length adjustment to be achieved. It is to be noted that relative rotation between the two sections la and lb of the main member 1 is prevented. In this case this is achieved by utilising rectangular sectioned members but could be achieved in any other convenient fashion as desired. In operation, the alignment jig is manipulated in much the same manner as is the conventional alignment tool. However, once the location plate 12 is accurately placed in position, two holes are drilled into the tibia and the two threaded headless pins referred to above are placed in the holes. Referring now to Fig 2, this shows a tibial cutting jig 20 which comprises a mounting portion 21 and a head portion 22 formed with a slot 23 which forms a guide for a cutting saw. It is to be noted that the cutting jig is either a left or right handed jig but is always medially biased. The jig is made of a single piece of moulded construction and if not made of metal may be made of plastic in which case the slot should be lined with a metal insert. The mounting portion of the cutting jig 20 is provided with a pair of holes 24 so that the cutting jig can be mounted on the headless locating pins that have previously been inserted into the tibia. One or more further pairs of holes such as those indicated by the reference numeral 25 can be provided to allow for repositioning of the height of the jig. In any event, once the jig is in position on the locating pins, it is fixed in position by driving two fixing pins into the tibia through the fixing holes 27. Once securely located on the tibia, cutting can be commenced and it will be noted that the lateral end of the slot is open to allow for optimum saw blade movement. The knee joint also includes the patella and although it can be replaced, more often than not it is simply resurfaced. A problem when carrying out resurfacing of the patella is that it is difficult to grip and maintain in a fixed position so as to be able to locate a drill guide onto it. A kit of instruments for operating on the patella comprises a gripper and a drill jig. As shown in Fig 3, the patella gripper comprises a tool arranged so as to provide a continual compressive force on the periphery of the patella and is provided with handles to enable the surgeon to hold or manipulate the patella at will. The arrangement shown in the drawing is such that the tool is made of two plastics parts 30,31 which are hinged together at one end 32. Each of the parts 30,31 adjacent the end 32 is either formed with or faced with metal. An interior surface 34 of each metal part is arcuately formed and provided with serrations while the upper and lower metal surfaces 35 are arranged to form a saw guide. The two parts 30,31 are provided with an interlocking arrangement such as that shown by the ratchet 36. In use, the gripper is opened to a degree sufficient to allow the patella to be received between the serrated surfaces 34 and then the parts 30 and 31 are squeezed together until the patella is securely gripped. The parts 30,31 are then held in this position due to the ratchet 36. If desired, the plastic parts 30,31 can be arranged so that the handles will deform if too much pressure is applied to the patella. Once gripped, the patella can be adjusted within the jaws 34 so as to expose a desired amount of bone for resectioning. A reciprocating saw is then used to resection the specified portion of the patella utilising the surfaces 35 of the clamp as a saw guide. Once the surface has been resectioned. a drill jig such as that shown in Fig 4 is used. The drill jig comprises a main body portion 40 provided with a jig locating portion

41 and a patella jig portion 42 which is made of metal and provided with sharp projections 43. The patella is arranged to be received between the jig portion 42 and a clamping member 43. Once the patella is securely held in position on the sharp projections 43, by a clamping member 45, holes can be drilled through guide holes 44 and

42 and portion 41 into the patella. These holes form the location holes for a surfacing member which can then be applied to the patella.

Claims

CLAIMS:

1. A kit of parts for use in resectioning an end of a bone during orthopaedic surgery comprising an alignment jig (1) and a cutting jig (20), the alignment jig including means (12) for positioning pins at a preselected location on the bone to be resectioned, and the cutting jig (20) being a block of molded material having apertures (24,25) for receiving the positioning pins, further apertures (27) for receiving means for fixing the cutting jig to the bone, and at least one slot (23) for receiving a cutting tool for resectioning the end of the bone.

2. A kit of parts according to claim 1, wherein the cutting jig is made of plastics material.

3. A kit of parts according to claim 2, wherein the slot (23) in the cutting jig is lined with metal.

4. A kit of parts according to claim 1, wherein there are two cutting jigs each with a slot of opposite hand and medially biased.

5. A kit of parts according to claim 1, wherein the alignment jig (1) comprises first and second elongate members (la, lb) which are telescopically connected together whereby the length of the jig is adjustable.

6. A kit of parts according to claim 5, wherein the first member (la) is provided with a resilient clip (4) for attaching one end of the alignment jig (1) to a body part.

7. A kit of parts according to claim 6, wherein the resilient clip (4) is spaced from said first member (la).

8. A kit of parts according to claim 7, comprising adjustable means (5,6) for changing the spacing between the resilient clip (4) and said first member.

9. A kit of parts according to claim 6, wherein the second member (lb) is provided with a spacer member (14).

10. A kit of parts according to claim 9, wherein the second member (lb) is provided with an elongate slot (15) extending along the length of the second member, and the spacer member (14) is mounted for movement in the slot whereby the position of the spacer member is changeable.

11. A kit of parts according to claim 5, wherein the positioning means (12) is a block having a plurality of apertures (12a), the block being located on one side of the second member and a predetermined distance from a free end of the second member.

12. A kit of parts according to claim 11, wherein the free end of the second member is provided with a stylus (10) for contacting the end of the bone.

13. A kit of parts according to dclaim 12, wherein the stylus (10) is a elongate member pivotally mounted to the free end of the second member, the ends of the elongate member being provided with projections (10a, 10b) of different lengths.

14. A kit of parts for use in knee surgery, comprising a kit of parts according to any one of claims 1 to 13 and further comprising a gripping device (30.31) and a drilling jig (40,45), the gripping device comprising two levers (30.31) pivotally connected to each other at one end (32) with each lever having two sections, one section forming a manually operable part and the other section forming a shaped gripping part (34,35), and the drilling jig comprises a main body portion (40) provided with a jig locating portion (41) and a jig body (42), the jig body (42) being made of a material different to that of the main body and jig locating portion.

15. A kit of parts according to claim 14, wherein the shaped gripping part of each lever (30,31) has a material which is harder than the material forming the manually operable part.

16. A kit of parts according to claim 15, wherein the harder material is a surface provided on a base member of the same material as that forming the manually operable part.

17. A kit of parts according to claim 15 or 16, wherein the material forming the manually operable part is a plastics material and the harder material is metal.

18. A kit of parts according to claim 17, wherein the metal is stainless steel.

19. A kit of parts according to any one of claims 15 to 18 wherein the two levers are additionally connected together by a ratchet mechanism (36).

20. A kit of parts according to claim 14, wherein the jig body (42) is made of metal and the other parts (40,41,45) of the drilling jig are made of plastics material.

21. A cutting jig for use in resectioning an end of a bone during orthopaedic surgery, comprising a unitary block (20) of molded material having a first plurality of apertures (24) for receiving positioning pins fixed to the bone to be resecitoned, a further plurality of apertures (27) for receiving means for fixing the cutting jig to the bone, and a slot (23) for receiving a cutting tool.

22. A cutting jig according to claim 21, wherein the jig has a main body portion (22) arranged to extend round a part of the circumference of the end of the bone and a secondary portion (21) extending from the main body portion and along a portion of the length of the bone, the main portion (22) being provided with the slot (23) and the secondary portion (21) being provided with the apertures (24,25,27) for receiving positioning pins and for fixing the jig to the bone.

23. A cutting jig according to claim 21, wherein the slot (23) has one end which is open to allow for optimum movement of a cutting tool.

24. A cutting jig according to claim 21, wherein the first plurality of apertures includes two sets of apertures (24,25) at different locations whereby the cutting jig may be fixed to the bone at two different positions.

25. An alignment jig for enabling the accurate location of positioning pins on a bone, comprising: first and second elongate members (la, lb) which are telescopically connected together whereby the length of the jig is adjustable, the first member (la) being provided with resilient clip (4) for attaching one end of the jig to a body part, and the second member (lb) being provided with a spacer member (14) for maintaining the elongate members spaced from the bone and with means (12) for positioning pins at a preselected location on the bone.

26. An alignment jig according to claim 25, wherein at least one of the resilient clip and the spacer member (14) is adjustable whereby to maintain the jig (1) parallel to and at the correct distance from the bone.

27. An alignment jig according to claim 26, wherein the second member (lb) is provided with a elongate slot (15) extending along the length of the second member, and the spacer member (14) is mounted for movement in the slot to a desired position.

28. An alignment jig according to claim 27, wherein the positioning means (12) is in the form of a block having a plurality of apertures (12a), the block being located on one side of the second member (lb) and a predetermined distance from a free end of the second member.

29. An alignment jig according to claim 28, wherein the free end of the second member (lb) is provided with a stylus (10) for contacting the end of the bone.

30. An alignment jig according to claim 29, where the stylus (10) is an elongate member pivotally mounted to the free end of the second member, the ends of the elongate member being provided with projections (10a,10b) of different lengths.