Arrangement and method used in the preparation of the proximal surface of the tibia for the tibia component of a prosthetic knee joint

Abstract

An arrangement for the preparation of the proximal surface of the tibia for a tibia component of a prosthetic knee joint, wherein the arrangement includes a preparation plate that assists in defining a reference plane. A cutting guide arrangement includes an indicator that provides orientation for a cutting blade or saw to cut the final bone resection of the proximal surface of the tibia the same as the reference plane. There is also a mounting arrangement between the joint liner and the cutting guide arrangement, so that in a first mounting position the indicator of the cutting guide is aligned with the same referenced plane defined by the underside of the joint liner and wherein the mounting arrangement also provides a second mounted position wherein the indicator of the cutting guide is aligned with the same referenced plane orientation of the underside of the joint liner but below the initial resected proximal surface of the tibia where the final resection of bone will take place.

Claims

1. An arrangement for preparation of a proximal surface of a tibia for a tibia component of a prosthetic knee joint, said arrangement including: a tibia and femoral stability gap preparation plate, said tibia and femoral stability gap preparation plate adapted to be placed upon an initially resected proximal surface of a tibia, said tibia and femoral stability gap preparation plate including an upper side, said upper side having a plurality of user operable height adjustable extension tabs; a joint liner, wherein each user operable height adjustable extension tab is adapted to engage said joint liner, wherein said joint liner further includes an upper articulated surface to engage a femoral component of a prosthetic knee joint, such that a height adjustment of said plurality of user operable height adjustable extension tabs creates a stability gap defined between the tibia and femoral stability gap preparation plate and the joint liner, wherein the stability gap is commensurate with a reference plane defined by an underside of the joint liner; a tibia cutting guide assembly including a slot configured to act as a reference guide for cutting the tibia; a mounting arrangement between said joint liner and said tibia cutting guide assembly, wherein said mounting arrangement is configured to provide a first mounted position between said joint liner and said tibia cutting guide assembly, wherein the slot is aligned with the reference plane; and said mounting arrangement further configured to provide a second mounted position wherein the slot aligned with the same reference plane of the underside of the joint liner is vertically below the first mounted position and below the initially resected proximal surface of the tibia.

2. The arrangement of claim 1 wherein a front side of the joint liner includes a pair of slots, and the tibia cutting guide assembly includes a pair of corresponding lugs.

3. The arrangement of claim 1 wherein the mounting arrangement includes a vertical support mount, wherein the vertical support mount allows the slot to be vertically adjustable there along said vertical support mount.

4. The arrangement of claim 3 wherein the vertical support mount is adapted to incrementally adjust and position the slot vertically there along said vertical support mount.

5. The arrangement of claim 4 wherein vertical incremental adjustment of the slot along the vertical support mount includes a ratchet arrangement, a clutch, gearing or cams.

6. The arrangement of claim 1 wherein the tibia and femoral gap preparation plate includes three user operable height adjustable extension tabs.

7. The arrangement of claim 1 wherein each user operable height adjustable extension tab is in communication with a corresponding user engageable knob.

8. The arrangement of claim 7 wherein each user operable height adjustable extension tab includes a mechanical, hydraulic, electrical, electronic or pneumatic drive action.

9. The arrangement of claim 1 further including a top plate restable on top of the plurality of user operable height adjustable extension tabs.

10. The arrangement of claim 1 wherein the joint liner includes a pair of lugs and the tibia cutting guide assembly includes a pair of corresponding slots.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1a and 1b show perspective views of the tibia and femoral stability gap preparation plate in a preferred embodiment of the invention wherein FIG. 1a shows the user operable extension tabs in a lowered position wherein FIG. 1b shows the user operable extension tabs in adjusted raised positions.

(2) FIG. 2 is a front view of the tibia and femoral stability gap preparation plate in a preferred embodiment of the invention.

(3) FIGS. 3a through to 3h are schematic representations showing the use of the arrangement for the preparation of the proximal surface of the tibia for the tibia component of a prosthetic knee joint.

DETAILED DESCRIPTION OF THE DRAWINGS

(4) Referring to the drawings now in greater detail wherein the tibia and femoral stability gap preparation plate which forms part of the overall arrangement of the preparation of the proximal surface of the tibia or a tibia component of a prosthetic knee joint for this invention is referenced generally as 10.

(5) The tibia and femoral stability gap preparation plate 10 in the preferred embodiment shown in FIGS. 1a, 1b and FIG. 2, includes a base plate 12, which we will discuss in greater detail on FIGS. 3a through to 3h.

(6) The base plate 12 is configured to rest appropriately upon the initial cut proximal surface of the tibia.

(7) In the preferred embodiment shown in FIGS. 1a, 1b and 2, there is also included the top plate or platform 22 shown in broken lines in FIGS. 1a and 1b. However, the user operable height adjustable extension tabs 13, 14 and 15 and the associated tip 19, 20 and 21 can also directly engage the underside 43 of the joint liner 37, again as to be discussed in greater detail when referencing FIGS. 3a to 3h, in the preferred embodiments the top plate 22 will engage the underside 43 of the joint liner 37.

(8) The user operable height adjustable extension tabs 13, 14 and 15 are in operable engagement with the rotatable knobs 16, 17 and 18. As referenced by arrows 23, 24 and 25 rotations of rotatable knobs 16, 17 and 18 translates to the vertical height adjustment of the tips 19, 20 and 21 of the corresponding user operable height adjustment extension tabs 13, 14 and 15.

(9) FIG. 1a shows tips 19, 20 and 21 of the user operable extension tabs 13, 14 and 15 in a lowered position and in FIG. 1b rotational movement of the user enagagable knobs 16, 17 and 18 has seen the elevated height of the tips 19, 20 and 21 of the corresponding height adjustable extension tabs 13, 14 and 15 raised which is representative of their adjustability in order to establish the stability gap during the appropriate adjustment as to be discussed in greater detail when referencing FIGS. 3a through to 3h.

(10) By having three tips 19, 20 and 21 this provides for a triangulation which is establishing an appropriate reference plane upon the plate 22 which will be discussed in greater detail in referencing FIGS. 3a through to 3h will then be translated to the orientation of the underside 43 of the joint liner 37, to which plate 22 of the tibia and femoral stability gap preparation plate 10 engages.

(11) In relation to FIGS. 3a through to 3h the illustrations need to be placed in the context of the intended outcome achieved through the use of arrangement and methods provided for in this invention.

(12) Orthopaedic surgeons during surgery aim to provide balance, unobstructed movement of the knee components for the complete arc of motion from extension, mid-flexion and flexion and then back again.

(13) Accordingly, the final bone resection of the proximal surface of the tibia is required to be cut correctly in order to present the appropriate profile to the tibia component positioning in the knee anthroplasty whether that be a total knee or uni-compartmental knee operation.

(14) FIG. 3a shows a knee joint generally as 29.

(15) A cutter 31, prepares for the initial resection of the proximal surface 28 of the tibia 27. The general distal end of the femur 30 is also shown. In FIG. 3b the tibia and femoral stability gap preparation plate 10 shown by way of arrow 34 is being inserted onto the initially resected proximal surface 35 of the tibia 27.

(16) From FIG. 3b it can realise that the general shape of the tibia and femoral stability gap preparation plate 10 is of a comparative dimension of the proximal surface 35 of the tibia 27.

(17) FIG. 3c shows the actual positioning of tibia and femoral stability gap preparation plate 10 on the proximal surface 35 of the tibia 27 and to be sandwiched therein between the femoral component 36 and the tibia and femoral stability gap preparation plate 10 is the joint liner 37.

(18) Arrow 38 is representative as to the location the joint liner 37 will be positioned in the knee joint 29.

(19) The joint liner 37 has an articulated upper surface 39 to engage the femoral component 36 of the femur 30.

(20) Importantly, the joint liner 37 on the front side 40 includes a pair of slots 41 of which will be discussed in greater detail when referencing the mounting arrangement between the joint liner 37 and the final bone resection proximal surface of the tibia cutting guide arrangement 42 which is introduced in FIG. 3e.

(21) 43 is representative of the under side of the joint liner 37.

(22) FIG. 3d shows the knee joint at mid-flexion. Operable knobs 16, 17 and 18 when rotated by way of arrows 45, 46 and 47 though the height adjustable extension tabs, 13, 14 and 15 will adjust the orientation of the underside 43 of the joint liner 37.

(23) This height adjustability although not shown in the illustrations would also have been completed at extension and then ultimately at flexion or 90 degrees.

(24) Accordingly, the user operable height adjustable extension tabs 13, 14 and 15 create a triangular support of the top plate 22, which then aligns and/or orientates the underside 43 of the joint line 37 accordingly. The stability gap that has been established is commensurate with the references plane that has now been established on the underside 43 of the joint liner 37 through the height adjustability of the height adjustable extension tabs 13, 14 and 15 from extension, mid-flexion and flexion.

(25) Hence albeit the tibia and femoral stability gap preparation plate 10 provides for a stability gap, this stability gap is then represented by the referenced plane now provided for on the underside 43 of the joint liner 37.

(26) With the referenced plane now established on the underside 43 of the joint liner 37, the final bone resection of the proximal surface of the tibia cutting guide arrangement is then mountable to the joint liner 37.

(27) The final bone resection of the proximal surface of the tibia cutting guide arrangement 42, as best seen in FIG. 3e, includes a cutting guide 50, wherein the cutting guide 50 includes an indicator in the form of a slot 51.

(28) The purpose of the slot 51 is that it will allow the blade or a saw to be guided to make a final resection cut of the proximal surface of the tibia in the orientation as to the alignment of the slot.

(29) It is therefore a requirement that the indicator, which in this preferred embodiment is a slot 51 included as part of the cutting guide 50 is aligned the same as the underside 43 of the joint liner 37 so as to make sure that the profile provided for by the final bone resection cut, will establish that same defined stability gap made available by the tibia and femoral stability gap preparation plate 10.

(30) The final bone resection of the proximal surface of the tibia cutting guide arrangement 42 as part of the mounting arrangement between the final bone resection of the proximal surface of the tibia cutting guide arrangement 42 and the joint liner 37 includes a pair of lug extensions or protrusions 52, which are adapted to be slotted to the corresponding pair of slots 41 on the front side 40 of the joint liner 37.

(31) FIG. 3f shows the final bone resection of the proximal surface of the tibia cutting guide arrangement 42 mounted to the joint liner 37 wherein the engagement between the lug extensions 52 of the final bone resection of the proximal surface of the tibia cutting guide arrangement 42 and that pair of slots 41 on the front side 40 on the joint liner 37 means that the indicator slot 51 of the cutting guide 50 aligns in the same orientation as the referenced plane of the underside 43 of the joint liner 37.

(32) As it is to be envisaged the pair of slots 41 of the joint liner 37, before any height adjustments of tibia and femoral stability gap preparation plate 10 would be generally on the horizontal plane consistent with the initial resected surface 35 of the tibia shown in FIG. 3b.

(33) None the less, as the height adjustment extension tabs 13, 14 and 15 of the tibia and femoral stability gap preparation plate 10 are adjusted to provide the stability gap this then alters the orientation of the underside 43 of the joint liner 37 and so to corresponding orientation of the slots 41 on the front side 40 of the joint liner 37.

(34) Accordingly, as the pair of slots 41 of the joint liner 37 have now been offset through height adjustment of the tibia and femoral stability gap preparation plate 10 means that the corresponding lug extensions 52 of the final bone resection of the proximal surface of the tibia cutting guide arrangement 42 will also be offset so that the indicator slot 51 of the cutting guide 50 will represent the same reference plane that exists on the underside 43 of the joint liner 37.

(35) This mounted engagement between the joint liner and the final bone resection of the proximal surface of the tibia cutting guide arrangement 42 shown in FIG. 3f provides for the first mounted position.

(36) There is then the requirement to establish a second mounted position so that the cutting guide 50 and notably the correctly aligned indicator slot 50 now orientated the same as the reference plane on the underside 43 of the joint liner 37 can cut into a new layer of bone below the initial resected surface of the tibia.

(37) Through the use of the vertical support mount 55 included a part of the final bone resection of the proximal surface of the tibia cutting guide arrangement 42, the cutting guide 50 can be incrementally adjusted vertically there along the vertical support mount 55 shown by way of arrows 57 in FIG. 3f.

(38) The vertical adjustment of the cutting guide 50 as part of the final bone resection of the proximal surface of the cutting guide arrangement 42 can be achieved through conventional incremental adjustments, such as through a ratchet, gearing, use of cams and so forth.

(39) As seen in FIG. 3g once the cutting guide 50 has been lowered, the cutting guide 50 can then be separated from the final bone resection of the proximal surface of the tibia cutting guide arrangement 42. Wherein the vertical support 52 is also withdrawn.

(40) Although the mounted means are not shown, the cutting guide 50 is mounted to the tibia 27 in the second mounted position which was provided for by the vertical support mount 55 included as part of the final bone resection of the proximal surface of the tibia cutting guide arrangement 42.

(41) Hence, the second mounted position has the cutting guide 50 fastenable in the correct vertical position for cutting into new bone below the initial resected proximal surface 35 of the tibia 27 shown in FIG. 3b.

(42) Also the indicator slot 51 for the correct orientation is aligned as the same reference plane established on the under side 43 of the joint liner 37. However, the practicalities of the final resection requires the main infrastructure of the final bone resection of the tibia cutting guide arrangement 42 to be withdrawn. So once the second mounted position has been established the cutting guide 50 as shown in FIG. 3f would be then mounted though various pins and or bolts (not shown) to the tibia 27.

(43) The cutting guide 50 is mounted with the indicator slot 50 correctly aligned and at the appropriate depth below the initially resected proximal surface 35 of the tibia 27, as seen in FIG. 3g, wherein the blade or saw 61 of a handheld cutting implement 60 is guidable and orientated through the slot 51 to enable for a final bone resection providing a profile of the proximal surface of the tibia, shown as 70 in FIG. 3h the same as the reference plane, ensuring a stability gap so that the tibia component insert of the prosthetic knee (not shown) is stable and balanced throughout the arc of motion in the artificial knee joint (not shown) that one would expect from a normal healthy knee.