WO2024089538A1

WO2024089538A1 - Drilling jig for guided drilling of a bone

Info

Publication number: WO2024089538A1
Application number: PCT/IB2023/060512
Authority: WO
Inventors: Patrick SADOGHI
Original assignee: Medizinische Universität Graz
Priority date: 2022-10-28
Filing date: 2023-10-18
Publication date: 2024-05-02
Also published as: AT526622A1

Abstract

In a drilling jig (1) for guided drilling of a bone, in particular the head of the human tibia, the drilling jig (1) comprising a bearing part (2) for supporting the drilling jig (1) on the bone and a drill guide (3) which can be fixed to the bearing part (2), the drill guide (3) having at least two guide holes (9) running parallel to one another along a first axial direction (10), the bearing part (2) has a plurality of supports (5), each with a lower support element for support on a joint surface of the bone, the support elements pointing in a second axial direction (11) perpendicular to the first axial direction (10), and the drill guide (3) being arranged outside a region spanned by the supports (4).

Description

Drilling j ig for guided drilling of a bone

The present invention relates to a drilling j ig for guided drilling of a bone , in particular the head of the human tibia, the drilling j ig comprising a bearing part for supporting the drilling j ig on the bone and a drill guide fixable to the bearing part , the drill guide having at least two guide holes extending parallel to each other along a first axial direction, and a set comprising such a drilling j ig .

Knee arthroplasty occupies a signi ficant place in orthopedic surgery . In particular, the implantation of total knee arthroplasties , i . e . knee arthroplasties with which both the entire tibial plateau and the entire condylar femoral portion are replaced, takes place routinely in everyday clinical practice and, in the best case , creates the possibility of treating patients with knee j oint arthrosis for being largely free of symptoms and for maintaining mobility in old age .

The various surgical techniques used in knee arthroplasty require that the femur and tibia be trimmed precisely according to the anatomical conditions in order, on the one hand, to remove the damaged cartilage and bone structures and, on the other hand, to create suf ficient space for the implantation of the tibial and femoral implants on the trimmed surfaces and for the placement of so-called inlays , for example made of highly crosslinked polyethylene , between the tibial and femoral implants . In addition to precise cuts to provide a suitable bearing surface for the tibial and femoral implants , the cut surfaces at the tibia and femur must also be aligned with respect to the existing leg axis or that desired after surgery and with respect to the conditions of the ligamentous apparatus of the knee j oint to provide a uni form articular gap in both flexion and extension of the knee j oint in mechanical alignment . I f there is a disbalance between the flexion gap and the extension gap, this has serious consequences for the functionality of the knee endoprosthesis , which mani fests itsel f in flexion or extension deficits and/or in the so-called "opening" of the prosthesis , i . e . instability of the knee prosthesis in mechanical alignment .

In knee arthroplasty, there are di f ferent concepts on how to align the cuts on the tibia and the femur . In the so-called mechanical alignment by the " femur first" approach, the femur is trimmed first , and the cutting block used for cutting is usually aligned and fixed first for the distal femoral cut using an intramedullary guide in the femoral medullary canal . The tibial cut is subsequently made at 90 degrees to the mechanical leg axis at the tibia to obtain a balanced extension gap . Thereafter, the rotation of the femoral component can be aligned either by tensioning the collateral ligaments in flexion or by reference to the posterior condyles . In the so-called " tibia first" approach, the tibial cut is made first with resection of the tibial plateau . Since the position and orientation of the cut surface defined by the tibial cut is both of utmost importance in itsel f for the stability of the knee endoprosthesis and, with this technique , all further cuts on the femur are oriented according to this cut surface , precise alignment of the corresponding cutting block is also of utmost importance with the " tibia first" approach .

In the prior art , an extramedullary orientation of the cutting block is usually chosen for this purpose . This type of alignment of the cutting block, which is fixed to the tibial head with drill pins or smooth pins , is done in such a way that a substantially rod-shaped alignment device is fixed to the lower leg proximally with a short smooth pin at the eminentia intercondylaris and distally with a tab around the ankle and is aligned mediolaterally at the second toe ray and anteroposteriorly with a so-called slope of approximately 3 ° to the tibial anterior edge . The alignment device includes a drill guide , generally provided on the cutting block as holes , for either directly screwing drill pins into the tibial head or, alternatively, drilling the tibial head through the drill guides and subsequently inserting smooth pins into the drill holes thus created . The pins support the cutting block after removal of the alignment device , so that the position and orientation of the pins on the anterior tibial head define the tibial cut .

In view of the immense importance of the tibial cut for the success of the entire surgery, the alignment based on the tibial edge and the second toe ray appears to be somewhat arbitrary and usually does not take into account the individual leg axis of the respective patient , which must be preserved in the so-called kinematic alignment during the surgical technique in order to restore the leg as it was originally aligned in the sense of rehabilitating the patient as quickly as possible in a true resurfacing technique . In addition, i f the leg axis is changed by the operation, there is a risk of wear and tear of previously undamaged j oints induced by this , for example in the area of the ankle j oint , or the risk of attachment tendinosis , such as pes anserinus syndrome due to changes in muscle traction .

Therefore , there is a need for a device with which the alignment of the drilling j ig and thus the subsequent position and orientation of the pins on the tibial head is not adj usted extramedullary, but based on the actual anatomical conditions of the tibial plateau with respect to a true resurfacing . It is therefore an obj ect of the present invention to provide such a device . This is particularly relevant in the surgical technique for kinematic alignment , since the natural tibial slope and the natural tibial varus of usually 3 degrees should be established here .

To solve this problem, a drilling j ig of the type mentioned at the outset is characteri zed according to the invention in that the bearing part has a plurality of supports , each with a lower support element for support on a j oint surface of the bone , the support elements pointing in a second axial direction perpendicular to the first axial direction, and the drill guide being arranged outside an area spanned by the supports . By providing support elements that are oriented perpendicularly with respect to the first axial direction and thus the orientation of the guide holes , the support elements of the supports can be placed directly on the tibial condyles . The drill guide with the guide holes , which is arranged outside the area of the supports on the drill j ig according to the invention so that it comes to lie in front of the tibial head, is thus oriented to the condyles of the tibia so that the anatomical situation at the tibial head flows into the orientation of the drill guide and the pins can be set accordingly after drilling . In this way, the anatomical leg axis can be preserved in the frontal and sagittal planes . Noteworthy, there is no di f ference in the axial plane between mechanical and kinematic alignment .

When implanting a knee endoprosthesis with the drilling j ig according to the invention, di f ferent degrees of wear of di f ferent areas of the tibial condyles can be taken into account i f the bearing part comprises a plurality of carrier elements , each support being detachably received in a carrier element , as corresponds to a preferred embodiment of the present invention . Supports of a certain axial length can thus be removed from the carrier elements and other supports with di f ferent axial lengths can be selected according to the degree of wear of the individual sections of the condyles in the medial , lateral , anterior and posterior regions in order to restore the original anatomical situation in relation to the leg axis during the operation . In this case , a support for a worn condylar region will be selected to be approximately 2 mm or exactly 2 mm longer than a support for a non-worn region, depending on the thickness of the cartilage .

With the same background, it may be provided according to a preferred embodiment of the present invention that the support elements are rounded or pointed . In this case , a rounded support element is used for bearing on a condyle in which the cartilage portion has been completely worn by the disease of the j oint , whereas a pointed support element is suitable for bearing on a condyle with a largely intact cartilage portion, the tip of the support element being used to pierce the cartilage in order to prevent slippage .

For releasably fixing the supports to the carrier elements , the present invention is preferably further embodied in that the supports are each releasably received in a bore in the carrier element pointing in the second axial direction . The bore and accordingly the respective support can be fixed in the bore in any conceivable way, but preferably the support is screwed into a thread in the bore . The drilling j ig according to the invention can be manufactured in di f ferent si zes for use on knee j oints of di f ferent si zes . However, in order to keep the instrumentation compact , the present invention is characteri zed, according to a preferred embodiment , in that the carrier elements are displaceable along at least two connecting rods in the first axial direction, the connecting rods being guided in bores passing through the carrier elements in the first axial direction . In this way, the anteroposterior distance between two carrier elements or the support elements accommodated therein can be adj usted to accommodate di f ferent si zes of the j oint .

In order to fix the axial position of the carrier elements on the connecting rods for the duration of the operation, the invention is advantageously further configured in that at least one of the bores passing through a respective carrier element is interrupted by a recess in the carrier element , in which recess a clamping element for a connecting rod is accommodated, the clamping element being loaded towards the outside of the carrier element , preferably by a spring at the bottom of the recess . Thus , a clamping element is created that , by pressing inwards into the carrier element , releases the corresponding connecting rod for adj usting the displacement position of the carrier element on the connecting rod, and subsequently, by the action of the spring, fixes this position by clamping the connecting rod .

In order to also be able to adj ust the mediolateral distance between the carrier elements and thus the support elements for adaptation to di f ferent si zes of j oints to be treated, the present invention can be advantageously designed in such a way that in each case two carrier elements are connected to one another via in each case one intermediate piece , to which intermediate piece the connecting rods are fixed, wherein preferably two intermediate pieces with in each case two carrier elements connected to the respective intermediate piece are displaceable along connecting rods in a third axial direction transverse to the first and transverse to the second axial direction relative to one another, wherein the connecting rods are guided in bores passing through the intermediate pieces in the third axial direction .

Here , too , a fixing of the set position of the guide rods in the intermediate pieces can be achieved i f at least one of the bores passing through a respective intermediate piece is interrupted by a recess in the intermediate piece , in which recess a clamping element for a connecting rod is accommodated, the clamping element being loaded towards the outside of the intermediate piece , preferably by a spring at the bottom of the recess , as it is in correspondence with a preferred embodiment of the present invention .

The drill guide is preferably fixed in that the drill guide is fixed to a connecting piece by connecting rods , the intermediate pieces being fixed to the connecting piece . In this way, a modular drilling j ig is provided overall , which is easily adaptable and easy to sterili ze when the drilling j ig according to the invention is disassembled into its individual parts for sterili zation .

By releasably securing the drill guide to an intermediate piece , drill guides can also be provided in di f ferent si zes depending on the si ze of the j oint to be treated, which is particularly desirable when the drill guide is also designed as a cutting block, as corresponds to a preferred embodiment of the present invention .

The present invention further relates to a set comprising the drilling j ig according to the invention and further comprising a plurality of supports , wherein the supports have extensions of di f ferent lengths in the second axial direction when received in the carrier elements . In turn, such a set can be used to meet the requirements for compensation of di f ferently worn condyles on a tibia .

The invention is explained in more detail below with reference to an example of an embodiment shown in the drawing . Figure 1 shows a perspective view of the drilling j ig according to the invention, Figure 2 a partially exploded view of a drilling j ig according to Figure 1 , Figure 3 a perspective view of a carrier element of the drilling j ig according to the invention, Figure 4 a perspective view of an intermediate piece of the drilling j ig according to the invention and Figures 5 and 6 show two di f ferent supports of the drilling j ig according to the invention .

In Figure 1 , the drilling j ig according to the invention is designated by the reference sign 1 . The drilling j ig 1 essentially consists of a bearing part 2 , with which the drilling j ig 1 is supported on the bone , and a drill guide 3 detachably fixed to the bearing part . Supports 4 are detachably fixed in carrier elements 5 and the carrier elements 5 are detachably connected to each other by means of connecting rods 6 and with the mediation of intermediate pieces 7 and a connecting piece 8 . The drill guide 3 has a plurality of guide holes 9 running parallel to each other along a first axial direction, this first direction being illustrated by the double arrow 10 . A second axial direction and a third axial direction are symboli zed by the double arrows provided with the reference signs 11 and 12 , respectively, whereby the person skilled in the art will understand that these directions each run transversely to one another .

In the further figures , identical or corresponding elements of the drilling device according to the invention are provided with the same reference signs .

Figure 2 now shows that the connecting rods 6 are accommodated in bores 13 in the carrier plates 5 and in bores 14 in the intermediate pieces 7 , the bores 13 and 14 passing through the carrier plates 5 and the intermediate pieces 7 , respectively . The connecting rods 6 , which connect the intermediate pieces 7 or the drill guide 3 to the connecting piece 8 , are accommodated with a tapered end in corresponding bores . The supports 4 are each detachably received in a bore 15 in the carrier element 5 pointing in the second axial direction 11 and have a support element 16 at their lower end for support on an articular surface of the bone .

With reference to Figures 2 and 3 , reference sign 17 denotes clamping elements which are each accommodated in a recess 18 in the carrier elements and the intermediate pieces 7 , respectively, and are loaded by a spring 19 at the base 20 of the recess 18 towards the outside of the carrier element 5 and the intermediate piece 7 , respectively . In the assembled state , the connecting rods 6 pass through the clamping elements 17 and are clamped by the action of the spring 19 . As a result of the connecting rods passing through the clamping elements , the carrier plates can be moved relative to each other along the first axial direction 10 in order to adj ust the si ze of the drilling j ig according to the invention .

Similarly, clamping elements 17 are provided in the connecting pieces 7 ( Figure 4 ) which, together with connecting rods 6 , allow clampable adj ustment of the intermediate pieces 7 along the third axial direction 12 . In Figure 3 , a carrier element 5 is shown enlarged and it can be better seen that the clamping element 17 has a bore 22 through which a connecting rod 6 can pass in order to be clamped . This is shown in Figure 4 in the same way for an intermediate piece 7 .

The support 4 according to Figure 5 has a pointed support element 16 for fixing the support element 16 to a cartilage of the tibia . The reference sign 21 indicates a thread with which the support 4 can be detachably fixed in a bore 15 by screwing it in .

The support 4 according to Figure 6 di f fers from the support 4 according to Figure 5 only in a slightly less of fset position of the support element 16 .

Claims

Claims :

1. Drilling jig (1) for guided drilling of a bone, in particular the head of the human tibia, the drilling jig (1) comprising a bearing part (2) for supporting the drilling jig

(1) on the bone and a drill guide (3) which can be fixed to the bearing part (2) , the drill guide (3) having at least two guide holes (9) running parallel to one another along a first axial direction (10) , characterized in that the bearing part

(2) has a plurality of supports (4) , each with a lower support element for support on a joint surface of the bone, the support elements pointing in a second axial direction (11) perpendicular to the first axial direction (10) , and the drill guide (3) being arranged outside a region spanned by the supports ( 4 ) .

2. Drilling jig according to claim 1, characterized in that the bearing part (2) comprises a plurality of carrier elements (5) , wherein a support (4) is detachably received in a respective carrier element (5) .

3. Drilling jig according to claim 1 or 2, characterized in that the support elements are rounded or pointed.

4. Drilling jig according to claim 2 or 3, characterized in that the supports (4) are each detachably received in a bore (15) in the carrier element (5) pointing in the second axial (11) direction.

5. Drilling jig according to claim 2, 3 or 4, characterized in that the carrier elements (5) are displaceable along at least two connecting rods (6) in the first axial direction

(10) , the connecting rods (6) being guided in bores (13) passing through the carrier elements (5) in the first axial

(10) direction.

6. Drilling jig according to claim 5, characterized in that at least one of the bores (13) passing through a carrier element (5) in each case is interrupted by a recess (18) in the carrier element (5) , in which recess (18) a clamping element (17) for a connecting rod (6) is accommodated, the clamping element (17) being loaded towards the outside of the carrier element (5) , preferably by a spring (19) at the bottom (20) of the recess (18) .

7. Drilling jig according to any one of claims 2 to 6, characterized in that in each case two carrier elements (5) are connected to one another via in each case one intermediate piece (7) , to which intermediate piece (7) the connecting rods

(6) are fixed, wherein preferably two intermediate pieces (7) with in each case two carrier elements (5) connected to the respective intermediate piece (7) being displaceable relative to one another along connecting rods (6) in a third axial direction (12) transverse to the first (10) and transverse to the second axial direction ( 11 ) , the connecting rods (6) being guided in bores (14) passing through the intermediate pieces

(7) in the third axial direction (12) .

8. Drilling jig according to claim 7, characterized in that at least one of the bores (14) passing through an intermediate piece (7) in each case is interrupted by a recess (18) in the intermediate piece (7) , in which recess (18) a clamping element (17) for a connecting rod (6) is accommodated, the clamping element (17) being loaded towards the outside of the intermediate piece (7) , preferably by a spring (19) at the bottom (20) of the recess (18) .

9. Drilling jig according to claim 7 or 8, characterized in that the drill guide (3) is fixed to a connecting piece (8) by connecting rods (6) , the intermediate pieces (7) being fixed to the connecting piece (8) .

10. Drilling jig according to any one of claims 1 to 9, characterized in that the drill guide (3) has, at least in the region of the guide holes (9) , a thickness in the first axial direction of between 0.5 cm and 2.5 cm, preferably between 1.0 cm and 2.0 cm and particularly preferably a thickness of 1.5 cm.

11. Drilling jig according to any one of claims 1 to 10, characterized in that the drill guide (3) is simultaneously designed as a cutting block.

12. A set comprising a drilling jig (1) according to any one of claims 1 to 11 and further comprising a plurality of supports (4) , the supports (4) having extensions of different lengths in the second axial direction (12) when received in the carrier elements (5) .