(19)
(11)EP 3 015 090 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
03.10.2018 Bulletin 2018/40

(21)Application number: 15189205.6

(22)Date of filing:  09.10.2015
(51)International Patent Classification (IPC): 
A61F 2/08(2006.01)

(54)

ARTIFICIAL LIGAMENT WITH FIXATION LOOP

KÜNSTLICHES BAND MIT BEFESTIGUNGSSCHLAUFE

TENDON ARTIFICIEL AVEC BOUCLE DE FIXATION


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 31.10.2014 GB 201419469

(43)Date of publication of application:
04.05.2016 Bulletin 2016/18

(73)Proprietors:
  • Biomet UK Limited
    Bridgend South Wales CF31 3XA (GB)
  • Oxford Joint Analysis Ltd.
    Headington Oxford OX3 8JN (GB)
  • Murray, David Wycliffe
    Oxford OX44 9HB (GB)

(72)Inventors:
  • MURRAY, David Wycliffe
    Oxford, Oxfordshire OX44 9HB (GB)
  • LLOYD, Russell
    Swindon, Wiltshire SN3 6EZ (GB)
  • ALINEJAD, Mona
    Oxford, Oxfordshire OX2 7NL (GB)
  • O'CONNOR, John Joseph
    Oxford, Oxfordshire OX3 8JN (GB)

(74)Representative: Mays, Julie 
Venner Shipley LLP 200 Aldersgate
London, EC1A 4HD
London, EC1A 4HD (GB)


(56)References cited: : 
EP-A1- 1 108 401
WO-A2-95/01140
US-A- 5 151 104
US-A1- 2010 305 709
EP-A1- 2 698 117
CA-A- 325 217
US-A1- 2010 249 930
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Technical Field



    [0001] This invention relates to artificial knee ligaments and is particularly, although not exclusively, concerned with artificial ligaments having looped ends.

    Background



    [0002] The statements in this section merely provide a background to the present disclosure and may not constitute prior art.
    Prosthetic knee joints replace one or more of the articulate surfaces of a patient's knee joint, and are employed to improve the strength and/or mobility of the joint or reduce pain of the patient. Sections of the bones being replaced may be diseased, injured, deteriorated or some combination of the three.
    In many cases the surgeon performing knee replacement surgery will take steps to preserve the ligaments of the knee which connect the bones of the knee across the joint. In some cases the ligaments themselves may be diseased or damaged, or the resection necessary to remove diseased portions of the bones may disrupt the integrity of the ligaments. If the ligaments are removed as part of the surgery and cannot be reattached, a prosthetic knee joint is required which places greater constraints on the movement of the knee joint. This can be achieved through the use of an artificial knee ligament joining the two sides of the joint.
    In one proposed artificial knee joint, artificial ligaments are attached to the prosthetic components by looping or tying the ends of the ligament over bosses or bollards provided on the prosthetic components. As the knee joint moves, the ligament is able to articulate around the body of the bollard as required. Whilst this articulation of the ligament prevents the ligament from being bent or kinked, over time the loops of the ligament can become worn.
    Artificial knee ligaments are not required to be tensioned when installed, however it is undesirable for ligaments to be excessively long or loose as this could reduce the stability of the joint. For similar reasons, it is not desirable for an artificial ligament to be flexible. In one possible surgical procedure, both prosthetic components are first implanted before alternative length ligaments are offered up by the surgeon and one can be selected which the surgeon judges will have suitably laxity when fitted. In order to fit the ligament, the knee must be overflexed to provide the necessary access to the ligament fixings on each side of the joint. This also has the effect of separating the bones of the knee and hence excess force is required to attach the ligament. A device may be required to pull or lever the ligament onto a fixing and there is a significant risk of damaging the artificial ligament in the process.

    [0003] In order to avoid this excessive manipulation of the knee joint and potential damage to the ligament, artificial ligaments have been designed with loops which are formed at the operative site, allowing the length of a ligament to be adjusted subsequently to its attachment to both sides of the joint.

    [0004] WO 2011/1502538 discloses a prosthetic knee joint assembly with an artificial ligament link. The ligament link extends between first and second ends and includes an outer wall defining an interior longitudinal passage portion. First and second apertures extend through the wall. The first end extends through the first and second apertures and the longitudinal passage portion to define a first adjustable loop, and the second end extends through the first and second apertures and the longitudinal passage portion to define a second adjustable loop. US 5151104 discloses a joint connector for implantation into the human femur so as to repair an anterior cruciate ligament.

    [0005] It is speculated that ligaments with preformed loops are still more reliable with less chance of becoming loose or failing after implantation. Hence, using a ligament with fixed loops is desirable in some cases.

    [0006] The present disclosure relates to a method for implanting an artificial ligament of fixed length without requiring the knee joint to be overflexed, or excessive force being applied to the ligament. An artificial ligament particularly suited for this use is also provided.

    Statements of Invention



    [0007] The invention is defined by claim 1. Claim 9 is directed towards a kit of ligaments according to claim 1.
    According to an aspect of the present invention there is provided an artificial knee ligament substantially formed of a first material, comprising an elongate body of fixed length and two ends, wherein a loop is provided at each of the ends and a portion of a second material is provided on at least one loop.
    According to another aspect of the present invention there is provided an artificial knee ligament comprising an elongate body and two ends, wherein a loop is provided at at least one of the ends; and a loop liner provided within the loop.
    The length of the ligament and/or the size of the loop may be fixed. The ligament may be configured to couple to a fixing provided on either a femoral or tibial component of a prosthetic knee joint.
    The loop liner may be provided in the area of the loop which contacts the fixing of the prosthetic component. In this way, the loop liner may be provided covering an inside face of the loop. The loop liner may be formed from a different material to the body of the ligament. The loop liner may be formed from polyethylene. The loop liner may be shaped to sit between the fixing of the prosthetic knee component, and the ligament loop. The loop liner may be moulded onto the loop of the ligament or alternatively, the loop liner may comprise a thimble which is trapped within the eye of the loop. Other forms of loop liner may also be possible.

    [0008] The loop liner may be resilient and may be elastically deformable to allow the ligament loop to be pushed over an enlarged head of the fixing of the prosthetic. The following methods do not form part of the invention.

    [0009] There is provided a method of implanting a prosthetic joint assembly, comprising a first component for attaching to a first bone (of the joint), a second component for attachment to a second bone (of the joint) and an artificial ligament, comprising the steps of:

    implanting the first prosthetic component into a patient;

    coupling the preformed artificial ligament to the prosthetic components; and

    implanting the second prosthetic component into the patient.



    [0010] There is provided a method of implanting a prosthetic knee joint assembly, comprising a tibial component, a femoral component and an artificial knee ligament, comprising the steps of:

    implanting the tibial component or the femoral component into a patient;

    coupling a preformed artificial ligament to the prosthetic components;

    implanting the other component into the patient.

    The tibial component may be implanted before the femoral component or alternatively, the femoral component may be implanted before the tibial component. The first prosthetic component may be implanted in a temporary manner.
    The method may further comprise the step of determining an appropriate length for a replacement knee ligament to link the tibial and femoral components of the prosthetic knee joint. This step may be completed prior to the step of coupling the preformed artificial ligament to the prosthetic components.
    Additionally or alternatively, the method may further comprise the step of selecting a preformed artificial ligament of a suitable length from a set of artificial ligaments. This step may be completed prior to the step of coupling the preformed artificial ligament to the prosthetic components.
    The step of installing a final meniscal bearing may be performed prior to the step of implanting the second prosthetic component into the patient. Alternatively the step of installing a temporary meniscal spacer may be performed instead and a final meniscal component may be installed between the tibial and femoral components of the prosthetic knee joint in an additional step which may be performed subsequently to the step of implanting the second prosthetic component into the patient.
    The tibial prosthetic component may comprise a fixed knee bearing.

    [0011] The method may be performed using the artificial ligament provided by a previously mentioned aspect of the invention.

    [0012] There is provided a method of determining a suitable length for an artificial ligament for use in a prosthetic joint assembly comprising a first prosthetic component for attaching to a first bone and a second prosthetic component connected to a second bone. The method comprising the steps of:

    coupling a trial first component to the first bone of a patient in a temporary manner;

    creating a trial ligament using an elongate element extended around a fixing on the trial first component and a second fixing on a previously implanted second component to form a continuous band;

    cutting the band and removing the trial ligament from the surgical site; and measuring the reassembled band.



    [0013] There is provided a method of determining a suitable length for an artificial knee ligament comprising the steps of:

    coupling first and second prosthetic components to a patient in a temporary manner;

    creating a trial ligament using an elongate element extended around a first fixing on the first prosthetic component and a second fixing on the second component to form a continuous band;

    cutting the band and removing the trial ligament from the surgical site; and measuring the length of the reassembled band.



    [0014] The first and/or second prosthetic components may be trial prosthetic components. Alternatively or additionally, either or both of the prosthetic components may be the final prosthetic components. The fixings provided on the femoral and tibial components may be bollards.

    [0015] The method may further comprise the step of installing a trial meniscal component between the tibial and femoral components of the prosthetic knee joint. This step may be performed prior to the step of creating a trial ligament. The trial meniscal component may also be the final meniscal component.

    [0016] The elongate element used in the method may comprise a trial ligament with one looped end and one open end which can be tied. Alternatively the elongate element may be a zip tie or any other elongate element suitable for being selectively formed into a continuous band.

    [0017] A pin may be used to mark the required length of elongate element whilst fitted to the patient. Alternatively or additionally, the elongate element may comprise markings allowing the length of the band to be determined from the markings on the elongate element.

    [0018] The method may be used to determine an appropriate length for a replacement knee ligament to link the tibial and femoral components as described in any preceding aspect of the invention.

    [0019] There is also described an artificial knee joint assembly comprising a tibial component, a femoral component and an artificial knee ligament which may be the artificial ligament as described in any preceding aspect of the invention.

    [0020] According to another aspect of the present invention there is provided a kit of artificial knee ligaments wherein each ligament within the kit has a different fixed length. The ligaments in the kit may be as described in any preceding aspect of the invention.

    [0021] There is also described instrumentation for measuring between first and second ligament fixings of prosthetic components comprising: an elongate body, an arcuate portion provided at or towards one end of the elongate body and a slideable jaw, configured to slide along the elongate body. The arcuate portion may be configured to closely engage the first fixing. The slideable jaw may be configured to engage the second fixing.

    [0022] The position of the slideable jaw may be selectively fixable relative to the elongate body. The jaw and the elongate body may be provided with cooperating formations and the jaw may fixed by rotating a portion of the jaw to engage the cooperating formations.

    [0023] The elongate body may further comprise a measurement scale. The measurement scale may indicate the size of artificial ligament required to link the first and second fixings.

    [0024] There is also described instrumentation for measuring between fixings of prosthetic components comprising: an elongate body with first and second ends; wherein the first end is configured to couple with a first fixing on a first prosthetic component; and the second end comprises a measurement scale. The scale allows the distance from the first fixing to a second fixing on a second prosthetic component to be measured. The scale may indicate the size of artificial ligament required to link the first and second fixings.

    [0025] The instrumentation may further comprise a jaw which may be axially slidable along the measurement scale of the elongate body. The jaw may be selectively lockable relative to the elongate body. The jaw and the elongate body may be provided with cooperating features and the jaw may be locked by rotating a portion of the jaw to engage the cooperating features. Alternatively or additionally, the jaw may be configured to engage a second fixing on a second prosthetic component.

    Brief Description of the Drawings



    [0026] For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example, to the accompanying drawings, in which:

    Figure 1 shows a full knee replacement prosthetic knee joint comprising an artificial ligament according to an example of the present invention.

    Figure 2 is a sectional view of a full knee replacement prosthetic knee joint comprising an artificial ligament according to an example of the present invention.

    Figure 3 shows an artificial knee ligament according to one example of the present invention.

    Figure 4 shows an artificial knee ligament according to a second example of the present invention.

    Figure 5 is a sectional view showing an example implementation of a biasing element and tension element used to provide the desired stiffness to an artificial ligament according to the present invention.

    Figure 6 shows an implanted trial prosthetic knee joint assembly according to an example of the present invention, including a trial tibial component and a trial artificial ligament.

    Figure 7 shows instrumentation for measuring the required length of a ligament.


    Detailed Description



    [0027] Referring to Figure 1, a knee prosthesis 2 comprises a tibial component 4 having a tibial tray 6 integrally formed with a stem 8, a femoral component 10 and a pair of bearing components 12, 13. The bearing components 12, 13 separate the tibial component 4 and the femoral component 10 and are formed with proximal and distal bearing surfaces which engage corresponding bearing surfaces 14, 15, 16 on the tibial tray 6 and on the femoral component 10. These various bearing surfaces enable the tibial component 4 to rotate and translate relative to the femoral component 10. The bearing components 12, 13 may be meniscal bearing components, rotational platform bearing components, or may be fixed bearing components. The combination of the bearing surfaces 14, 15, 16 and the bearing components 12, 13 allows the knee prosthesis to achieve a similar range of movements to an anatomical knee joint.

    [0028] An artificial knee ligament 20 is provided within the knee prosthesis 2 to restrict undesirable movements of the knee prosthesis, improving the stability of the joint in use, as well as reducing the risk of dislocation of the bearing components 12, 13. The ligament 20 is elongate in form and constructed substantially of a first biocompatible material which has high tensile strength and stiffness.

    [0029] With reference to Figure 2, the ligament 20 is terminated at the proximal end by a proximal loop 22 and at the distal end by a distal loop 24, both loops having a fixed size. In the embodiment shown, the loops are formed by looping back the material at each end of the ligament to form the loops, and gluing the free ends of the ligament back to itself to secure the loop. Alternatively, another method for securing the loop could be used, for example the individual fibres of the ligament could be separated, then woven back in to the ligament to secure the loop or the ligament could be passed through a washer looped on one side of the washer then the individual fibres of the ligament could be fed back though holes in the washer to secure the loop.

    [0030] The distal loop 24 is connected to a fixing provided on the tibial component 4 which may comprise a tibial bollard 26 and the proximal loop 22 is connected to a fixing provided on the femoral component 10 which may comprise a femoral bollard 28. The bollards 26, 28 comprise a neck portion and a head portion, with the neck portion being narrower in form than the head portion. When the ligament 20 is fitted to the knee prosthesis 2, the loops 22, 24 rest on the neck portions of the bollards and are prevented from sliding or working themselves off the bollard by the wider head portion.

    [0031] With reference to figure 3, a wear portion 30, is provided on the inside of the proximal and distal loops 22, 24. In the embodiment shown in Figure 3, the wear portion 30 is moulded into the loop to form a single component. The wear potion 30 is located in the area of each loop 22, 24 where the loop contacts the neck of the tibial or femoral bollard when the ligament is fitted. The wear portion may be shaped or dipped to rest against the fixing in use. The wear portion 30 may be formed in a second biocompatible material, such as polyethylene, which has a greater resistance to abrasive wear than the first biocompatible material which forms the ligament. The wear portion 30 may comprise a resilient ring of material and may be configured to pull the loop towards a closed or partially closed configuration. The wear portion 30 may thus be configured to grip the bollard 26, 28 when fitted, further reducing the possibility of the ligament becoming disconnected. The wear portion 30 may be elastically deformable allowing the loops 22, 24 to become substantially circular in an open configuration. In the open configuration, as shown in figure 3, the loops can be fitted over the head portion of the bollards 26, 28.

    [0032] With reference to Figure 4, the loops 22, 24 of the artificial ligament 20 may be further secured by the use of ferrules 32. In the embodiment shown in Figure 4 the wear portions 30 comprise thimbles which are formed as separate loops which are trapped within the eyes of the ligament loops 22, 24. The thimbles are resilient and may be configured hold the loops in the closed condition when not fitted to the bollards, as shown in Figure 4.

    [0033] With reference to Figure 5, a biasing element 538 may be provided between the tibial bollard 26 and the tibial component 4. The biasing element 538 is provided within a bore 508 of the stem 8 of the tibial component 4. The tibial bollard 26 may also be received within the bore 508. The bore 508 opens onto the bearing surface 14 of the tibial tray 6. The artificial ligament 20 extends into the bore 508 through a space 516 between the bearing components 12, 13, so that the artificial ligament 20 substantially does not interfere with the bearing components 12, 13 during normal articulation of the prosthesis.

    [0034] The biasing element 538 comprises a resilient element 40. In the illustrated embodiment, the resilient element 40 is a coiled compression spring 42 and the bearing element 44 is a plate 46. However, the resilient element 40 may consist of or comprise any appropriate spring or springs, for example a Belleville washer or an elastomeric member. An appropriate bearing element may be selected according to the choice of resilient element or may be omitted if not required.

    [0035] With continued reference to Figure 5, the knee prosthesis also comprises a tensioning element 518. The tensioning element 518 is mounted in the stem 8 of the tibial component 4. The tensioning element 518 is cylindrical and formed with an external thread 520 which engages with an internal thread 522 formed in the bore 508. The tensioning element 518 acts between the biasing element 538 and the tibial component 4. The tensioning element 518 is adjustable, to allow the tension in the ligament 20 to be set to appropriately.

    [0036] In the embodiment shown, the resilient element 538 and the tensioning element 518 are both provided on the tibial component 4 of the knee prosthesis 2. It is equally envisaged that both could be provided on the femoral component 10, or one could be provided on each of the prosthetic components. Alternatively one or both could be omitted.

    [0037] With reference to Figure 6, in order to determine a suitable length of artificial ligament 20 to be fitted to the knee prosthesis 2, a trial ligament 620 may be created. When the trial ligament is created, the tibial component 4 of the knee prosthesis 2 may not have been implanted and hence a trial tibial component 604 may be used temporarily within the knee joint assembly. The trial tibial component 604 also comprises a tibial tray 606, a stem 608 and a tibial bollard 626. The connection between the trial tibial component 604 and the trial ligament 620 is substantially the same as the connection between the tibial component 4 and the ligament 20 as shown in Figure 1. Similarly, the final bearing components 12, 13 may not be fitted, and trial bearing components 612, 613 may be temporarily used in the assembly when creating the trial ligament 620. The trial ligament 620 can be formed by tying a length of surgical string around the femoral bollard 28 and the trial tibial bollard 626. Alternatively the trial ligament could be formed from a zip tie or any other suitable elongate element which is selectively connectable to form a continuous band. In some cases, the trial tibial component 604 may be the final tibial component 4 which has been fitted in a temporary manner.

    [0038] In order to address the shortcomings recognised in a method for implanting a prosthetic knee joint, as presented in the background section above, improved methods of implanting the prosthesis 2 are herein described.

    [0039] In one method of implanting the prosthesis 2, the femoral component 10 is implanted into the distal end of a femur 650; the trial tibial component 604 is fitted temporarily to the proximal end of a tibia 652 such that the tibial tray 606 rests of the resected proximal end of the tibia 652. Trial bearing components 612, 613 are placed between the femoral component 10 and the trial tibial component 604. The trial ligament 620 is then created by tying off a length of surgical string after it has been tightened around the femoral bollard 28 and the trial tibial bollard 626. The trial ligament 620 is then cut away and removed from the operative site. The trial ligament 620 can then be reassembled into a closed loop and the length of the loop measured to determine the length of artificial ligament 20 required to be fitted into the knee prosthesis 2.

    [0040] In an alternative method (not shown), the trial ligament 620 could comprises a tie which is colour coded, such that the length of ligament required can be determined by the colour of the trial ligament 620 at the position it has been tied. Alternatively, the trial ligament 620 could comprise a zip tie with a ratchet head and rather than being tied, the zip tie could be tightened around the bollards using the ratchet head, the colour of the tie at the position of the head could be noted and the tie could then be undone and removed from the operative site. Alternatively, rather than being colour coded, the tie could be marked with numbers or letters, denoting the length of tie used.
    Once the length of trial ligament 620 has been determined, an artificial ligament 20 of a suitable length may be selected from a range or kit of artificial ligaments available.

    [0041] With reference to Figure 7, a ligament gauge 700 can alternatively be used to determine the length of ligament required. The ligament gauge 700 comprises a hook 702, which is configured to couple with a femoral bollard 28, and an elongate shaft portion 704. A slider 706 is configured to be axially movable along the shaft 704. The slider comprises a body 708, a jaw 710 and a locking component 712. The locking component 712 can be rotated relative to the slider body 708 and shaft 704 to lock the slider axially with respect to the shaft 704. Measurement markings 714 are provided on the shaft for the required length of ligament to be read off. In use, the hook 702 is coupled to the femoral bollard 28 of a prosthetic component implanted on to the femur of a patient. The slider is moved along the shaft until the jaw 710 engages with the tibial bollard 26. The locking component is then rotated to lock the position of the slider. The locking action may be achieved through the use of tabs (not shown) provided on the inside of the locking component 712 which engage with grooves in the shaft 704. The shaft may be configured such that the tabs on the locking component 712 do not engage the shaft 704 in the unlocked position. The ligament gauge 700 can be rotated about the femoral bollard 28 to disengage the jaw 710 from the tibial bollard 26. The hook 702 can then be unhooked from the femoral bollard 28 and the gauge can be removed. In this way, the measurement recorded on the ligament gauge 700 can be read after the gauge has been removed from the operative site.

    [0042] Once a suitable artificial ligament 20 has been selected, the trial tibial component 604 is removed from the joint. The distal loop 24 of the artificial ligament 20 is attached to the tibial bollard 26 of the final tibial component 4. The proximal loop 22 of the artificial ligament 20 is then attached to the femoral bollard 28 of the femoral component 10. By attaching the artificial ligament to both the tibial component 4 and the femoral component 10 before the tibial component 4 is finally implanted, the problem highlighted in the current methods is avoided.

    [0043] At this stage the trial bearing components 612, 613 may be removed, and the final bearing components 12, 13 may be inserted between the tibial tray 6 and the bearing surfaces 15, 16 of the femoral component 10. Alternatively, if desirable, a meniscal spacer (not shown) which is slightly thinner than the final bearing components 12,13 can be fitted to the prosthetic joint 2 to reduce loading of the ligament 20 during the final stages of the implantation. The tibial component 4 is then implanted into the proximal end of the tibia 652.

    [0044] If the meniscal spacer or the trial bearing components 612, 613 are still present within the joint, they are now removed and the final bearing components 12, 13 are fitted to the knee prosthesis 2.

    [0045] Although in the example shown, the final femoral component 10 is implanted first, and the tibial component 4 of the knee prosthesis is then fitted loosely or a suitable trial tibial component 604 is fitted to allow the required length of the artificial ligament 20 to be determined, it is equally envisaged that the final tibial component 4 could be implanted first, and the femoral component 10 or a suitable trial femoral component (not shown) could be fitted thereafter to allow the required artificial ligament length to be determined. It is also considered, that both the femoral and tibial components could be trial components and could be fitted temporarily whilst the trial ligament 620 is formed.

    [0046] Aspects of the ligament which do not form part of the invention are set out below:

    Aspect 1. A method of implanting a prosthetic knee joint assembly, comprising a tibial component, a femoral component and an artificial knee ligament, comprising the steps of:

    implanting the tibial component or the femoral component into a patient;

    coupling a preformed artificial ligament to the prosthetic components;

    implanting the other component into the patient.

    Aspect 2. The method according to aspect 1 wherein the first prosthetic component is implanted in a temporary manner.

    Aspect 3. The method according to aspect 1 or 2 wherein the tibial component is implanted before the femoral component.

    Aspect 4. The method according to any of aspects 1 to 3 further comprising the step of determining an appropriate length for a replacement knee ligament to link the tibial and femoral components of the prosthetic knee joint, this step being completed prior to the step of coupling the preformed artificial ligament to the prosthetic components.

    Aspect 5. The method according to any aspects 1 to 4 further comprising the step of selecting a preformed artificial ligament of a suitable length from a set of artificial ligaments, this step being completed prior to the step of coupling the preformed artificial ligament to the prosthetic components.

    Aspect 6. The method according to any of aspects 1 to 5 further comprising the step of installing a final meniscal bearing, this step being performed prior to the step of implanting the second prosthetic component into the patient.

    Aspect 7. The method according to any of aspects 1 to 5 further comprising the steps of:

    installing a temporary meniscal spacer, this step being performed prior to the step of implanting the second prosthetic component into the patient; and

    installing a final meniscal component between the tibial and femoral components of the prosthetic knee joint, this step being performed subsequently to the step of implanting the second prosthetic component into the patient.

    Aspect 8. The method according to any of aspects 1 to 5 wherein the tibial prosthetic component comprises a fixed knee bearing.

    Aspect 9. The method according to any of aspects 1 to 8 wherein the artificial knee ligament comprises the ligament of the invention.

    Aspect 10. A method of determining a suitable length for an artificial knee ligament comprising the steps of:

    coupling first and second prosthetic components to a patient in a temporary manner;

    creating a trial ligament using an elongate element extended around a first fixing on the first prosthetic component and a second fixing on the second component to form a continuous band;

    cutting the band and removing the trial ligament from the surgical site; and measuring the length of the reassembled band.

    Aspect 11. The method according to aspect 10 wherein the first and/or second prosthetic component is a trial prosthetic component.

    Aspect 12. The method according to aspect 10 or 11 wherein the first and/or second prosthetic component is a final prosthetic component

    Aspect 13. The method according to any of aspects 10 to 12 wherein the fixings comprise bollards provided on the femoral and tibial prosthetic components.

    Aspect 14. The method according to any of aspects 10 to 13 further comprising the step of:
    installing a trial meniscal component between the tibial and femoral components of the prosthetic knee joint, this step being performed prior to the step of creating a trial ligament.

    Aspect 15. The method according to aspect 14, wherein the trial meniscal component is also the final meniscal component.

    Aspect 16. The method according to any of aspects 10 to 15 wherein the elongate element comprises a trial ligament with one looped end and one open end which can be tied.

    Aspect 17. The method according to any of aspects 10 to 16 wherein a pin is used to mark the required length of elongate element whilst fitted to the patient.

    Aspect 18. The method according to any of aspects 10 to 17 wherein the elongate element comprises a zip tie.

    Aspect 19. The method according to any of aspects 10 to 18 wherein the elongate element comprises markings allowing the length of the band to be determined from the markings on the elongate element.

    Aspect 20. The method according to aspect 4, or any of aspects 5 to 9 when depending upon aspect 4, wherein the step of determining an appropriate length for a replacement knee ligament to link the tibial and femoral components of the prosthetic knee joint comprises the method of any of aspects 10 to 19.




    Claims

    1. An artificial knee ligament (20) comprising an elongate body and two ends, wherein a loop (22, 24) is provided at at least one of the ends; and wherein:

    the loop (22, 24) is configured to couple to a fixing (26, 28) provided on either a femoral (10) or tibial (4, 604) component of a prosthetic knee joint (2); and,

    a loop liner (30) is provided within the loop (22, 24) characterized in that

    the loop liner is moulded onto the loop (22, 24) of the ligament (20); and,

    the loop liner (30) is resilient and can be deformed elastically to allow the ligament loop (22, 24) to be pushed over an enlarged head of the fixing of the prosthetic (26, 28) component (2).


     
    2. The artificial knee ligament (20) of claim 1 wherein the loop liner (30) is formed from a different material from the body of the ligament (20).
     
    3. The artificial knee ligament (20) of claim 1 or claim 2 wherein the length of the ligament (20) is fixed.
     
    4. The artificial knee ligament (20) of any of claims 1 to 3 wherein the loop liner (30) covers an inside face of the loop (22, 24).
     
    5. The artificial knee ligament (20) of claim 4 wherein the loop liner (30) is shaped to sit between the fixing (26, 28) of the prosthetic knee component (2), and the ligament loop (22, 24).
     
    6. The artificial knee ligament (20) of any of claims 1 to 5, wherein the loop liner (30) comprises a thimble.
     
    7. The artificial knee ligament (20) of any of the preceding claims wherein the loop liner (30) is made from polyethylene.
     
    8. An artificial knee joint assembly (2) comprising a tibial component (4, 604), a femoral component (10) and an artificial knee ligament (20) according to any of claims 1 to 7.
     
    9. A kit of artificial knee ligaments (20) wherein each ligament within the kit has a different fixed length, and wherein the artificial knee ligaments comprise the ligament according to any of claims 1 to 7.
     


    Ansprüche

    1. Künstliches Knieband (20), das einen länglichen Körper und zwei Enden umfasst, wobei an wenigstens einem der Enden eine Schlaufe (22, 24) vorgesehen ist; und wobei:

    die Schlaufe (22, 24) so gestaltet ist, dass sie eine Kopplung mit einer Fixierung (26, 28) vorsieht, die entweder an einer femoralen (10) oder tibialen (4, 604) Komponente einer Kniegelenkprothese (2) bereitgestellt ist; und

    eine Schlaufenauskleidung (30) in der Schlaufe (22, 24) bereitgestellt ist,

    dadurch gekennzeichnet, dass

    die Schlaufenauskleidung an die Schlaufe (22, 24) des Bands (20) geformt ist; und

    die Schlaufenauskleidung (30) elastisch ist und elastisch verformt werden kann, um es zu ermöglichen, dass die Bandschlaufe (22, 24) über einen vergrößerten Kopf der Fixierung der Komponente (2) der Prothese (26, 28) geschoben wird.


     
    2. Künstliches Knieband (20) nach Anspruch 1, wobei die Schlaufenauskleidung (30) aus einem anderen Material als der Körper des Bands (20) besteht.
     
    3. Künstliches Knieband (20) nach Anspruch 1 oder 2, wobei die Länge des Bands (20) fest ist.
     
    4. Künstliches Knieband (20) nach einem der Ansprüche 1 bis 3, wobei die Schlaufenauskleidung (30) eine Innenseite der Schlaufe (22, 24) bedeckt.
     
    5. Künstliches Knieband (20) nach Anspruch 4, wobei die Schlaufenauskleidung (30) so geformt ist, dass sie zwischen der Fixierung (26, 28) der Komponente (2) der Knieprothese und der Bandschlaufe (22, 24) sitzt.
     
    6. Künstliches Knieband (20) nach einem der Ansprüche 1 bis 5, wobei die Schlaufenauskleidung (30) einen Fingerhut umfasst.
     
    7. Künstliches Knieband (20) nach einem der vorstehenden Ansprüche, wobei die Schlaufenauskleidung (30) aus Polyethylen besteht.
     
    8. Künstliche Kniegelenkeinheit (2), umfassend eine tibiale Komponente (4, 604), eine femorale Komponente (10) und ein künstliches Knieband (20) nach einem der Ansprüche 1 bis 7.
     
    9. Kit künstlicher Kniebänder (20), wobei jedes Band in dem Kit eine andere feste Länge aufweist, und wobei die künstlichen Kniebänder das Band nach einem der Ansprüche 1 bis 7 umfassen.
     


    Revendications

    1. Ligament de genou artificiel (20) comprenant un corps allongé et deux extrémités, une boucle (22, 24) étant prévue à au moins une des extrémités ; et :

    la boucle (22, 24) étant conçue pour s'accoupler à une fixation (26, 28) prévue sur un élément fémoral (10) ou tibial (4, 604) d'une prothèse d'articulation du genou (2) ; et,

    une doublure de boucle (30) étant prévue à l'intérieur de la boucle (22, 24), caractérisée en ce que

    la doublure de boucle est moulée sur la boucle (22, 24) du ligament (20) ; et,

    la doublure de boucle (30) est élastique et peut être déformée élastiquement pour permettre à la boucle de ligament (22, 24) d'être poussée sur une tête agrandie de la fixation de l'élément (2) de prothèse (26, 28).


     
    2. Ligament de genou artificiel (20) selon la revendication 1, caractérisé en ce que la doublure de boucle (30) est formée à partir d'un matériau différent du corps du ligament (20).
     
    3. Ligament de genou artificiel (20) selon la revendication 1 ou 2, la longueur du ligament (20) étant fixe.
     
    4. Ligament de genou artificiel (20) selon l'une quelconque des revendications 1 à 3, la doublure de boucle (30) couvrant une face intérieure de la boucle (22, 24).
     
    5. Ligament de genou artificiel (20) selon la revendication 4, la doublure de boucle (30) étant formée de sorte à s'asseoir entre la fixation (26, 28) de l'élément de prothèse du genou (2) et la boucle de ligament (22, 24).
     
    6. Ligament de genou artificiel (20) selon l'une quelconque des revendications 1 à 5, la doublure de boucle (30) comprenant une bague.
     
    7. Ligament de genou artificiel (20) selon l'une quelconque des revendications précédentes, la doublure de boucle (30) étant en polyéthylène.
     
    8. Ensemble d'articulation de genou artificiel (2) comprenant un élément tibial (4, 604), un élément fémoral (10) et un ligament de genou artificiel (20) selon l'une quelconque des revendications 1 à 7.
     
    9. Kit de ligaments de genou artificiels (20), chaque ligament du kit ayant une longueur fixe différente, et les ligaments de genou artificiels comprenant le ligament selon l'une quelconque des revendications 1 à 7.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description