Implant and implant system
An implant system for implantation at a joint. The implant system includes an implant device with a body portion having first and second ends, and a first elongate member, extending from the first or second end of the body portion. The implant system has a corresponding fixation device with at least one latching element. The first elongate member has at least one cooperating element capable of cooperating with the at least one latching element of the fixation device in use.
1. A method for implanting a prosthetic meniscus in a patient, between a tibial plateau and femoral condyle of the patient, said method comprising the steps of:
providing a prosthetic meniscus, said prosthetic meniscus comprising:
a crescent-shaped body portion having an upper surface for engagement with a patient's femur, an opposing lower surface for engagement with a patient's tibia plateau, a first end, a second end, and an arcuate outer rim extending from the first end to the second end,
a first elongate member extending from the first end of the body portion and terminating in a free end, at least a portion of the first elongate member being strap-shaped or substantially crescent shaped in cross-section,
a second elongate member extending from the second end of the body portion and terminating in a free end, at least a portion of the second elongate member being strap-shaped or substantially crescent shaped in cross-section,
a reinforcing element, which extends continuously through the first elongate member, through the body portion, and through the second elongate member, the reinforcing element being a planar, strap-shaped element,
a structural element comprising a plurality of fibres embedded within the body portion, and
a first corresponding fixation device for securing the first elongate member in a first bone tunnel in the tibia plateau of the patient, the first corresponding fixation device comprising external threading forming a plurality of latching elements to interlock with the first elongate member;
creating the first bone tunnel, the bone tunnel having first and second ends, the bone tunnel running between the first and second ends, the bone tunnel having a first opening in the tibial plateau at its first end and a second opening below the tibial plateau at its second end, said first bone tunnel running between the first opening and second opening;
placing the body portion between the tibial plateau and femoral condyle of the patient;
inserting the first elongate member into the first opening of the first bone tunnel;
inserting the first corresponding fixation device into the second opening of the first bone tunnel to engage the first elongate member and secure the first elongate member in the first bone tunnel, the external threading of the corresponding fixation device penetrating into bone on the side of the first bone tunnel when installed,
wherein the second elongate member is securable to the tibial plateau of the patient,
wherein the prosthetic meniscus is made from a functionally graded material, having at least one mechanical property that varies in a radial direction relative to the crescent-shaped body portion and/or in a circumferential direction relative to the crescent-shaped body portion,
wherein the body portion has a high tensile stiffness along an axis substantially parallel with the arcuate outer rim of the body portion of less than 2 GPa, and a low shear stiffness in a plane substantially transverse to the arcuate outer rim of the body portion of less than 50 MPa.
2. A method according to claim 1 , wherein the first and/or second elongate member of the prosthetic meniscus terminates in a free end.
3. A method according to claim 1 , wherein the first corresponding fixation device is a screw, the screw being externally helically threaded.
4. A method according to claim 1 , wherein the reinforcing element has a planar face, the planar face being substantially perpendicular to a transverse plane of the body portion.
5. A method according to claim 1 , wherein at least a portion of each of the fibres extends through the body portion.
6. A method according to claim 5 , wherein each of the fibres extends through the first elongate member, through the body portion, and through the second elongate member.
7. A method according to claim 1 , wherein the plurality of fibres are arranged such that each fibre crosses over at least one other fibre.
8. A method according to claim 1 , wherein the body portion of the prosthetic meniscus has an elastic modulus gradient, the elastic modulus gradient varying spatially within the body portion.
9. A method according to claim 8 , wherein the elastic modulus gradient increases in a radial direction, towards the arcuate outer rim of the body portion.
10. A method according to claim 8 , wherein the elastic modulus gradient increases in a circumferential direction towards free ends of the first and second elongate members.