Tensioned Meniscus Prosthetic Devices and Associated Methods

• US 20090259311A1
• Filed: 04/09/2008
• Published: 10/15/2009
• Est. Priority Date: 04/09/2008
• Status: Active Grant

• Current Assignee: Active Implants Corporation
• Original Assignee: Active Implants Corporation
• Inventors: Shterling, Avraham, Linder-Ganz, Eran, Danino, Amir
• Granted Patent: US 8,016,884 B2
• Time in Patent Office: Days
• US Class Current: 623/14.120
• CPC Class Codes: A61F 2/30756 Cartilage endoprostheses A61F2/3603 takes precedence
• CPC Class Codes: A61F 2/30965 Reinforcing the prosthesis by embedding particles or fibres during moulding or dipping
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3872 Meniscus for implantation between the natural bone surfaces
• CPC Class Codes: A61L 2430/06 for cartilage reconstruction, e.g. meniscus
• CPC Class Codes: A61L 27/18 obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• CPC Class Codes: A61L 27/48 with macromolecular fillers
• CPC Class Codes: A61L 27/50 Materials characterised by their function or physical properties , e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
• CPC Class Codes: C08L 23/06 Polyethene
• CPC Class Codes: C08L 75/04 Polyurethanes

Abstract

A prosthetic device for use as an artificial meniscus is disclosed. The prosthetic device restores shock absorption, stability, and function to the knee joint after removal of the damaged natural meniscus. In some embodiments, the prosthetic device is pre-tensioned to improve the fit of the prosthetic device within the knee joint and, thereby, maximize the contact area of the load-bearing surfaces to distribute loading through the prosthetic device in a manner substantially similar to that of a healthy natural meniscus. In some embodiments, the pre-tensioned prosthetic device is smaller, or scaled-down, relative to the size of a healthy natural meniscus.

Claims

1. A prosthetic device for replacing a damaged meniscus, the prosthetic device comprising:

a central portion having an upper surface for engagement with a portion of a femur and an opposing lower surface for engagement with a portion of a tibia, the central portion comprising a resilient polymeric material;

an outer portion surrounding the central portion and having an increased thickness relative to the central portion, the outer portion comprising the resilient polymeric material and tensioned with at least one reinforcing fiber embedded the resilient polymeric material;

wherein the outer portion is sized and shaped such that a compression force imparted on the prosthetic device by the femur and the tibia displaces the outer portion radially outward from the central portion.

2. The prosthetic device of claim 1, wherein the at least one reinforcing fiber is tensioned at a force between about 5 N and about 78 N.

3. The prosthetic device of claim 2, wherein the at least one reinforcing fiber is tensioned at a force between about 7 N and about 8 N.

4. The prosthetic device of claim 2, wherein the at least one reinforcing fiber is tensioned at a force between about 8 percent and about 12 percent of the at least one reinforcing fiber'"'"'s maximum tension.

5. The prosthetic device of claim 1, wherein the compression force imparted on the prosthetic device is at least partially transformed into a tensile load on the at least one reinforcing fiber.

6. The prosthetic device of claim 5, wherein the at least one reinforcing fiber extends completely around the central portion within the outer portion.

7. The prosthetic device of claim 1, wherein the central portion stretches as the outer portion is displaced radially outward by the compression force.

8. The prosthetic device of claim 7, wherein a contact area between the portion of the femur and the upper surface of the central portion increases with the stretching of the central portion.

9. The prosthetic device of claim 7, wherein a contact area between the portion of the tibia and the lower surface of the central portion increases with the stretching of the central portion.

10. The prosthetic device of claim 1, wherein the resilient polymeric material is a medical grade polyurethane based material.

11. The prosthetic device of claim 10, wherein the resilient polymeric material is a polycarbonate polyurethane.

12. The prosthetic device of claim 11, wherein the at least one embedded fiber comprises an ultra high molecular weight polyethylene.

13. The prosthetic device of claim 1, wherein the outer portion comprises a first section comprising a semi-ellipsoidal profile similar to a natural meniscus.

14. The prosthetic device of claim 5, wherein the outer portion comprises a bridge portion connecting first and second ends of the semi-ellipsoidal profile of the outer portion.

15. The prosthetic device of claim 6, wherein the bridge portion is sized to engage a femur notch.

16. A meniscus prosthetic device for use in a knee joint, the meniscus prosthetic device comprising:

a central portion having an upper surface for engagement with a portion of a femur and an opposing lower surface for engagement with a portion of a tibia, the central portion comprising a resilient polycarbonate polyurethane;

an outer portion surrounding the central portion and having an increased thickness relative to the central portion, the outer portion comprising a resilient polycarbonate polyurethane embedded with tensioned ultra high molecular weight polyethylene reinforcing fibers, the outer portion comprising a first section having a semi-ellipsoidal profile similar to a natural meniscus and a second section connecting ends of the first section, the second section sized and shaped to engage a femur notch to secure the meniscus prosthetic device within the knee joint without penetrating bone.

17. The meniscus prosthetic device of claim 16, wherein the central portion has a minimum thickness less than about 3 mm between the upper surface and the lower surface and wherein the increased thickness of the outer portion is between about 4 mm and about 15 mm.

18. The meniscus prosthetic device of claim 16, wherein the ultra high molecular weight polyethylene reinforcing fibers are tensioned at a force between about 8 percent and about 12 percent of the ultra high molecular weight polyethylene reinforcing fibers'"'"' maximum tension.

19. The meniscus prosthetic device of claim 18, wherein the ultra high molecular weight polyethylene reinforcing fibers are tensioned at a force less than 10 N.

20. A meniscus implant, comprising:

a central portion having an upper surface for engagement with a portion of a femur and an opposing lower surface for engagement with a portion of a tibia, the central portion comprising a resilient polycarbonate polyurethane, the central portion resiliently deformable between an unloaded position and a loaded position, the upper and lower surfaces of the central portion having increased contact with the femur and tibia in the loaded position;

an outer portion surrounding the central portion and having an increased thickness relative to the central portion, the outer portion comprising a resilient polycarbonate polyurethane embedded with tensioned ultra high molecular weight polyethylene reinforcing fibers, the outer portion comprising a first section having a generally semi-ellipsoidal profile similar to a natural meniscus and a second section connecting ends of the first section, the second section sized and shaped to engage a femur notch to secure the meniscus prosthetic device within a knee joint without penetrating bone, wherein the outer portion is resiliently deformable between an unloaded position and a loaded position, at least a section of the outer portion being displaced radially outward from the central portion in the loaded position.