NL8900692A - BONE IMPLANT. - Google Patents

Description

κ.

V.0. 2087

Title: Bone implant.

The invention relates to a bone implant used in a surgical operation for the repair or reconstruction of skeletal deformities. These bone implants were used by orthopedic surgeons in the treatment of hip and knee joints for the reconstruction of articulating joints as well as in trauma situations for the attachment of broken bones.

Several metals have been proposed for the manufacture of bone implants. For example, titanium and cobalt-chromium are widely used because of their biocompatibility with the bone tissue and their strength properties in bearing loads applied to the skeletal structure after implantation. With a metal bone implant, U.S.-A-3,605,123 and 3,900,550 provide a porous metal surface to improve fixation of the implant to resected bone at the intramedullary canal. These metals are stronger than bone, but bone is slightly flexible, and the flexibility of the rigid metals does not exactly match that of bone. As a result, numerous recent articles and patents propose the use of composites or non-metals for the construction of bone implants, in order to provide the implant with a substantially equal modulus of bone.

In US-A 4,662,887 a polyether ether ketone, commonly referred to as PEEK, is described for use as an orthopedic device. The PEEK polymer is biocompatible and flexible enough in its final form to approximate the anatomical elasticity of bone. US-A-3893196, 30 issued to Hochmann, discloses a composite hip implant having a core of graphite fibers, the core-defining outer layer of graphite fiber, and the fiber-encapsulating plastic skin that provides a porous plastic surface to enable bone to be attached thereto. grow fast. A further support for the latter patent 88 0 0692 4 -2-λ is US-A-4,164,794, which provides a porous composite material to the surface of a hip prosthesis to improve bone fixation.

If one compares the metal implant with the composite implant, one sees advantages and disadvantages. With the metal implant, the strength properties of metals in a rigid implant result, which can cause stress in contact areas of the bone. To date, no composite implant has established the intimate relationship with bone, which is considered necessary for the bonding of bone for long-term fixation, despite the numerous attempts to provide a porous composite surface for the composite implant. It is further believed that polymer surfaces may be insufficiently durable for load transfer and insufficiently abrasion resistant for long term fixation.

The present invention relates to an orthopedic implant of which the advantages of metal and composite materials are part. Rather than relying on a total composite or total metal implant, the invention provides a composite core that closely approximates the flexibility of bone and a metal surface attached to the composite core so that bone fouling and / or cement easily penetrate and adhere to the porous metal surface for Long-term fixation of the orthopedic implant.

It is an advantage of the present invention that the composite / metal implant approximates the flexibility of bone and provides a porous metal surface that is well compatible with bone to allow for an unobstructed growth of bone into the porous surface. porous metal surface is sufficiently strong and durable to ensure long-term fixation. In addition, the porous metal surface is formed by a metal fiber pad that is abrasion resistant and remains integrally attached to the composite core during implantation as well as after implantation.

8900 692. "-3-

In the accompanying drawings, Fig. 1 is a side view of a femur component after implantation. Fig. 2 is a cross-sectional view along line II-II of FIG. 1. Fig. 3 is a cross-sectional view taken along line III-III 5 of FIG. 1. FIG. 4 is a cross-sectional view of the porous metal fiber pad, separate from the composite member, and FIG. 5 is a similar view to FIG. 3, showing a modified embodiment of the invention.

The femur component 10 is surgically implanted in the intramedullary canal 12 of the femur 14. The intramedullary canal 12 is exposed by resection of the anatomical femur head (not shown). A head 16 is coupled to a neck 18 of the femur component. The head 16 is spherical to provide movement within a cup 20 of a joint cup 22 in the hipbone.

The thigh component 10 includes a core 20 consisting of a plurality of longitudinally extending fibers, an intermediate layer 26 consisting of a braided 20 jacket of fibers, and the core 24 and the intermediate layer 26 enveloping skin, and a pair of porous metal fiber pads 30 and 31 attached to the skin 28. In the drawings, the cushion layer 26 is shown, for illustrative purposes only, with a larger fiber diameter than that of the core 24. The core 24 and the intermediate layer 26 are made of the same fibers.

The core 24, the interlayer 26 and the skin 28 extend from the distal end 33 to a proximal end 32 forming the neck 18. The porous metal fiber pads 30 and 31 are preferably located near the neck 18 and on both sides, the front and the back, of the thigh component.

The many core 24 forming fibers and the braided sheath of the interlayer 26 forming fibers are made from APC-2 as marketed by FIBERITE, a subsidiary of Imperial Chemical Industries, see FIBERITE Data Sheet 3a propriety data or 89 00692.

♦ -4- aromatic polymer composite, APC-2 / Hercules Magnamite AS4 Carbon Fiber. This material comprises a continuous carbon fiber, with PEEK impregnated therein.

The skin 28 is made of polyetherether-5 ketone or PEEK, according to the teachings of US-A-4,662,887. This material is available from Imperial Chemical Industries according to the specification for Victrex 450G Polyetherether Ketone (PEEK), a granular molding resin with a natural color.

The metal fiber pads 30 and 31 are described in US-A-3,906,550 as short titanium wires crimped in a sinusoidal pattern with a specific amplitude to period ratio of 0.24. Numerous short wires are sintered together to form a unitary porous pad for skin fixation 28.

To manufacture the femur component 10, the longitudinal fibers of the core 24 are bundled and pulled through braiding devices to braid a sheath or layer 26 over the core 24. With the jacket or layer covering the core 24, a suitable piece is cut and applied in a mold, so that the skin 28 can be injection molded over the jacket 26 and the core 24. The PEEK material for skin 28 is heated during the injection molding step and readily adheres to PEEK impregnated into the carbon fibers of skin 26 and core 24. After the skin has cooled, a metal fiber pad as shown in Fig. 4 is heated to a high enough temperature to allow the skin to penetrate the heated pad. It is believed that a temperature of about 315.6 ° C is sufficient for penetration. A heated fiber-metal pad is then pressed into each side of the stem so that it penetrates the skin 28 over a predetermined distance with melting. Preferably, the fiber-metal pad is allowed to penetrate half its thickness as is Comparing Figures 35 and 4, see. As the metal fiber pad cools, the penetrated portion of the fiber metal pad becomes 8900632.

PÜPW'Ï! "" -5- m trapped inside either attached to the skin 28, while the outer portion of the metal fiber pad remains porous or open for intimate contact with bone and the resulting inwardly growing bony material, which follows in view of the affinity of bone to associate with titanium wire.

In the modified embodiment of FIG. 5, a metal boundary layer 40 divides the metal fiber pads 30 into an inner metal fiber portion 42 and an outer metal fiber portion 44. The boundary layer 40 separates the portion of the pad known for penetration into the skin. growing inward from the bone-like material portion of the metal fiber cushion.

Although the foregoing description proceeds to mention PEEK and titanium metal fiber cushions, it is also possible to use other composite cores with or without fiber reinforcement, with other types of metallic porous surfaces, e.g. spheres for creating a hybrid composite / metal-20 bone implant with a modulus substantially equivalent to that of bone and a porous metallic surface to promote bone growth. Prostheses for knee parts can also be formed by the composite / metal / bone implant of the present invention. In addition, the composite bone implant with the porous metallic surface of the present invention can also be readily adapted for use in a cemented hip arthroplasty using PMMA bone cement to attach the implant 30 to bone.

In the foregoing, the material for skin 28 has been referred to as polyether ether ketone or PEEK, however, this material is also referred to as polyaryl ether ketone. It is believed that, as an alternative material, polyether ketone 35 (PEEK) or polyether ketone ketone (PEKK) is suitable for skin formation and as a matrix for the carbon fibers of 89 00692.

-6- the core and the braid. Polyether Ketone (PEK) is available from Imperial Chemical Industries and Polyether Ketone Ketone is available from DuPont as PEKK polymer. As such, this material is included in the invention for which exclusive rights are claimed.

39 00 692 .1

Claims (17)

Bone implant comprising a non-metal core and a porous metal component fixedly attached to the non-metal core. Bone implant according to claim 1, wherein the non-metal core forms polyether ether ketone and the porous metal component forms a metal fiber cushion. Bone implant according to claim 1, wherein the metal porous surface component comprises a substantially non-porous bounding layer forming part embedded therein and the non-metal core extends into the metal porous surface component up to but not beyond it. non-porous boundary layer forming part. The bone implant of claim 1, wherein the non-metal core comprises a first set of fibers oriented in a longitudinal direction from one end to the opposite end of the bone implant, a second set of fibers in the first set of fibers covering a braided sheath, and a polymer layer surrounds the first and second sets of fibers. 5. A hip prosthesis bone implant comprising a first set of composite fibers extending longitudinally from one end to an opposite end of the implant, a second set, a braided sheath over the first set of fibers, one the first and the second a set of fiber-enveloping polymer skin, and a porous metal pad fixedly attached to the polymer skin that is suitable for intimate contact with the hip bone. Bone implant according to claim 5, wherein of the first set of fibers, the second set of fibers and the polymer skin, polyetheretherketone is a material component of each part. 8900 69 2: * \ -8- Bone implant according to claim 5, wherein the first set of fibers and the second set of fibers are intended to carry a substantial part of the load transferred to the bone implant, and the polymer skin 5 is intended to transfer load from the bone to the bone implant. first and second sets of fibers, and the porous metal pad is intended to promote the growth of a bone inwardly therein to securely attach the bone implant to the hipbone. Bone implant according to claim 5, wherein the first set of fibers consists of a large number of long fibers made of polyetheretherketone impregnated carbon, the second set of fibers consists of a large number of long fibers made of polyetheretherketone impregnated carbon, and the polymer skin is made of polyether ether ketone for easy assimilation with the first and second sets of fibers. The bone implant of claim 5, wherein the porous metal pad penetrates an outer portion of the polymer skin such that an inner portion of the polymer skin separates the porous metal pad from the second set of composite fibers. 10. A bone implant manufacturing method comprising the steps of: (a) providing a non-metallic composite core with a predetermined configuration for orientation near the bone, (b) providing a metal, porous pad, (c) heating the metal porous pad to a temperature high enough to allow penetration of the core into the metal porous pad, (d) engaging the heated metal porous pad with the non-metallic composite core to provide a portion of the core is melted and permits penetration of a portion of both the core and pad into each other, and 8900692. -9- (e) cooling the heated metal porous pad to the same temperature as the non- metal composite core, such that the intruded portion of the metal porous pad fixes this pad 5 to the non-metallic composite core. The method of claim 10, wherein the heating step and the engaging step take place in the absence of oxygen. 12. A hip prosthesis bone implant comprising a reed metal core that forms a predetermined shape adapted for fitting into a femoral canal of the hip, and a metal porous surface fixedly attached to the non-metallic core for intimate contact with the femoral canal. Bone implant according to claim 12, wherein the porous metal surface is formed from a metal fiber pad. A bone implant according to claim 13, wherein the metal fiber pad defines an inner portion embedded within the non-metallic core, and an outer portion with open pores for bone growth. Bone implant according to claim 12, wherein the non-metal core comprises a large number of fibers, some of which extend in a longitudinal direction and wherein a skin envelops the large number of fibers, and the metal porous surface is fixedly attached to the skin . A bone implant according to claim 15, wherein the metal porous surface consists of a discrete metal porous element, wherein a first part of the element is embedded in the skin and a second part of the element forms open pores. A bone implant according to claim 12, wherein the non-metal core contains polyether ketone ketone. 8900692. "