DD300262A7

DD300262A7 - METALLSPONGIOSA

Info

Publication number: DD300262A7
Application number: DD32099988A
Authority: DD
Inventors: Peter Kurze; Klaus Rabending; Rainer Morgenstern; Waldemar Krysmann; Peter Daniel; Manfred Polster
Original assignee: Technische Universitaet Karl-Marx-Stadt,De
Priority date: 1988-10-24
Filing date: 1988-10-24
Publication date: 1992-06-04

Abstract

Die Erfindung betrifft eine Metallspongiosa aus Titanium oder Tantal oder deren Legierungen in Form einer offenzelligen Drahtgitterstruktur, deren gesamte Oberflaeche mikrostrukturiert und bioaktiv geschichtet ist. Die Metallspongiosa dient als Knochenersatz in der Unfallchirurgie bzw. Orthopaedie und heilt bindegewebslos ein. Die Hohlraeume koennen vollstaendig oder teilweise mit resorbierbaren Biomaterialien gefuellt sein.{Metallspongiosa; metallisches Dauerimplantat; Bioaktivbeschichtung; Medizin; Unfallchirurgie; Orthopaedie; offenzelliges Stuetzgeruest; Titanium, mikrostrukturierte Oberflaeche; bindegewebsloses Einwachsen}The invention relates to a metal spongiosa of titanium or tantalum or their alloys in the form of an open-cell wire mesh structure, the entire surface of which is microstructured and bioactively layered. The metal spongiosa serves as a bone substitute in trauma surgery or orthopedics and heals without connective tissue. The cavities may be completely or partially filled with resorbable biomaterials {metal spongiosa; permanent metal implant; Bioaktivbeschichtung; Medicine; Trauma; Orthopedic; open-celled support structure; Titanium, microstructured surface; connective tissue ingrowth}

Description

aus Reinmetall können auch biokompatible Legierungen, beispielsweise Ti₆AI₄V Verwendung Finden. Die gesamte innere und äußere Metallspongiosaoberfläche ist mit einer bis zu 10pm starken bioaktiven Schicht versehen, die metallseitig aus reinem Oxid des Substratmaterials besteht und in Richtung zum Hohlraum bzw. zur Umgebung aber wachsende Mengen Kalziumphosphat bis zu einer Oberflächenkonzentration von 12% enthält. Die bioaktive Schicht ist außerdem derart mikrostrukturiert, daß pro mm² mindestens 10⁴ Poren mit einem Porendurchmesser > 1 pm und einer maximalen Porentiefe von Va der Bioaktivschichtstärke vorhanden sind. Die nach außen führenden Kanäle oder der gesamte Hohlraum können zusätzlich vollständig oder teilweise mit resorbierbaren Biomaterialien ausgefüllt sein. Der Vorteil der so aufgebauten Metallspongiosa besteht darin, daß die Gerüststruktur der natürlichen Spongiosastruktur sehr ähnlich ist, die chemische Zusammensetzung und die Mikrostrukturierung der Oberfläche den angrenzender. Knochen zum Einwachsen in das Implantat anregen. Tierexperimentelle Untersuchungen zeigen, daß bei einer lichten Weite der durchgängigen Kanäle von > 0,8mm das Implantat völlig vom Knochengewebe durchwachsen wird, wodurch sich das Implantat auch zur Defektüberbrückung bei noch nicht abgeschlossenem Längenwachstum jugendlicher Patienten eignet.Pure metal can also be used to find biocompatible alloys, for example Ti ₆ Al ₄ V. The entire inner and outer metal spongiosa surface is provided with up to 10pm strong bioactive layer, the metal side consists of pure oxide of the substrate material and towards the cavity or the environment but containing growing amounts of calcium phosphate to a surface concentration of 12%. The bioactive layer is also microstructured such that at least 10 ⁴ pores with a pore diameter> 1 pm and a maximum pore depth of Va of the bioactive layer thickness are present per mm ² . The outwardly leading channels or the entire cavity may additionally be filled completely or partially with resorbable biomaterials. The advantage of the metal spongiosa constructed in this way is that the framework structure is very similar to the natural spongiosa structure, the chemical composition and the microstructuring of the surface are adjacent. Stimulate bone to grow into the implant. Animal experiments show that with a clear width of the continuous channels of> 0.8 mm, the implant is completely penetrated by the bone tissue, whereby the implant is also suitable for bridging the defect in incomplete growth of young patients.

embodiment

Ein rotationssymmetrisch geformter Metallspongiosa-Implantatkörper für eine Defektüberbrückung an der Speiche nach unfallbedingten Stücktrümmerbrüchen im Unterarmbereich hat eine Gesamtlänge von 42 mm und gliedert sich in drei zylindrische Abschnitte, deren mittlerer 30mm lange Abschnitt einen Durchmesser von 18 mm aufweist, während die beiden 6mm langen Enden einen Durchmesser von jo 6mm besitzen. Der implantatkörper besteht aus einem Stützgerüst aus Reinsttitaniumdrähten mit rechteckigem Querschnitt von 0,5 mm mal 1 mm, welche jeweils im Abstand von 2 mm alternierend mit zwei anderen Drähten stoffschlüssig über eine Länge von 1mm verbunden sind, so daß zwei benachbarte Drähte jeweils alle 5 mm verbunden sind und keine stoffschlüssig ungebundenen Drähte auftreten. Die jeweils 2 mm langen nicht stoffschlüssigen verbundenen Drahtabschnitte sind in unregelmäßiger Weise umgeformt und miteinander verschlauft, so daß eine offenzellige Drahtgitterstruktur mit unregelmäßig geformtem Hohlraum vorliegt, welcher durch Kanäle unterschiedlicher Form und Größe vugängig ist. Die Dichte des Implantatkörpers, dessen Form durch mehrere Kaltumformungen erreicht wird, beträgt 56% dor Dichte des Reintitaniums.A rotationally symmetrical metal spongiosa implant body for a defect bridging at the spine after accidental fragmental fractures in the forearm has a total length of 42 mm and is divided into three cylindrical sections, the central 30mm long section has a diameter of 18 mm, while the two 6mm long ends one Diameter of jo 6mm own. The implant body consists of a support framework made of pure titanium wires with a rectangular cross-section of 0.5 mm by 1 mm, which are connected at intervals of 2 mm alternately with two other wires cohesively over a length of 1mm, so that two adjacent wires every 5 mm are connected and no cohesively unbound wires occur. The respective 2 mm long non-cohesively connected wire sections are irregularly formed and looped together, so that there is an open-cell wire grid structure with irregularly shaped cavity, which is vugängig through channels of different shape and size. The density of the implant body, whose shape is achieved by several cold forming, is 56% of the density of the pure titanium.

Die gesamte innere und äußere Oberfläche des Implantatkörpers trägt eine 5μηι dicke Titanlumoxidschicht, die an der Oberfläche 7% Kalziumphosphat enthält. Rasterelektronenmikroskopische Untersuchungen der Oberfläche zeigt η auf einer Fläche von 1mm² 2 10⁴ Poren mit einem Mindestdurchmesser von 1 pm. Die Druckfestigkeit des Implantatkörp jrs beträgt > 300 N/mm².The entire inner and outer surface of the implant body carries a 5μηι thick titanium lum oxide layer containing 7% calcium phosphate on the surface. Scanning electron micrographs of the surface show η on an area of 1mm ² 2 10 ⁴ pores with a minimum diameter of 1 pm. The compressive strength of the implant body jrs is> 300 N / mm ² .

In Betracht gezogene Druckschriften: DD 243855 (A61C8/00) DE-OS 3629813(A61F2/02)Documents considered: DD 243855 (A61C8 / 00) DE-OS 3629813 (A61F2 / 02)

Claims

1. A metal-pongiosa of open-pore structure of titanium of a titanium alloy having apertured surface structures in the form of connected, irregularly twisted, cold-formed wires coated on all sides with a bioactive oxide, characterized in that the metal cancellous bone consists of a metal body with regularly punctiform and cohesively connected wires of square or rectangular cross-section and that the layer metal-side consists of pure oxide and in the direction of the environment growing amounts of calcium phosphate to a surface concentration of 12% and is microstructured so that per mm ² at least 10 ⁴ pores with a pore diameter> 1 μιη and a maximum pore depth of ¹ lz the layer thickness are present.

2. metal cancellous bone according to claim 1, characterized in that cavities are completely or partially filled with resorbing biomaterials.

Field of application of the invention

The invention relates to a metal spongiosa for use in human medicine, in particular in trauma surgery and orthopedics.

Characteristic of the known state of the art

Are known metallic permanent implants of bionated pure metals or their alloys, which are used for example in the form of joint prosthesis in surgery and their firm contact with the bone with the help of bone cement.

Because of the gradual structural changes of the bone cement it comes to the loosening and shortening of the implant. For this reason, cementless implant bone connections are desired. It is known to structure the surfaces of the metal implants in a suitable manner or to encase with lattice-shaped elements, as described for example in AT-PS383268, whereby a positive anchoring to the bone tissue is to be made possible. Particularly strong implant-bone composites are said to arise when irregular open-cell spongiosa-like implants or implant surfaces are used which allow trabecular ingrowth or bone growth into the implant.

According to HENSSGE (Focus MHL 2 [1985] 4,1-8), these metal spongiosa are casting bodies, preferably of cobalt-base alloys, which have been developed as soutae implants for stabilization, for functional purposes or for surface structuring for joint replacement implants. Development in this area is not yet completed (and long-term results are still missing). However, it is known that using cobalt-based alloy tissue does not result in binge-tissue-free bone contact and can lead to rejection reactions. In addition, the production of the metal spongiosa casting is technically complicated and the surface purity is insufficient. It is also well known. To use titanium or titanium alloys for implants, which may be additionally coated with bioactive materials (DEOS3629813, DDPS243855). Here, the manufacturing process of the titanium implant according to DEOS3629813 operations (welding, selective dissolution by means of acid), which require a very complicated removal of biologically incompatible impurities. Furthermore, local potential differences can lead to corrosion at the welds. In DD-PS243855 reference is made in general terms to flexible metal and Koramikstrukturen for implants, but without naming practicable embodiments.

Object of the invention

The aim of the invention is to provide a high-strength metal cancellous bone with little technical effort, which guarantees a long period of time, postoperatively immediately at least exercise-stable and shortens the hospitalization of patients.

Explanation of the essence of the invention

The invention has for its object to provide a high-strength sr.hwermetallfreie or heavy metal metal spongiosa, which is mikrostrukturiesi and bioactive over the entire surface and promotes a connective tissue ingrowth or growth of bone tissue. According to the invention, the object is achieved by using open-cell bioinert cell structures of titanium or titanium alloys with open-surface structures in the form of connected, irregularly twisted and cold-formed wires in that the metal cancellous bone in the required shape punctiform and cohesively connected with each other at regular intervals, and irregularly form-fitting with each other devoid of tone, highly cold-formed wires of square or rectangular cross-section made of titanium or titanium alloys, tantalum or tantalum logs, so that a scaffold of the density of 50 to 90% of the Diciite of the substrate material is present with irregularly structured cells. The cells are connected to each other, so that the entire implant body has an irregularly perforated cavity which is accessible on all sides by irregularly shaped channels the ingrowing bone tissue. The wires have a cross section up to 3 mm ² . Instead of wires