Surgery – Instruments – Orthopedic instrumentation
Patent
1997-11-25
1999-12-28
Buiz, Michael
Surgery
Instruments
Orthopedic instrumentation
606 72, 606 77, A61B 1784
Patent
active
060075392
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a fastening nail made of bioresorbable plastic material for the fixing of a covering membrane to an endogenous bone surrounding a bone void filled with bone replacement material, having a nail head of larger diameter, enabling impact with a pressure and/or striking tool, and, connected thereto, a nail shaft of a smaller diameter, comprising an essentially cylindrical holder part and, connected thereto, a tip part having a jacket cone surface tapering in the direction towards the nail tip.
Known fastening nails of this type, whose structure is specified for example in DE-PS 43 00 039, are generally manufactured by the injection molding method, in such a way that the liquified thermoplastic plastic material is injected into the injection mold proceeding from the nail head.
Due to the unavoidable sprue, a burr thereby forms on the nail head, which must either be removed by means of expensive processing, or else, if it remains on the fastening nail for economic reasons, can lead to irritation of the soft tissue surrounding the nail head. In addition, the known fastening nails made of bioresorbable plastic material leave something to be desired with regard to their holding force in the bore made in the endogenous bone before their insertion.
SUMMARY OF THE INVENTION
The invention is based on the object of developing the fastening nail according to this generic type in such a way that an improved holding force results, whereby irritations of the soft tissue due to sprue formation on the nail head are moreover preferably avoided, and the manufacturing is to be simplified. In addition, in a particular embodiment of the fastening nail an improved applicability as a gingiva pin is also to be ensured.
According to the invention, this object is achieved in that the plastic material is at least partially non-crystalline (amorphous), and has a glass transition temperature in the region of body temperature, and in that the plastic material in the region of the nail shaft comprises a preferred molecular orientation that runs essentially parallel to the longitudinal axis of the fastening nail.
It can thereby be provided that the plastic material consists essentially of a linear polymer whose chain molecules in the region of the nail shaft run at least predominantly parallel to the longitudinal axis.
The invention also proposes that the plastic material is biologically decomposable.
In addition, it can be provided that the plastic material consists of a thermoplast.
In addition, the invention provides that the thermoplast comprises at least one polyester from the family of the poly-.alpha.-hydroxyl acids, such as polytrimethylene carbonate, polydioxone, polyglycolide, polylactide, poly(L-lactide-co-glycolide) together with other copolymers, polyorthoester and/or polycaprolactone (polyhydroxybuterate and polyhydroxybuterate-co-hydroxy valerate).
In addition, it can be provided that the glass transition temperature of the plastic material is approximately 37.degree. C.
In addition, it can be provided that the plastic material contains bone replacement material.
The invention also proposes that the plastic material and/or the bone replacement material is/are mixed with growth factors.
It can thereby be provided that the plastic material is injected proceeding from the nail tip.
The invention also proposes that the cylinder projection is formed by the injection molding projection.
In addition, it can be provided that the tip part, connected to the sloped surface towards the nail tip, is provided with a cylinder projection.
In addition, the invention provides that the holder part is provided with an external threading at least over a part of its axial extension.
In addition, it can be provided that the holder part is provided at least over a part of its axial extension with at least one longitudinal slot, open towards the nail tip, and that the tip part is provided with at least one such slot, open towards the nail tip.
In addition, it can be provided that the jacket surfa
REFERENCES:
patent: 4898186 (1990-02-01), Ikada et al.
patent: 5492452 (1996-02-01), Kirsch et al.
Hutmacher Dietmar
Kirsch Axel
Axel Kirsch
Buiz Michael
Reip David O.
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