Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1990-02-20
1992-07-28
Isabella, David
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 18, 623 66, 623901, A61F 228, A61F 230, A61F 254
Patent
active
051337568
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process for producing a bone replacement material in which natural bones are used as starting material, the soft tissues are removed from the bone, a removal of the residual organic substances is effected and the remaining osseous substance is then sintered at temperatures between 1100.degree. and 1500.degree. C.
It is known that it is possible and preferable to produce bone replacement material, which is penetrated by the tissue of the body and not rejected by this tissue, from natural bone material from which the organic substances have been removed, and the essentially unchanged matrix of which is then sintered (U.S. Pat. No. 4 314 380; EP-A 141004). In these known processes, after the mechanical removal of soft tissues, a considerable portion of the organic material is extracted from the bone material by treating the bone with a solution of hydrogen peroxide. Apart from such a treatment being troublesome and requiring precautions because of the bleaching effect of a solution of this type, the removal of the organic material from the bone matrix is not entirely successful in this way. During the subsequent incineration of the bone at elevated temperatures the remaining organic material is combusted, and volatile components can arise in such amounts that the microstructure of the bone matrix is damaged by this. It has to be taken into account here that the bone matrix gains its mechanical strength only on sintering, and before sintering the matrix shows only very poor mechanical stability.
The object of the invention is to improve a process of the abovementioned type in such a way that, while simplifying the production process, a milder treatment of the bone material and a higher degree of retention of the structure of the bone material is made possible.
In a process of the kind described in the introduction this object is achieved according to the invention by drying the bone at an elevated temperature of up to a maximum of 150.degree. C. after the removal of the soft tissues, then raising the temperature with a reduced air supply or in a reducing atmosphere to about 550.degree. C., in a following step heating the bone to a temperature of between 750.degree. and 800.degree. C. with an increased air supply, and by subsequent sintering.
Owing to the fact that the bone material, after drying under mild conditions at a maximum of 150.degree. C., is subjected to an elevated temperature with a reduced air supply or in a reducing atmosphere, pyrolysis takes place, that is to say a thermal decomposition of the organic material, which leads to a carbonization of the organic bone material with elimination of volatile constituents.
In the next step the carbon is then combusted with an increased air supply at temperatures of up to a maximum of 800.degree. C. Volatile constituents are no longer present during this pure combustion process, so that damage to the inorganic bone matrix is avoided.
The described process has the advantage that no chemical treatment of the bone whatsoever is necessary, on the contrary after the mechanical removal of the soft tissues the bone is subjected only to heat treatment which is divided up into various sections.
It can be provided that the bone is dried at an elevated temperature of up to a maximum 150.degree. C. for between 24 and 72 hours in order that the drying is carried out under conditions which are as mild as possible. Moreover it is beneficial if, during drying, the temperature is gradually increased from the ambient temperature to the maximum temperature of 150.degree. C. Gradually means here that the increase can take place continuously throughout the whole period of drying. This avoids the onset of an explosive vaporization at the boiling point of water, which could damage the bone material. Gradually increasing the temperature results in continuous vaporization of the volatile constituents throughout the whole period of drying, with no major evolution of gas occurring.
It can also be provided that the bone is treated for approximately 8 to 24
REFERENCES:
patent: 4314380 (1982-02-01), Miyata et al.
Bauer Gerd
Vizethum Freimut
Isabella David
Merck Patent Gesellschaft mit beschraenkter Haftung
Nguyen Dinh X.
LandOfFree
Process for producing a bone replacement material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing a bone replacement material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing a bone replacement material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1684839