Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1996-09-18
1998-07-07
Milano, Michael J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
623 18, A61F 242
Patent
active
057762023
DESCRIPTION:
BRIEF SUMMARY
Such a joint prosthesis is disclosed in EP 0 245 846 B1. Actually such known prostheses are used for hip joints.
In contrast thereto in connection with small joints like finger joints or toe joints shaft prostheses are actually used exclusively, which are cemented into the ends of the finger and toe bones, respectively, after the old joint has been resected, the cement used being a plastics material based cement. Such cemented joint prosthesis for small joints are of comparatively low working life, since the shafts of the prosthesis members will detach from the walls of the bones.
It is thus an object of the present invention to provide a joint prosthesis of the kind described above being improved in that it is suited for use in small joints like finger joints and toe joints.
In accordance with the invention this object is solved by a joint prosthesis of the present invention.
In the bones of the hand and the foot, which are of small dimension, only, as compared to the thigh bones and pelvic bones, there is only a comparatively small usable volume of spongiosa. The inventors found out that nevertheless cementless implantation of a prosthesis member into these tube bones can be obtained, if provisions are made warranting that the different anchoring elements are located close to the hard corticalis. Thus tilting moments exerted onto the anchoring unit can be well taken up and a large free space is available for the spongiosa to form a stable spongiosa structure after regeneration. In order to allow for such an arrangement of the prosthesis member inspite of the individual bone geometries changing from one person to another, in accordance with the present invention it is suggested to form the anchoring elements at least in the end portions thereof as elastically or plastically deformable members. Thus an anchoring unit will automatically conform to a bone which is to receive a prosthesis member, it being understood, that large dimensional differences are taken account of by providing anchoring units of different size, as is customary in connection with prostheses.
The further improvement of the invention provides for long flectional portions of the anchoring elements and independence of the deformations the anchoring elements undergo in conforming to the respective geometry of the bone.
In accordance with the present invention the stiffness of the anchoring elements may be increased in the immediate neighbourhood of the mounting plate and additional anchoring surfaces defined between the spongiosa and the anchoring unit may be provided in that space, where the spongiosa filled volume of the bone has still noticeable dimensions.
In a joint prosthesis of the present invention the anchoring unit has a particularly simple geometry. The anchoring unit can thus be produced at particularly low cost.
In connection therewith the further improvement of the invention results in the fact that the contact surfaces, through which the anchoring unit and the spongiosa material locally cooperate, are comparatively small. Thus a local stimulation of the spongiosa is obtained, which is advantageous in good blood circulation and continuous good regeneration.
The further improvement of the invention is also advantageous in view of good geometric adjustment of the anchoring unit to the actual bone geometry.
If a joint prosthesis is formed in accordance with the present invention, there is a large number of small contact surfaces between the anchoring unit and the spongiosa material, which is advantageous in view of good anchoring and good dynamic regeneration of the spongiosa.
In this connection the further improvement of the invention is advantageous in view of ease of production of the casting molds for producing the anchoring units and in view of ease of insertion of the anchoring unit into the emptied end portion of the bone.
The further improvement of the invention warrants homogeneous transfer of forces into the different portions of the spongiosa material. In addition the various secondary anchoring elements also form a ca
REFERENCES:
patent: Re34632 (1994-06-01), Berggren et al.
patent: 3899796 (1975-08-01), Bahler et al.
patent: 4064568 (1977-12-01), Grundei et al.
patent: 4156296 (1979-05-01), Johnson
patent: 4204284 (1980-05-01), Koeneman
patent: 4375703 (1983-03-01), Evans
patent: 4725280 (1988-02-01), Laure
patent: 4936859 (1990-06-01), Morscher et al.
patent: 4955916 (1990-09-01), Carignan
patent: 5002579 (1991-03-01), Copf
patent: 5032129 (1991-07-01), Kurze
patent: 5047059 (1991-09-01), Saffar
patent: 5061288 (1991-10-01), Berggren et al.
patent: 5147386 (1992-09-01), Carignan et al.
patent: 5314486 (1994-05-01), Zang et al.
patent: 5534033 (1996-07-01), Simpson
patent: 5549681 (1996-08-01), Segmuller
Copf Franz
Herman Srecko
Reill Peter
Rentsch Gunter
LandOfFree
Joint prosthesis does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Joint prosthesis, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Joint prosthesis will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1200673