Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1995-01-09
1997-08-19
Brittingham, Debra S.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
A61F 238
Patent
active
056583419
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a sliding tricompartmental knee prosthesis.
In a well-known manner, this type of prosthesis essentially comprises a femoral implant and a tibial implant. The invention specifically relates to a tibial implant of the type comprising a metallic socket accepting a polyethylene plate suitably shaped to receive, on sliding, the condyles of the femur.
The tibial sockets on known devices have a stabilizing and/or anchoring pin intended to be impacted in the spongy substance of the proximal extremity of the tibia. These pins are firmly attached, directly or indirectly, to the tibial socket and can have stabilizing fins acting as anti-rotatory devices.
Indirectly attached pins are usually fixed by means of screws under the tibial socket. For example, reference can be made to French Patent Nos. 9,103,595 and 9,109,247 and U.S. Pat. Nos. 4,938,769 and 4,944,757.
In each of the above referenced patents, the stabilizing and/or anchoring pin is supported against the lower face of the tibial socket, while one or more screws are inserted from the upper face of the tibial socket into corresponding fittings in the pin. In some cases, the pin can have a centering head inserted in an opening in the tibial socket. For example, see French patent 9,109,247 and U.S. Pat. No. 4,944,757.
However, it is still necessary in the previously known devices to insert the pin from the underside of the socket and then to fix it in place from above.
It is therefore evident that in all of these previously known devices that the fixing in place of the pin is performed from the underside of the tibial socket in such a way that it is necessary to firmly attach the pin to the socket before its impaction.
Given that it is the pin which determines the positioning of the socket relative to the proximal extremity of the tibia, such previously used arrangements are not rational in that they do not provide appropriate regard for the quality of the fixing of the device in the patient.
The object of the invention is to remedy these drawbacks in a simple, sure, effective and rational manner. Namely, the current invention allows for the impaction of the tibial socket in the leg of a patient prior to the introduction of an optional stabilizing and/or anchoring pin. This allows for a final fitting of the device in the patient rather than before the impaction process begins, as was previously known.
Under the current invention, a tibial socket has been conceived and developed. The tibial socket has a recess and a protuberance jutting out from a lower face of the tibial socket. The protuberance being shaped to act as a pre-anchoring pin to aid in the impaction of the tibial socket. This tibial socket also has a recess of a given shape and section such that the engagement, centering and securing of a stabilizing and/or anchoring pin can be accomplished through an upper face of the tibial socket. Furthermore, the stabilizing and/or anchoring pin optionally has fins and is capable of angular orientation within the tibial socket.
Advantageously, the protuberance jutting out from the lower face of the tibial socket has a flattened cone-shaped external surface.
To ensure that the stabilizing and/or anchoring pin can be locked securely in place, the pin has a head with a shoulder that cooperates with a counterboring in the recess in the tibial socket. Such cooperation allows for the securing of the pin taking into account its insertion from the upper face of the tibial socket. Both the head and the recess cooperating with the head are generally in circular form.
The fins on the stabilizing and/or anchoring pin ensure the rotatory stability of the tibial implant. The fins communicate with traversing slits in the recess of the tibial socket whose number and orientation correspond to the number and orientation of the fins on the pin.
According to a further aspect of the invention, the head of the stabilizing and/or anchoring pin has fittings for fixing to the recess. The fittings comprise vertical slits formed around the periphery of the head for
REFERENCES:
patent: 4822362 (1989-04-01), Walker et al.
patent: 4944757 (1990-07-01), Martinez et al.
patent: 5062852 (1991-11-01), Dorr et al.
patent: 5152797 (1992-10-01), Lockman et al.
patent: 5246459 (1993-09-01), Elias
patent: 5330535 (1994-07-01), Moser et al.
patent: 5387241 (1995-02-01), Hayes
patent: 5413605 (1995-05-01), Ashby et al.
Brittingham Debra S.
Medinov S.A.
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