Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1985-10-24
1990-02-27
Apley, Richard J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
A61F 230
Patent
active
049042645
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an artificial joint system for cement-free implantation, the system including an implant and a clamping device and is suitable, for example, for artificial hip joints, artificial knee joints and artificial elbow joints. This invention covers, in particular, those joint systems which include an intermediate member (bone shaft member) extending in the direction of the bone shaft and supporting a joint head associated with a joint socket and a clamping device with which the intermediate member can be pressed to the bone in the resection plane. The clamping device is understood to also include, in particular, a shaft extending in the longitudinal direction of the long bone and being placeable into a bore of the long bone, the shaft having a head section provided with a threaded bore extending perpendicularly to the resection plane into which bore the intermediate member is screwed. The invention further relates to a method for implanting such a joint system.
2. Background of the Art
It is known that numerous structures of different design are used as artificial joint prostheses. For example, German Pat. No. 2,854,334 discloses a femur-hip joint endoprosthesis which, particularly in the head section of the shaft, has a fill bore into which the spongy tissue can be inserted so as to reach the exterior of the shaft through perforations and thus assure secure growth around the endoprosthesis. In this shaft prosthesis, as well as in the other prior art shaft prostheses with and without collar, there is a greater or lesser amount of unphysiological introduction of force into the long bone, either due to unphysiological radial stresses in the shaft prostheses or due to changes in longitudinal stresses in the long bone, for example, as a result of pretension. Moreover, the prior art clamping systems result in unphysiological introductions of force at the side of the long bone opposite the resection plane and thus result in fault-inducing stresses on the bone. In all prior art artificial joint systems, this results in limited durability which, on the average, today lies between five and ten years.
SUMMARY OF THE INVENTION
It is the object of the invention to provide an artificial joint system and a method for implanting it, as well as a surgical instrument with which the natural flow of forces in the long bone can be completely restored after healing. In particular, a durable and life-long bond or anchorage, respectively, of the artificial joint system with the natural bone is to be assured to thus prevent or completely avoid repetitive surgery in connection with implantations.
This is accomplished in that the clamping device and particularly the shaft are wholly or partially resorbable and the bone's resection plane joins specifically the contact portion of the implant or of the intermediate member have a surface which enhances growth into the bone. An implant including an intermediate member is preferably inserted in such a manner that, in the resection plane, the implant rests medially on the cortex under pretension.
Advantageously, a combination is thus provided of a defined pretension in the implant in the resection plane and a wholly or partially resorbable shaft or clamping system so that, after a transition period after implantation, the intermediate member or the contact member of the implant joins itself with the remainder of the bone in the resection plane and the shaft required in the long bone for the transition period is decomposed at its surface, or the clamping system of the intermediate member is decomposed to such an extent that unphysiological force transmissions through the shaft of the implant or through the clamping system into the bone are no longer possible. Advantageously, this artificial joint system can be used for all long bones, i.e. for artificial hip joints, artificial knee joints, artificial elbow joints, etc. While in its first phase after surgery, pretension between the implant and the remainder of the b
REFERENCES:
patent: 4089071 (1978-05-01), Kalnberz et al.
patent: 4532660 (1985-08-01), Field
Apley Richard J.
Fried. Krupp GmbH
Isabella David J.
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