Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Patent
1995-09-26
1998-03-03
Milano, Michael J.
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
A61F 238
Patent
active
057230153
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns an elbow prosthesis for implantation in destroyed elbow joints, with an ulnar component and a humeral component in tissue-compatible material, wherein the head of the ulnar component is designed in a bifurcated form with two horns, wherein the head of the humeral component comprises a rotatable, replaceable spool or spindle of a tissue-compatible and strong plastic material between two projecting flanges and wherein the joint component of the prosthesis is formed by the head of the ulnar component being arranged to engage with the rotatable spindle of the humeral component.
2. Description of Related Art
A large number of elbow prostheses are known in the literature and the art EP-0098 466 shows an elbow prosthesis wherein a fixed spindle on the humeral component engages with a substantially cylindrical sliding piece in a cut-out on the spindle and wherein the sliding piece is anchored on a shaft which is attached to the ulnar component. The sliding piece is thereby rotatably mounted in the fixed spindle and is locked to it by means of a sleeve which has a C-shaped cross section and which is pushed over the spindle.
Furthermore EP-A-0 057 793 shows an elbow prosthesis of a similar kind with a spindle-like element on the humeral component and a bifurcated element on the ulnar component. The object is to achieve an optimum joining of the joint components and ensure stability, low loading and mobility with a minimum removal of bone tissue.
SUMMARY OF THE INVENTION
The basis for the present application is NO patent application no. 76 3136 which was submitted on 14, Sep. 1976 by one of the present inventors and shelved on 4. Nov. 1977 without having been made generally available. In this an elbow prosthesis is shown with a rotatable spindle or spool which engages with a bifurcated section of the second prosthesis component and wherein the prosthesis components are attached in the usual way to the medullary cavities in those bones which are to be connected, i.e. the humerus and the ulna. This prosthesis has later become known in practice and it will be referred to here in its entirety as an example of the state of the art which forms the basis of the present invention.
The known prosthesis consists of several sizes of humeral components and several sizes of ulnar components with a common joint component, thus enabling for each patient the selection of the component size which is best suited to the individual bones. The joint connection is free and this prosthesis is therefore dependent on good ligaments and muscle tendons in order to keep the joint in place. If the ligaments are not adequate, e.g. due to fracture and injury, the prosthesis will be able to come out of joint.
Thus the object of the present application is to modify the known prosthesis in such a way that the free joint connection can be blocked and convened to a so-called "semi-constrained" prosthesis which can also be used where the ligaments are not adequate and there is a risk of the prosthesis coming out of joint.
This object is achieved with an elbow prosthesis according to the present invention, characterized in that in each of the horns on the ulnar component there is provided a groove which terminates in a respective blind hole on each horn, the blind holes being approximately diametrically opposite each other in relation to the ulnar component's joint centre, that the elbow prosthesis contains a C-ring-like clip ganged to connect the heads of the ulnar component and the humeral component while maintaining the desired degree of freedom of movement for the elbow joint and a predetermined tolerance of movement, and that the clip embraces the spindle on the humeral component with a clearance between the arc of the clip and the spindle and is locked to the ulnar component, the ends of the clip being inserted into the grooves on the horn of the ulnar component and engaging with the blind holes. Further features and advantages of the elbow prosthesis according to the
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patent: 3760427 (1973-09-01), Schultz
patent: 3795922 (1974-03-01), Herbert
patent: 3816854 (1974-06-01), Schlein
patent: 3934272 (1976-01-01), Wearne
patent: 4059854 (1977-11-01), Laure
patent: 4383337 (1983-05-01), Volz
patent: 4538306 (1985-09-01), Dorre
patent: 4923472 (1990-05-01), Ugolini
patent: 5314484 (1994-05-01), Huene
patent: 5370701 (1994-12-01), Finn
Johnsen Knut
Risung Finn
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