Elbow prosthesis
AssigneeAscension Orthopedics, Inc.
InventorWilliam F. Ogilvie
Life of this patent
Estimating the term…
Abstract
Asymmetric and axisymmetric prostheses for replacement of the radial head are shown which are designed to smoothly interengage with the annular ligament of the radius and effectively allow a patient to recover normal functioning of the forearm. These prostheses have head, collar and stem sections, and the undersurface of the head which surrounds the collar provides a shoulder which is excellently gripped by the annular ligament through which the prosthesis is inserted during implantation, assuring achievement of the desired juxtaposition between the periphery of the prosthesis head and the radial notch of the ulna. In the asymmetric embodiment, shaping the head to provide a proximal surface of generally oval cross-section having an offset concave surface and a medial region of greater thickness offers particular advantages.
Claims12
An elbow prosthesis for insertion into a human elbow to replace the end portion of the radius, which prosthesis comprises
- a body having a head, a collar and a stem,
- said stem being proportioned to be received within the medullary cavity of the radius,
- said head being shaped so as to smoothly interface with the capitulum of the humerus, and
- said head having a peripheral surface which extends completely about said head, an undersurface and a concave proximal surface for contact with the capitulum, which concave surface is surrounded by a rim,
- a medial region of said head extending further in a distal direction than does a lateral region thereof so that said medial region of said head is substantially thicker than said lateral region of said head and said peripheral surface has a greater height in said medial region than in said lateral region,
- said collar being located between said undersurface and said stem and being aligned at an angle to the axis of rotation of the radius in pronation-supination movement, and
- said collar being lesser in cross-sectional dimension than said head so that said undersurface of said head circumscribes said collar providing a peripheral shoulder.
An elbow prosthesis for insertion into a human elbow to replace the end portion of the radius and to interengage with the capitulum of the humerus and the radial notch of the ulna, which prosthesis comprises
- a one-piece body having an integral head, collar and stem,
- said stem being of polygonal cross-section and being proportioned to be received within the medullary cavity of the radius,
- said head being shaped so as to smoothly interface with the capitulum of the humerus,
- said head having a peripheral surface which extends completely about said head, an undersurface that extends from said peripheral surface inward to said collar, and a concave proximal surface for contact with the capitulum, which concave surface is surrounded by a rim portion,
- said undersurface being substantially planar and aligned at an angle between about 95° and about 105° to said axis of rotation,
- a medial region of said head extending further in a distal direction than does a lateral region thereof so that said medial region of said head is substantially thicker than said lateral region of said head and said peripheral surface has a greater height in said medial region than in said lateral region,
- said collar being located between said undersurface and said stem and being aligned at an angle of between about 8° and about 22° to the axis of rotation of the radius in pronation-supination movement, and
- said collar being lesser in cross-sectional dimension than said head and being proportioned to be received within the annular ligament, so that said undersurface of said head circumscribes said collar providing a peripheral shoulder against which said annular ligament abuts.
An elbow prosthesis for insertion into a human elbow to replace the proximal end portion of the radius, which prosthesis comprises
- a one-piece body having an integral head, collar and stem,
- said stem being proportioned to be received within the medullary cavity of the radius,
- said head being shaped so as to smoothly interface with the capitulum of the humerus,
- said head having an outermost peripheral surface which extends completely about said head, an undersurface and a concave proximal surface for contact with the capitulum, which concave surface is surrounded by a rim, and
- said collar being located between said head and said stem and being lesser in cross-sectional dimension than said head with both said head and said collar being of generally circular cross-section and the radius of curvature of said collar being between about 70% and about 80% of the radius of curvature of said head, said collar being spaced from said outermost peripheral surface of said head so that said undersurface of said head circumscribes said collar providing a peripheral shoulder having the form of an annular surface region of decreasing diameter against which the annular ligament of the elbow articulates.
Dependencies are inferred from the claim text.