Orthopaedic Research Institute, Inc.

David A McQueen

Dustan L Hahn

Francis W Cooke

Christoph A Roth

C Douglas Pence

A hip prosthesis () having a shell (), liner (), and retainer ring () is utilized for hip arthroplasty. The liner () fits inside the shell (), which is attached to a patient's pelvis, and the retainer ring () engages a terminal liner margin () to inhibit expansion of and decrease the size of a restricted liner opening () defined by the liner margin (). By inhibiting expansion of the liner opening (), the ball () of a patient's femur () is securely held in the liner (). In one embodiment, the liner () is inhibited from rotation relative to the shell () by a plurality of protrusions () which mate with recesses () in the shell (). In that embodiment, the liner () is provided with catch lips () to hold the liner () in the shell () and a positioning flange () which operates to form a relief gap () between the shell () and the liner (). In another embodiment, the retainer ring comprises an attachment portion () and a retainer portion () with a threaded connection () between the attachment portion () and the retainer portion ().

Constrained acetabular insert for total hip arthroplasty

An orthopaedic device designed to replace an articulating surface in a joint is provided. The device has a relatively low stiffness factor and is capable of applying normal physiological load onto the underlying bone. A low stiffness factor is achieved by a relatively thin device made from materials that have a low bulk modulus of elasticity. The device is provided with curvature to minimize bending stress in the device so that the device has sufficient mechanical strength to prevent stress induced failure. A tibial component made in accordance with this invention is also provided.

Prosthesis with low stiffness factor

An orthopaedic surgical implant apparatus includes an elongated intramedullary rod assembly 10 for use in uniting a pair of bone segments wherein each of the bone segments includes a medullary cavity. The elongated intramedullary rod assembly 10 defines a central longitudinal axis when assembled and includes first and second points of attachment 26, 48, the rod assembly 10 being adapted to be positioned within the medullary cavities of the bone segments and secured to the first bond segment at the first point of attachment 26 and to the second bone segment at the second point of attachment 48. Structure 18, 52 is provided for shortening the predetermined distance between the first and second points of attachment 26, 48 of the rod assembly in the direction of the longitudinal axis after the rod assembly has been connected to the first and second bone segments so that the first and second bone segments are brought into contact with and press against one another. A method of implanting the apparatus is also disclosed.

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Wichita, KS, United States of America

David A McQueen