Patent 5002580 Issued on March 26, 1991. Estimated Expiration Date: October 7, 2008. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
The bone prosthesis of the present invention comprises a first body member or stem for placement into a bone cavity, such as an intramedullary canal. The body member is configured and dimensioned so as to provide a nonuniform interference press-fit. The apparatus further comprises a second body member or broach for placement into the broach configured and dimensioned so as to prepare and removal from a bone cavity, the bone cavity so as to provide a nonuniform interference press-fit with the stem. THe apparatus further comprises a distal sleeve configured and dimensioned so as to be attached to the stem so as to centralize the stem in the bone cavity. The distal sleeve preferably is provided with an interior conical slope and an exterior conical slope on a portion thereof to aid in insertion into the canal. The stem further comprises at least one groove and preferably a plurality of grooves along its corners. These grooves are nonparallel to the longitudinal axis of the stem and do not extend over any one entire side of the stem. The stem can be provided with an area of cancellous texture which comprises substantially randomly patterned array of multiple curved-line surface unevenness, such as indentations or protrusions. The present invention also is directed to a method comprising utilization of the broach, the stem and the distal sleeve so as to provide a nonuniform press-fit between the bone prosthesis and the bone cavity while centralizing the stem in the bone cavity.