Apparatus for guiding a reaming instrument

Claim 1

A guide rod assembly for reaming a medullary canal of a bone and for placement of a guide rod into said medullary canal comprising: at lease one hollow reaming instrument; an elongated rod having an external surface of a substantially constant diameter along its length, said substantially constant diameter being of a size smaller than the internal diameter of said at least one hollow reaming instrument so that said rod can serve as a guide for said at least one remaining instrument; said elongated rod having a smoothly shaped distal end to facilitate movement of said elongated rod through bone material within an unreamed medullary canal of said bone during placement of said elongated rod in said canal; a retention mechanism for holding said elongated rod in a desired position in said medullary canal during retraction of a hollow reaming instrument out of said medullary canal wherein said reaming instrument is being guided by said elongated rod during said retraction; said retention mechanism including at least one member movable from a first position within said substantially constant diameter of said external surface to a second position outside said substantially constant diameter of said external surface such that said at least one member extends beyond said external surface of said elongated rod so as to come into contact with material in said bone and thereby hold said elongated rod in said desired position during retraction of said at least one reaming instrument; said retention mechanism disposed at a distil end of said elongated rod; and, a removable handle situated at a proximal end of said elongated rod such that said elongated rod may receive said at least one reaming instrument when said handle is removed.