Zimmer Gmbh

Kathryn J Hoffman

Albert K Chin

Milton B McColl

Diane E Caramore

A cement plug received within a bone recess is extracted by forming a bore within the plug, tapping the bore to form internal screw threads therein, engaging the threads with a pulling tool, and applying tension to the tool to extract the plug. The bore is formed through means of a rod inserted into the plug while in a fluid state and/or a drill bit having a tubular guide received therearound to maintain the bit in generally aligned condition with the bone recess and limit the depth to which the bit penetrates the plug. The degree to which the bore is tapped and engaged by the pulling tool is controlled to avoid exceeding the extent of the bore and the screw threads formed therein. One embodiment employs a self-tapping extraction rod which serves both as a tap to form the screw threads and as the pulling tool to apply tension to extract the plug. Another embodiment employs a tap which is separate from the pulling tool. In both embodiments, a sleeve received around the tap and tool serves to measure and limit the extent to which the screw threads are formed and engaged.

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Redwood City, CA, United States of America

Kathryn J Hoffman