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Court Clarifies Claim Constructions for Hip-Joint Prosthesis Patent

March 28, 2005

Decision icon Decision

Last Month at the Federal Circuit - April 2005

Judges: Rader (author), Dyk, and Prost

In Howmedica Osteonics Corp. v. Tranquil Prospects, Ltd., No. 04-1302 (Fed. Cir. Mar. 28, 2005), the Federal Circuit reversed a district court’s finding that certain claims could not be construed and were therefore indefinite and found error with other claim constructions.

Howmedica Osteonics Corporation (“Howmedica”) sought a DJ in the district court that the claims of U.S. Patent Nos. 5,222,985 (“the ‘985 patent”) and 4,636,214 (“the ‘214 patent”) were invalid. Tranquil Prospects, Ltd. (“Tranquil”) counterclaimed for patent infringement. The two patents concern the implantation of an intramedullary prosthesis, which replaces the ball of the hip joint. The patents-in-suit overcame problems of the prior art by introducing methods and an apparatus for insulation of an intramedullary prosthesis that is substantially the same size and shape of the medullary canal, as defined by the softer cortical bone or cortex.

The district court found the claims of the two patents-in-suit invalid because it found that one of ordinary skill in the art would not understand the meaning of the claim phrase “transverse section dimensions” as it applies to the medullary canal. According to the Federal Circuit, however, the record shows that one of ordinary skill in the art would readily understand from the written description that the “transverse section dimension” calls for a two-dimensional measurement because a one-dimensional linear measurement would defeat the purpose of the invention to enable a snug fit of the prosthesis in the medullary canal. The Federal Circuit also vacated a portion of the district court’s claim construction precluding stems coated with bone cement, either before or after insertion, from satisfying a “coated stem” limitation.