Plain Language of "At Least One" Does Not Require Two, Despite Disclosures in the Specification to the Contrary

In Howmedica Osteonics Corp. v. Wright Medical Technology Inc. (No. 07-1363; Sept. 2, 2008), the Federal Circuit vacates a stipulated judgment of noninfringement due to an "incorrect" claim construction by the district court.

A knee prosthesis patent described the replacement of the lower portion of the femur, including one or both of its rounded projections called condyles. A "unicondylar" prosthesis replaces one condyle; a "bicondylar" prothesis replaces both. The district court construed the term "femoral component including at least one condylar element" as requiring that both condyles in a bicondylar prosthesis meet the geometric requirements of the claim.

Because the plain language of the claim requires only one condylar element, the Federal Circuit rejects the district court's claim construction. Further none of Wright's proffered arguments showed that the term should be interpreted other than by its plain language. First, there is no requirement that every claim be limited to encompass all the advantages or purposes disclosed in the specification, which Wright argued could not be achieved by only one condyle meeting the geometric limitations. Second, although every disclosure of a bicondylar knee in the specification showed two condyles meeting the geometric requirements, this single embodiment, without more, is insufficient to limit the claim. Third, a letter between a prosecuting attorney and a patent applicant reporting on the results on an examiner interview is not part of the prosecution history and, moreover, is of "no value" to the construction of the claim. Finally, the testimony of an inventor of the patent, even if to narrow the scope of the claims and thus against the interest of the inventor, is irrelevant on the issue of claim construction.