Molnlycke Health Care AB v Wake Forest University & Anor

For anticipation, the prior art must clearly describe, or clearly instruct the skilled person to make, something that would necessarily infringe, and must be sufficiently clear and complete to be performed without undue effort. Obviousness is assessed using the structured inquiry requiring identification of the skilled person, common general knowledge, the inventive concept or properly construed claim, the differences from the prior art, and whether those differences require invention. A correction allowed under Rule 88 may constitute an amendment for the purposes of the prohibition on extending patent protection. If post-grant correction widens the claims and was not immediately evident as the only intended correction, the patent is revocable.

The claimant sought revocation of a patent for apparatus using negative pressure, an open-cell polymer foam, a sealing sheet and suction to facilitate wound healing. The patent was challenged for lack of novelty, obviousness, insufficiency and unlawful post-grant extension of protection. The defendants conditionally applied to amend the patent.

The Court considered claims 4 and 16 and proposed claim 22. It assessed prior art including Zamierowski and Bagautdinov, and considered whether a correction to the claimed pressure range was permissible under the European Patent Convention and the Patents Act 1977.

1. Construction and anticipation. The claims were construed broadly. Apparatus facilitating wound healing could include apparatus removing exudate or pus, and the claims were not confined to devices producing a suture effect. Applying the test stated in Synthon v SmithKline Beecham [2005] UKHL 59, Zamierowski did not anticipate because it did not clearly disclose open-cell polymer foam. Bagautdinov did not anticipate because it did not disclose the adhesive polymer sheet or cyclical vacuum operation.
2. Obviousness. Applying the structured approach in Pozzoli v BDMO [2007] EWCA Civ 588, claims 4, 16 and proposed claim 22 were obvious over Zamierowski. The claims were also obvious over Bagautdinov: adopting an adhesive film and using a Gomco pump or equivalent for cyclical suction would have been obvious. The allegations based on Johnson and Jeter failed because they required abandoning their essential teaching, and the proposed substitution of foam was hindsight-driven.
3. Insufficiency. The patent sufficiently taught the skilled person how to implement the screen means to prevent tissue overgrowth without undue effort.
4. Extension of scope. The change from a lower pressure limit of 10.1kPa to 1.01kPa widened the protection. Following G11/91 CELTRIX/Correction of errors [1993] EPOR 245, a correction under Rule 88 was a kind of amendment and remained subject to the prohibition in Article 123(3) EPC and section 76(3) of the Patents Act 1977. The correction was not immediately evident as the only intended correction. The skilled person would have recognised competing possibilities, including deliberate limitation during prosecution.
5. The protection conferred by the patent had therefore been extended by an impermissible amendment. The patent fell to be revoked under section 72(1)(e) of the Patents Act 1977. The proposed pressure-range amendment would, if necessary, also have been refused for added matter because the range was not clearly and unambiguously disclosed in the context of the flexible polymer-sheet embodiment.