19 / PRNewswire-FirstCall / -- Smith & Nephew 's Advanced Wound Management division ( LSE : SN ; NYSE : SNN ) announced that the United States Patent and Trademark Office ( Patent Office ) has rejected as unpatentable three of KCI 's negative pressure wound therapy ( NPWT ) patents during re-examination of the patents at Smith & Nephew 's request . The Patent Office found that prior art showed that almost all of the re-examined claims are not patentable , including the claims that require foam .