Molnlycke Health Care AB v Wake Forest University & Anor

This is a patent revocation action in which the claimant (“Mölnlycke”) seeks revocation of European Patent (UK) No. 0 620 720 B2 (“the Patent”) in the name of the defendants (collectively “Wake Forest”).

The Patent has a priority date of 14 November 1991 and is entitled “Apparatus for treating tissue damage”. The invention it describes relates generally to wound healing and, more specifically, to apparatus for treating wounds that are unlikely to heal completely using conventional methods. The invention has found practical application in a commercial embodiment known as the V.A.C. System. There is no doubt that this has been enormously successful and made a significant contribution to patient care. It is used for treating serious open wounds involving substantial tissue loss, such as diabetic leg ulcers and gun shot wounds which, before the invention, were in many cases very difficult to heal. The V.A.C. System has now been used on more than three million patients.

The action has come on for trial in unusual circumstances, as I shall explain. But first I mustprovide a little background. Mölnlycke commenced these proceedings on 14 March 2008. It did not give details of any proposed product, so there is no counterclaim for infringement.

In December 2008, Smith & Nephew announced the launch of a new product which Wake Forest believed fell within the scope of the Patent. It therefore launched infringement proceedings on 15 December 2008 and applied for an interim injunction. The application was heard and an interim injunction was granted by Lewison J on 13 January 2009. He directed the trial of the action be expedited and a trial date was fixed for March 2009.

Smith & Nephew alleged invalidity of the Patent on one ground only, namely that the Patent was invalid for lack of novelty or obviousness in the light of an article entitled “Variant of External Vacuum Aspiration in the Treatment of Purulent Diseases of Soft Tissues” published in 1986 in Current Problems in Modern Clinical Surgery by Chuvasia State University, USSR (“Bagautdinov”) and which had not at that time been cited in these proceedings by Mölnlycke. It was at least partly upon that basis that Lewison J made the directions that he did, so allowing the two actions to proceed in parallel rather than ordering the Smith & Nephew proceedings to be tried at the same time as these proceedings which had, by that time, had their trial date fixed for July 2009.

Mölnlycke did not in fact become aware of Bagautdinov until late 2008 and on 24 February 2009, it applied to amend its Grounds of Invalidity so as to plead it as an additional citation which rendered the Patent invalid for lack of novelty or obviousness.

By two applications dated 18 and 19 February 2009, Wake Forest applied first, for directions in the light of Mölnlycke’s request to amend to plead Bagautdinov and second, for permission to make a conditional application to amend the Patent in the light of Bagautdinov.

All of those applications were dealt with at a joint case management conference between Wake Forest, Smith & Nephew and Mölnlycke which came before me on 26 February 2009. I recognised it was plainly desirable for the actions to be tried together but declined to make an order to that effect essentially for two reasons: first, Smith & Nephew was subject to an injunction and strongly resisted any delay in the hearing of its trial. Second, Mölnlycke had so arranged its affairs as to be ready for a trial in July 2009 and, relying as it was not just upon Bagautdinov but a number of other pieces of art, made clear it was simply not going to be ready for a trial in March 2009. I also granted Wake Forest permission to issue and serve a conditional application to amend the Patent in the light of Bagautdinov and directed that any objections by either Smith & Nephew or Mölnlycke were to be served by 12 March 2009. That amendment application was made in the Smith & Nephew action only. Mölnlycke did not file a Statement of Objections, having taken the view that if the Patent was invalid in the light of Bagautdinov then the proposed amendment could not save it.

The trial of the Smith & Nephew action took place over three days at the end of March 2009 before Mr Roger Wyand QC sitting as a deputy High Court judge. Expert evidence was adduced from a Dr Orgill for Wake Forest and a Dr Gordon for Smith & Nephew. The deputy judge gave judgment on 1 May 2009. He found that claim 1 and certain dependent claims of the Patent were anticipated by or obvious in the light of Bagautdinov; claims 4, 16 and 19 of the Patent were valid; and that Smith & Nephew’s device infringed those valid claims.

After judgment, Wake Forest applied to amend claim 1 in the manner set out in the Bagautdinov amendment application. Essentially that amendment involved the addition of the words “by increasing the rate of formation of granulation tissue”. The deputy judge held that that did not amount to a material limitation of the claim and therefore did not save claim 1 from a finding of invalidity.

Smith & Nephew accepted the findings of infringement but appealed against the finding that claims 4, 16 and 19 of the Patent were valid. Wake Forest contended by its cross-appeal that all the claims were valid.

In summary, therefore, following the trial of the Smith & Nephew action, the only claims of the Patent found to be valid and infringed were original claims 4, 16 and 19. The injunction was continued and accordingly the appeal was expedited. It was heard on 9 July 2009.

On 13 July 2009, I asked the parties to appear before me and canvassed with them the possibility of inviting the Court of Appeal to consider whether, if the court had reached a concluded view on the appeal, it would be prepared to give its decision, if not its reasons, in advance of the commencement of this trial. On 14 July 2009, and no doubt in the hope it would avoid the need for this trial, the Court of Appeal notified the parties to the Smith & Nephew proceedings that it had decided to announce its decision, with written reasons to follow. That same day the Court of Appeal announced its decision that the Patent was wholly invalid over Bagautdinov and adjourned all other outstanding matters for further argument to a date to be fixed.

On 15 July 2009, at the commencement of the trial, Wake Forest applied to adjourn the trial, essentially upon the basis that the Patent having been adjudged by the Court of Appeal to be invalid, to proceed with the trial would potentially involve a substantial waste of costs and judicial time. At the same time, however, Wake Forest made clear that it anticipates inviting the Court of Appeal to stay any order for revocation pending an application to the House of Lords or the Supreme Court for permission to appeal and, if permission should be granted, pending the disposal of the appeal. Mölnlycke resisted the application. It contended that it had planned its commercial activities on the assumption that the trial would proceed and determine the validity of the Patent, not just on the basis of Bagautdinov but also on the basis of the other prior art upon which it relies, and an additional attack that the protection conferred by the Patent has been extended. It also submitted that, in the light of the position taken by Wake Forest, it would not be right to proceed on the basis that a further appeal has no prospect of success. If such an appeal were to succeed, adjournment of the trial would mean a delay in the determination of the issues which arise in these proceedings potentially until sometime in 2011. That, it contended, would be most unjust. It also pointed out that the costs of and occasioned by the trial had to a very substantial extent already been incurred. The parties and the witnesses were present before me and the trial was ready to be heard. In all the circumstances, but not without some hesitation, I decided that the trial should proceed but with effective case management to ensure that it took no longer than necessary. In the event it was heard over some two and a half days.

The relevant claims of the Patent are alleged to lack novelty in the light of:

They are also alleged to be obvious over:

The Patent is said to be insufficient arising from the requirement in the claims that the device be such as to prevent overgrowth of tissue in the wound. Mölnlycke says that if this limitation adds anything to the teaching of the prior art then it is not sufficiently described for the skilled person to be able to make such a device without undue effort.

More substantively, there is also an allegation that the protection conferred by the Patent has been extended by an amendment which should not have been allowed. In related proceedings the German equivalent of the Patent has been revoked by the Bundespatentgericht upon this ground.

I also have before me a conditional application by Wake Forest to amend the Patent in two ways:

In these proceedings the parties have focused on those claims upheld by the deputy judge in the Smith & Nephew proceedings, namely claims 4, 16 and 19. The difference between claims 16 and 19 is immaterial and I need only consider the former. In addition, there is proposed claim 22 which is sought to be introduced by amendment. So overall, I have been invited to consider the validity of claims 4, 16 and proposed claim 22.

Mölnlycke called Dr Steven Thomas as its expert witness. He is a technical consultant in the field of wound dressings and wound management and has founded a medical device technical consultancy service called Medetec. He is a pharmacist by training but has worked in the field of wound management for over 30 years. His experience includes laboratory-based research, development work and clinical practice. As a result, he had a good understanding of the different types of wound dressings available at the priority date and their clinical use.

Wake Forest makes no criticism of the honesty or integrity of Dr Thomas but submits his approach to the case was steeped in hindsight. I accept that over the years Dr Thomas has had considerable experience of and exposure to the V.A.C. System and that this must inevitably have been in his mind in considering the prior art cited in this case. It also emerged that he was presented with the Patent and the prior art at the same time and, moreover, that the prior art was selected for him. In the light of these various matters I believe it is right for me to be cautious in considering Dr Thomas’ opinions as to what would or would not have been obvious to persons skilled in the art at the priority date. Nevertheless, I found Dr Thomas to be a knowledgeable and objective witness and I have found his evidence of assistance.

Wake Forest served two expert reports of a Dr Luc Téot, a clinician specialising in plastic and reconstructive surgery. In the event, and following the cross examination of Dr Thomas, Wake Forest decided not to call Dr Téot and has not sought to place any reliance upon his opinions. It did, however, agree to permit Mölnlycke to refer to certain passages of evidence in the Smith & Nephew proceedings without the need for a CEA notice on the footing that it too was able to refer to documents in those proceedings which place the passages upon which Mölnlycke seeks to rely in context and enable me to consider the appropriate weight to give to them. Accordingly, both parties have referred me to passages in the evidence in the Smith & Nephew proceedings and I have given due consideration to them all in arriving at the conclusions expressed in this judgment.

The Patent is addressed to persons likely to have a practical interest in apparatus for facilitating the healing of wounds. I therefore understand it to be addressed primarily to manufacturers and developers of such apparatus and, in particular, to a team of persons including a clinician with regular experience of treating wounds and a person such as a biomedical engineer with expertise and experience in the manufacture of wound dressings. Such a team would, in my judgment, have a good understanding of the types of wound dressings available on the market.

The common general knowledge is all that knowledge which is generally known and generally regarded as a good basis for further action by the bulk of those engaged in the art to which the invention relates: Beloit Technologies Inc v Valmet Paper Machinery Inc [1997] RPC 489 at pages 494-495. It also includes all that material in the field in which the skilled person is working which he knows exists, which he would refer to as a matter of course if he cannot remember it and which he understands is generally regarded as sufficiently reliable to use as a foundation for further work or to help understand the pleaded prior art: Raychem Corporation’s Patents [1988]RPC 31.

A good deal of the background common general knowledge was not in dispute. I begin with wounds. As Dr Thomas explained, a wound is any defect or break in the skin that results from damage or that develops as a result of the presence of an underlying medical or physiological disorder. There are many different types of wounds and they vary in size and severity. They may be acute, resulting from some sort of physical, mechanical or thermal damage or chronic, such as leg ulcers and diabetic ulcers, in which case they are often associated with some form of metabolic or physiological disorder. They may be shallow, surface wounds or deep cavity wounds. They also come in a variety of conditions, with clean wounds at one end of the spectrum and those covered with slough or necrotic or infected tissue at the other.

Wound healing was known to involve essentially four phases:

Sometimes a prolonged inflammatory phase results in the production of excess granulation tissue which rises above the surface of the surrounding area in a condition often called overgranulation or hypergranulation. Typical treatments for overgranulation in 1991 included external compression and the use of permeable dressings allowing oxygen to reach the wound.

It was well understood that optimal conditions for wound healing included keeping the wound moist with exudate but not macerated; free of clinical infection and excessive slough; free of toxic chemicals, particles or fibres; and undisturbed by avoiding frequent or unnecessary dressing changes.

It was also well understood that a good surgical dressing has to provide good absorption of blood and exudate; be sterilisable, non-toxic, non-adherent, and not shed loose material into the wound.

Moving on to more contentious issues, the evidence established that a variety of materials were known to be suitable for use as wound dressings. Gauze was applied dry, to absorb blood or exudate, or wet, soaked with a sterile solution. The two principal disadvantages of gauze were known to be that it has a tendency rapidly to adhere to the granulating surface of a wound and, in addition, new tissue may grow into the interstices within the structure of the gauze, both of which result in damage to the wound bed and pain to the patient when the gauze is removed. It was also known to suffer from the disadvantage that fibrous and other material may be lost from it into the wound and cause infection.

I am also satisfied that by 1991 various different kinds of foam were commonly used. These included Silastic foam which was presented in the form of two liquids which were mixed together immediately before introduction into the wound and was used primarily as a cavity wound dressing; Lyofoam, an early foam dressing designed for use in the treatment of shallow wounds; and Allevyn, a hydrophilic polyurethane foam bonded to a semi-permeable film which proved to be much more absorbent than Lyofoam and was regarded by many as the dressing of choice for clean, heavily exuding wounds such as leg ulcers.

These foam dressings had a number of advantages: they did not shed fibres or particles, were easily cut or shaped, helped to maintain a moist environment at the surface of the wound and were gas-permeable. I am, however, satisfied that unmodified open-cell polyurethane foam had not gained general acceptance as a dressing. All of the foams to which I have referred were modified in one way or another so as to adapt them for the particular purposes for which they were sold.

Plastic films were also commonly used as components of dressings. Typically these consisted of a thin plastic sheet made from polyurethane coated with an adhesive layer based upon an acrylic polymer. A protective layer was placed over the adhesive which was removed immediately prior to use. Some adhesive films contained medication which was generally included in the adhesive mass. One example was Ioban, a polyester film which contained iodine. Other particularly well known brands were Opsite, Tegaderm and Bioclusive.

These adhesive films varied in their permeability to air, water and water vapour. Some contained very small holes or perforations which allowed the passage of air and liquid water. Others, described as semi-permeable, allowed the passage of air and water vapour but not liquid water. Examples of dressings incorporating this type of film included Opsite and Tegaderm. These semi-permeable adhesive film dressings could be removed relatively easily and without causing significant pain to the patient.

Wound management was primarily carried out by nurses, although doctors carried ultimate responsibility. The treatment of any serious wound began with the removal of any dead tissue, a process called debridement. This might be carried out in theatre by a surgeon using a scalpel, by a nurse at the bedside or by the use of dressings and topical agents. It was also well understood that it is important to remove excessive exudate in order to avoid infection. Wounds of limited depth were often treated with a simple absorbent dressing placed over the surface, but deeper cavity wounds were normally packed with an appropriate material to eliminate the dead space where liquid can accumulate. Historically, wound cavities were packed with gauze, often with a film dressing applied over the top to prevent leakage. But by 1991, gauze was often replaced with an appropriate foam dressing. Vacuum drains were also commonly used to remove excessive exudate and pus. It was well understood that if a wound is not drained, then a number of serious problems can result, including haematomas, infection, inflammation and pain. Wounds were also encouraged to close by mechanical means. Suturing and stapling were widely practised techniques but it was understood that to close a large wound requires high tensile forces on the skin at the wound edge. As a result, there is a risk that the sutures or staples might cause further tissue degradation, exacerbating the condition.

In broad terms, the Patent describes an apparatus for facilitating the healing of a wound which comprises an open-cell polymer foam, a flexible tube which has an inlet inserted into the foam and an outlet connected to a suction pump and a sealing cover which is placed over the wound and polymer foam and adheres to the surrounding skin so as to allow the vacuum source to create and maintain a sub-atmospheric environment in and around the wound.

The specification begins with a section entitled “Field of the invention” which explains that the invention relates generally to wound healing, and more specifically to apparatus for treating wounds that are unlikely to heal completely using conventional methods.

The problem addressed by the invention is explained in the next section, “Background of the invention”. Here it is said that the treatment of open wounds that are too large spontaneously to close has been a troublesome area for many years and that what has been needed is a method of closing the wound without the localised stresses that accompany suturing while at the same time treating any infection which may be present.

The specification continues with a “Detailed Description of the Invention” which elaborates upon each of the elements of the apparatus of the invention. As for the vacuum means, paragraph [0013] says that the invention is practised using a negative pressure ranging from 1.01 to 100.3kPa (0.01 to 0.99 atmospheres) and, more preferably, using a negative pressure ranging from between 50.7 and 81.1kPa (0.5 to 0.8 atmospheres). The time period for use of the method of the invention on the wound is said preferably to be at least 12 hours, but can be from 1 to 30 days, or even longer. It is also said that the invention can be practised with the application of a substantially continuous negative pressure or using a cyclic application of pressure in alternate periods of application and non-application. The range of these periods is broad, with a ratio of duration of application period to non-application period extending from 1:10 to 10:1. A preferred pattern is said to be five minutes of pressure application followed by five minutes of relief.

The purpose of the open-cell foam is to form a screen which may be placed over the expanse of the wound to prevent its overgrowth. Paragraph [0020] explains that the size and configuration of the screen can be adjusted to fit the individual wound and that it can be formed from a variety of porous semi-rigid materials, which are sufficiently porous to allow oxygen to reach the wound and sufficiently rigid to prevent wound overgrowth. It is also said that the open-cell structure permits direct connection of the screen to the vacuum means through the flexible hose.

The nature of the sealing means is described in paragraph [0021]. It is said that if an adhesive sheet is used, it must have sufficient adhesion to remain in contact with the skin and form a seal under negative pressure. In addition, it must be sufficiently flexible to overlay the screen means and still conform to the skin around the wound. Alternatively, the sealing means may comprise a semi-rigid cup, such as an adult CPR mask with an inflatable sleeve, which protects the wound from external contact.

The description also includes observations as to the benefits the apparatus of the invention may bring and how it may be used. First, it is noted that the use of the apparatus provides tension on the tissue bordering the wound and causes accelerated tissue migration and increased formation of granulation tissue, both of which may aid the healing process. It is also observed that application of negative pressure to a wound reduces the bacterial density of the wound; an effect thought to be due either to the bacteria’s incompatibility with a negative pressure environment or the increased blood flow to the wound area.

Paragraphs [0016] and [0017] explain that the invention is suitable not just for treating deep wounds but also burns and tissue grafts. In the case of the latter, the specification elaborates that the graft may comprise a flap of tissue from an area adjacent to the wound or a section of skin which is fully detached from another skin surface and grafted onto the wound. The application of negative pressure to the wound-graft complex is said to reduce bacterial density in the complex and improve blood flow to the wound, thereby improving the attachment of the grafted tissue.

Wake Forest has helpfully broken down the features of the claims in issue in the following way:

Claim 4 (incorporating claim 1):

(1)

An apparatus for facilitating the healing of a wound,

comprising

(2)

vacuum means (11,23) for creating a negative pressure on the area of the skin including and surrounding the wound and

(3)

sealing means (12,20) operatively associated with said vacuum means for maintaining said negative pressure on said wound by contacting the skin surrounding said wound,

characterised in that

(4)

said negative pressure is between about 1.01 and 100.3 kPa (0.01 and 0.99 atmospheres) and

(5)

in that said apparatus comprises screen means (10,24) for positioning at the wound within the sealing means for preventing overgrowth of tissue at the wound

(6)

in which said screen means (10,24) comprises an open-cell polymer foam

(7)

in which said sealing means (12) includes a flexible polymer sheet overlying said screen means,

(8)

said polymer sheet having adhesive on at least a surface facing the wound to attach and seal said polymer sheet to said surrounding skin

Claim 16:

An apparatus according to any one preceding claim, in which

(9)

said vacuum means (11,23) operates cyclically to provide periods of application and non-application of suction

“Claim 22”:

An apparatus according to any one preceding claim, wherein

(10)

the size and configuration of the screen means is adjusted to fit the wound.

The claims raise a number of issues of interpretation which I shall address in turn.

(1) “apparatus for facilitating the healing of a wound”. Wake Forest contends that the Patent is concerned with the process of healing and formation of granulation tissue in open wounds involving substantial tissue damage which are too large to close spontaneously, and for apparatus to make this process work faster and better. It therefore does not include things which, for example, are merely configured to remove pus or effluent.

I am unable to accept this submission. Plainly the scope of the claim extends to apparatus which is suitable for use on large open wounds. But it also includes apparatus which is suitable for use in connection with much simpler wounds such as those associated with burns or skin grafts. Moreover, the specification explains that the application of negative pressure to a wound reduces the bacterial density of the wound. The removal of pus or exudate will also reduce bacterial levels and will therefore assist in wound closure. In my judgment this feature means what it says. The claim extends to apparatus which facilitates the healing of the wound by creating conditions which will promote wound closure and healing.

(2) “vacuum means for creating a negative pressure on the area of the skin including and surrounding said wound”. Wake Forest again contends for a narrow interpretation of this feature and maintains that what the Patent is getting at is that enough negative pressure must be applied to the area around the wound to draw the borders of the wound together, thereby fulfilling the function of sutures but without the drawbacks of using sutures on large wounds. Again, I have no doubt that the claim extends to vacuum means which will operate in that way. But it also encompasses devices for creating a negative pressure on the area of the skin surrounding partial thickness burns and skin grafts. Moreover, it is clear that in the case of embodiments comprising a flexible sheet which lies flat over the wound, the only area of skin which will experience any negative pressure will be the very edge of the wound itself.

(3) “sealing means operatively associated with said vacuum means for maintaining said negative pressure on said wound by contacting the skin surrounding the wound”. Clearly the sealing means must form a seal and maintain negative pressure throughout the contemplated period of application. But, as I have mentioned, the specification places no upper or lower limit upon that period. In my judgment the system must be suitable for maintaining negative pressure for a period sufficient to facilitate the healing of the wound. As Dr Thomas elaborated, the negative pressure range described and claimed is exceptionally wide. For example, 1.01kPa is equivalent to four inches of water, the level of suction required to suck liquid up a drinking straw from a bottle into the mouth. By contrast, 100.3kPa is equivalent to 0.99 of an atmosphere, almost a complete vacuum. Further, the period for which the negative pressure is maintained may be very short, as shown by the discussion of cyclical operation with five minutes of pressure application followed by five minutes of relief.

(5) “screen means”. Wake Forest contends that the word “screen” connotes a particular function of the foam in that it must communicate negative pressure to every part of the wound and that the claim calls for the tube and the screen to be “operatively associated” for this purpose. I disagree. The claim requires the screening means to be suitable for preventing overgrowth of tissue in the wound. It is the sealing means and the vacuum means which are operatively associated so as to maintain negative pressure on the wound.

(7) and (8) “polymer sheet having adhesive on at least a surface facing the wound to attach and seal said polymer sheet to said surrounding skin”. These features are derived from original claim 4 and limit the claim to an apparatus comprising a flexible polymer sheet and exclude the semi-rigid cup embodiment described in the specification. The polymer sheet must have an adhesive on one surface which is such as to attach and seal the sheet to the skin.

(9) “said vacuum means operates cyclically”. This creates no particular difficulties of interpretation. The vacuum means of claim 16 must be capable of operating cyclically with alternate periods of application and non application of pressure.

(10) “the size and configuration of the screen means is adjusted to fit the wound”. Wake Forest contends that the screen means must be located within the wound so that it can communicate negative pressure evenly to all parts of the wound. I am unable to accept this submission. In the case of apparatus used to facilitate the healing of burns and skin grafts, it is not possible to locate the screen means wholly within the wound. Further, this feature appears to be an attempt to introduce a method or process limitation into an apparatus claim. This is a matter to which I must return in addressing the prior art.

The House of Lords explained the test to be applied in considering an allegation of anticipation in Synthon v SmithKline Beecham [2005] UKHL 59; [2006] RPC 10. It is necessary for the party attacking a patent to show two things: first, that the prior art contains a clear description of, or clear instructions to make, something that would necessarily infringe the patent if carried out after the grant of the patent; second, that the description in the prior art is sufficiently clear and complete for it to be performed by a person skilled in the art without undue effort. In this case the dispute between the parties has been as to the first rather than the second of these requirements.

Zamierowski is acknowledged in paragraph [0005] of the Patent. It is concerned with wound dressings and treatment methods. It teaches a wound dressing which can be used either to introduce fluid into or evacuate fluid from a wound site and which is said to protect against infection and promote healing and be suitable for use in protecting and treating a variety of wounds including burns, cuts, scrapes and ulcers of various types.

Zamierowski discloses two particular embodiments of his invention. In these proceedings, Mölnlycke focuses on the second which is depicted in figures 9 and 10:

It comprises first, a cover membrane (222) which is said preferably to comprise a breathable semi-permeable material characterised by an ability to pass moisture vapours but be impervious to liquids, and a skin contact surface with an adhesive coating. The specification explains that such membrane materials were commercially available, a suitable example being Tagoderm (sic).

A tube extends under the membrane and has a distal or free end (238) which is adapted for connection to a collection device for draining and evacuating fluid from the wound site or for connection to a fluid source for introducing fluid to the wound site. In the case of active drainage the tube communicates with a suction or vacuum source which comprises a motorised pump which can be actuated at predetermined time intervals or in response to wound site conditions such as an accumulation of fluid under the membrane.

The specification also explains that the evacuation treatment steps can be timed and sequenced so as to achieve the treatment objectives. For example, treatment of a skin graft donor site may involve fluid withdrawal and drainage for about two days immediately following the skin graft operation followed by treatment steps comprising the introduction of antibiotics or growth factor solutions to the wound site. The evacuation and introduction steps can be alternated, and the intervals between such steps can be progressively increased or decreased as necessary to facilitate healing. So, for example, as the wound heals, progressively smaller amounts of fluid will ooze from it and the frequency and duration of drainage operations can be reduced and eventually discontinued.

An important feature of the second embodiment is an intermediate layer of material (250) between the wound site (212) and the cover membrane (222). It is primarily located in a chamber (246) formed between the wound and the membrane and can be made of a variety of different materials with different properties. These include hydrophilic colloid materials which tend to absorb fluids; meshes or sheets of synthetic material which are generally non-absorbent and tend to wick fluid from the wound site and yet further materials such as polyurethane foam and polyurethane mesh.

Zamierowski also explains that, in use, the membrane perimeter is pressed against the healthy skin surrounding the wound site to form a relatively liquid tight adhesive bond. Membranes can be provided in various sizes to accommodate wounds of different sizes and the user should normally select a membrane which is sufficiently large to provide ample overlap of the perimeter over the healthy skin to ensure a good bond between them.

When the membrane is secured, a chamber is formed between the wound site and the membrane contact surface and is surrounded by the membrane perimeter. If a tube is used, it communicates with the chamber and, when the dressing is used in an evacuation mode of operation, such as might be desirable for 48 hours or so after removal of a skin graft at a donor site, fluid which accumulates in the chamber is removed through the tube for collection and disposal.

I turn now to address particular features of the claims in issue and consider the submissions made by the parties in relation to them.

(1) “apparatus for facilitating the healing of a wound”. Wake Forest contends that when used in active drainage mode, Zamierowski is for draining excess fluid from the wound. It thereby facilitates healing only in the general sense of providing optimal healing conditions, not the specific sense contemplated by the Patent. This is a point I have addressed in considering the interpretation of the Patent earlier in this judgment. For the reasons I have given, I am satisfied that removing exudate to assist healing does fall within the scope of the claims of the Patent.

(2) “vacuum means for creating a negative pressure on the area of the skin including and surrounding the wound”. Wake Forest contends that Zamierowski teaches that the intermediate layer should be above the chamber and that this is achieved by having the foam overlap the wound border. In such a configuration it would be impossible to exert pressure on the wound border in the manner called for by the Patent, that is to say to provide the suture effect. Once again I believe that Wake Forest is reading far too much into the claim. It simply calls for sealing means associated with the vacuum means for maintaining negative pressure on the wound by contacting the skin surrounding the wound. That is exactly what Zamierowski does. The semi-permeable membrane has an adhesive coating which sticks to the skin and so creates a seal. In association with the vacuum means, this must maintain a negative pressure sufficient to evacuate the fluid from the wound, and so keep the wound substantially free from exudate.

(4) “said negative pressure being between about 1.01 and 100.3 kPa (0.01 and 0.99 atmospheres)”. This feature is disclosed by Zamierowski. The range is so broad that it covers virtually all pressures which could be achieved.

(5) and (6) “screen means [comprising] an open-cell polyurethane foam.” The intermediate layer, if made of polyurethane foam, is a “screen means” within the meaning of the claim. There is, however, no mention of it being open-cell. Therefore I do not believe this feature is disclosed by Zamierowski.

(7) and (8) “… a flexible polymer sheet…” Zamierowski discloses a flexible polymer sheet overlying the screen and that it has adhesive on at least the surface facing the wound to attach and seal the polymer sheet to the surrounding skin.

(9) “said vacuum means operates cyclically”. As I have mentioned, Zamierowski specifically discloses that the suction or vacuum source may comprise a motorised pump which can be actuated at predetermined time intervals or in response to wound site conditions of a particular kind. In my judgment Zamierowski does therefore disclose apparatus which can operate cyclically to provide periods of application and non application of suction as called for by claim 16.

(10) “the size and configuration of the screen means is adjusted to fit the wound”. Wake Forest says that this is not taught by Zamierowski, nor was it obvious. It continues that Zamierowski teaches the creation of a chamber which is easily maintained if the intermediate layer overlaps the edges as shown in figure 10, but which would not be possible to maintain if the foam fitted within the wound. Moreover, it says, the instruction for use of foam dressings at the priority date was that they should overlap the wound border by 2 to 3 cm or more, and it would require imagination to adjust them so as to fit inside a wound.

This again raises the issue which I have touched upon in considering the proper interpretation of the claims. The feature appears to require the person fitting the apparatus to adjust the screen to fit the wound. But of course this is an apparatus and not a method claim. So I think the skilled person would understand that the feature must mean either that the apparatus is such that the screen can be adjusted to fit a wound or, alternatively, it is of such a size that it does fit a wound. Since wounds come in all shapes and sizes, the latter would seem not to be a limitation at all because any reasonable screen is likely to fit at least somewounds. Accordingly, I believe the skilled person would consider the former is what the patentee intended. On this assumption, is the feature disclosed by Zamierowski? I think it is. One only has to look at figures 9 and 10 and the associated description to see that the intermediate layer (246) has been fitted to the wound. It is true that the intermediate layer extends beyond the wound cavity but as I have interpreted claim 22, it does not require the screen to be wholly within the wound. I consider later in this judgment whether, if I am wrong as to interpretation, this feature was obvious.

To summarise, I reject the case of anticipation. Zamierowski does not give clear directions to use feature (6), an open cell polymer foam. Wake Forest also makes the general point that Mölnlycke’s case depends upon the skilled person picking exactly the right combination of options to suit its purpose. In particular Mölnlycke has to say that the skilled person would use the dressing for drainage, select active drainage, decide to use an intermediate layer and, of all the other possibilities, select a polyurethane foam. This, it says, is far from a case of anticipation. In light of my finding in relation to feature (6), I am prepared to assume that this is so, and it is a matter to which I return in considering the allegation of obviousness.

Bagautdinov describes a method and system for the physical treatment of purulent wounds and a means to accelerate healing of the wound process.

Bagautdinov opens with a summary of the various shortcomings of known vacuum treatments. These include first, the need for the periphery of the working part of the vacuum device to correspond to the shape and dimensions of the skin defect of the wound; second, the real practical difficulties in dealing with wounds in areas of bone protrusion and physiological bends in the surface of the body; and third, the use of gauze, rubber strips and tubes as drains does not ensure uniform vacuum treatment of the entire surface of the wound.

The dressing Bagautdinov proposes to address these shortcomings comprises a “drain” of polyurethane foam adapted to the shape and size of the wound, a polyethylene film which covers the foam and the surrounding skin and a tube which passes through a hermetically sealed hole in the polyethylene and is attached to a vacuum pump which is capable of applying a vacuum of 10 to 60 mmHg.

The treatment method itself involves the following steps. It begins with surgical treatment of the purulent wound and stemming the flow of blood. The polyethylene foam drain is then placed into the wound or onto its surface. The surrounding skin is smeared with sterile vaseline or its equivalent and covered with the polyethylene film. In the case of purulent abscesses on the forearm, shoulder, shin and thigh, the polyethylene film may take the form of a sleeve which is attached at each end to the skin with plaster, and in the case of hands and feet it may form a sack which is attached to the skin with plaster proximal to the wound. The tube, hermetically sealed through a hole in the polyethylene, is connected to a vacuum pump through a collection vessel. At a vacuum of 10 to 60 mmHg the film encloses the wound along its skin boundaries, and the porous structure of the foam is said to result in the application of a uniform vacuum to the walls of the wound cavity and the elimination of exudate. The duration of the treatment session depends upon the degree of vacuum applied and ranges from 30 minutes to 2 hours after which the polyethylene film is removed and replaced with a gauze bandage. Sessions are conducted daily until the wound is cleaned. This procedure is said to take, on average, 3 to 4 days.

Bagautdinov also explains that 170 observations were carried out and yielded very good results. The polyurethane foam produced a good suction effect and after 24 hours the foam was impregnated with exudate up to ten times the weight of the foam itself. The wound was apparently cleared on average in four to five days after surgical treatment. In some patients the wounds were sutured and in all cases the wounds healed without complications. A comparative evaluation with traditional methods of treatment revealed acceleration of the healing periods and rehabilitation of the patients in all cases.

In the related Smith & Nephew proceedings, the Court of Appeal has affirmed the decision of the deputy judge that Bagautdinov discloses all of the features of claim 1 of the Patent. Nevertheless, Wake Forest invites me to come to a different conclusion and I did not understand Mölnlycke to suggest that course is not open to me, though I expressed some concern about it myself. Accordingly, I propose to express my own conclusions and will do so by addressing each of the features in issue in turn.

(1) “apparatus for facilitating the healing of a wound”. Wake Forest contends that Bagautdinov is purely for removing pus from a purulent defect and is not concerned with wounds of the kind the Patent describes or any kind of mechanism for actively promoting healing. This is an issue which again turns upon the proper interpretation of the Patent. For the reasons I have given, I am satisfied that it is not limited to apparatus which facilitates the healing of a wound in any particular kind of way and, in any event, it seems to me that the removal of pus from a wound will reduce bacterial levels and assist in wound closure in precisely the way contemplated by the Patent. Further, I do not understand the teaching of Bagautdinov to be limited to pus removal. The method and apparatus are said generally to accelerate the wound healing process.

(2) “vacuum means for creating a negative pressure on the area of the skin including and surrounding the wound”. Wake Forest contends there can be no suggestion that Bagautdinov discloses the exertion of pressure on the wound border so as to provide a suture effect. I disagree. It seems to me to be clear that the generation of a vacuum will create a negative pressure on the area of the skin including and surrounding the wound. Wake Forest also suggests it is not clear how this could be achieved with an approach using a lubricant such as vaseline between the film and the skin. But this is exactly what Bagautdinov teaches since it describes the creation of a vacuum of 10 to 60 mmHg which results in a film enclosing the wound strictly along its skin boundaries. Moreover, Bagautdinov also describes a system in which the polyethylene sleeve or sack is attached to the skin with plaster and in this case it seems to me there can be no doubt at all that the system will create the negative pressure called for by the claim.

(3) “sealing means operatively associated with said vacuum means for maintaining said negative pressure on said wound by contacting skin surrounding the wound”. This is much the same point. It is said that Bagautdinov uses a plastic sheet sitting on skin smeared in lubricant which would not maintain negative pressure. Again, I disagree. Bagautdinov expressly teaches that the vacuum may be maintained from thirty minutes to two hours. Further, and as I have said, the polyethylene sleeve may be attached to the skin with plaster.

(5)-(6) “screen means [comprising] an open-cell polyurethane foam”. Here it is said that Bagautdinov mainly discloses the use of foam to absorb pus and, moreover, does not teach the use of an open-cell foam. I am unable to accept this submission. It is clear that the foam used by Bagautdinov is an open-cell foam since it is described as having a “porous structure” and that the system achieves a “uniform vacuum treatment” of the walls of the wound.

(8) “polymer sheet having an adhesive on at least a surface facing the wound to attach and seal said polymer sheet to said surrounding skin.” On the face of it this feature is not disclosed because a lubricant such as vaseline is not an adhesive. But Mölnlycke points to the description of the sleeve and sack arrangements which are secured to the skin with plaster. This is a powerful argument but in the end I have come to the conclusion that this feature is not disclosed. I am not satisfied that the skilled person would have understood the patentee to be claiming sheets secured with sticking plaster, but this teaching undoubtedly assists the case of obviousness, as I shall explain.

(9) “ vacuum means operates cyclically.” This feature is not disclosed.

(10) “the size and configuration of the screen means is adjusted to fit the wound”. Bagautdinov expressly describes the use of foam adapted in size and shape to fit the cavity of the wound.

To summarise, Bagautdinov does not disclose feature (8) of claim 4, the use of a polymer sheet having an adhesive on the surface facing the wound, or feature (9) of claim 16, vacuum means which operates cyclically. I therefore reject the allegation of anticipation of the claims now in issue.

It is convenient to address the question of obviousness by using the structured approach explained by the Court of Appeal in Pozzoli v BDMO [2007] EWCA Civ 588; [2007] FSR 37. This involves the following steps:

I have identified the person skilled in the art and the common general knowledge earlier in this judgment. As for question (2), it is convenient to take the claims as identifying the inventive concept. The differences between Zamierowski and the claims are feature (6), the use of an open-cell polymer foam and the use of the particular combination of options necessary to produce an apparatus that would, subject to feature (6), fall within the claims.

That brings me straight to question (4), namely whether it was obvious to use an open cell polymer foam together with the particular combination of options described in Zamierowski necessary to make an apparatus falling within the claims.

As Dr Thomas explained, Zamierowski teaches two embodiments: one in which there is an intermediate layer and one in which there is not. It also teaches two ways of using the apparatus: evacuation and introduction of fluid, although both may be used. It was his view that the person skilled in the art would understand that the intermediate layer is advantageous because of the various properties it may have; for example, it may confer absorbency, a wicking or capillary action or surface contact action. It would therefore be reasonable to opt for an inert intermediate layer embodiment if there was a clinical need for it, for example to facilitate the passage of wound fluid from the entire wound surface to the end of the drain under negative pressure without becoming clogged.

Dr Thomas also expressed the view and maintained under cross examination that the person skilled in the art would be attracted to the use of a polyurethane foam because it would not be sucked into the tube when the vacuum was turned on. He also made clear that polyurethane foam would have to have an open-cell structure to permit fluid to be drawn through it. As for the use of a pump which is capable of cyclical operation, this is specifically taught by Zamierowski to permit the evacuation and introduction steps to be timed as necessary, and that the intervals may be progressively increased or decreased to facilitate healing.

Finally, Dr Thomas explained that adjusting the screen to fit within a cavity wound is something nurses would naturally do. If material was not located fully in the wound it might inhibit the flexible polymer sheet from sticking properly to the surrounding skin and might cause exudate to run up over the top of the surrounding skin, possibly causing infection and maceration.

I found the explanation and reasoning of Dr Thomas to be persuasive and it was not answered by any evidence from Wake Forest. In my judgment the claims in issue are obvious over Zamierowski.

I can begin here with question (3). The differences are that Bagautdinov does not disclose feature (8), the use of a polymer sheet having an adhesive on the surface facing the wound, or feature (9), vacuum means which operates cyclically. That brings me to the crucial question (4), whether it was obvious to take those steps. In considering this question, the following points are material.

The starting point is the clear and unambiguous teaching of Bagautdinov that his device was clinically very effective. I believe it would have been of interest to the skilled person seeking to make an improved system for treating wounds in 1991 and I had no persuasive evidence to the contrary.

Turning to the obviousness of feature (8), Wake Forest relies heavily on the teaching that the skin is smeared with sterile vaseline which, it says, is particularly suitable for Bagautdinov’s purposes because it is to be used for short periods and at low pressures. After use it has to be removed with as little pain and damage as possible. So vaseline is perfect for this application. By contrast the Patent needs and uses a much more secure arrangement comprising a polymer sheet with an adhesive on one surface. In summary, it says it was therefore not obvious to substitute a suitable adhesive film because the creation of a robust long term seal is not necessary for aspiration; the polyethylene sheet in Bagautdinov needs to be removed after a short period of time every day and vaseline facilitates this; in contrast, removing an adhesive sheet has the potential to cause unnecessary pain or damage to the skin; and finally, adhesive on the covering sheet would make it difficult to remove the sheet while leaving the foam in place in the wound.

These are serious arguments. But in my judgment they take no adequate account of the fact that Bagautdinov itself describes attaching a polyethylene sleeve or sack to the skin with plaster. This seriously undermines the notion that the skilled person would be deterred from using an adhesive sheet because of the risk of inflicting pain or damaging the skin.

Further, Dr Thomas gave a series of convincing reasons as to why it was in any event obvious for the skilled person to adopt an adhesive film when implementing Bagautdinov. Most importantly, the skilled person would immediately recognise the limitations of the polyethylene/vaseline combination. He would have considerable difficulty obtaining supplies of sterile polyethylene film but would have easy access to semi-permeable films with an adhesive coating which are stocked by virtually all hospital wards and departments that deal with wounds. Moreover, a self-adhesive film dressing is more secure than a polyethylene/vaseline combination, being less likely to slip as the patient moves about and less likely to lead to maceration of the skin surrounding the wound, a condition which can lead to the proliferation of bacteria in that local area. Finally, although Dr Thomas accepted that replacing an adhesive film dressing might be slightly more painful and might cause more trauma than the polyethylene/vaseline combination, he had earlier explained that it was known how to remove self-adhesive film dressings without causing undue pain and I did not understand him to retreat from his overall view that the use of such dressings would have been the obvious way to implement Bagautdinov, at least in the UK and the US where they were and remain readily available. Indeed, he remained “absolutely confident” the skilled person would not use vaseline and polyethylene.

Turning to feature (9), there is, as I have said, no description in Bagautdinov of a vacuum means which is capable of operating cyclically. The question therefore is whether or not it was obvious to use a pump which had such a facility. Mölnlycke says that medical vacuum pumps at the priority date, such as the Gomco pump, had cyclical functions which could be used if needed and that is enough to satisfy the claim. If such pumps were available and it was obvious to use them, then I agree.

Dr Thomas did not himself have knowledge of the Gomco pump because, as I understood him, he did not work in a hospital, but here Mölnlycke turned to the evidence given by Dr Gordon and Dr Orgill in the related Smith & Nephew proceedings. Both explained that one form of suction often used in hospitals was a bedside vacuum pump. Dr Gordon said that the Gomco was probably the most widely used pump and Dr Orgill said he used the Gomco frequently.

Dr Thomas explained that, had he been in a hospital, he would have asked which pumps were available. Further, had he found the Gomco, he would probably have used it rather than wall suction, the reason being that it is more convenient to use a pump which can be moved around. There was no effective answer to this evidence.

In the light of the foregoing I conclude it was indeed obvious to use a Gomco pump or its equivalent and this satisfies feature (9) of the claims. It also follows the claims in issue are obvious over Bagautdinov.

Johnson describes a new way of firmly fixing a skin graft in place and absorbing tissue fluids from the area of the operation and which is said to be an improvement upon the bulky and tightly fitted dressings used hitherto. The Johnson system comprises a piece of fine mesh gauze impregnated with antibiotic ointment, two layers of standard gauze dressing, a rigid suction drain and an occlusive membrane dressing which is placed over the entire assembly.

Johnson explains that the impregnated fine gauze and the two layers of standard gauze dressing are fashioned to fit over the skin graft. The impregnated gauze is applied first, followed by a dry gauze, the rigid suction drain and then the final layer of gauze. Benzoin is applied around the area and the occlusive membrane dressing is placed over the assembly. As for the occlusive membrane, Johnson explains that any of the commercially available flexible, transparent, adhesive synthetic film dressings are suitable. The drain is either connected to a self-contained suction drum or to wall suction.

Johnson suggests that his technique provides secure fixation and avoids the bulk and discomfort associated with commonly used stent dressings. The dry gauze dressing on either side of the suction drain is said to prevent occlusion of drain holes.

The essential difference between Johnson and the Patent concerns the nature of the screen means called for by features (5) and (6).

Dr Thomas suggested that the skilled person would have recognised that an open-cell polymer foam could be substituted for gauze in the apparatus. He thought that not only would it prevent occlusion of the drain holes but it would be a preferable material to use because it is more bulky and resilient than gauze and would therefore be more effective at putting pressure on the wound-graft complex, particularly in convex areas which Johnson acknowledges are difficult to dress effectively.

In the light of Dr Thomson’s cross examination, I am satisfied that this expression of opinion was given with the benefit of hindsight and with the Patent firmly in mind. As I have mentioned, Johnson teaches that the benefit of the dressing described is that it is not bulky or uncomfortable and so I do not believe the skilled person would consider it appropriate to use an open-cell polymer foam which, as Dr Thomas said, is more bulky. Moreover, the assembly described by Johnson involves the use of a series of gauze layers which are specifically adapted for their purpose. The fine mesh gauze is impregnated with antibiotic to prevent infection and the two dry gauze dressings on either side of the suction drain prevent occlusion of drain holes. Essentially the whole teaching of Johnson would have to be abandoned in order to make a device falling within the claims of the Patent. The allegation of obviousness over Johnson therefore fails.

This article is, as its title suggests, a review of established and new ways of treating incisional and cutaneous fistulae.

As Dr Thomas explained, a fistula is a channel that forms between two organs or between an organ and the skin. A problem frequently encountered in the treatment of fistulae is the leakage of effluent from the internal organ affected. The focus of Jeter is a new technique and system of treatment which involves the application of closed suction so as continuously to evacuate effluent from the wound bed. This, in conjunction with an occlusive dressing, maintains optimal tissue hydration and prevents the formation of mechanical barriers to wound healing. The authors express the belief that this new closed suction technique results in an increased rate of granulation and re-epithelialization.

The Jeter technique is carried out in the following way. First, the wound bed is irrigated thoroughly with saline. Then a moistened gauze is opened and laid across the wound bed. This is followed by the placement of a drain in the wound bed. Gauze squares, saturated with saline, are then opened and fluffed into the wound to cover the drain completely and fill the defect to skin level. A dressing and then a film are placed over the packed wound and sealed to the skin. Continuous suction is then applied.

The principal difference between Jeter and the Patent is that Jeter uses gauze and not an open-cell polymer foam as called for by features (5) and (6). Dr Thomas said in his report that it would have been obvious to the skilled person to substitute foam for the fluffed up gauze squares. Jeter teaches the use of gauze to obliterate the dead space in the wound cavity and, Dr Thomas suggested, foam is a better material to use for this purpose because it is more bulky than gauze.

In assessing this evidence I think it important to have regard to what Jeter teaches. First of all, Jeter emphasises that the new system is better than those previously used because it involves the use of a dressing that conforms to the wound bed. This conformation, combined with moist wound healing principles, is said by Jeter to be critical to fistula closure and wound contraction. Second, this is achieved by the laying across the wound bed of a moistened gauze square. Third, the authors of Jeter were clearly aware of foam since, in their introduction, they referred to the availability of a variety of management alternatives for the most serious and extensive wounds, including foam and non-adherent dressings, absorbent gels and pouching systems. Nevertheless, they chose to adopt gauze for their system.

In the course of his cross examination Dr Thomas accepted all these aspects of the teaching of Jeter. He also accepted that none of the readily available foams would be suitable and, moreover, without testing, the skilled person would not know if any foam would be an improvement.

Overall, I did not find the case of obviousness over Jeter convincing and I have again reached the conclusion that the opinions expressed by Dr Thomas were influenced by hindsight. This allegation therefore fails.

This is a very small point and it relates to feature (5) which requires the screen means to be positioned in such a way as to prevent overgrowth of tissue in the wound. Mölnlycke says that no explanation is given in the Patent as to what the expression “preventing overgrowth” means. Further, no description is provided as to how to make an apparatus which will prevent overgrowth.

Dr Thomas considered that the term “overgrowth” must mean “overgranulation”. This was known to be a problem associated with the use of oxygen impermeable membranes. As Dr Thomas explained, various ways of treating overgranulation were known and these included the application of external compression and the use of a membrane permeable to oxygen.

Paragraph [0020] of specification explains that the screen means is placed over substantially the expanse of the wound to prevent its overgrowth and that it must be sufficiently porous to allow oxygen to reach the wound, and sufficiently rigid to prevent wound overgrowth. Similarly, it is said at paragraph [0023] that the preferred embodiment of the invention shown in figure 1 comprises a substantially flat section of open cell polyester foam which is sufficiently large to cover the wound and thus prevent wound overgrowth.

At the end of the day, I did not understand this allegation to be at the forefront of Mölnlyncke’s submissions and it was really deployed as a squeeze to prevent Wake Forest from suggesting that this feature was not inherent in the cited prior art. Nevertheless, I must assess the allegation on its merits and I am satisfied it is not made out. There was no persuasive evidence before me that the skilled person would not be able to implement the teaching of the Patent without undue effort.

On 18 March 1998, the grant of the Patent was first mentioned in the Bulletin. Claim 1 specified that the negative pressure to be applied to the wound must be between about 10.1 and 100.3kPa (0.1 and 0.99 atmospheres).

The body of the specification (“the B1 specification”) stated, at page 3, line 19:

“The invention is practiced using a negative pressure ranging from 10.1 and 100.3kPa (0.01 to 0.99 atmospheres) and more preferably practiced using a negative pressure ranging between 50.7 and 81.1kPa (0.5 to 0.8 atmospheres).”

On 2 November 2006, and following opposition proceedings, the Patent was amended and a revised specification (“the B2 specification”) was published. The B2 specification differs from the B1 specification in that claim 1 now requires the negative pressure applied to the wound to be between “about 1.01 and 100.3kPa (0.01 and 0.99 atmospheres)”. The body of the specification has also been amended so as to say “the invention is practiced using a negative pressure ranging from 1.01 and 100.3kPa (0.01 to 0.99 atmospheres)”.

In these circumstances Mölnlycke says that it is perfectly clear that the protection afforded by the Patent has been extended post-grant. The scope of claim 1 has been widened so as to increase the negative pressure range of claim 1 from 10.1 to 100.3kPa to 1.01 to 100.3kPa.

The application for the Patent (“the PCT application”) was filed on 27 May 1993. It stated on page 5, lines 23-24:

“The method is preferably practiced using a negative pressure ranging from 0.01 to 0.99 atmospheres.”

The PCT application specified the same pressure range in method claims 4, 17 and 36. It also included apparatus claims but these did not include any equivalent pressure range limitations.

On 6 December 1994, the application entered the European phase. All the method claims were deleted and the original apparatus claims 37 and 38 became claims 1 and 2.

On 12 April 1996, the Examiner issued a communication informing Wake Forest that the subject-matter of claim 1 was completely anticipated by Zamierowski.

By letter dated 21 August 1996 from its patent attorneys, Messrs JY & GW Johnson, Wake Forest proposed amendments to the PCT application and recast claim 1 into conventional two part form starting from Zamierowski. The characterising portion of new claim 1 introduced two limitations, namely first, that the negative pressure be between about 0.1 and 0.99 atmospheres and second, that the apparatus must comprise screen means for positioning at the wound within the sealing means for preventing overgrowth of tissue at the wound. The letter said in terms at paragraph 10:

“The characterising portion of new claim 1 states that the negative pressure is between about 0.1 and 0.99 atmosphere and that the apparatus comprises screen means for positioning at the wound within the sealing means for preventing overgrowth of tissue at the wound.

Regarding WO-A-90/11975 (Zamierowski) this relates to a fluid connection system for wound drainage or fluid introduction. The device comprises a cover membrane which overlies a wound. The proximate end of a tube fluidically communicates with the wound through an opening in the cover membrane. The device can be operated to evacuate or introduce fluids in either an active or a passive manner. When operated in an active mode, the distal end of the tube as connected to a suction source for draining the wound or to a fluid source for introducing fluid to the wound.

Although Zamierowski does not specify a range of workable pressures, only a minimal positive or negative pressure is needed to introduce fluid into or drain fluid from a wound. Typically, fluid introduction and drainage devices operate with a pressure of about 0.08-0.10 atmospheres or less. In fact, Zamierowski discloses that the device can function in a passive mode by using gravity to effectuate the evacuation or introduction of fluid (see Zamierowski page 14, lines 5-8). Accordingly, Zamierowski does not teach or suggest the apparatus as claimed by the applicants.

In contrast to Zamierowski, the present invention relates to a device for directly promoting wound healing. The present invention works to assist wound healing by supplying a sufficient negative pressure to the wound to effect healing. The use of negative pressure provides tension on the epithelial and subcutaneous tissue at the border of the wound, thereby causing accelerated tissue migration toward the wound. Thus, it is the application of a negative pressure to the wound which directly accelerates the healing process. Indeed, the application of negative pressure to the wound which directly accelerates the healing process. Indeed, the application of negative pressure is employed to effect wound healing even during time periods when there is no liquid to be drained from the wound. Accordingly, the use of negative pressures in accordance with the claimed range of the present invention is critical to obtain the beneficial effects of the invention.”

It is apparent from this letter that Wake Forest was seeking to distinguish the claimed invention from Zamierowski upon the basis that Zamierowski disclosed a different pressure range and, moreover, that the use of negative pressure in the claimed range of the invention was critical to obtain the beneficial effects of the invention.

It seems that in the course of further prosecution, the examiner decided that the negative pressure range should be expressed in SI units. In the claims, the lower end was duly given as 10.1kPa (0.1 atmospheres) but in the description, the examiner changed the lower limit to 10.1kPa (0.01 atmospheres). Clearly there was now a mismatch because 10.1kPa is not 0.01 atmospheres but rather 0.1 atmospheres. Nevertheless, the Patent duly proceeded to grant.

Oppositions against the Patent were filed by two companies and they each relied upon Zamierowski and a number of other publications. By letter dated 13 February 2002, the Opposition Division expressed its preliminary opinion that none of the prior art documents cited by the opponents described in combination all of the features of claim 1 and, in relation to Zamierowski, that it did not indicate or suggest the use of a negative pressure within the range indicated by claim 1.

Over a year later, on 14 August 2003, Messrs Jenkins, patent attorneys, wrote to the European Patent Office drawing attention to the fact that the negative pressure range in claim 1 of the Patent did not correspond to the range originally stated in the application. They suggested this was a mistake, observing:

“The applicants filed amendments on 21.08.96 through their representatives, Messrs JY & GW Johnson, and these amendments included the change from 0.01 atmosphere to 0.1 atmosphere. Presumably this was an error. However, the Examiner did not notice this error and the application was granted without correction. Neither opponent seems to have noticed this error.”

They continued that, having regard to the changed range, the Patent was objectionable under Article 123 (2) EPC for added matter.

During the oral hearing of the opposition proceedings, Wake Forest agreed with Jenkins’ analysis and asked that the mistake be corrected under rule 88 of the Implementing Regulations. The correction was resisted by the Opponents but the Opposition Division ruled that it was allowable as an “obvious error”. The Patent was duly maintained in the form of the B2 version which is the Patent as it now stands.

Article 123(3) EPC provides that the claims of a European Patent may not be amended during opposition proceedings in such a way as to extend the protection conferred. This article is reflected in section 76(3) of the Patents Act 1977 (“the 1977 Act”). And section 72(1)(e) of the 1977 Act provides that it is a ground for revocation that the protection conferred by a patent has been extended by an amendment which should not have been allowed.

Rule 88 (since re-numbered as rule 139) reads as follows:

“Rule 88

Correction of errors in documents filed with the European Patent Office

Linguistic errors, errors of transcription and mistakes in any document filed with the European Patent Office may be corrected on request. However, if the request for such correction concerns a description, claims or drawings, the correction must be obvious in the sense that it is immediately evident that nothing else would have been intended than what is offered as the correction.”

Wake Forest contends that Mölnlycke must therefore establish three things to make good this attack on the Patent:

I am content to adopt this approach, although, as I shall explain, there is a degree of overlap between these points.

Wake Forest’s primary contention is that the correction was a proper correction under rule 88 and, as such, is strictly declaratory in nature and therefore incapable of extending the scope of protection. On the assumption that the correction was a proper correction, I agree. This is an issue which I consider below.

Wake Forest further contends there has been no substantive increase in the scope of protection in any event. It says that although, as a matter of mathematics, it might appear that a device which can produce (for example) 0.05 atmospheres of negative pressure would infringe claim 1 of the B2 version but not claim 1 of the B1 version, there is no evidence that such a device existed at the priority date.

I reject this submission. The negative pressure range has plainly been extended and that remains the case irrespective of whether or not a device existed at the priority date which operated only within the extension itself. Further, and in any event, such a device could have been made, as Zamierowski demonstrates.

Wake Forest submits that the amendment relied upon by Mölnlycke was not an amendment either under the 1977 Act or under Article 123 EPC. Indeed it was not an amendment at all. It was a correction under rule 88 and, like the 1977 Act, the EPC and the Implementing Regulations are careful to draw a distinction between an amendment and a correction.

The argument then continues as follows. First, there is a clear distinction between the framework applicable to amendments under the 1977 Act and corrections under the 1977 Act, which can be made at any time. Second, a patentee ought to be entitled to rely on an EPO decision that a correction is allowable under rule 88 (or a UK IPO decision under section 117, the equivalent provision under the 1977 Act). If it were otherwise the patentee, through no fault of his own, could find his patent declared invalid simply because the national court later disagreed with the patent office’s administrative decision. Third, unlike an amendment, anyone can request a correction to be made of a document under rule 88 or section 117. That means that if a correction were to be treated as an amendment then a patent could be revoked as a result of a correction suggested by a third party. Fourth, it therefore would be unfair if a patentee could lose his patent simply because the EPO had allowed a correction under rule 88 (especially one initiated by the party) which a national court later found should not have been allowed.

Attractively though these submissions were presented, I must reject them. In case G11/91 CELTRIX/Correction of errors [1993] EPOR 245 the Enlarged Technical Board of Appeal of the EPO held that infringement of the prohibition of extension under Article 123 is a ground for both opposition and revocation regardless of whether it results from a correction or some other amendment. It also held that a correction under rule 88 is indeed a kind of amendment. Plainly a decision of the Enlarged Technical Board is of great persuasive authority and I believe the decision in Celtrix is one I should follow absent very good reasons for not doing so. In my judgment no such reasons have been advanced by Wake Forest. Indeed, it would seem to me to be wrong in principle that a correction not properly admissible under rule 88 and which has resulted in an extension of protection should escape the prohibition contained in Article 123.

Wake Forest also contends that the correction was properly allowed under rule 88 on the basis that the correction was obvious in the sense that it was immediately evident that nothing else would have been intended than that which was offered as the correction.

Here it seems to me the analysis must begin with a consideration of what the skilled person would have derived from the B1 specification. As I have explained, claim 1 contained a lower limit to the pressure range of 10.1kPa (0.1 atmospheres). Reference to the body of the specification would have revealed the lower limit of 10.1kPa (0.01 atmospheres). These two figures are of course inconsistent with each other but one of them, the figure of 10.1kPa, is consistent with both figures in the claim. I agree with Mölnlycke that the skilled person would have simply assumed that the single parenthetical conversion in the description is an error, rather than assuming that this was the only correct figure and that the other three figures (including two in the claims) were all wrong. I certainly do not believe it would have been immediately evident that nothing else would have been intended than that which was offered as the correction.

Assuming the skilled person looked back at the PCT application he would have seen the statement that the method is preferably practised using a negative pressure range from 0.01 atmospheres and, indeed, the incorporation of that lower limit in the method claims. He would then have appreciated there were two possibilities. Either the lower limit of 0.01 atmospheres had been wrongly converted to a figure of 10.1kPa or, alternatively, the patentee had narrowed his claim in the light of the cited prior art, including Zamierowski, which was written into the description of the B1 specification. Again, it seems to me, it would not have been immediately evident that a mistake had been made.

Assuming the skilled person investigated the matter still further and looked through the file then he would have found the letter from JY & GW Johnson. At this point I believe that any uncertainty would have been resolved and he would have concluded that the patentee had deliberately limited his claim.

I conclude that the protection afforded by the Patent has been extended post-grant. The scope of claim 1 has been widened and, as each of the subsidiary claims is dependent upon claim 1, the scope of all of the claims has been widened as well. The amendment of the B1 specification was impermissible under section 76(3) of the 1977 Act and therefore the Patent falls to be revoked pursuant to section 72(1)(e) of the 1977 Act.

By an application dated 15 June 2009, Wake Forest seeks to amend the pressure range from “between about 1.01 and 100.3kPa (0.01 and 0.99 atmospheres)” to “between about 13.8 and 41.4kPa (0.14 and 0.41 atmospheres)” in an attempt to address the post-grant extension objection. It is not suggested, however, that the proposed amendment would address my other findings of invalidity and accordingly it is not strictly necessary to deal with it. Nevertheless, since I heard some, albeit not full, argument on the point, I will express my conclusions shortly.

Mölnlycke opposes this application on the basis that the proposed amendment would result in the specification disclosing additional matter contrary to sections 75 and 76 of the 1977 Act.

In European Central Bank v Document Security Systems [2008] EWCA Civ 192, the Court of Appeal approved the following summary of the relevant general principles:

“[96] The test for added matter was explained by Aldous J in Bonzel v Intervention Ltd [1991] R.P.C. 553 at 574:

“The decision as to whether there was an extension of disclosure must be made on a comparison of the two documents read through the eyes of a skilled addressee. The task of the Court is threefold:

(a)

To ascertain through the eyes of the skilled addressee what is disclosed, both explicitly and implicitly in the application.

(b)

To do the same in respect of the patent as granted.

(c)

To compare the two disclosures and decide whether any subject matter relevant to the invention has been added whether by deletion or addition.

The comparison is strict in the sense that subject matter will be added unless such matter is clearly and unambiguously disclosed in the application either explicitly or implicitly.”

[97] A number of points emerge from this formulation which have a particular bearing on the present case and merit a little elaboration. First, it requires the court to construe both the original application and specification to determine what they disclose. For this purpose the claims form part of the disclosure (s.130(3) of the Act), though clearly not everything which falls within the scope of the claims is necessarily disclosed.

[98] Second, it is the court which must carry out the exercise and it must do so through the eyes of the skilled addressee. Such a person will approach the documents with the benefit of the common general knowledge.

[99] Third, the two disclosures must be compared to see whether any subject matter relevant to the invention has been added. This comparison is a strict one. Subject matter will be added unless it is clearly and unambiguously disclosed in the application as filed.

[100] Fourth, it is appropriate to consider what has been disclosed both expressly and implicitly. Thus the addition of a reference to that which the skilled person would take for granted does not matter: DSM NV's Patent [2001] R.P.C. 25 at [195]–[202]. On the other hand, it is to be emphasised that this is not an obviousness test. A patentee is not permitted to add matter by amendment which would have been obvious to the skilled person from the application.

[101] Fifth, the issue is whether subject matter relevant to the invention has been added. In case G1/93, Advanced Semiconductor Products , the Enlarged Board of Appeal of the EPO stated (at paragraph [9] of its reasons) that the idea underlying Art. 123(2) is that that an applicant should not be allowed to improve his position by adding subject matter not disclosed in the application as filed, which would give him an unwarranted advantage and could be damaging to the legal security of third parties relying on the content of the original application. At paragraph [16] it explained that whether an added feature which limits the scope of protection is contrary to Art 123(2) must be determined from all the circumstances. If it provides a technical contribution to the subject matter of the claimed invention then it would give an unwarranted advantage to the patentee. If, on the other hand, the feature merely excludes protection for part of the subject matter of the claimed invention as covered by the application as filed, the adding of such a feature cannot reasonably be considered to give any unwarranted advantage to the applicant. Nor does it adversely affect the interests of third parties.

[102] Sixth, it is important to avoid hindsight. Care must be taken to consider the disclosure of the application through the eyes of a skilled person who has not seen the amended specification and consequently does not know what he is looking for. This is particularly important where the subject matter is said to be implicitly disclosed in the original specification.”

Here the added matter is said to be of a particular kind, namely an intermediate generalisation. This was considered by the Court of Appeal in LG Philips LCD Co Ltd v Tatung (UK) Ltd [2007] RPC 21. At paragraph [32] of his judgment, Neuberger LJ cited with approval the following explanation of what the concept means which was given by Pumfrey J in re Palmaz’s European Patents (UK) [1999] RPC 47:

“If the specification discloses distinct sub-classes of the overall concept, then it should be possible to amend down to one or other of those sub-classes, whether or not they are presented as inventively distinct in the specification before amendment. The difficulty comes when it is sought to take features which are only disclosed in a particular context and are not disclosed as having any inventive significance and introduce them into a claim deprived of that context. That is a process sometimes described as “intermediate generalisation”.

Applying all these principles in the context of the present case I believe the following points are material.

First, the proposed negative pressure range of 13.8 and 41.4kPa (0.14 and 0.41 atmospheres) is disclosed only in examples 1 to 3 of the PCT application. These all relate to studies carried out on pigs using the apparatus described by reference to figure 2. This is the semi-rigid cup embodiment – such as the CPR mask – which is now excluded from the proposed claims, limited as they are to sealing means including a flexible polymer sheet. Moreover, no particular significance is attached to the selection of this range in these examples.

Second, the teaching of the application is that the method of the invention is preferably practised using a negative pressure ranging from 0.01 to 0.99 atmospheres, and more preferably practised using a negative pressure ranging between 0.5 to 0.8 atmospheres. It is to be noted that the negative pressure range of the proposed amended claim does not overlap at all with that of the more preferred range, although it does of course lie entirely within the broader range.

Third, and considering the disclosure of the PCT application as a whole, I do not believe the skilled person would assume that the same pressure ranges are equally applicable to different embodiments. There is no express teaching in the PCT application to that effect I have no evidence to suggest that the skilled person would so understand it.

In the light of the foregoing, I conclude the proposed negative pressure range has not been clearly and unambiguously disclosed in the context of the flexible polymer sheet embodiment. Put another way, its use in that application is not directly and unambiguously derivable from the PCT application. Accordingly, and were it necessary to decide the matter, I would refuse this application to amend.

The Patent is invalid and must be revoked.