MÖLNLYCKE HEALTH CARE AB v BSN MEDICAL LIMITED

By this action, the claimants, Mölnlycke Health Care AB and Mölnlycke Health Care Limited (together “Mölnlycke”) sue the defendants BSN Medical Limited and BSN Medical GmbH (together “BSN”) for infringement of European patent (UK) No 0 855 921. BSN denies infringement and maintains that the patent is invalid for lack of novelty, obviousness and insufficiency.

The patent relates and has claims to wound dressings, and to a method of making them. Only the product claims are in issue here. The BSN products accused of infringement are part of a range marketed by them under the brand name Cutimed Siltec.

Mr Iain Purvis QC argued Mölnlycke’s case with Ms Anna Edwards-Stuart; Mr Richard Meade QC argued the case for BSN with Mr Tim Powell.

Mölnlycke called two main expert witnesses, Mr Larry Bogart and Professor Stephen Clarson.

Mr Bogart joined Scott Paper Company in 1969 to work in process development for non-woven materials. In 1988 he went to work for Scott Healthcare, to work on the development of new wound care products and in particular wound dressings. His evidence goes primarily to the validity of the patent.

Professor Clarson is a Professor in the Department of Chemical and Materials Engineering at the University of Cincinnati in Cincinnati, Ohio. He holds a doctorate in chemistry from the University of York, and is a fellow of the Royal Society of Chemistry and a Member of the American Chemical Society. He is an expert on silicon and silicone chemistry. His evidence goes primarily to the issue of infringement.

BSN called two expert witnesses, Dr Andrew Reed and Professor Joseph Gardella.

Dr Reed obtained a doctorate in the area of polymers for use in medicine and surgery from the University of Liverpool. Since then he has held a variety of posts in industry developing polymers for bio-medical applications. By the priority date he had worked at the Imperial Chemical Industries PLC/ University of Liverpool Joint Laboratory, for Millipore Corporation, Mitral Medical, Matrix Medica and Polymedica Industries. He is currently president and chief executive officer of a consultancy company based in Florida, USA.

Professor Gardella is the John and Francis Larkin Professor of Chemistry at the State University of New York. He is an expert on surface analytical chemistry, in particular spectroscopic and microscopic analysis related to the characterisation of polymers, membranes, coatings and films. He obtained a PhD in analytical chemistry from the University of Pittsburgh in 1981. His evidence relates to the experiments carried out by both parties aimed at establishing the structure of the alleged infringing products.

I came to the conclusion that in giving their oral evidence all these principal experts were doing their best to be frank with, and to assist, the court. Mr Purvis criticised Dr Reed for some of the statements in his written reports, but I did not understand him to say that this affected the value of his oral evidence. I am satisfied that Dr Reed was not setting out to mislead the court. In any case Mr Purvis’ attack was limited to very specific aspects of Dr Reed’s report, which are better dealt with in the context in which they arise.

Mölnlycke served a witness statement from Dr David Haberthür concerned with the carrying out of their x-ray tomography experiments. He was not cross-examined. In addition they called Dr Barbara Fayard and Mr Peter Löwenhielm. I gave permission, which in the end was unopposed, for these witnesses to give expert evidence about the experiments which they conducted. No real criticism was levelled at Dr Fayard’s evidence about her tomography experiments. The experiments which Mr Löwenhielm conducted were more or less abandoned by Mölnlycke, so discussion of the value of his report and oral evidence is unnecessary.

The patent in suit has a priority date of 14^th May 1996. The title of the specification of the patent is “Wound dressing and manufacturing method therefor”.

The specification begins by describing the wound dressings disclosed in a prior European Patent Specification, and a further international patent application. It explains at [0002] that the wound dressing disclosed in the prior specifications has a layer of silicone gel on the skin-facing side, and that an advantage of such a layer is that it will adhere to dry skin, but not to the surface of a wound. Such gel layers are preferably perforated to enable excess fluid from the wound to be absorbed into an absorbent body placed on top of the gel layer. The perforation is obtained by supporting the layer on a carrier that includes a pattern of holes, such as a knitted textile material or a perforated plastic film (a gel carrier). The prior art discussed in this paragraph is said also to disclose the use of an absorbent layer in combination with such a gel layer (including its carrier).

A further international patent application, number WO-93/19710 is also referred to in this introductory paragraph. It is acknowledged as describing a three-component dressing having an absorbent body on top of such a gel layer (i.e. a perforated gel layer supported on a gel carrier) and a liquid-impermeable layer on top of the absorbent body.

The specification then explains at [0003] that:

“The object of the … invention is to provide a wound dressing … whose properties are as good as or better than the properties of the aforedescribed dressing which has a simpler construction which can be produced much more cheaply ...”

The objects of the invention are said at [0004] to be achieved by having:

“a layer of absorbent foam material that includes a pattern of holes which open [on the skin-facing side], wherein the foam material is coated with a layer of hydrophobic gel which adheres to the skin, and wherein the walls of the holes in the foam material are coated with gel at those end parts of the walls which lie proximal to the wearer's skin when the dressing is used.”

The specification explains that, because the foam material is used as the gel carrier, the dressing has a simpler construction and can be produced more easily. It continues:

“Even a thin gel layer will function as a spacer layer, because it covers an end part of the hole walls and therewith prevents contact between foam material and skin, which reduces material requirements and therewith the cost of the dressing".

There is said to be an additional advantage as well:

"because of its hydrophobicity, the spacer layer will prevent spontaneous reflux of the absorbed fluid to the skin or the wound."

I have quoted extensively from [0004] because an important issue of construction, and probably the most important issue in this case, is the meaning of the expression “the walls of the holes in [the] foam material are coated with gel at those end parts of the holes that lie proximal to the wearer’s skin when the dressing is worn”. These statements in [0004] explain in general terms why the gel needs to coat the end parts of the hole walls.

Two preferred embodiments are described. In the first, which is said to be intended for wounds from which fluid is exuded only slightly or in normal quantities, the holes of the hole pattern are comprised of pores in the foam material. In the second embodiment, said to be intended for wounds that exude fluid in normal to copious quantities, the holes are created in the foam material and are through-penetrating.

Still in the general part of the description at [0008], the specification gives values for the skin and adhesion force of the dressing, measured in Newtons. At [0010] it states that the thickness of the layer of gel, in the first embodiment, is 0.1 to 1.0 mm. This figure contrasts with a thickness of the total gel layer in the specific embodiment described, including the penetration into the pores of the foam material, of 0.2-2.0mm (see [0013]).

The specification then goes on to describe the specific embodiments in more detail by reference to figures. Figures 1 and 1A which contain an exploded partial view of the structure are reproduced below:

The dressing is thus comprised of an absorbent foam material (2) which has been coated with a gel layer (3) on the skin-facing side. The specification explains:

"As illustrated schematically in Figure 1A, the gel layer 3 is disposed so that even a part of the walls of the open cells or pores 4 in the foam material that open into the gel-coated side thereof are gel coated. Because the gel layer 3 does not close, but only covers, a part of the walls in an end portion of the pores of the foam material that face the wound, excess wound fluid can be drawn into the foam material 2 and absorbed thereby. The gel layer also forms a spacing layer which prevents the foam material from coming into direct contact with the wound or skin of the wearer.”

Some of the pores may be blocked by the gel layer: the specification gives a figure of between 5 and 100% for the unblocked.

The specification explains at [0018] that, because the gel adheres to the skin surrounding the wound, the dressing will be held firmly in place, while the gel affords a sealing function and prevents maceration of the skin (softening from contact with wound exudate).

An important distinction which the specification draws at [0019] with adhesives typically used to secure dressings is that the gel layer in accordance with the invention is much softer and has better wetting ability. This is said to enable the gel to be given much lower specific adhesion. The specification explains that the gels provide a larger surface area for adhesion because they flow down into microscopic cavities and cracks in the skin more effectively than other adhesives. It is further explained in [0019] that, in contrast with conventional adhesive dressings, the dressings of the invention can be removed from the skin and re-fastened without loss of adhesiveness. Conventional adhesives do not share this ability, because a large part of the adhesive surface becomes covered with skin residues after the first removal.

The second embodiment has added perforations to allow for more copious wound exudate. This is illustrated by reference to Figures 2 and 2A which are reproduced below:

The silicone gel layer is thus shown clearly “lining” the perforations. The specification explains that the gel layer thus “extends slightly into the openings 6 and, of course, into the pores of the foam material”.

The method of manufacture is described by reference to Figure 3. A layer of uncured gel mixture is placed on a film on a conveyor. The foam material is brought down from above into contact with the gel under the influence of a roller. The laminate of adhesive film, gel and foam is then passed into an oven where the gel cures and forms a gel layer on the underside of the foam. The specification explains that the gel mixture is drawn by capillary action into the pores or holes in the foam. It explains again that the gel mixture should preferably be applied to the thickness 0.1 to 1.0 mm, but the total thickness of the gel mixture, including air and foam, will have a thickness of 0.2 to 2.0 mm.

At [0031] the specification describes a skin adherence test which produces a value for peeling force, F1. The details do not matter, but it is explained that:

“In order to obtain a functioning inventive dressing, the peeling force F1 shall be at least 0.1 N.”

Finally, at [0036] the specification explains that because of their softness, the dressing is suitable for use in combination with compression bandages.

Claim 1 is in the following form:

“(a)

A wound dressing, characterized by

(b)

a layer of absorbent foam material

(c)

which includes a pattern of holes,

(d)

wherein the holes open out in that side of the foam material that lies proximal with the wearer's skin when the dressing is worn,

(e)

and which is coated with a layer of a skin-adhering hydrophobic gel,

(f)

wherein the walls of the holes in said foam material are coated with gel at those end parts of the holes that lie proximal to the wearer's skin when the dressing is worn.”

Claim 2, which is claimed by Mölnlycke to be independently valid, is as follows:

“(a)

A wound dressing according to claim 1 characterised in that:

(b)

the hole pattern is comprised of the pores of said foam material

(c)

wherein the gel also extends partially into those open pores of the foam material that border on the gel layer

(d)

without closing all pores.”

Claim 7 and 12 are relevant to construction. Claim 7 claims a skin adhesion force greater than 0.1N. Claim 12 claims values for penetration number (a measure of hardness or softness).

There was some debate about the identity of the person skilled in the art, but in the end this turned out to be more a debate about the extent of the common general knowledge. The patent is addressed to a scientist working in the design and development of wound dressings. He or she would be likely to have a degree in Materials Science or Chemistry or a related field, and some real experience in industry. That experience would include experience of or knowledge about the use of dressings in wound management.

The skilled addressee is not a polymer chemistry expert, although he or she would have sufficient knowledge of the handling and curing of polymers to make the wound dressing described with the assistance of the teaching of the patent.

The skilled person would know about the following as part of his or her common general knowledge.

For optimum healing a wound should be kept moist with exudates, but not so saturated that the skin becomes macerated. Adherence of the dressing to the wound bed, as opposed to the surrounding skin was known to undesirable.

There was a wide range of dressings and dressing materials available at the priority date and of which the skilled person would have been aware. The dressing chosen by the carer from amongst these different materials depended on the particular application (chronic wound, burn, skin graft etc), the degree to which the wound releases exudates, and the stage of wound healing.

Polyurethane foam was known as a useful component of wound dressings. It could be used alone, or with an added adhesive layer to hold it in place, and also with a semi permeable or water impermeable outer layer.

One such product was Allevyn marketed by Smith & Nephew. This was a polyurethane foam with a vapour permeable film on the back, and a mesh or net on the wound facing side. Initially it was sold in non-adhesive form, which would require a secondary fixation. Allevyn Adhesive was an adhesive variant launched shortly before the priority date. It came with a layer or border of adhesive applied to the mesh to provide adhesion to the skin.

Another such foam product was Lyofoam which has a compressed, open-cell foam for more rapid absorption.

Yet further, there was a product called Granuflex marketed by Convatec (although it went under other names). This had a thin film backing layer, a central layer of foam, and an adhesive wound facing layer. The wound facing layer was a hydrocolloid material (which formed a gel when in contact with water in the wound exudates) combined with absorptive materials such as gelatine, pectin and adhesive polymers.

Finally in this category (although not strictly a foam product) was MitraFlex (also called SpyroSorb) marketed by Polymedica. Dr Reed played a role in the design of this product. Mitraflex consisted of a film backing layer which was moisture vapour permeable but liquid impervious, a central layer of polyurethane microporous membrane which was hydrophilic, and a wound facing adhesive layer of porous pressure sensitive adhesive.

In addition to these composite three-layered dressings, there were stand-alone wound contact layers available at the priority date. These were designed to be used with separate absorbent material which could be changed periodically when saturated without disturbing the wound contact layer. An example of such a product was Mölnlycke’s Mepitel, which could be used in combination with a gauze and tape. It consisted of a fine mesh polyamide dressing encapsulated with hydrophobic silicone gel, leaving holes. This coated mesh layer is itself adhesive to the skin surrounding the wound and stays in place in use. As the gel is hydrophobic, it does not adhere to the wound. It could be easily removed from the skin and wound bed. In addition, because of the low adherency, the absorbent material could be easily removed and replaced.

Mepitel was first made commercially available in 1990. It was used predominantly for the treatment of burns, particularly for children, although it was designed and promoted for a wider range of wounds. Mölnlycke accept, correctly, that it was common general knowledge in the wound care field. Mr Bogart said it was a “niche” product, because of its limited actual application. Be that as it may, its construction and use for wound care was part of the skilled person’s common general knowledge.

Gels were used in wound dressings in the form of hydrophilic hydrogels. Mepitel was the only product on the market which used a hydrophobic gel.

Perhaps rather unhelpfully, chemists distinguish between silicon, which is the chemical element, and silicone which is a word for polymeric siloxanes, which are more complex molecules. Silicones are organic polymeric materials based on the -Si-O- repeating unit with organic side-chains. The organic side-chain groups on individual polymer molecules can themselves form covalent bonds with each other, so as to produce a cross-linked network of polymer molecules.

Silicones had been used in wound care in the form of silicone release papers designed to peel away from adhesive layers when the product is about to be applied. There were also silicone dressings. For example silicone sheets were used in specialised applications such as the management of keloid scars.

Mepitel, described above, used a silicone gel in an adhesive, wound facing layer.

There was no dispute about the correct approach to construction of a patent specification. In Kirin Amgen v TKT [2005] RPC 9 the House of Lords explained that the determination of the extent of protection only involves asking what a person skilled in the art would have understood the patentee to have used the language of the claim to mean. Guidelines to assist the court in construing the patent are summarised by the Court of Appeal in Virgin Atlantic v Premium Aircraft [2009] EWCA Civ 1062; [2010] FSR 10 at paragraph 5, approving the statement by Lewison J (as he then was) at first instance in the same case:

“[5] One might have thought there was nothing more to say on this topic after Kirin-Amgen v Hoechst Marion Roussel [2005] RPC 9. The judge accurately set out the position, save that he used the old language of Art 69 EPC rather than that of the EPC 2000, a Convention now in force. The new language omits the terms of from Art. 69. No one suggested the amendment changes the meaning. We set out what the judge said, but using the language of the EPC 2000:

[182] The task for the court is to determine what the person skilled in the art would have understood the patentee to have been using the language of the claim to mean. The principles were summarised by Jacob LJ in Mayne Pharma v Pharmacia Italia [2005] EWCA Civ 137 and refined by Pumfrey J in Halliburton v Smith International [2005] EWHC 1623 (Pat) following their general approval by the House of Lords in Kirin-Amgen v Hoechst Marion Roussel [2005] RPC 9. An abbreviated version of them is as follows:

(i)

The first overarching principle is that contained in Article 69 of the European Patent Convention;

(ii)

Article 69 says that the extent of protection is determined by the claims. It goes on to say that the description and drawings shall be used to interpret the claims. In short the claims are to be construed in context.

(iii)

It follows that the claims are to be construed purposively—the inventor's purpose being ascertained from the description and drawings.

(iv)

It further follows that the claims must not be construed as if they stood alone—the drawings and description only being used to resolve any ambiguity. Purpose is vital to the construction of claims.

(v)

When ascertaining the inventor's purpose, it must be remembered that he may have several purposes depending on the level of generality of his invention. Typically, for instance, an inventor may have one, generally more than one, specific embodiment as well as a generalised concept. But there is no presumption that the patentee necessarily intended the widest possible meaning consistent with his purpose be given to the words that he used: purpose and meaning are different.

(vi)

Thus purpose is not the be-all and end-all. One is still at the end of the day concerned with the meaning of the language used. Hence the other extreme of the Protocol—a mere guideline—is also ruled out by Article 69 itself. It is the terms of the claims which delineate the patentee's territory.

(vii)

It follows that if the patentee has included what is obviously a deliberate limitation in his claims, it must have a meaning. One cannot disregard obviously intentional elements.

(vii)

It also follows that where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context.

(vii)

It further follows that there is no general "doctrine of equivalents."

(viii)

On the other hand purposive construction can lead to the conclusion that a technically trivial or minor difference between an element of a claim and the corresponding element of the alleged infringement nonetheless falls within the meaning of the element when read purposively. This is not because there is a doctrine of equivalents: it is because that is the fair way to read the claim in context.

(ix)

Finally purposive construction leads one to eschew the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge.”

The word “coated” appears twice in claim 1, once in each of features (e) and (f). It is used to describe the physical relationship between the gel and foam. Mr Purvis submits, in my view rightly, that in the context of a product claim one is concerned with the end result, rather than the means by which the gel layer is applied. At one point it appeared that BSN would suggest that a lamination process, in which two solid flowable layers are pressed together did not result in coating. Coating, according to this argument, required the application of one material in liquid form. I think that is an incorrect approach: the skilled person would understand that what was required was that the foam and gel were in intimate contact in the product, as required by the relevant features. The product claim does not require an investigation into how that contact was achieved.

Mölnlycke contend that this term does not impart any particular degree of skin adherence. Any degree of skin adherence is useful and sufficient. The more adherent the dressing, the greater its durability. They submit that there is no reason to suppose that the patentee intended to put any particular limit on this characteristic.

BSN submit that the term implies the degree of skin adherence necessary to form a seal to prevent maceration of the skin. They rely on the passage I have quoted from [0031] in the specification. They also sought to draw a distinction between adherence, and “tack”. Dr Reed said that tack was “a very short term event, rather than adherence”.

On this issue I prefer Mölnlycke’s submissions. The skilled person would understand the specification to be teaching that gentle adherence was advantageous for ease of removal. He or she would also understand that it was not necessary for the dressing to be able to form a seal and prevent maceration solely by virtue of its own skin-adherency, but that secondary attachment means were a possibility. They would see no reason to suppose that the patentee intended the dressing to be self sufficient in this respect. I also do not think that the skilled reader would make any distinction between skin adherence and tack. The passage in the specification at [0031] is advisory: it is not purporting to set the limits of claim 1.

There is no universal definition of the term “gel”. Professor Clarson attempted a definition for the purposes of silicones which was based on the amount of unreacted silicone within the cross-linked matrix. Whilst a gel may be made by leaving unreacted precursors within the matrix, I am not persuaded that the skilled person would consider this to be a sufficient approach to determining whether something was a gel within the context of the patent. In the context of the patent the focus would be on the physical properties of the material.

In the end it was common ground that a necessary but not sufficient feature of a gel was that it was formed of a cross-linked matrix containing an extractable, unreacted liquid component.

Mölnlycke submitted that a material constructed in that way will be a gel. The liquid component will give the material (i) a degree of softness (ii) a degree of adhesion and (iii) no loss of adhesion due to skin stripping. These characteristics of a gel can be decreased by reducing the amount of the liquid component or adding further components, such as fillers or other polymeric components which do not have these gel-like characteristics. Ultimately one may reach a point where the material no longer has softness or adhesion, and can thus no longer be properly called a gel. There was, however, no basis for introducing numerical limits for softness or adherency into the claim, particularly as these were the subject of subsidiary claims.

BSN agree that it is physical characteristics which are important. They submit that in deciding whether something was gel the skilled person would have regard to the characteristics identified in the patent, and the numerical ranges given for them. As Mr Meade put it, the fact that a range is given for softness and peel strength in the subsidiary claims does not require one to abandon common sense as to what is or is not a gel for the purposes of claim 1.

In my judgment claim 1 is not concerned so much with any particular numerical limit, but with whether the material is sufficiently gel-like to perform in accordance with the invention. It must have a cross-linked structure and extractable liquid. Beyond that it is must retain sufficient softness and adhesion to adhere to the skin. Nothing more is required. If the patentee had wanted to limit the claims to particular degrees of softness and adherence to skin, he could have done so - as was done in the dependent claims.

The debate on this issue is best understood by reference to Figures 2 and 2A, which I have reproduced above. No one disputes that, as shown there, the walls of the holes are coated at their end parts as required by this feature. But what if the silicone gel layer comes up to the perimeter of the hole and stops there, without any gel actually entering the hole in the foam. Does that gel cover an “end part”?

Mölnlycke submitted that the claim certainly covered this case, and even covered a case where the gel stopped short of the holes and merely functioned as a spacer layer. BSN submitted that neither of these cases was covered, and the claim requires the gel to penetrate into the hole.

On this aspect of the case it is necessary to form a view of what the skilled person would understand the patentee to be saying about the purpose of coating the end part of the holes. Central to this is paragraph [0004], which I have quoted from extensively above. One must approach it as a skilled person, rather than by indulging in meticulous lawyerly analysis.

The patentee is saying in the first part of [0004] that his inventive dressing is not just a layer of gel coated onto foam: there is something more required. The something more is that, in addition to coating the foam material with a layer of gel, he coats the walls of the holes in the foam at their end portions. That immediately tells the skilled person that the gel goes into the holes. If a mere coating is required, the patentee would not have had to say anything more.

The sentence beginning “Even a thin gel layer will function as a spacer layer…” is not the most happily expressed. But the sense is quite plainly that a thin layer will both function as a spacer layer (preventing contact between skin and foam) and reduce the amount of material and cost, because the gel covers the end part of the hole walls. One can easily visualise how material is saved: penetration into the pores in the foam gives a greater effective thickness for the gel layer, compared with a layer which does not penetrate. The numbers for thickness elsewhere in the patent support this as well. The skilled person would also understand that the regions where the gel penetrates the foam are themselves effective at preventing the foam from coming into contact with the wound. Mr Bogart was very clear about this:

Q. A further issue, Mr. Bogart, is that when you put these dressings on obviously you press them into contact. The healthcare provider presses them into contact?

A. Yes.

Q. And that will tend to urge the foam towards the wound.

A. Yes.

Q. And they may be held in contact by a compression bandage as we see in the patent in some instances as well.

A. Right.

Q. The foam coming into contact with the wound was understood to be a bad thing.

A. Yes.

Q. The reader of the patent would understand that you do not want the foam in contact with the wound.

A. Correct.

Q. And quite apart from pressing it into contact in the way that I have described, the exudate is a sort of gluey proteinaceous material?

A. Yes.

Q. And if the foam is too close to the wound, you can get a sort of gluey bridge formed between them?

A. That is what we are trying to avoid.

Q. Yes. You would like some physical separation of the foam from the wound?

A. Yes.

Q. And that is another reason why the silicone coating the inside walls of the pores is a good thing.

A. Yes.

The final sentence of [0004] says that the hydrophobicity of the spacer layer will prevent reflux of absorbed fluid to the wound. This would clearly be the case if the gel layer went into the holes, because the “lining” of the holes in this way would be directly in the path of any reflux of exudate. It would also in theory function in this way if the gel layer came up to very edge of the hole, provided that the gel layer was thick enough.

This latter point about reflux was illustrated by a series of forensic drawings handed up at trial. They have to be treated with caution, as they are certainly not to scale: the pores are shown rather more elongated in the vertical axis than would be true if the dimensions in the patent were observed. But they are good enough to illustrate the point. The first in the series shows the overall construction of the dressing in place on a wound, on the basis that the pores are themselves coated internally with gel:

The wound exudate flows or is pressed into the pores and into the body of foam beyond. When the wound has healed or the outflow of exudate decreases, the coating on the walls of the pores operates to prevent the reflux of exudate. The idea is to prevent contact with the wound and a process known as “bridging” whereby the refluxed exudate connects with the wound. An illustration of successful prevention of reflux is shown in the next drawing:

The above illustrations are then contrasted with a situation in which the gel layer merely extends to the edge of the pore, without going inside. In this case the exudate in the foam will be able to touch the wound, and cause bridging, which is undesirable:

I have circled the small triangles where a surface tension effect would be found. This could well be inadequate to prevent reflux and bridging. Mr Bogart said it would probably not work to prevent bridging. Of course, a thicker layer might be adequate: but that would be more wasteful of material.

Viewed in isolation, the point about reflux would be fairly neutral. No doubt reflux could be prevented with a thicker layer which did not go into the pores. However, the passage in question has to be read in the context in which it occurs. That context includes the use of a thin layer and the reduction in material quantity and cost.

BSN submit that when one comes to claim 1 with this teaching in mind, the skilled person would see that the claim requires more than a coating of the gel onto the foam layer, but goes on to require coating of the walls of the holes at their end parts. They submit that it would be clear to the skilled person that the gel must go inside the holes. Only in this way could the invention behave as described in [0004]. They say that, unless one construes this feature to require the gel to enter and coat the holes, these words in the claim are mere surplusage: there is already a requirement for coating.

Mr Purvis submitted that this feature of the claim was necessary because it made clear exactly where the gel layer was to go. I reject that submission. The first part of the claim has already made clear that the foam is to be coated with a skin-adhering hydrophobic gel, which makes it clear that it is on the skin-facing side. If something more explicit were necessary, it would have simply said that the gel is on the skin-facing side. There would no need for the reference to the walls of the holes or their end parts.

Mölnlycke rely heavily on the fact that claim 2 says explicitly that the gel also extends partially into the open pores without closing all the pores. This, they say, shows that, in claim 1, an arrangement is permitted in which the gel does not extend into the open pores. They find particular significance in the use of the word “also”.

The argument that a claim should be construed so as to give a separate meaning to dependent claims is a common canon of construction in patent cases. It is at its most powerful as an aid to construction when a single feature is added by the dependent claim. If this feature adds nothing to the claim from which it is dependent, one may ask why the dependent claim is there at all. Where a number of features are added by a dependent claim, the argument is less compelling: it amounts to saying that there is some surplusage in the subsidiary claim. Even then, courts have said that dependent claims may simply fail to introduce any new limitation: see the discussion in Terrell on the Law of Patents (17^th Edn.) at 9-121-122. If the argument is taken to extremes one can use the dependent claims to make a nonsense of the claims from which they depend (Footnote: ¹).

In the present case, claim 2 introduces a number of limitations clearly not present in claim 1, not least that the holes are required to be pores in the foam material, rather than perforations or any other type of hole. The word “also” is neutral: it could mean “as in claim 1”. I do not regard the claim 2 point as anything like conclusive in Mölnlycke’s favour. The true position is that the court is faced with a choice between finding surplusage in claim 1 if it accepts Mölnlycke’s submissions, or claim 2 if it accepts BSN’s.

Next Mölnlycke say that the passage in [0004] supports their position. They point to the fact that it says that a thin layer of gel functions as a spacer layer. But they do not give any weight to the fact that it is said that material is saved. Indeed, [46] of Mölnlycke’s opening skeleton omits the reference to reducing material requirements from the quotation. Mr Purvis, when pressed, said that this was simply a reflection of the fact that the layer was a thin one. I do not think that is how a skilled person would read the passage. It attributes the ability to use a thin layer to the fact that the gel covers the end part of the hole walls. Mölnlycke’s construction makes no sense of this statement. Indeed, if Mölnlycke are right about what is sought to be conveyed by the passage, it seems odd that it should refer to the end parts of the hole walls at all.

Finally, Mölnlycke submit that the skilled person would see that the hydrophobic gel layer would provide a useful effect even if it did not go into the pores. That is a submission that the two cases (walls coated and not coated) are equivalent, and that I should take that into account in construing the claim. As I hope I have explained, I accept that a thick hydrophobic gel layer would provide a useful effect even if it did not go into the pores. But the skilled person would also see that he or she is being told that the invention can be used with a thin layer because the end parts of the hole walls are coated. Although I must, and do, take account of equivalents, the two cases (walls coated and not coated) are not equivalent.

I have concluded, for the reasons advanced by BSN, that the claim requires the gel to coat the inside of the hole walls, and not merely to abut the edge of the hole. Quite apart from the general passages at [0004], the specification is replete with references to the penetration of the gel into the holes in the foam. There is everything to suggest that the patentee thought it to be an essential part of his invention, and nothing to the contrary.

A product description was supplied by BSN in respect of each of the accused Cutimed Siltec products. Each has a three layered construction: a layer of silicone on the skin-facing side, a foam layer and a waterproof backing layer. Small recesses in the distal side of the foam layer contain super-absorbent particles to assist with soaking up exudate.

The silicone layer is made from a mixture of two silicone components. One of the silicone components is a silicone gel, MED 6340. The second silicone is a silicone rubber containing about 12% of filler. The resulting product in the silicone layer was shown by Mölnlycke to have an extractable liquid silicone fluid content of about 26%

The silicone is cured on a belt with small, blunt needles on it. The silicone mixture is extruded onto a moving, heated, metal belt that has the needles extending upright from it. The perforated silicone layer supported on the heated belt moves towards a lamination station where a continuous web of the foam layer is brought into contact with it at a heated nip area between a pressing roller and the belt. The laminate of silicone layer and foam is subsequently separated from the belt.

The 5 Cutimed products in suit are Siltec, Siltec B, Siltec L, Siltec Heel and Siltec Sacrum.

Professor Gardella accepted that there was a boundary between the layers of silicone and foam where the silicone was in contact with the foam. Dr Reed also accepted that the silicone and foam were in close contact, due to the pressing of the silicone into the foam. I am satisfied that first coating requirement in the claim is present in all the Cutimed Siltec products.

Skin adherence tests carried out in corresponding Swedish proceedings on the Siltec products showed an average mean adhesive force in the range 0.07 to 0.08 Newtons. This, arguably at least, falls outside the range in claim 7 (lower limit: 0.1 N). I do not regard this as conclusive on the issue of infringement under this feature, for reasons I have given when dealing with construction.

BSN have promoted the dressings as being “gently adherent to the skin”. Dr Reed sought to explain this as aimed at nurses and carers, but I do not accept that, in the context of wound care, the manufacturer and the user would treat the term differently. The experts were not agreed as to whether the skin adherence was sufficient to create a seal and prevent maceration without the use of a secondary dressing. On the whole I accept Mr Bogart’s evidence that it would create a seal, albeit a rather temporary and unreliable one. But the dispute does not matter, because Dr Reed accepted that the seal would be made with the aid of a secondary dressing, and that in my view is sufficient.

The BSN products have this feature.

A number of experiments were done in order to seek to establish that the BSN silicone layer was a gel.

BSN performed a manual delamination experiment in which they showed that it was possible, with care, to remove the silicone layer from the foam in an example of the BSN product. The layer so removed had a few tears, but retained its form, so that, for example, the holes made by the needles retained their layout. The experiment showed that the BSN silicone layer has some of the properties of an elastomer, but does not, to my mind, establish that the material was not a gel.

BSN also performed penetrometry experiments on the material of the silicone layer. In qualitative terms these showed that BSN material is a lot harder than either of the proprietary gels used in the patent. Indeed it is harder than a prior art hot melt adhesive, Duro-Tak. The mean values were (smaller is harder):

On the construction of the term gel which I have arrived at, the hardness value cannot amount to an absolute answer to the question of whether something is a gel. The question is whether the material is sufficiently gel-like to perform as described. The most that can be said is that the hardness values are sufficiently different from the materials in the patent to make it dangerous to assume without evidence that the material will perform as described in the patent.

Mölnlycke did some atomic force microscopy experiments. These produced erratic results. Although Mr Purvis did not formally abandon them, he came about as close to doing so as it possible to go. For my part I derived no real assistance from them.

Mölnlycke also performed solvent extraction tests on the layer. These showed that the product had 26% extractable silicone liquid. BSN do not challenge this figure, but point out the absence of a positive control: one does not know what level of silicone fluid would be found in the NuSil and Wacker products referred to in the patent. In my judgment, this experiment shows that the BSN products satisfy what I have described as a necessary, but not sufficient, condition for being a gel.

Dr Reed agreed that a major component of the ultimate BSN silicone layer was a material which, on its own, would be a gel. However, he pointed out, obviously correctly, that it was the properties of the ultimate product which were important. I found the following passage of his cross-examination illuminating:

Q. …There is not much point, is there, in selecting as a major component of your ultimate silicone something which is a gel unless you want to keep some of those gel-like characteristics in the ultimate product?

A. The ultimate product is what dictates what those characteristics are, so you have to look at the ultimate product to determine what the characteristics are.

Q. The only reason for starting with a gel as one of the principal components is because you want a product to end up with some of the characteristics of a gel.

A. Then it will be counterintuitive to basically use the mystery component [i.e. the non-gel component in the BSN product] which basically has silica in it.

Q. Yes, which will make it less soft, but still not, as we have agreed, completely negate the qualities of the gel. Correct?

A. It will have qualities of both probably, yes.

Q. That, I think, is probably common ground. If the gel was not there in the recipe, and I am talking about the 6340, it would not have the gel-like characteristics that, for example, give it skin adherence. Correct?

A. It would not have the physical characteristics, the softness or the adherence.

I accept that evidence. In the light of it, given that the meaning of “gel” is heavily context dependent, it is impossible to say that the BSN silicone layer is not sufficient of a gel for the purposes of this patent. I conclude that this feature is satisfied.

Much of the evidence of the experts was directed to this issue. The two sides approached it using different experimental techniques. Mölnlycke used X-ray tomography (XRT), whereas BSN used scanning electron microscopy (SEM).

XRT is a non-destructive technique which involves using X-rays to determine the physical density of the sample throughout its bulk. It is what would be called a CAT scan if carried out for medical purposes on a human subject. The technique is able to distinguish the densities of the silicone layer, the foam and air. In addition it is possible to identify the presence of a boundary layer between two substances of different densities, i.e. that layer where the density reading has a value between the densities of the two substances.

SEM is a topographical analytical technique. It allows for the very high magnification of the surface of a sample. It does not allow examination of features below any exposed surface. SEM, as used in BSN’s experiments, involved fracturing the sample so as to expose a vertical section through the product. It was supported by other analytical techniques which identified the layers in the BSN product.

Professor Gardella reviewed the SEMs in his expert report. A typical SEM shows the silicone layer sitting on top of the foam layer, and looks like this:

Professor Gardella concluded in his report that the SEM data did not show a product in which the silicone layer had coated the walls of the pores of the underlying foam material. Although the pores in the foam are in many cases in close proximity with the silicone layer, his view was that the silicone layer does not extend into the pores, even in discrete areas.

Mr Purvis relied on an answer in which Professor Gardella gave in cross-examination that there was one image where the silicone had “run into” a pore in the foam. But Professor Gardella explained this as being a place where the silicone was in contact with the edge of the foam. I did not understand Professor Gardella to be qualifying the general view which he expressed in his report.

The XRT experiments produced images which showed the foam, the silicone layer and the contact surface. The following images show the results from one of the samples. First the whole sample including the silicone (pink) and foam (yellow), then the foam with the contact area (blue), and finally the underside of the silicone layer showing the contact area:

Dr Fayard’s conclusions from the XRT experiments were expressed in the following way. She first noted that there was a contact region, rather than a series of contact points as one might obtain if the foam were to be placed on a rigid material such as glass. Next she noted that it could be seen that in some places at the ends of the walls of the cavities in the foam material, and also where it extends down into the cavities, the silicone material was in contact with the foam. Thirdly she noted that, insofar as the silicone extends down into the cavities, it did so without completely filling the cavities.

Dr Fayard made no attempt to identify precisely where in her opinion these effects were occurring in the micrographs which she had produced. When she was asked about this in cross-examination, she said that the places where the foam descended into the cavities were “not the most representative case” and “really a few images compared to the whole” and “unusual” and she agreed that the silicone did not extend into the holes “in the great majority of cases”. She also agreed that it was typical of the materials she looked at that there was no sign of contact between the silicone and the foam inside the pores in most cases. She agreed that if there was contact between the silicone and the foam inside the pores one would see the silicone rising up on the underside view (such as that shown in the third image above). Accordingly, by the time that Mölnlycke’s case closed, there was little or nothing by way of support on the facts for the suggestion that the walls of the pores were coated with foam.

Professor Gardella gave some evidence about the XRT experiments and was cross-examined on it. The conclusions he reached in his report were subject to certain criticisms which he made about the XRT technique. However, even accepting them at face value he said that they supported the view that the end parts of the holes of the foam layer were not coated in silicone.

The cross-examination of Professor Gardella drew attention to gentle slopes on the surface of the foam where there was contact with the silicone layer. Professor Gardella agreed with the fact that these were present, but he did not accept in all cases that they were part of the walls of a pore. Even in those cases where it could be argued that the sloping surfaces were part of the walls of a pore, it was not suggested to him that these sloping surfaces were typical.

A common problem with the examination of micrographs in court is ensuring that all concerned, cross-examiner, witness, judge, and everyone else are looking at the same place on the photograph. In dealing with the micrographs in court in this case, the parties used a separate grid to indicate regions on the photographs. They are to be commended for this, although it imposes a particular burden on those carrying out the photocopying to ensure that the pages are all aligned in same way across all bundles. It worked well in the present case. An alternative is to print the photographs with a grid.

In more detail:

It is notable that Mölnlycke did not really suggest that these isolated contact points has any functional significance in the control of exudate. It was also notable that they did not press any suggestion that the holes which matter, namely those created by the perforations, had walls coated with silicone. They do not.

In my judgment the experimental evidence does not support a conclusion that feature (f) is satisfied. Mr Purvis submitted that a consideration of the way in which the BSN product was made supported a conclusion of infringement. He relied on some very general cross-examination of Dr Reed about the process of manufacture. It is true that the silicone layer is not fully cured when it is pressed into the foam. But that does not mean, and Dr Reed did not accept, that at that stage it was sufficiently flowable to coat the insides of the pores in the foam. Mr Purvis suggested that Dr Reed had already accepted that adhesion between the two layers was only achieved because the silicone layer was retained within the pores. He relied on this question and answer:

Q. The reason that there is at least some degree of adhesion sufficient to hold the dressing together is that the silicone layer has been pressed into the pores on the surface of the foam and a mechanical grip of some kind has been achieved between the layers. Correct?

A.

That is how I understand it, yes.

But the notions of “some kind of mechanical grip” and coating of the inside of the pores are not the same. Dr Reed had accepted in his first report that there might be protrusions left by the lamination process. Most importantly, none of this can substitute for the experimental evidence which shows that the walls of the pores are not coated. The most it shows, other than in isolated unrepresentative instances, is that there is contact with the undulations on the top surface of the foam.

I conclude that feature (f) is not satisfied by the BSN products, and there is no infringement.

BSN attack the validity of the patent on the grounds of lack of novelty, obviousness and insufficiency. On the former two grounds they rely on the prior publication of United States Patent Specification 4,995,382 (“Lang 1”). An additional citation, referred to as Kawaguchi, was abandoned following exchange of evidence in chief; a third, referred to as Lang 2 did not feature independently in the arguments advanced at trial, and I need not consider it separately. No case of obviousness over common general knowledge alone was advanced. I turn therefore to Lang 1.

Lang 1 was published on February 26 1991, some five years before the priority date of the patent in suit. The patent was assigned to Smith & Nephew, a large and respected company in the wound dressing field, which commercialised the Allevyn dressing I have already described.

The dressing described in Lang 1 has (a) a low wound adherency wound-facing layer, (b) an absorbent layer and optionally (c) an outer layer. The absorbent layer may be an open-cell foam. There are two options for the wound facing layer: a conformable, apertured film or net of elastomer coated with an adhesive on its wound facing surface or alternatively a pattern of adhesive spread in a conformable net-like configuration. The difference between the two embodiments of the wound-facing layer is that, in the first, the adhesive layer is a separate adhesive-coated, discontinuous polymer layer, whereas, in the second, the adhesive is coated directly onto the foam in a discontinuous pattern.

Lang 1 tells the skilled reader that suitable adhesives are those which do not adhere to the moist surface of the healing wound (column 2 lines 41-2). Suitable adhesives can be any of those pressure sensitive adhesives normally used for adhesive surgical or medical dressings. Preferred pressure sensitive adhesives are acrylate ester copolymers and polyvinyl ether adhesives (column 3 lines 26-32). In the first embodiment the previously formed individual layers are brought together by a lamination process (column 6 lines 37-40). The direct pattern spreading of the adhesive onto the foam required for the second embodiment is said to be done “conventionally” (column 7 23-24).

To deprive a claim of novelty, the prior document must contain a clear and unambiguous disclosure of, or clear and unmistakeable directions to do or make, something falling within the scope of that claim: Synthon v SmithKlineBeecham [2006] RPC 10 at [21] to [25]. If there are gaps in the disclosure then the claim will not fail on the ground of lack of novelty.

Lang 1 does not contain clear and unmistakeable directions to make a dressing with a hydrophobic gel layer. Even on the approach to the meaning of “gel” which I have adopted, the evidence does not establish that carrying out the directions of Lang 1 would result in something with the necessary gel-like qualities. Lang 1 therefore does not deprive claim 1 of novelty.

In Conor v Angiotech [2008] RPC 28, [2008] UKHL 49 at [42], Lord Hoffmann approved Kitchin J’s statement about the approach to obviousness in Generics (UK) Ltd v. H Lundbeck A/S [2007] RPC 32, para. 72:

"The question of obviousness must be considered on the facts of each case. The court must consider the weight to be attached to any particular factor in the light of all the relevant circumstances. These may include such matters as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them and the expectation of success."

The court should normally adopt the structured approach endorsed by the Court of Appeal in Pozzoli v BDMO [2007] EWCA Civ 588; [2007] FSR 37. I have endeavoured to do so here.

I have identified the skilled person and the common general knowledge above. The inventive concept is a wound dressing having the features of claim 1 as I have construed them. One difference between Lang 1 and the inventive concept is the use of a hydrophobic gel layer as the wound facing layer. There are also no clear directions in Lang 1 to cause the wound facing layer to coat the walls of the pores in the foam. I have to consider whether, without any knowledge of the invention, the skilled person would take that step. BSN’s case is that it would be obvious to employ a silicone gel adhesive layer as the wound facing layer following the directions in Lang.

A critical question is whether a silicone gel layer would come to mind as a “pressure sensitive adhesive used for adhesive surgical and medical dressings”.

Dr Reed said in his first report that the skilled person would recognise that hydrophobic gels (in particular silicone gels) existed which would have the same properties and therefore perform the same role as the pressure sensitive adhesives described in Lang 1. The foundation for this statement was an earlier section of his report where he relied heavily on extracts from what he described as a standard reference work in the wound care field at the priority date, namely “Advances in Pressure Sensitive Technology - 2 (edited by Satas; 1995) and in particular a chapter in that work by Ulman et al.

Mr Bogart did not agree that Satas was a standard work. In his second report he explained that, although he was active in the wound care field at the time, he had never heard of it, or of any other reference works with a similar level of detail relating to silicone polymers. Dr Reed’s response was somewhat surprising. He said that he was not aware of Satas at the time either, although he was aware of other works by the same author. He pointed out however that the Ulman chapter was a review chapter and that the information would have been part of the common general knowledge in the wound field.

I do not accept that knowledge equivalent to that set out in the chapter in Satas by Ulman et al. would have been part of the common general knowledge of the skilled person. Had it been so I would have expected to see other documents produced to evidence that state of knowledge.

In the absence of this level of common general knowledge, there is, it seems to me, a missing link in the obviousness case as advanced by Dr Reed. BSN sought to overcome this difficulty by submitting that, if the skilled person had approached an adhesive supplier with the information in Lang, namely that he wanted a pressure sensitive adhesive which would not stick to the wound but stick to skin, then the adhesive supplier would or might have suggested a silicone pressure sensitive adhesive. Mr Meade got some way with this proposition in his skilled cross-examination of Mr Bogart, but it got no further than his acceptance that a silicone supplier might suggest silicone gel, and he qualified his answers by saying that he did not know of any dressing besides Mepitel that used a silicone adhesive at the time.

There was also evidence from what actually happened in the art at the relevant time. Dr Reed’s own product, Mitraflex, used an adhesive specifically modified to be hydrophilic. Granulflex used a hydrophobic adhesive but contained within a hydrophilic layer. The evidence about the nature of the adhesive used in Allevyn Adhesive was not entirely clear. Dr Reed had assumed it was hydrophobic without checking whether it was in fact. Mr Purvis flourished a document of somewhat uncertain origin and which had not been shown to Dr Reed in advance, which said that the acrylic-based adhesive broke down in the presence of moisture. This might suggest that the adhesive itself was hydrophilic, but it is not clear, and another document suggested that it was only the tack, rather than the adhesive substance itself, which broke down.

However, even placing Allevyn Adhesive to one side, it is far from clear that a skilled person would choose a hydrophobic adhesive. Dr Reed had gone to the trouble of modifying his adhesive to make it hydrophilic.

It is of course necessary to recall that Mepitel was on the market, generally known and made of a hydrophobic silicone gel. But Mepitel was sold as a separate sheet. There was no evidence that a silicone gel adhesive had ever been applied directly to foam. Moreover Mepitel was used with absorbent pads which were meant to be removable and replaceable. This hardly brings to mind a composite dressing in which the silicone layer is intimately incorporated into the structure of the foam.

I have come to the conclusion that BSN have not made out their case of obviousness of claim 1 over Lang 1. It is not necessary to consider any subsidiary claims.

Section 72(1)(c) of the Patents Act 1977 provides that a patent will be invalid if the specification does not disclose the invention clearly enough and completely enough for it to be performed by a person skilled in the art. As I said in Zipher v Markem [2008] EWHC 1379 (Pat); [2009] FSR 1, at [362] insufficiency is a single objection to the validity of a patent which may arise in different ways. One of the ways in which it may arise is where the claimed invention is to a class of products and the extent of the monopoly exceeds the technical contribution: see for example Biogen v Medeva [1997] RPC 1 at 54.

BSN’s grounds of invalidity include the following under the heading of insufficiency:

“(a)

The specification of the Patent sets out methods to determine the adhesive properties of the dressing and provides that in order to obtain a functioning inventive dressing the degree of adhesion must exceed the minimum values set out in those tests.

(b)

If and to the extent that at least claims 1, 2, 6 and 10 of the Patent encompass dressings with less than the said minimum degree of adhesion:

i.

there are no or no sufficient directions given for the skilled person to determine the degree of adhesion necessary for dressings to have the claimed advantages of the purported invention; and

ii.

these claims encompass dressings that do not have the claimed advantages of the purported invention and owe nothing to the teaching of the Patent.

(c)

The specification of the Patent sets out a method to determine the softness of the wound contact layer and provides that in order to obtain a functioning inventive dressing the wound contact layer must have penetration numbers as determined by the specified method of 5-20mm.

(d)

If and to the extent that at least claims 1, 2, 6 and 10 of the Patent encompass dressings with a wound contact layer outside the range of softness:

i.

there are no or no sufficient directions given for the skilled person to determine the softness of the wound contact layer necessary for dressings to have the claimed advantages of the purported invention; and

ii.

these claims encompass dressings that do not have the claimed advantages of the purported invention and owe nothing to the teaching of the Patent.”

In view of the fact that I have held that the claims in question do extend beyond the numeric values for the identified parameters, the allegation of insufficiency does fall to be decided.

BSN say that insufficiency is demonstrated by the fact that Mölnlycke have to rely on tests which are not specified in the patent in order to demonstrate adhesion and softness. They submit that the case is analogous to Pharmacia v Merck [2002] RPC 41. In that case the defendant contended that many of the claimed chemical compounds would not pass the test set out in the specification. The patentee’s answer was that the skilled person would be able to substitute alternative tests. At [74] Aldous LJ rejected the patentee’s contention:

“The Judge was right to test whether the extent of the monopoly claimed exceeded the technical contribution by adopting the criteria which were used in the specification to explain the technical contribution.”

Mr Purvis’ answer is that the patentee’s contribution in the present case goes beyond a particular degree of skin adherence and softness, but includes a novel configuration of dressing. He points out that in Pharmacia the list of compounds in the claim was not inventive: the technical contribution was only the identification of a class which had Cox-II selectivity, a particular property explained in the specification. It made sense there to say that whether monopoly exceeded the technical contribution must be tested by the same standard.

As Aldous LJ explained in Pharmacia, that was a case in which the technical contribution could only be the quality alleged to be possessed by all the compounds. On that ground alone Pharmacia is distinguishable from the present case. Here the technical contribution lies in the novel structure and its components. I am not persuaded that the reasoning in Pharmacia applies to this case. The ground of invalidity based on insufficiency fails.

The patent in suit is valid, but it is not infringed by any of the BSN products.