Wednesday, 29 July 2015

T 0837/13 - Priority: identical technical problem, identical technical solution

In this opposition appeal, the importance of identity or lack of identity of the technical problem(s) and its solution(s) for validity of priority was discussed, and in particular also to which level. 

Summary of Facts and Submissions
I. By its decision posted on 21 March 2013 the Opposition Division decided that European patent No. 1 341 482 in amended form according to the main request then on file and the invention to which it related met the requirements of the EPC.
II. The appellant (opponent 02, Terumo Kabushiki Kaisha) lodged an appeal against that decision in the prescribed form and within the prescribed time limit.
III. Further appeals were filed by opponent 01 (Boston Scientific Scimed, Inc.) and by the proprietor (OrbusNeich Medical, Inc.). Moreover, an intervention was filed by opponent 03 (Boston Scientific Medizintechnik GmbH).
IV. With letter dated 11 May 2015 (received on 12 May 2015), sent on behalf of opponents 01 and 03, the opposition and appeal of opponent 01 and the intervention of opponent 03 were withdrawn.
V. In view of the letter of the proprietor of 13 March 2015 and the main request mentioned therein (i.e. maintenance of the patent in amended form as upheld in the decision under appeal), the appeal of the proprietor was - as also accepted by the proprietor during the oral proceedings - deemed to be withdrawn.
VI. In view of the changes to the procedural roles mentioned in the two preceding paragraphs, in the following the opponent is referred to as the appellant and the proprietor as the respondent.
VIII. The only claim of the main request reads as follows:
"A balloon expandable stent comprising a main body (11), wherein the main body has a generally cylindrical shape and a cylindrical axis (5) and, when the stent is unexpanded, the main body comprises a plurality of expandable helical segments (30, 40), wherein the main body further comprises a plurality of main body cylindrical elements (100) having collinear cylindrical axes, wherein the main body cylindrical elements (100) are adjacent to one another and attached to one another by the helical segments (30, 40), each main body cylindrical element (100) having a circumference (110) that is substantially identical to that of an adjacent cylindrical element, and comprising a plurality of expandable circumferential segments (50, 60) positioned between consecutive connecting elements (250) which connect said cylindrical element to an adjacent cylindrical element, wherein the circumferential segments (50, 60) are joined together by portions of the helical segments (30, 40) to form the cylindrical elements (100), wherein the plurality of circumferential segments (50, 60) comprise a majority of the circumference (110) of each cylindrical element (100), characterized in that the cylindrical elements (100) comprise first circumferential segments (50) alternating with second circumferential segments (60), in that said second circumferential segments resemble a generally S-shaped structure, having three linear portions connected to each other by two curved portions, in that said first circumferential segments have five linear portions connected to each other by four curved portions, in that adjacent cylindrical elements are connected to one another by two connecting elements (250), in that second circumferential segments (60) of adjacent cylindrical elements are joined together by connecting elements (250) to form one of two first expandable helical segments (30, 40), in that first circumferential segments (50) of adjacent cylindrical elements are joined together by connecting elements (250) to form one of two second expandable helical segments (200, 210), in that said first expandable helical segments (30, 40) are generally parallel one to another and 180 degrees apart, and in that said second expandable helical segments (200, 210) are generally parallel one to another and 180 degrees apart, and wherein the first circumferential elements (50) comprise linear portions (320) and curved portions (328) that join the linear portions (320) together to form a repeating pattern, and wherein second helical segments cross the first helical segments in shared connecting elements."
X. The essential arguments of the appellant can be summarised as follows:
According to acknowledged case law, see e.g. T 647/97 of 1 February 2001, in order for a priority to be valid, the claimed invention must not only provide the same solution to a particular problem but also relate to the same technical problem. In the present case, however, neither the problem posed nor the solution was the same.
Whereas the present patent shared with the priority document the problem related to the prior-art Palmaz-Schatz stent, it did not even address the additional problem posed in the priority document with respect to the Cordis stent, namely to provide a wide range of design options.
Furthermore, also the solution as claimed in the patent was different from what was disclosed in the priority document. In fact, the priority document did not even mention the second helical segments or the cylindrical elements, which the respondent had identified as the fundamental structures of the invention. Moreover, numerous features which the priority document disclosed in combination with the features claimed in the patent were not part of the claimed subject-matter, thus broadening the subject-matter and leading to an invention different from the one disclosed in the priority document. In particular, the invention as defined in the priority document required a uniform wall thickness. Moreover, it related to "a stent expandable from within" - a feature which was different from the claimed balloon-expandability. The stent pattern further comprised undulation elements and S-shaped elements, which had no correlation with the circumferential segments joined from linear and curved portions claimed in the patent.
Therefore, with the problem to be solved and the solution disclosed in the priority document being different from the subject-matter claimed in the patent, the priority was not valid.
XI. The essential arguments of the respondent can be summarised as follows:
The stents disclosed in the priority document and claimed in the patent clearly both addressed the problems of the Palmaz-Schatz stent, namely low stent-to-vessel ratio uniformity, comparative rigidity and limited flexibility. The problem to be solved was thus the same.
Furthermore, the claim of the patent basically defined the specific stent pattern shown in Figures 1, 2a, 2b, 3, 4, 6, 10 and 11 of the priority document. Even if a slightly different wording was used, the technical subject-matter claimed was the same as previously disclosed. A stent which was capable of acquiring a second diameter in an expanded and deformed state upon the application from the interior of a radially outwardly extending force was the same thing as a balloon-expandable stent. Even if the second helical elements were not specifically mentioned, their existence was clearly and unambiguously shown in the drawings, e.g. in Figure 1. The same was true for the circumferential elements and the cylindrical elements - even if referred to by the slightly different terms undulation element, S-shaped element or circumferential element.
As a result, the invention claimed was the same as that disclosed in the priority document, and the priority was thus validly claimed.
Reasons for the Decision


3. Article 123(2) EPC
3.1 The claims as filed
Claim 1 of the main request is based on claim 1 as filed and incorporates all the features thereof.
Claim 1 as filed is not restricted to a particular helical pitch, and nor does it specify a certain dimensional ratio of the first and second circumferential segments, or prescribe that endzones are present. On the contrary, the endzones are defined in a dependent claim (claim 5 as filed) and thus optional features. Dependent claim 8 as filed - mentioned by the appellant - refers to alternating linear and curved segments of the rings in each endzone and not to linear and curved segments in the circumferential elements. Moreover, it is dependent on dependent claim 5 (defining the end zones) and the claim structure is therefore in accordance with the endzones being optional. Consequently, the argument that the structure of the claims as filed required the presence of end zones in combination with the particular claimed structure of the circumferential segments fails.
The further analysis of the claim structure as filed brought forward by the appellant is based on dependent claims which belong to different independent claims. It therefore cannot change the above analysis.
Therefore, from the analysis of the claim structure as filed, no unallowable broadening can be derived.
3.2 Features from the description and the drawings
With respect to claim 1 as filed, claim 1 of the main request has been further amended. These amendments will be analysed in the following:
3.2.1 The stent being balloon-expandable
Claim 1 as filed defines the stent to be an expandable stent. As disclosed in the description page 1, lines 17, 18, there are "typically two types of stents: self expanding stents and balloon expandable stents". Although this statement is made in the prior-art section of the description, it is considered to express the skilled person's general knowledge. With claim 1 as filed referring to an expandable and not to an expanding stent, the claims as filed define a member of the second category, i.e. a balloon-expandable stent. Nothing more is expressed by the amendment.
3.2.2 The particular stent structure claimed - the definition of the circumferential elements
The further definition of the stent structure is based on the disclosure of a particular embodiment illustrated in Figures 1-7 and described on pages 4, line 3 to page 7, line 23. Whereas the figures show one specific way to realise said embodiment, the corresponding part of the description is worded in broader terms, referring to some features as optional ("may have", "may range", "in some but not all embodiments", etc.).
However, not every feature is referred to as optional. Regarding the structure of the first and second circumferential elements, the description refers to some features in the indicative: "In the embodiment shown in Figs. 1-5, the first circumferential elements 50 comprise linear portions 320 and curved portions 328 that join the linear portions 320 together to form a repeating pattern" (first circumferential segment, page 5, lines 16-18). "In the embodiment shown in Fig 6, the second circumferential element 60 comprises linear portions 412 and curved portions 414 having a filament width 407, and resembles generally an S-shaped structure" (second circumferential segment, page 5, lines 26-28). These features are part of the claimed subject-matter. In this respect it is considered an implicit property of a repeating pattern to have amplitude and period. Equally, a circumferential segment joined from linear and curved portions implicitly has some filament width.
In contrast therewith, numerous other features are disclosed as being optional: the orientation of the linear portions (page 5, lines 18-19; page 5, line 32 to page 6, line 2), the specific amplitude and period and its relationship (page 5, lines 19-23; page 6, lines 2-8), the existence of an angled portion (page 5, line 28 to page 6, line 2), the contributions of the respective first and second circumferential elements to the overall circumference (page 6, lines 7-11), the H-shape of the connecting elements (page 6, lines 18-21), the particular pitch of the helices (page 6, lines 21-25), the existence of endzones (page 7, lines 24-25; page 4, lines 11-12) etc.
Thus, contrary to the appellant's view, the description does not simply provide a reservoir of optional features to arbitrarily choose from. Instead, it draws a fine line between some features which are part of the embodiment, and some others which may be part of the embodiment. For the features which "may" be part of the embodiment, the person skilled in the art thus clearly and unambiguously understands these to be optional. Even if a feature - such as the specific number of linear and curved elements - is only derivable from the drawings, it becomes clear to the skilled person - taking the combined teaching of the description and the figures into account - that said feature is not inextricably linked with the other features present in the drawing, but disclosed as optional in the corresponding part of the description.
While the respective number of linear and curved elements influences the size of the circumferential elements, i.e. the contribution of these elements to the overall circumference, and while - because the circumferential elements are part of the helical segments - it also influences the pitch of the helices, the description discloses both these properties to be variable in the embodiment. The same is true for the angulation of the S-shaped structure shown in the drawings, which may vary, with an angle of zero degrees being explicitly disclosed (page 5, line 32 - page 6, line 2). Thus the specific number of linear and curved portions of the circumferential segments can be taken from the drawings (i.e. Figures 1-7) without unallowable intermediate generalisation.
3.3 The particular stent structure claimed - the definition of the helices and cylindrical segments
According to the description, page 6, lines 14-15, the stent may have "a main body comprised of two (or more) first helical segments as well as two (or more) second helical segments". Furthermore, see page 6, lines 17 and 18, "in some, but not all embodiments, the first and second helical segments may share a common connecting element". Such a stent having exactly two first and two second helical segments, which respectively share a common connecting element, is depicted in Figures 1, 2, 3, 4 and 7. As further discussed on page 6, lines 21-34 and page 7, lines 11-17, the helical segments are (circumferentially) expandable, with the first helical segments being formed from a plurality of first circumferential elements that in turn are made up of linear and curved segments, and with the second helical segments being comprised of other (second) circumferential elements that are in turn comprised of linear and curved segments. With the circumferential segments being formed of linear and curved portions respectively, the contribution of each helical segment to the overall circumferential dimension of each cylindrical element is greater than just the contribution of the filament widths of the individual segments (taking into account that for creating two linear portions which are side by side some material is disclosed to be removed inbetween, see page 9, last paragraph of the application as filed).
As shown in the drawings and as also disclosed on page 4, lines 18-20, the two first helical segments may be generally parallel to each other and opposite each other by 180 degrees. It can be appreciated in the drawings that such a configuration - in view of the above-discussed definition of the helices as comprising common connecting elements and being formed from the connecting elements and the respective circumferential elements - results in also the second helical segments being parallel to each other and 180 degrees apart. It further results in the cylindrical elements being formed of first circumferential elements alternating - i.e. one after the other - with second circumferential elements and being positioned between and connected to one another by consecutive connecting elements.
Because the cylindrical elements are attached to one another by the helical segments - with two of the respective two first and two second helices sharing a respective connecting element - there are exactly two connecting elements which connect adjacent cylindrical elements to one another.
Consequently, all features stipulated in claim 1 find a basis in the disclosure as originally filed, the allegedly omitted features being either disclosed as optional or being implicitly present.
Therefore, claim 1 is in accordance with the requirements of Article 123(2) EPC.

5. Priority
5.1 Identical technical problem
It is uncontested that both the patent and the priority document aim at solving technical problems of the Palmaz-Schatz stent, i.e. a low stent-to-vessel ratio uniformity, comparative rigidity and a limited flexibility. The problem posed in the patent is thus identical to one of the problems posed in the priority document.
The appellant argues however that the priority document solved a second problem which was not even addressed in the contested patent, namely to provide a wide range of design options.
The priority application derives this further problem with respect to the drawbacks of the Cordis coronary stent, which consists of a single piece of wire that is wrapped to form a continuous sine wave and helically wound along a longitudinal axis, with the ends of the wire being weld-terminated. Such a stent design does not have cylindrical elements and therefore is fundamentally different from the stent as claimed in the present main request. Due to the fundamentally different design, the omission of the further problem is justified.
Furthermore, there is no reason why the priority-claiming application would need to solve all problems raised in the priority document. In fact, the priority-claiming application may well relate to only one aspect of the disclosure in the priority document, not to its full disclosure. What may be objected to - see case T647/97 cited by the appellant - is a situation where the priority-claiming application solves a new problem different and not derivable from the problem posed in the priority document. In the present case there is however no doubt that the problem solved in the patent is the same as at least one of the problems posed in the priority document.
It is further noted that the stent of the present invention, which is typically made by removing various portions of the tube's wall (paragraph [0029] of the specification), does not suffer from the bemoaned restriction in design options. During the discussion on Article 123(2) EPC, the appellant complained that the wording of the claim of the main request still allowed a wide range of modifications, which indicates that the subject-matter claimed - although it is not explicitly stated - still solves the problem of providing a wide range of design options.
Thus, the appellant's attack on the validity of the priority based on an alleged non-identity of the problems posed fails.
5.2 Identity of the solution to the problem posed
As correctly pointed out by the respondent, the overall disclosure of the priority document has to be taken into account. Even if the wording of the two documents does not exactly match, the technical content of the claimed features - which is the decisive criterion - is disclosed. Figure 1 of the priority document shows the two first helices formed of S-shaped circumferential elements joined by connecting elements. Although it is true that second expandable helical segments are not explicitly mentioned, they are - for the person skilled in the art - clearly and unambiguously shown in Figure 1. Thus explicitly claiming these second expandable helical segments only puts in words what the skilled person clearly and unambiguously recognises in the figures (see Figures 1, 2a, 2b, 3, 4, 6, 10, 11) of the priority document. First and second circumferential elements as claimed are further individualised in Figure 2 (Nos. 2.01, 2.02), as are the cylindrical elements. This disclosure is also supported by the description, albeit using the terms circumferential element instead of cylindrical element, undulation element instead of first circumferential segments, and S-shaped element instead of second generally S-shaped circumferential segments.
With respect to a uniform wall thickness - considered essential by the appellant - the description of the priority document on page 11, second paragraph, provides support for this feature being optional ("The wall of the stent may have a substantially uniform thickness").
The stent is furthermore explicitly referred to as "the balloon expandable stent of the invention" ("Summary of the invention", page 4, first sentence), which is brought into the expanded / deformed state upon the application from the interior of the tubular member of a radially outwardly expanding force ("Summary of the invention", third sentence). Therefore, the alleged difference between balloon-expandability and "expandable from within by application of a radially outwardly expanding force" is not present.
Although not contested by the appellant, the Board notes that the endzones shown in some of the drawings are not at all mentioned in the description or in the claims, such that they are recognised by the skilled person as not essential to the invention disclosed in the priority document. Furthermore, the description states that the helices and the circumferential elements intersect at "one point", thereby indicating that also the H-shape of the connecting elements shown in the drawings is not an essential feature.
Consequently, the invention claimed is the same as the one disclosed in the priority document, and the priority is therefore validly claimed.
6. Novelty
6.1 D18
The Board agrees with both parties that at least in view of the validly claimed priority, D18 - a divisional application of the patent in suit - is not prior art under Article 54(3) EPC.
6.2 D12
As explicitly confirmed during the oral proceedings, the elements identified by the appellant as being "cylindrical elements" are in fact sub-segments of the continuous helix making up the stent shown in Figure 6. This means that these sub-segments are, although covering full 360°, an open spiral structure. Such an open structure does not qualify as a "cylindrical element". Consequently, the subject-matter of claim 1 is novel over D12.
6.3 D3
It is uncontested that Figure 9 shows an embodiment with four connecting elements. On page 8, lines 19 and 20, document D3 further discloses that "while a minimum of one connecting element is required to join adjacent band-like elements, two or more interconnecting elements are preferred". However, this disclosure is made in the context of the embodiment shown in Figures 2 and 3, which is considerably different from the Figure 9 embodiment. In fact, reference to the particular embodiment of Figures 2 and 3 is made repeatedly in the passages surrounding the citation reproduced above, starting at page 7, lines 17-21, and continued on page 8, lines 13, 15, 21 and 32. It is only on page 9, line 3 that the description turns to a different embodiment ("In another embodiment...."). There is furthermore no indication to combine the teaching of the Figure 9 embodiment with the statement made in the specific context of the embodiment of Figures 2 and 3.
Thus, D3 does not clearly and unambiguously disclose a stent as defined in claim 1 of the main request.
6.4 Accordingly, the subject-matter of claim 1 is novel.
7. Inventive step
7.1 D12 as closest prior art
Therefore, the stent claimed is non-obvious in view of D12 as closest prior art.
7.2 D3 as closest prior art
To conclude, to arrive at the claimed subject-matter, the person skilled in the art has to make a sequence of consecutive particular selections, a process which is hindsight-driven and cannot be considered obvious.
7.3 D4 as closest prior art
Consequently, claim 1 is not obvious in view of D4, even taking into account the teaching of D12 or D21.
7.4 Thus, the subject-matter of claim 1 involves an inventive step.
For these reasons it is decided that:
1. The decision under appeal is set aside.
2. The case is remitted to the opposition division with the order to maintain the patent in amended form on the basis of the following documents:
- Claim 1 filed as main request during the oral proceedings on 13 May 2015 (Annex E to the minutes)
- Description pages 2 to 6 filed during the oral proceedings on 13 May 2015 (Annex F to the minutes)
- Figures 1 to 15 of the patent specification.

This decision T 837/13 (pdf) has European Case Law Identifier:  ECLI:EP:BA:2015:T083713.20150513. The file wrapper can be found here. Photo "3D Problem Solving" by Chris Potterobtained via Flickr under CC BY 2.0 license (no changes made).

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