This decision concerns a computer-implemented method of planning a surgical procedure. The Opponent argued that distinguishing features of the statistical shape model of the body part and also incorporating planning data of the surgery did not lead to a technical effect and thus the claim was not inventive. The Board disagreed and indicated that features provide the technical effect that allows anatomical variations in both shape and surgical planning to be accounted for. Even if it was accepted that the subject-matter of the claim did not lead to an improvement over the prior art method, the problem to be solved by the distinguishing features would be to provide an alternative model to the model used in the prior art. Since the solution was not common knowledge, the subject-matter was considered inventive. Here are the practical takeaways from the decision T 0803/17 of June 21, 2022, of the Technical Board of Appeal 3.2.02.
Key takeaways
Use of a statistical shape model of the body part and also incorporating planning data of the surgery provides the technical effect that it allows anatomical variations in both shape and surgical planning to be accounted for.
Even if it was accepted that the subject-matter of the claim did not lead to an improvement over the prior art method, the problem to be solved by the distinguishing features would be to provide an alternative model to the model used in the prior art.
The invention
The invention relates to a computer-implemented method of planning at least a part of a surgical procedure to be carried out on a body part of a patient.
The method uses a statistical shape model of the body part. This model may be derived, for example, from a database of images. The model is instantiated for the specific patient using data derived from the real body part. This may be achieved for example by spatially matching the model to X-ray or ultrasound images of the patient.
The model also comprises data representing at least a part of the planned surgical procedure to be carried out. For example, when the surgery involves the replacement of the acetabular cup, these may be two points – defined by their three-dimensional coordinates – which are used to describe the orientation of the acetabular cup and its radius.
Instantiating the model also adapts the part of the planned surgical procedure to reflect the patient’s real body part. Continuing with the example of the replacement of the acetabular cup, instantiating the model would result in the points describing the orientation of the cup and its radius also being adapted to the specific patient’s anatomy.
Thereby the surgeon is provided with information which can be used, for example, to determine the best type and/or size of the implant(s) to be used.
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Claim 1 of the Main Request
Is it patentable?
In the first instance, the Opposition Division rejected the opposition and maintained the patent as granted as the claims were considered inventive. The Opponent appealed against the decision.
The Board noted that the cited document E1 relates to a method for computer-aided navigation and/or treatment planning. It teaches providing a generic model of a body structure and adapting the model to a specific patient. However, the Board then decided that although the generic model of E1 includes “a statistical model of the body structure”, this is not a statistical shape model of claim 1. Furthermore, the Board also decided that although the cited document E1 may include the planning data, it does not disclose the statistical model incorporates the planning data. Therefore, the distinguishing features were identified as follows:
6.10 In summary, E1 discloses neither a statistical shape model nor that the statistical model of paragraph [0013] incorporates planning data. It follows that the subject-matter of claim 1 is novel over E1 (Article 54 EPC).
The Opponent argued that the distinguishing features over the prior art E1 (US 2003/0185346) did not lead to a technical effect and thus the claim was not inventive. In particular, it was argued that the patent specification did not include evidence showing any improvement from including the planning data in the statistical shape model. The inclusion did not lead to any technical effect, or was even detrimental, implying more work to create the model and more data in the model. Hence no inventive step could be acknowledged.
The Board disagreed with the Opponent and noted that the feature provides a technical effect:
8.1 It is disputed whether the subject-matter of claim 1 involves an inventive step over E1 and common general knowledge.
8.2 Use of a statistical shape model (first distinguishing feature) also incorporating planning data (second distinguishing feature) allows anatomical variations in both shape and surgical planning to be accounted for (see paragraph [0035] of the patent specification).
8.3 The appellant argued that there was no evidence that this would lead to an improved surgical plan in the method of claim 1.
8.4 Even if the appellant’s submission that the subject-matter of claim 1 did not lead to an improvement over the method taught by E1 were to be accepted, the problem to be solved by the two distinguishing features would be to provide an alternative model to the model used in E1.
8.5 E1 does not mention a statistical shape model, let alone suggest its use as an alternative model. Moreover, even if a person skilled in the art using common general knowledge were to consider using a statistical shape model as the statistical model of E1 and adapt the model creation and adaptation/instantiation accordingly, E1 does not suggest incorporating the planning data into this model. This incorporation would additionally require variation information for the planning data, information which is not mentioned in E1.
8.6 Hence the person skilled in the art starting from the method of E1 and wanting to provide an alternative model would not arrive at a method as defined by claim 1 using common general knowledge. It follows that the subject-matter of claim 1 is inventive (Article 56 EPC).
Therefore, the Board decided that the subject-matter of claims involves an inventive step, and the application was allowed.
More information
You can read the full decision here: T 0803/17 of June 21, 2022, of the Technical Board of Appeal 3.2.02.