An amendment by which a surgical step is no longer part of a claimed method can be suitable for avoiding exclusion from patentability under Art. 53(c) EPC

• A method step worded as “acquiring, by the computer, three-dimensional position data […] in three-dimensional anatomical space” may in the light of the description be interpreted as encompassing a surgical step of obtaining the data by the surgeon palpating the patient's anatomy.
• With the amended wording “receiving, at the processor, three-dimensional position data […] in three-dimensional anatomical space”, the step of acquiring the position data itself is not part of the claimed method and the surgical step is not encompassed.

This is an article about EPO case: T 2136/19

Background

The application relates to a computer-implemented data processing method for assisting a surgeon in the positioning of a first medical structure relative to a second medical structure, for example the positioning of a medical implant relative to a bony structure of a patient. The method determines correspondence information by comparing point-distances measured in a 2D image of a patient’s anatomy with corresponding point-distances obtained directly on the actual patient’s anatomy. For determining such correspondence information, two points assigned to the first and second medical structures (called the base point and the reference point, respectively) are obtained in the 2D image. Furthermore, the actual positions of these two points in the 3D anatomical space are received, e.g. following their acquisition by the surgeon palpating the patient’s anatomy and the implant with a surgical instrument such as a navigated pointer.

According to the description, it was possible for a surgeon to verify the correct positioning of the second medical structure with respect to the first medical structure along the predetermined position using the correspondence information. A surgeon may better judge the patient's individual anatomy on the basis of 2D projection images such as x-ray images, than on the basis of image-free navigation techniques alone (page 12 of the description as originally filed, second paragraph). This allows the surgeon to plan the surgical operation more easily.

Under point 12.3 of the decision to refuse, the ED argued that in claim 1, the step of “acquiring, by the computer, three-dimensional position data comprising position information describing the position of the base point (3) and the reference point (4) in three-dimensional anatomical space, in particular relative to the first medical structure (1)” encompassed the use of a surgical instrument such as a pointer to determine points on the bony anatomy of a patient. According to the ED, this interpretation was confirmed by “Annex A” page 3 stating “the base point then has to be palpated” and page 8, third paragraph of the description.

In amended claim 1 of the main request---filed during appeal proceedings and with amendments relative to claim 1 as filed originally---the corresponding amended feature reads as follows:

1. A medical data processing method for assisting the positioning of a first medical structure (1) relative to a second medical structure (2) in at least one of two directions, the method being constituted to be executed by a computer and comprising the following steps:

[…]

• [delete: acquiring] receiving, at the processor, three-dimensional position data comprising position information describing the position of the base point (3) and the reference point (4) in the three-dimensional anatomical space [delete: , in particular relative to the first medical structure (1)];

[…]

The Board’s opinion on exception to patentability

Claim 1 of the main request was directed to a data processing method "to be executed by a computer". All the method steps recited in claim 1 were explicitly defined as being carried out at or by a digital processor of a computer. These steps were limited to receiving some data at the processor (for example, receiving image data such as data defining an x-ray image) and to determining, by the processor, some data on the basis of other data (for example, calculating directional distances on the basis of position data).

The step of acquiring three-dimensional position data that the ED had identified as encompassing the surgical step, had been replaced with a step of "receiving, at the processor" this three-dimensional position data. According to the Board, with the limitation that the three-dimensional position data was received, at the processor, and not acquired, by the computer, it was clear that the claimed method did no longer encompass the use of a pointer to palpate the patient’s anatomy.

The Board acknowledged that the three-dimensional position data may well be acquired by palpating the patient's anatomy, thus by a step of a surgical nature; however, by virtue of the amendment, the step of acquiring the position data itself is not part of the claimed method.

The Board agreed with the ED that the claimed method was for "assisting" the positioning of the first medical structure relative to the second medical structure. Based on information provided by applying the method, a surgeon could "verify the correct position of the second medical structure with respect to the first medical structure" and, if needed, move them relative to each other. The actual positioning of the first or second medical structures was therefore not part of the claimed method.

According to the Board, the claimed method was limited to a purely “passive” data processing method which is carried out exclusively in a computer without causing any effect on the patent’s body as a result. Therefore, the claimed method  did not recite any method step encompassing a physical activity that constitutes a method step for treatment of a human or animal body by surgery The Board considered irrelevant that the claimed method might be performed after or even iteratively during a surgical intervention on the body, as described in the description, because in any event, there would be no functional link between the claimed method and any effects of a surgical or therapeutic nature that would occur during this intervention. Therefore, in the absence of such a functional link, the claimed method as such did not qualify as a method for treatment of the human or animal body. With regard to the requirement of a "functional link", the Board referred to G 1/07, point 4.3.2 of the Reasons.

The Board’s decision

The Board decided that the main request overcomes all the objections on which the decision under appeal was based (clarity, added-matter, sufficiency, exclusion from patentability), and remitted the case to the ED for further prosecution to deal with other requirements of the EPC, in particular those in relation to novelty and inventive step, since no search at all had been carried out yet.