Advanced Bionics AG v MED-EL Elektromedizinische Geräte GmbH

Hearing dates: 23–24 May 2023

Approved Judgment

Introduction

The Defendant (“Med-El”) appealed with permission granted by myself against an order dated 21 September 2022 of Campbell Forsyth sitting as a Deputy High Court Judge revoking Med-El's European Patent (UK) No. 3 138 605 entitled “MRI-safe disk magnet for implants” (“the Patent”) for the reasons given in the judge's judgment dated 1 June 2022 [2022] EWHC 1345 (Pat). As its title suggests, the Patent discloses and claims a cochlear implant which comprises a magnet that makes the implant safer in MRI scanners than prior implants. There was no challenge to the claimed priority date of 23 April 2010. The judge held that the Patent was obvious in the light of Med-El's International Patent Application No. WO 03/081976 entitled “Reducing effect of magnetic and electromagnetic fields on an implant's magnet and/or electronics” (“Zimmerling”); but that, if the Patent had been valid, the Claimants (“Advanced Bionics”) would have infringed it by dealings in their HiRes Ultra 3D cochlear implant device. Advanced Bionics contended by a respondents' notice that, if the Patent was valid, they had not infringed it.

After the judge's judgment and order, the Patent was maintained in amended form by the Technical Board of Appeal of the European Patent Office in decision T 732/21 dated 28 September 2022 for reasons given in writing on 12 December 2022. It was common ground on the hearing of the appeal that: (i) this Court had to consider the Patent as so amended; (ii) the amendments made no difference to the obviousness issue; and (iii) the amendments made no difference to the infringement issue considered by the judge, but gave rise to an additional issue which could and should be considered by this Court.

At the conclusion of the argument on obviousness, the Court announced that the appeal would be dismissed for reasons to be given in writing later. It followed that it was unnecessary to hear argument on infringement. My reasons for concurring in that disposition of the appeal are as follows.

The skilled team

It is common ground that the Patent is addressed to a team consisting of a biomedical engineer with experience in designing cochlear implants and a clinician specialising in otolaryngology and neurotology.

The experts

Each side called two expert witnesses, a biomedical engineer and a clinician. Little turns on the evidence of the clinicians. Med-El's biomedical engineering expert was Professor Gregg Suaning while Advanced Bionics's biomedical engineering expert was Professor John Parker. The judge found Prof Parker at [21] and [31] to be “an extremely open and helpful expert”, “a good educator for the court” and “a fair witness” who “came across as keen to assist, educate and willing to make concessions as appropriate”. The judge rejected at [22]–[31] and [223]–[233] criticisms advanced by Med-El that Prof Parker had failed properly to consider the issue from the perspective of the skilled person and that his approach had been tainted by hindsight. By contrast, the judge found Prof Suaning at [20] to be at times “too controlled and overly careful in his answering questions to the point it came across as slightly partisan to the Med-El case”, although “a good educator for the court” who “made sensible concessions as appropriate”. More specifically, the judge's assessment of Prof Suaning's evidence as to whether it was common general knowledge that a diametrically magnetised permanent magnet could rotate when interacting with an external magnetic field was that some of his responses “appeared blinkered” and at times he “came across as trying to justify his positions rather than answering the questions” ([49]); and the judge's assessment of Prof Suaning's evidence as to the teaching of Zimmerling was that “[h]is answers could come across as evasive and at times contradictory” ([213]).

Common general knowledge

The judge appended to his judgment as Annex B an agreed statement of common general knowledge prepared by the parties. The judge made findings as to certain disputed areas at [40]–[63]. The common general knowledge which is relevant to the appeal can be summarised as follows.

Magnets

Permanent magnets have a magnetic moment which describes the strength and orientation of the magnetic field of the magnet. This is called the magnetic dipole. It is a vector quantity (it has direction). The magnetic fields of two magnets (whether permanent or electromagnetic) will interact with one another. The force induced from that interaction (called torque) will depend on the shape and strength of the magnetic fields. The force is proportional to the magnetic field strength and inversely proportional to the square of the distance between the magnets. The tesla (“T”) is the standard unit for magnetic flux density – a measure of the strength of a magnetic field.

Magnets were available in 2010 in any reasonable basic shape and they could be magnetised in a variety of different ways. Axially magnetised permanent magnets have their magnetic dipole positioned in the axial direction as schematically shown below (with green denoting the north pole and red the south pole) for a disk-shaped magnet.

Diametrically magnetised permanent magnets have their magnetic dipole positioned across their face as schematically shown below. The diagram again shows a disk-shaped magnet as an example, but the principle is of general application. In the case of a spherical magnet, whether it is considered diametric or axial would depend on its orientation.

A diametrically magnetised permanent magnet can rotate when interacting with an external magnetic field. A common example of this is a magnetic stirrer of the kind used to stir liquids in laboratories, in which a diametrically magnetised permanent magnet shaped like a cylinder is caused to rotate about an axis perpendicular to the cylinder by an external magnetic field.

Cochlear implants

A cochlear implant is a small electronic device that assists a person who is profoundly deaf or hard of hearing to perceive sound. One part – the external component – is placed on the skin behind a person's ear, while another part – the internal component – is surgically implanted under the skin. The implant works by directly stimulating the neural tissue within the cochlea with electrical pulses, thus bypassing damaged portions of the inner ear. The implant's signals are sent to the brain, which recognizes the signals as sounds.

The internal component contains an RF receiver coil, a processor, a flexible electrode array, a permanent magnet and optionally a ground electrode. The external component comprises a microphone, speech processing electronics, a battery, an RF coil to transmit sound and power to the internal component and a magnet. The internal component is intended to last for the lifetime of the patient, whereas the external component can be replaced if it is damaged or when more advanced products become available.

The surgery to implant the internal component is usually performed under general anaesthesia. A small incision is made behind the ear. It is then necessary to perform a mastoidectomy (open the hollow, air-filled spaces in the skull behind the ear) to gain access to the facial recess. The processor component is placed posteriorly through the skin incision, so it lies over the skull behind the mastoid bone. A pocket may be drilled in the skull to recess some of the device and the lead that goes to the electrode. In some cases, a larger recessed area can be made in the bone that includes the posterior aspect of the implant including the receiver coil, of the internal component to sit in. This larger recessed area requires more exposure and often a bigger incision. Devices being implanted in 2010 were generally thinner than earlier devices, however, and did not generally require bone drilling for the posterior aspect of the implant including the receiver coil and the magnet.

In 2010 there were three major suppliers of cochlear implants: Advanced Bionics, Med-El and Cochlear. By that date the designs of the internal components of commercial cochlear implants had converged into a flat, thin and planar coil housing (containing the receiver coil, a disk-shaped magnet in the middle of the coil and a silicon chip for sound processing) and a section containing additional electronics which was also flat and of broadly similar depth. The two elements were angled to each other in order to conform to the curve of the skull, as shown below.

In 2010 the external component typically had two parts: a part that sat behind the ear and a puck-shaped part containing the RF coil that sat on the skin over the corresponding RF coil of the internal component. The puck-shaped part was held in place by magnetic attraction between the magnet in the middle of the RF coil in the internal component and a magnet in the middle of the RF coil in the puck-shaped part of the external component. The magnets also ensured appropriate alignment of the internal and external RF coils. The magnets of the internal...