Silk patch that heals a burst eardrum

ATINY implant made from silk could speed up the healing process for thousands of people who suffer burst eardrums. Called ClearDrum, the contact lenssized implant is stitched over the hole in the eardrum and acts as a ‘scaffold’ on to which the patient’s own healthy new tissue can grow. It can also transmit sound just as a healthy eardrum would do.

The silk patch could do away with the need for complicated operations to insert grafts, where surgeons take a tiny patch of the patient’s own tissue (usually from behind the ear) and sew it over the hole in the eardrum.

This involves highly intricate surgery that fails around 30 per cent of the time — leading to repeat attempts to heal the damage with even more grafts.

Scientists behind the ClearDrum implant claim the silk patch is tough enough and flexible enough to mean patients only need one operation.

The eardrum is a round membrane in the middle part of the ear which is stretched tight and connects to three tiny bones in the inner ear, called the ossicles.

As sound waves hit the eardrum, it vibrates and moves these tiny bones so that the sound is transmitted through them deep inside the inner ear and on to the brain.

The eardrum can become torn or perforated, usually due to an infection and inflammation which puts pressure on the eardrum and can cause it to split.

OTHER causes include damage from instruments used to clear wax, or very loud noises, such as gunfire or explosion.

Most perforations heal themselves in a few weeks, but those that do not can require surgery.

This involves a general anaesthetic and grafting a piece of soft tissue over the hole.

The risks include damage to a nerve that controls taste, which runs very close to the eardrum. Surgery can also cause permanent hearing loss in a small number of patients. It can even lead to facial paralysis if the nerve for the muscles of the face — which also runs through the ear — is damaged.

Scientists at the Ear Science Institute Australia, in Perth, have spent the past eight years developing a replacement eardrum that does away with the need for the complicated graft procedure.

Such is the promise of the new treatment that the Wellcome Trust, the UK-based research funding body, has contributed more than £2 million to the costs of developing the silk implant. A study published last December in the Journal of the Mechanical Behavior of Biomedical Materials showed it was able to transmit sound almost as well as a healthy human eardrum. The implant was also able to withstand considerable pressure.

Australian scientists built a simulated ear canal to test the silk implant’s strength and durability and blasted it with sound waves of varying levels. This is crucial because existing grafts can fail if they cannot withstand the force exerted on them when the eardrum vibrates, or if the surrounding tissue that they are attached to retracts slightly.

TRIALS on patients are due to begin in Australia within the next year and if these prove successful, ClearDrum could be widely available in three to five years.

Adam Frosh, a consultant ear, nose and throat specialist at the Lister Hospital, Hertfordshire said that the silk implant could significantly improve current treatment — especially if it reduces the failure rate seen with current procedures.

‘If trials show silk provides a good scaffold for healthy new tissue to grow on then that would potentially be very useful.’

MEANWHILE a silk implant has also been developed to treat knee injuries and avoid knee replacement surgery.

In an international trial — including Southmead Hospital, Bristol — 120 patients with meniscal injuries, where shockabsorbing cartilage in the knee joint is torn as a result of a sports injury or ageing, will be given the FibroFix implant.

The patients’ recovery will then be monitored for a year. Earlier studies have suggested that the silk implant can successfully replace and strengthen the damaged cartilage.