Spider silk patch can ease knee arthritis

Ahigh-tech patch based on spider silk could ease the agony of worn-out knees. the man-made graft, which is placed inside the knee joint, mimics the qualities of spider silk — which is five times stronger than steel — and replaces the cartilage lost due to osteoarthritis.

A small clinical trial is now under way at Southmead hospital in Bristol. it is the first time human patients will undergo the treatment to see if the implants can reduce pain and boost mobility.

As well as replacing missing cartilage, the silk implant, called FibroFix, has been shown to encourage the growth of new human cartilage.

While it’s not clear exactly how it does this, scientists at Orthox Ltd, the Oxfordshire-based company that developed the graft, suggest it’s probably because the protein ( called fibroin) they extract from silk to make the patch is very similar to fibronectin, a protein found in human cartilage which helps it grow.

tests on sheep, published in the journal Knee in 2014, showed the silk patch was as good as healthy cartilage at withstanding everyday impact on the joints.

if the trial — involving six patients — is similarly successful, it’s hoped that the patch could eventually mean many osteoarthritis patients can avoid knee replacement surgery.

Osteoarthritis usually develops as a result of age-related wear and tear, although other risk factors include being overweight, a family history and sports injuries.

As a result, the cushioning cartilage in the joints breaks down, meaning the bones rub against each other, causing inflammation and pain.

Patients often need antiinflammatory painkillers and, while these do help, they can damage the stomach if used for long periods.

Steroid injections can dampen inflammation but there is a risk of cortisone flare, where the injected steroid ( cortisone) crystallises inside the joint and triggers more inflammation.

Around 100,000 people a year in the UK have a knee replacement. this is major surgery which can leave a foot-long scar and can take up to a year to fully recover.

the silk substitute, in contrast, can be inserted through an incision as little as 1cm long, with the surgery taking just an hour or so. the patient, who has a local anaesthetic, can go home the same day.

After two weeks with no loadbearing activity on the affected knee, the volunteers will then be able to do light activities for two weeks, before returning to normal.

the protein used to make the grafts is extracted from silk made by mulberry silk moths, before being turned into a fibre that has the same complex structure as the much stronger spider silk. Silk moths are used because they produce around 1,000 times more silk than spiders — enough to massproduce the implants.

the trial has received £1.2 million in funding from the National institute for health and care Research.

COMMENTING on the technology, Professor Philip conaghan, head of the institute of Rheumatic and musculoskeletal medicine at Leeds University, said the silk patch might help patients who have lost a small amount of cartilage in the knee, perhaps due to a sporting injury.

But he added: ‘it may be less useful in joints where there is more extensive cartilage loss, or damage to other structures, such as the bone underlying the cartilage.’

■ MEANWHILE, a vegan diet can ease arthritis pain due to higher intake of anti- inflammatory compounds found naturally in plants, according to a recent study in the American Journal of Lifestyle medicine.

Scientists at Loma Linda University, california, put 44 people with rheumatoid arthritis on a vegan diet for a month and found their joint pain and swelling reduced.