Knee ache eased ...by injection of antibiotic pellets

TINY antibiotic pellets no wider than a human hair may be a new way to tackle knee pain caused by osteoarthritis. The grains, less than 0.07mm long, are created when powdered antibiotics are mixed with a special ‘carrier’ liquid.

The solution is injected into blood vessels in the arthritic knee, where the pellets clump together until they block the flow.

When the blood flow is permanently blocked off, the vessels die, as do pain-carrying nerves in the area.

A Japanese study found that patients who had the treatment saw a fourfold drop in pain levels after just one month, and symptoms continued improving during the following year.

Similar procedures are already widely used to treat defects in the body’s blood vessels, known as arteriovenous malformations (AVMs), uterine fibroids and some forms of cancer.

Osteoarthritis affects more than eight million people in the UK, with symptoms of knee arthritis seen in one in ten people aged 55 and over.

Treatments range from painkillers and physiotherapy for relatively mild forms of the disease, to joint replacements for severe cases.

However, there are few options for those with drug-resistant moderate arthritis which is not severe enough to warrant jointreplacement surgery.

It had been thought that the discomfort associated with osteoarthritis was down to the loss of cartilage, the cushioning material that lines joints, but recent research has found that the degree of cartilage loss is not an indicator of pain level.

Instead, an emerging theory is that osteoarthritis pain is caused by angiogenesis – the growth of new blood vessels – which occurs where there is chronic inflammation.

This brings with it growth of new nerves which are involved in the transmission of pain.

More than 90 per cent of people with osteoarthritis have been found to have had angiogenesis, often close to the area where the pain is felt.

Blocking or reducing blood supply in vessels using tiny particles, known as geniculate artery embolisation, is now being trialled by doctors in Japan as a way to tackle osteoarthritis pain.

The study of the new treatment, carried out at the Musculoskeletal Intervention Center in Tokyo, involved 14 osteoarthritis patients who had not responded to treatment for at least three months. After identifying the rogue blood vessels around the patients’ knee with scans, doctors inserted a catheter loaded with pellets containing a solution of the antibiotics imipenem and cilastatin sodium. Once injected, the pellets blocked the vessels.

After just four weeks, there was an average fourfold reduction in pain, and patients also reported less pain while walking and climbing stairs.

DR PHIL Conaghan, Arthritis Research UK spokesman and professor of musculoskeletal medicine at the University of Leeds, said the new treatment could offer an alternative for those who have not responded to medication.

‘We know that very tiny blood vessels and nerves grow into areas of damaged cartilage in osteoarthritis, and these may be important in producing some of the pain people get from their osteoarthritis,’ he added.

‘Although the treatment described in this study is still in development and the study is very small, it’s exciting to see a potential new method for reducing pain.

He cautioned: ‘Lots of care will be needed in developing the therapy as blocking larger blood vessels could be harmful to joints.’