The cause is unknown but triggers include injury and rheumatoid arthritis. It can also be a side effect of treatments such as steroids, chemotherapy or radiotherapy.
It is particularly common in the hip, with 150,000 AVN patients undergoing a total hip replacement in Europe and the US every year. Radio 4 presenter Jenni Murray, who suffers from AVN, had both hips replaced in 2008.
The new trial will compare the effectiveness of the osteoblastic (bone-forming) product Preob to other treatments, and the trusts taking part - Cambridge University Hospitals, King's College Hospital London, Newcastle upon Tyne Hospitals, University Hospital Southampton and the Royal Orthopaedic Hospital Birmingham - are among 37 centres across Europe involved. The trial will run until late 2017.
The procedure involves taking bone marrow from the patient and harvesting their stem cells, which have the unique ability to change into different cell types. The cells are processed in a laboratory to turn them into bone-forming cells, and then injected through the skin into the faulty hip bone tissue to 'regrow' it.
Mr Shah says the results could transform the treatment of AVN, which is also found in the knee and shoulder. He adds: 'The prospect of a non-invasive treatment is very exciting, and could have the ability to change people's lives.'
AVN patients often use crutches to take the weight off the damaged joint, and must exercise to keep it mobile, but most eventually need surgery called core decompression - part of the inside of the bone is removed to relieve pressure and allow new blood vessels to form. Alternatively, they have bone grafts, using healthy bone from elsewhere in the body.
Hip replacements are also an option, although as AVN is found mainly in people aged 30 to 50, these are not always recommended as they may need to be replaced several times during the patient's lifetime. The longevity - and the success rate - reduces every time.
Leila Hamrang, of Manchester, was diagnosed with AVN in her hips at 19. She says her condition may have been caused by the gruelling rounds of chemotherapy, radiotherapy and steroids she endured while being treated for leukaemia.
Now 26, Leila sometimes relies on crutches to move around. Her low blood pressure rules out many pain medications so she uses hot-water bottles and music for relief. She says trials like this give hope that she will one day be pain-free.
'For me, a hip replacement is the only option now but I can't have it too soon because of my age,' she says. 'I'm scared of complications and having to have multiple replacements, so something that doesn't involve a lot of operations would certainly appeal.'
Preob has been developed by Belgian biotechnology company Bone Therapeutics.
- Daily Mail
