New Treatments Trials for AVN

Article written by charity trustee Jon Murnaghan.

It is difficult to organise large scale trials of new treatments for AVN because it is an uncommon condition and finding enough patients to include in a trial, ideally, you would want hundreds or even thousands, is impossible. So most research is done on small groups of tens of patients, usually without a control group who would receive a standard recognised treatment for comparison with the new treatment being tested. Because of this, testing a new treatment and getting it accepted as being better than an existing treatment is slow.
These treatments are being used, and they do have promising results from small trials, however, they haven’t been proved to be more effective than the currently accepted treatments such as core decompression. Some also have their own risks of side effects like Biphosphonate-related Osteonecrosis of the Jaw (BRONJ).
I have included links to research articles. In some cases, only the abstract or summary of the article can be read without payment.

Bisphosphonates

These are a group of drugs that affect bone remodeling, the process in which bone cells are constantly resorbed and new bone cells laid down. They block the action of osteoclast cells which are responsible for bone resorption. Bisphosphonates are now commonly prescribed for the treatment of osteoporosis and they are also used in the treatment of bone tumors.
There are ten types of bisphosphonate each having different strengths including clodronate (bonefos) alendronate (fosamax) and Zoledronic Acid. There have been a small number of trials using bisphosphonates to treat AVN of the hip which has shown that people taking bisphosphonates are less likely to suffer damage to the joint and to require surgery. Whilst the results are promising these trials were very small with only a few tens of subjects. They also used different criteria for entry to the trial and different bisphosphonates were given in different ways and with different dosages which makes comparisons between the trials impossible. The trials only lasted for a maximum of two years. In contrast, the biggest trial of bisphosphonates for the treatment of osteoporosis had 50,000 participants and lasted initially for ten years. That trial is continuing to follow the participants for a further ten years.
The commonest side effect of bisphosphonates taken as pills for osteoporosis is irritation of the stomach.

BRONJ side effect

A serious, paradoxical but rare side effect of bisphosphonate use is Bisphosphonate-Related Osteonecrosis of the Jaw (BRONJ). This usually only occurs in people receiving high dose intravenous bisphosphonate injections for bone cancers and is often associated with a dental operation. If taking bisphosphonates, it is important to inform your dentist and to take extra care with dental hygiene.
Bisphosphonates stay in the body for years and their long term effects are still unknown.

References:

1. Cardozo JB, Andrade DM, Santiago MB. The use of bisphosphonate in the treatment of avascular necrosis: a systematic review. Clin Rheumatol. 2008 Jun;27(6):685-8. doi: 10.1007/s10067-008-0861-9. Epub 2008 Feb 13. Review. PubMed PMID: 18270760.
2. Lozano-Calderon SA, Colman MW, Raskin KA, Hornicek FJ, Gebhardt M. Use of bisphosphonates in orthopedic surgery: pearls and pitfalls.Orthop Clin North Am. 2014 Jul;45(3):403-16. doi: 10.1016/j.ocl.2014.03.006. Review. PubMed PMID
3. Goytia RN, Salama A, Khanuja HS. Bisphosphonates and osteonecrosis: potential treatment or serious complication? Orthop Clin North Am. 2009 Apr;40(2):223-34. doi: 10.1016/j.ocl.2008.12.002. Review. PubMed PMID: 19358907.
4. Teitelbaum SL, Seton MP, Saag KG. Should bisphosphonates be used for long-term treatment of glucocorticoid-induced osteoporosis? Arthritis Rheum. 2011 Feb;63(2):325-8. doi: 10.1002/art.30135. PubMed PMID: 21279986; PubMed Central PMCID: PMC3069536.