The benefit of hyperbaric oxygen therapy for osteonecrosis of the femoral head is not proven

It is currently not proven that patients with idiopathic osteonecrosis of the femoral head (a specific type of destruction of the hip joint) need surgery less often, or experience less pain or increased mobility of the joint if they receive hyperbaric oxygen therapy (HBOT) in addition to conventional treatment. There is currently a complete lack of relevant studies. This the result of the final report of the German Institute for Quality and Efficiency in Health Care (IQWiG), published on 4 October 2007. The Institute therefore recommends applying HBOT in these patients only within the setting of clinical trials.

Additional oxygen aims to prevent tissue necrosis

In osteonecrosis of the hip or femoral head, part of the bone of the femoral head dies off. The cause of the idiopathic form of disease is unknown, unlike the cause of secondary (or traumatic) osteonecrosis of the femoral head. However, the disease is relatively often associated with alcohol or nicotine abuse. In the advanced stage of disease, the femoral head can collapse, so that the hip joint needs to be either surgically stabilised or replaced by a prosthesis.

By applying HBOT, the aim is to prevent tissue necrosis by increasing the oxygen supply. In a pressure chamber, the patient inhales pure oxygen through a mask or a head tent. Red blood cells, which transport oxygen, are already nearly saturated under normal conditions and can carry little more oxygen. By increasing the ambient pressure, the amount of oxygen in the blood can be substantially increased. As with carbonic acid in an (unopened) carbonated water bottle, due to the increase in pressure more oxygen dissolves into the blood plasma. This is alleged to increase the oxygen supply to the body tissue and stop necrosis.

Application only in the setting of clinical trials

The final report concludes that reliable statements on the benefit of HBOT for idiopathic osteonecrosis of the femoral head in adults are currently not possible. Although this type of therapy has been tested for about 20 years, data only on about 100 to 200 patients have been published worldwide. The only available comparative study that investigated the research question of this report could not be included in the evaluation because of deficits in methodology and content. Due to the complete lack of appropriate clinical trials, HBOT for osteonecrosis of the femoral head in adults should only be applied in a suitable clinical trial setting in order to obtain long-term reliable findings, according to the Institute.

It remains unclear why the evidence base is so poor: specific organisational problems are unlikely, as it is not a rare disease. Moreover, it is not an emergency therapy and patients are usually capable of giving informed consent. Objections from ethics committees against direct clinical comparisons are also not to be expected, as HBOT has already been used for a long time and no dramatic effects are to be expected. Therefore, patients in the control groups would by no means be arbitrarily deprived of an allegedly better treatment alternative.

Procedure of report production

IQWiG published the preliminary report on the Internet on 25 April 2007. Comments could be submitted on this version up to 23 May 2007. IQWiG received 2 comments, which did not, however, contradict the general conclusions of the preliminary report. Additional relevant publications that had not already been identified by IQWiG were not reported, either. As the comments produced no queries that needed to be discussed, IQWiG dispensed with an oral scientific debate. However, the comments submitted were considered. Objections referring to the content of the preliminary report are discussed in the final report (see pages 31-34) and are fully presented in a separate document. The final report was sent to the contracting agency, the German Federal Joint Committee, on 8 August 2007.

Contact: Tel. ++49(0)221-35685-0, info@iqwig.de