Repetitive 1.6 ATA hyperbaric oxygen therapy for bilateral ARCO Stage II steroid-associated osteonecrosis of the femoral head.

Hyperbaric oxygen (HBO2) therapy has been demonstrated to have beneficial effects on the early stages of steroid-associated osteonecrosis (SAON) of the femoral head. Since high HBO2 pressure (e.g., 2.4-2.5 atmospheres absolute/ATA) has been commonly considered to have a greater ability to restore tissue oxygenation in the femoral head than low pressure (e.g., 1.6 ATA), the latter HBO2 protocol is rarely used for SAON treatment. In this paper, we present the case of a 36-year-old female diagnosed with bilateral early stage (Association for Research on Osseous Circulation, ARCO stage II) SAON caused by steroid therapy for neuromyelitis optica spectrum disorder (NMOSD). Because the patient could not endure high HBO2 pressures, the treatment pressure was adjusted to 1.6 ATA, which was the highest pressure the patient could withstand. After 20 treatment sessions, her symptoms were relieved significantly. Her visual analog score (VAS: using a 0-10 score) decreased from 7 to 2, and after 50 treatment sessions her symptoms disappeared almost completely. A significant improvement was also observed radiologically by computed tomography (CT) and magnetic resonance imaging (MRI) examinations. This case study provides a potential HBO2 treatment protocol with reduced pressure for early-stage femoral head necrosis. Further research is needed to validate this finding and explore the potential mechanism of HBO2 on SAON.