Osteomyelitis is an infection of the bone or bone marrow. It is called refractory osteomyelitis when the bacteria continues to reside in the bone, even after antibiotics and surgery have been attempted to cure it. Refractory means it is in the chronic stage. Refractory osteomyelitis is often treated with hyperbaric oxygen therapy (HBOT), after other methods to heal the bone have failed. This is usually after a period of 4 to 6 weeks of infection and when the other therapies such as antibiotics and debridement (removal of infected or dead tissue and bone) could not clear out the infection.