Hyperbaric oxygen increases oxygen availability in blood plasma to relieve ischemia caused by poor vascularization of the femur head. The reparative processes result in enhanced fibroblastic, angioblastic, osteoblastic, and osteoclastic activity, which are all extremely important in healing necrotic bone structures.
In a recent large and long term study, Koren (2015) showed 88% of the treatment group had improvement on MRI when AVN was treated in stage I and II for 68 patients (78 joints). At 11.1±5.1 years follow-up a total of 54 patients (58 joints) were located and answered the questionnaires showing 93% survival rate of the joints. Earlier clinical studies (Reis 2003) showed similarly 81% of patients who received hyperbaric oxygen therapy returned to normal MRI in contrast to only 17% in the untreated group (Reis 2003).
Avascular necrosis (AVN) or osteonecrosis of the femur head (ONFH) is a result of an interruption of blood supply to the bone. The femoral head lays at the most remote part of the bone’s vasculature and is enclosed by cartilage. Its access to local blood vessels is restricted, making the femur head vulnerable to necrosis caused be ischemia (lack of blood supply).
The possible causes may be idiopathic, alcohol- or drug-induced, blockage in a blood vessel supplying the femoral head, or fat embolism. Other causes are anemia, Gaucher disease, increase bone marrow pressure, impaired arterial supply, obstruction of venous drainage, vasculitis, intermedullary hemorrhage and hypofibrogenemia.
Hyperbaric oxygen therapy can positively address some of the causes of AVN such as: steroid or alcohol induced, anemia, Gaucher disease, increase bone marrow pressure, impaired arterial supply, obstruction of venous drainage or vasculitis, however presently, more clinical studies are needed.
Joint pain is usually the initial symptom which can either be dull, aching, sharp, or intermittent. Pain may be confined over the hip or radiating to the buttocks, gonads, or knee and is usually aggravated by standing or walking and relieved by rest. The pain can be debilitating, limiting the joint range of motion.
The main mechanism of AVN is hypoxia (lack of oxygen) to the bone which results in ischemia and death of the marrow and the osteocytes. This can be addressed by exposing the affected area to hyperbaric oxygen. Inhalation of hyperbaric oxygen increases the availability of plasma oxygen and restores oxygenation to the tissues. With the main therapeutic goal of preventing collapse of the femoral head and preserving the joint rather than replacing it, hyperbaric oxygen can accomplish this alongside with other orthopedic interventions. Predominantly, hyperbaric oxygen reduces joint edema, stimulates revascularization and boosts bone resorption and regeneration.
