What Is Osteonecrosis?
Osteonecrosis, also known as avascular necrosis, is a serious condition in which bone tissue dies because its blood supply is interrupted or severely reduced. Without an adequate supply of blood, bone cells cannot survive, and the affected tissue gradually begins to collapse.
It most commonly affects the head of the femur, causing significant problems in the hip, but it may also occur in other areas, including the knee, shoulder or ankle. It primarily affects adults between the ages of 30 and 60.
Recognised risk factors include corticosteroid use, alcohol consumption, trauma, certain haematological disorders and decompression sickness.
Symptoms include:
- pain in the affected area;
- stiffness;
- progressive difficulty bearing weight.
Symptoms often appear at a later stage, once the condition has already progressed.
Osteonecrosis: Stages and Characteristics
Osteonecrosis progresses through a series of stages, from initial ischaemia to collapse of the articular surface. In the early stages, classified as Ficat stages I and II, the condition may not be visible on standard X-rays and may only be detected by MRI. In the advanced stages, Ficat stages III and IV, subchondral bone collapse and secondary osteoarthritis may occur, often leading to the need for joint replacement surgery.
One of the most insidious characteristics of the condition is its silent progression. Many patients do not experience pain until osteonecrosis has already reached an advanced stage.
For this reason, early diagnosis and prompt initiation of treatment are essential in helping prevent joint collapse.
Bilateral involvement, affecting both hips or both knees, is also relatively common, particularly among patients receiving systemic corticosteroid therapy.
Scientific Evidence
The body of scientific evidence supporting the use of hyperbaric oxygen therapy in osteonecrosis has grown steadily in recent years.
Prospective studies have evaluated the use of hyperbaric oxygen therapy in the early stages of osteonecrosis of the femoral head, reporting reduced pain, improved function and, in some cases, a slowing or arrest of the progression of necrosis.
The proposed mechanism is clear: restoring oxygenation to ischaemic areas under hyperbaric pressure may support the survival of cells in the surrounding penumbra, promote neovascularisation and stimulate osteoblast activity.
These findings have led several clinical centres to incorporate hyperbaric oxygen therapy into treatment protocols for early-stage osteonecrosis, alongside conservative or minimally invasive treatments.
Hyperbaric Oxygen Therapy for Osteonecrosis
In the treatment of osteonecrosis, hyperbaric oxygen therapy serves as an important adjunctive intervention, particularly during the early stages of the condition, when preserving the viability of bone tissue is the primary therapeutic objective.
By breathing pure oxygen under increased pressure, the amount of oxygen dissolved in the blood rises to levels that allow it to diffuse even into areas where the microcirculation is severely compromised. This may have a dual effect: limiting the expansion of the necrotic area while activating the tissue’s natural repair mechanisms.
Hyperbaric oxygen therapy is particularly recommended for patients with stage I or II osteonecrosis, before collapse has occurred, in combination with reduced weight-bearing on the affected joint and, where clinically indicated, medication such as bisphosphonates or prostaglandins.
In patients who have undergone core decompression surgery, hyperbaric oxygen therapy may support postoperative recovery and contribute to an improved clinical outcome.
A typical treatment protocol consists of 30 to 40 sessions, accompanied by close monitoring and follow-up imaging. The decision to include hyperbaric oxygen therapy in the treatment plan is always made in consultation with the treating orthopaedic surgeon, considering the stage of the condition, its underlying cause and the patient’s overall state of health.