Hyperbaric Oxygen Therapy for Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease caused by multiple factors such as trauma, hormones, and alcohol. In children, due to immature skeletal development, osteonecrosis of the femoral head presents different clinical manifestations and pathophysiological processes, known as Legg‑Calvé‑Perthes disease (LCPD). In recent years, the incidence of this disease has been rising, the onset age has been significantly earlier, and the function of the affected limb has been severely impaired. In the United States, there are 10,000 to 20,000 new cases each year, accounting for 5% to 18% of total hip arthroplasties, which has attracted increasing attention from scholars at home and abroad.

Definition

Osteonecrosis of the femoral head is a disease caused by venous stasis, impaired or interrupted arterial blood supply of the femoral head, leading to partial death of osteocytes and bone marrow components followed by repair processes, which further results in bone tissue necrosis, structural changes and collapse of the femoral head, and eventually causes hip pain and dysfunction.

Clinical Manifestations

Early-stage osteonecrosis of the femoral head is characterized by indistinct clinical symptoms. Most patients seek medical attention for pain in the groin area, deep buttock pain, anterior thigh pain and/or knee pain. Due to atypical clinical symptoms, missed diagnosis and misdiagnosis are common. As the disease progresses, pain in the affected limb worsens progressively, accompanied by claudication, and then loss of normal hip function. In the late stage, the affected hip shows adduction and flexion deformities, rest pain, and significantly limited joint motion.

For early non‑traumatic osteonecrosis of the femoral head, X‑ray films can show blurred trabecular structure or even irregular cystic changes in the necrotic area, provided that the trabeculae in the necrotic area are destroyed and resorbed.

Diagnosis

Diagnosis is formulated according to the Expert Consensus on Adult Osteonecrosis of the Femoral Head and international diagnostic criteria for osteonecrosis of the femoral head.

• Clinical features: Mainly pain in the hip, buttock or groin, occasionally accompanied by knee pain and limited internal rotation of the hip. Often associated with a history of hip trauma, corticosteroid use, heavy drinking, or occupational exposure such as diving.

• MRI findings: MRI has high sensitivity for osteonecrosis of the femoral head, showing localized subchondral linear low signal on T1WI or “double‑line sign” on T2WI.

• X‑ray findings: Anteroposterior and frog‑lateral views are basic positions for diagnosing osteonecrosis of the femoral head, usually showing sclerosis, cystic degeneration, “crescent sign”, etc.

• CT scan: Usually shows a sclerotic bone zone surrounding necrotic and reparative bone, or subchondral bone fracture.

• Radionuclide examination: Bone scan shows a cold area in the acute phase of femoral head necrosis; the repair phase shows a cold area within a hot area, i.e., a “doughnut‑like” change. Single‑photon emission computed tomography (SPECT) may improve the diagnostic sensitivity of radionuclide examination for osteonecrosis of the femoral head. Positron emission tomography (PET) may detect signs of osteonecrosis of the femoral head earlier than MRI and SPECT, and can predict the progression of the disease.

• Bone biopsy: More than 50% of osteocytic lacunae in bone trabeculae are empty, involving multiple adjacent trabeculae, with bone marrow necrosis.

• Digital subtraction angiography (DSA): Shows impaired, interrupted or stagnant blood supply to the femoral head. Routine use for diagnosis is not recommended.

Diagnostic criteria: Meet item 1 plus any one of items 2–7.

Conventional Treatment

Treatments include non‑surgical and surgical treatment.

1. Non‑surgical Treatment

(1) Protective weight bearing: Avoid impact and contact sports. Using crutches can effectively relieve pain; wheelchair use is not recommended.
(2) Pharmacological therapy: Combined application of anticoagulants, fibrinolytics, vasodilators and lipid‑lowering drugs is recommended, such as low‑molecular‑weight heparin, alprostadil, warfarin combined with lipid‑lowering drugs. Combined use of anti‑osteoclastic and osteoanabolic drugs, such as bisphosphonates, madopar, is also optional. Pharmacological therapy can be used alone or in combination with hip‑preserving surgery.
 (3) Traditional Chinese medicine (TCM) treatment: Guided by the holistic view of TCM, following the basic principles of “combination of motion and rest, equal emphasis on muscles and bones, integrated internal and external treatment, and doctor‑patient cooperation”. It emphasizes early diagnosis, combination of disease and syndrome, and early standardized treatment. For high‑risk groups and early asymptomatic patients, TCM mainly focuses on promoting blood circulation to remove blood stasis, supplemented by resolving phlegm and dampness, tonifying the kidney and strengthening bones, which promotes necrotic repair and prevents collapse. For early symptomatic osteonecrosis of the femoral head, TCM for promoting blood circulation, removing blood stasis, inducing diuresis and resolving dampness is used on the basis of protective weight bearing; combined with surgical repair, it can improve the effect of hip‑preserving surgery.

 (4) Physical therapy: Including extracorporeal shock wave, electromagnetic field, traction, etc.

2. Surgical Treatment

Osteonecrosis of the femoral head progresses rapidly with poor non‑surgical efficacy, so most patients require surgery. Surgical methods are divided into two categories: repair and reconstruction to preserve the native femoral head, and total hip arthroplasty. Hip‑preserving surgeries include core decompression, osteotomy, vascularized or non‑vascularized bone grafting, etc., suitable for early or middle‑stage osteonecrosis of the femoral head with a necrotic volume >15%. Effective hip‑preserving surgery can avoid or delay total hip arthroplasty.

Hyperbaric Oxygen Therapy

1. Therapeutic Mechanisms

(1) Increase arterial partial pressure of oxygen, extend oxygen diffusion distance in capillaries, enhance oxygen supply to the lesion area, elevate local oxygen tension, correct hypoxia, and restore aerobic metabolism of local tissues.
(2) Promote proliferation and division of osteoblasts, osteoclasts, fibroblasts and endothelial cells; accelerate proliferation of granulation tissue, fibrous tissue and connective tissue; speed up bone growth, repair of necrotic bone tissue and fracture healing.
(3) Enhance the phagocytic ability of phagocytes against bacteria and necrotic tissue, strengthen anti‑infection and debridement effects.

2. Treatment Protocol

Hyperbaric oxygen therapy is one of the methods for treating aseptic osteonecrosis of the femoral head and should be combined with comprehensive treatment. For patients with Ficat stage I and II osteonecrosis of the femoral head, hyperbaric oxygen therapy achieves similar effects to orthopedic interventions. The pressure is mostly 2–2.5 ATA, with 2 ATA being the most commonly used. Oxygen inhalation lasts 90 minutes per session. Generally, 6–10 treatment courses are required, with a 1–2‑week rest after every 3 courses before the next phase.

3. Precautions

(1) Hyperbaric oxygen therapy is contraindicated in patients with untreated pneumothorax, large pulmonary bullae or severe emphysema.
(2) Infective foci should be debrided and treated with antibiotics; pathological fractures require fixation.

4. Evidence‑based Evaluation

Among 8 clinical studies (2 randomized controlled trials, 1 historical control study, 5 case series), 4 combined hyperbaric oxygen therapy with other interventions, making it impossible to draw definitive conclusions on the specific efficacy of hyperbaric oxygen therapy alone. In studies using hyperbaric oxygen therapy alone, the hip survival rate was 95.5% for Steinberg stage I lesions, 89% for Steinberg stage II lesions, and 100% for Ficat stage II lesions. Multiple studies indicate that hyperbaric oxygen therapy has certain clinical value in the treatment of osteonecrosis of the femoral head. However, further randomized controlled trials are needed to better clarify the therapeutic role of hyperbaric oxygen therapy in osteonecrosis of the femoral head.

References