OSTEONECROSIS: A DISABLING DISEASE NOT TO BE IGNORED IN ASTHMA AND ATOPIC CONDITIONS.

Osteonecrosis, also referred to as avascular necrosis is a disease characterized by necrosis or death of bone secondary to impairment in blood supply. The condition affects the epiphyseal ends of bones such as the femur and the humerus, but can also involve the metacarpal and metatarsal bones, the patella, the knee, vertebrae and the jaw. A plethora of inflammatory, autoimmune, hematological, thrombotic and vascular diseases can lead to osteonecrosis. Corticosteroids are intimately linked to the development of osteonecrosis. The frequent use of systemic corticosteroids in patients with asthma, eczema, nasal polyposis, sinusitis, urticaria and angioedema, or anaphylaxis make this disease of great relevance to the practicing allergist and pulmonologist. Untreated, bone necrosis leads to frustrated bone remodeling and angiogenesis, leading to subchondral fractures and collapse of the articular heads of bones, and culminating in debilitating osteoarthritis, often requiring arthroplasty. Recent studies have shed light on the molecular mechanisms underlying osteonecrosis and on the role of glucocorticoids. The gold standard test in patients suspected of having the disease is MRI scanning, with plain radiographs having a lower sensitivity and specificity. Early diagnosis and intervention are essential. The allergist should avoid the frequent use of glucocorticoids and consider early introduction of steroid-sparing alternatives for asthma or sinusitis. Smoking and alcohol ingestion need to be addressed, and the management of glucocorticoid-induced osteoporosis may be helpful. It is essential for allergists to familiarize themselves with the disease and its diagnosis and consider early referral to an orthopedic surgeon for surgical intervention.