Avascular Necrosis of the Hip, Risk Factors and Clinical Presentation

Amie, an advanced musculoskeletal practitioner, explains that the femoral head carries high load but depends on small terminal vessels from the medial and lateral circumflex arteries and the cruciate and trochanteric anastomoses. When these are occluded, ischemia leads to bone death and, without prompt restoration of blood supply, articular surface collapse. Traumatic causes include femoral head and neck fractures, acetabular fractures, failed dynamic hip screws, dislocations and hip contusions in contact sport. Alcohol and corticosteroids are involved in up to 80% of cases: 40 units a week over six months raises risk, as do long-term steroids at 15 to 20 mg, with short high-dose courses also relevant. Lupus, rheumatoid arthritis, sickle cell, smoking, obesity, diabetes and COVID-19 add to the picture. Patients often show the C sign of arthrogenic pain radiating toward the knee, pain with shoes and socks, walking and car transfers, and night pain. Amie watches gait, listens for clunking, assesses range, uses FADIR with care and always clears the lumbar spine and knee. AVN can also be asymptomatic or present as knee pain.