The Condition
Avascular Necrosis (AVN) is a disease where there is cellular death (necrosis) of bone components due to interruption of the blood supply. Without blood, the bone tissue dies and the bone collapses.
When avascular necrosis involves the bones of the hip joint, it often leads to destruction of the joint articular surfaces resulting in deformity of the femoral head and separation of the overlying cartilage.
In the late stages of AVN, progressive damage to the hip joint results in early osteoarthritis.
Known risk factors include the use of corticosteroid medications, high alcohol consumption and hip joint trauma (dislocations and fractures). In most cases no cause is identified, and this is termedb’Idiopathic AVN’.
The natural course of AVN depends on a number of factors. In the early stages of AVN, good medium term results can be obtained with the use of the medication bisphosphonate, which decrease the rate of bone loss. Once collapse of the femoral head has occurred, the outcome for the hip joint is
less favourable. Surgical intervention may offer some improvement. Hip joints with significant collapse and deformity of the femoral head due to AVN reliably develop early onset osteoarthritis.
THE DIAGNOSIS
During your orthopaedic consultation, history and examination findings would help with the diagnosis. Imaging such as X-rays and MRI scans can be used to better assess the joint and degree of damage. You may also be sent for a bone scan.
THE SYMPTOMS
Patients will likely complain of pain around the joint but this can be very mild to start with. As disease progresses, range of movement will be reduced.
THE TREATMENT
Hip arthroscopy (keyhole surgery) can repair damage of the labrum. If no damage to the actual joint has occurred then acetabular osteotomy can be performed which is a procedure to ‘cover the femoral head’. This involves breaking the bone around the hip socket and ‘re-setting’ it. In advanced cases, hip replacement is the surgical treatment for acetabular dysplasia.
There are a number of considerations in deciding the best time to do this operation. Artificial joint replacements are reliable and safe. However, younger patients have a much higher chance of needing a repeat hip replacement over their lifespan. In selected patients, early surgical intervention can slow or prevent the progression of joint damage and improve symptoms.
