Avascular Necrosis (AVN) of Femoral Head


Dr Sanket Diwanji is the Best Hip Surgeon in surat.
In India, AVN or Osteonecrosis of femoral head is most common indication for Total Hip joint Replacement.

How does AVN occur?

Avasular Necrosis literally means death due to lack of blood supply. All of the blood supply  comes into the ball that forms the hip joint through the neck of the femur (the femoral neck), a thinner area of bone that connects the ball to the shaft. If this blood supply is damaged, there is no backup. This leads to death of bone of femoral head and subsequent collapse of head leading to secondary arthritis of hip joint.

avn

Causes of AVN

AVN can occur in patients without any particular risk factor, this is known as idiopathic AVN. There are several factors that increases the risk of AVN such as, steroid medication intake, alcohol, and smoking. It is also seen in  patients having blood disease such as sickle cell anemia and leukemia. Sometimes it is observed after pregnancy. It is also commonly seen after injury to hip joint, particularly fracture of femoral head or dislocation of hip joint. Recently it is found to be associated with HIV infections and drugs used to treat HIV.

Signs and Symptoms of AVN

Initially patients feel dull ache in groin which gets worse on walking, turning in bed and sitting in crossed leg position. Some patients feel pain in side of hip, buttocks, front of thigh or rarely knee of same leg. Pain gradually worsens and leads to restriction of movement of hip joint. Patinet feel difficulty in sitting on chair, getting in and out of car or riding a scooter. In advanced stage as the head collapses and limb becomes short, patient starts noticing limp.

The diagnosis can be made on X ray,  MRI or  Bone scan.

Early Avn

Late Avn

Treatment

Once AVN has occurred, the treatment choices are determined by how far along the problem is and your symptoms. Other factors that guide treatment decisions include your age, activity level, general health (and any specific health problems present), and life expectancy. 

Nonsurgical Treatment

Anti-inflammatory medicine is often used to ease pain. Bisphosphonates (Osteofos) are another groups of medications that can be helpful. Bisphosphonate  has been shown effective in reducing the risk of femoral head collapse in patients with avascular necrosis.

Surgery

If the femoral head has not begun to collapse, surgeries to relieve pressure within femoral head and improve blood circulations can be attempted. These procedures are known as Head-Preserving surgeries.

Core decompression of the Femoral Head

The simplest operation is to drill one or several holes through the femoral neck and into the femoral head, trying to reach the area that lacks blood supply. The drill bores out a plug of bone within the femoral head. This operation is thought to do two things: (1) it creates a channel for new blood vessels to quickly form into the area that lacks blood supply, and (2) it relieves some of the pressure inside the bone of the femoral head. Relieving this pressure seems to help decrease the pain patients experience from AVN.

Core Decompression and Fibula Grafting

A more complicated procedure to try to increase the blood supply to the femoral head is a vascularized fibular bone graft procedure. This is actually a tissue transplant. The graft is taken from the fibula (the thin bone that runs next to the shin bone). The graft is vascularized, meaning it has a blood supply of its own. This operation does two things: (1) it brings blood flow to the femoral head through the bone graft, and (2) the fibular bone graft is strong and keeps the femoral head from collapsing as the bone heals itself. This procedure is an inpatient procedure and will require you to stay in the hospital for several days.

This is a very complicated operation and is not commonly done. It is not always successful because the blood supply to the graft is fragile and may not form completely.

Total Hip Replacement


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