Avascular Necrosis

AVASCULAR NECROSIS
By: Robert H. Sheinberg, D.P.M., D.A.B.F.A.S., F.A.C.F.A.S.
 

Avascular necrosis is an uncommon condition that can affect the bones of the foot or ankle. It is due to a loss of blood supply to the bone or a portion thereof. Loss of blood supply causes death of the bone cells, which may predispose the bone and joint to collapse. 

The loss of blood supply to the bone is usually temporary. Over a period of time through a process called creeping, substitution the blood supply may return and the bone is partially revitalized. Although this condition can occur in any bone it is most common in the talus (small anklebone), navicular (part of the arch bones) or first metatarsal head (area of the bunion).

Avascular necrosis of bones is usually due to a traumatic injury to the blood supply to the bone. It may also be seen in nontraumatic events such as in patients with chronic alcohol abuse or patients who have been on cortical steroids for a long period of time. Smoking also causes the problem to worsen.

As avascular necrosis to the bone progresses, a portion or all of the bone slowly dies. The early symptoms are stiffness and soreness in a joint or a deep ache inside the foot or ankle. Progressive loss of motion and stiffness are felt. If the disease advances, the bone surface may collapse causing severe arthritis to the foot or ankle. 

Diagnosis of this condition is achieved utilizing MRIs. X-rays are usually negative in the early stages. The MRI will show the portion of the bone that has been affected and the severity of the problem. Bone scans can also be performed to evaluate the disease process.

Treatment of avascular necrosis early on may help to prevent long-term problems. If weightbearing bones have been affected, relieving the stress to the bone until it revascularizes (gets new blood supply) is important to prevent the bone from collapsing. This will require a period of nonweightbearing using crutches. Occasionally decompressing the bone could help to alleviate some of the deep pain within the area and allow new blood supply to return. Removing some of the dead bone and packing it with healthy bone may also aid in the healing process. At times, electrical stimulation to the bone will also help stimulate new bone formation. If the joint collapses, procedures including joint replacements or fusions may be necessary to allow pain free movement.

This is a minimally invasive surgery where we are drilling a pattern of K-Wires into the tibia to decompress it in a patient with Tibia AVN.

MRI of AVN of the sesamoid. The bone should be white like the other bones. The sesamoid is darker indicating lack of blood flow to the bone.

  

The sesamoid should be a white color similar to the other bones (green arrow). The sesamoid that is darker is damager and can lead to AVN (red arrows).

The bones should all be similar appearance of white. The tibial sesamoid is darker indicating damage to the bone.

Intraop pics of synptomatic sesamoid that was completely removed.