Avascular necrosis of the talus happens when the talus bone, the bone in the center of your ankle, loses some of its blood supply and is no longer alive. Your bones are made out of living bone cells, which allow your bones to constantly remodel to stay strong and healthy. When the bone loses its blood supply, the bone cells die. This can lead to pain and even collapse of the talus in severe cases.
Some patients may do well with no treatment or medication treatment, while others may require surgery to address the problem. Causes of avascular necrosis include trauma (previous broken bone), steroid use, alcohol abuse, and blood disorders like sickle cell anemia.
People with talar avascular necrosis usually have deep pain in the ankle that comes on gradually. The pain usually gets worse after spending more time on your feet or being active and can be accompanied by swelling. Most people with ankle pain do not have talar avascular necrosis, since it is pretty rare and there are many other causes of ankle pain.
There are various causes of talar avascular necrosis:
Trauma: If you have broken your talus bone, whether or not it was treated with surgery, you are more likely to get talar avascular necrosis. This is because the injury may have cut off the blood supply to part of the talus, leading to part of the bone dying. The more severe the injury, the greater the chance of this happening. Usually talar avascular necrosis after a fracture can be diagnosed within one year after the injury, when you are still healing.
Steroid use: If you have used steroids in high doses or for a long time, you are at increased risk for avascular necrosis. Reasons you might have taken high doses of steroids include treatment of asthma, an autoimmune disease, or cancer.
Alcohol abuse: If you drink alcohol heavily on a daily basis, you are more likely to get talar avascular necrosis. Drinking heavily increases the amount of fat traveling in your blood vessels. It is thought that drops of fat block small blood vessels, which is what leads to avascular necrosis.
Blood disorders: Blood disorders associated with clotting of small vessels, such as sickle cell anemia, can lead to talar avascular necrosis.
Foot and ankle orthopaedic surgeons typically diagnose talar avascular necrosis through X-rays and/or MRI. X-rays should be weightbearing (taken while you are standing) to enable your surgeon to better evaluate the alignment of your bones. Weightbearing X-rays also allow your surgeon to identify narrowing of the joint spaces around the talus, which is a sign of arthritis (loss of joint cartilage that can cause pain and stiffness).
An MRI can show exactly how much of the bone is affected, and how much damage there may be to the cartilage in the joints around the talus. CT scans can also be helpful to identify any associated fractures or fragmentation of the bone.
An MRI image showing talar avascular necrosis with fragmentation and collapse. The green arrow points to the healthy bone of the tibia, while the red arrow points to the dead bone of the talus.
Treatment for avascular necrosis depends on the severity: how much of the talus is involved and whether there is any collapse or fragmentation. Your foot and ankle orthopaedic surgeon may recommend one of these options, based on their examination and your goals for treatment.
Medication: There are some medications that can help prevent collapse of the talus. This class of medications is called bisphosphonates. They work by shutting down your osteoclasts, the cells that break down bone. This prevents breakdown of the bone around the area of avascular necrosis.
Core decompression: In this procedure, your foot and ankle orthopaedic surgeon drills into the area of avascular necrosis. The goal is to relieve pressure in the area of dead bone and create space for new bone to form. Usually some bone graft is inserted at the time of surgery to help encourage your bone to heal. This is a good surgery for patients with smaller areas of avascular necrosis, without joint collapse or arthritis.
Vascularized bone grafting: Your surgeon may recommend a vascularized bone graft to help bring a new blood supply to the talus. A vascularized bone graft is a piece of bone from another part of the foot or even somewhere else in the body that is attached to a blood vessel. When the bone is inserted into the talus, it helps bring more blood to the talus, which will help new bone to form. This is a major surgery with a long recovery, but it is often successful. This surgery is a good option for patients with severe avascular necrosis without any collapse or arthritis.
Joint fusion: If your avascular necrosis is associated with bad arthritis (loss of cartilage in one of the joints around the talus), then your surgeon may recommend a joint fusion. In a fusion, your surgeon removes the joint and connects two bones together so they grow into each other and become one bone. This process can help heal avascular necrosis and get rid of pain, although you will lose some motion. The amount and type of motion lost depends on the joint being fused.
Total talus replacement: This surgery is an option for patients with severe avascular necrosis who may have collapse or fragmentation of the bone. It involves replacing the talus bone completely with a custom-made metal talus. This is a newer procedure, and while most patients do well in the first few years after surgery, we do not know how patients do in the long-term.
Recovery from surgery depends on the procedure performed. Most surgeries require at least a few weeks of non-weightbearing after surgery. For surgeries that require bone healing, such as joint fusion, the recovery will be longer, ranging from 6-12 weeks of non-weightbearing. Full recovery can take 1-2 years as you will need to regain your strength and function after surgery.
The risks and complications depend on the procedure performed. The more extensive the surgery, the greater the risks. Prior to surgery, you should have an in-depth discussion with your foot and ankle orthopaedic surgeon about the risks of the particular surgery.
Not necessarily. If you are not having surgery, you should have regular follow-up with X-rays and/or MRI with your foot and ankle orthopaedic surgeon to look for any worsening over time.
If you have been diagnosed with talar avascular necrosis and you experience increasing pain, swelling, or stiffness, you should see your foot and ankle orthopaedic surgeon for repeat X-rays/MRIs. Your surgeon will look for any changes, such as signs of worsening arthritis, collapse, or fragmentation.
Original article by Elizabeth Cody, MD
Contributors/Reviewers: Sudheer Reddy, MD
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