What are the goals of an ankle arthrodesis?
The goal of ankle arthrodesis (also commonly known as ankle fusion) is to relieve pain and maintain or improve function for a patient with ankle arthritis. Ankle arthritis is degeneration of the cartilage that covers the ends of the bones that form the ankle joint. These bones are the tibia, the fibula, and the talus. Pain typically is made worse with movement of the arthritic
ankle. The goal of ankle arthrodesis is to take the ankle bones and fuse them into one bone. This eliminates motion and reduces pain from the arthritic joint.
What signs indicate an ankle arthrodesis may be needed?
Patients may be candidates for ankle arthrodesis if they have severe ankle arthritis and more conservative treatments have failed. Many patients may find relief from the pain associated with ankle arthritis using:
Injections of steroids into the ankle joint
Modification or limitations of activity
Walking aids (such as canes)
Specialty braces that stabilize the ankle and restrict its movement
Cushioned and specially contoured shoes
These treatments do not reverse ankle arthritis. In many patients they may temporarily or permanently provide relief from pain. Non-operative treatments avoid the potential complications of surgery. If these measures fail to provide adequate pain relief or maintain function, a patient may be a candidate for ankle fusion.
When should I avoid surgery?
Contraindications to ankle arthrodesis include, but are not limited to:
Insufficient quantity or quality of bone for fusion
Neurologic or vascular illness that decreases healing or recovery
Medical conditions that increase the risk of anesthetic
Severe deformity of the limb
General Details of Procedure
Patients are typically asleep or sedated in the operating room during the procedure and do not feel pain during the procedure. Incisions are made in and around the ankle to access the joint. Any remaining cartilage within the ankle joint is removed so that there is contact between the bony surfaces. The ankle is held in the most functional position with metal hardware. This allows the bones to heal together.
Ankle arthrodesis may be performed through an incision on the outside of the ankle or the front of the ankle. Sometimes a bone graft may be used to aid in fusion. This graft may be taken from the pelvis, heel bone or just below the knee. Ankle arthrodesis may be performed through small incisions that allow a camera and tools to be placed into the joint. This is known as arthroscopic surgery.
After the joint has been accessed, tools are used to scrape away remaining cartilage and the joint surface is prepared for fusion. Screws or screws and plates may be used to hold the ankle in the correct position for fusion. If a patient is having his subtalar joint fused at the same time, a nail (a tubular piece of metal that goes in the middle of the bone) may be used to hold the joints in position. Hardware may be placed through the incision used to access the ankle joint and/or through small poke holes. In rare cases, pins and bars outside the skin are used to hold the ankle in position.
X-rays are used during surgery to check the alignment of the joint and the placement of hardware. The choice of approach and hardware depends on a patient’s specific anatomy, condition and the surgeon’s preference.
Incisions are closed with sutures or staples. Patients are often placed in splints (non-circumferential casts) or plastic boots to protect the ankle fusion.
What happens after surgery?
During the immediate post-operative period it is important to keep the fused ankle elevated to minimize swelling. Ideally this means keeping the ankle above the heart by lying down or sitting in a reclined position. Pain pills and intravenous pain medication are used to control pain.
The tibia and talus require at least six to eight weeks before they are fused sufficiently to begin weightbearing. It may take as long as 10 to 12 weeks. During this time patients typically do not put weight on their operative leg. Most patients find navigating their daily lives without putting weight on one leg difficult. Patients typically use crutches, walkers, wheelchairs or knee scooters to get about. Preparation with a physical therapist prior to surgery may be advisable. It is helpful to have someone on hand to help with basic tasks and activities at home, especially during the first two weeks. A patient’s home should be prepared appropriately. Ramps may be needed to navigate stairs. Beds may need to be transferred to ground level. Aids such as shower chairs, commodes and railings may be needed.
Non-absorbable stitches or staples are typically removed 10 to 14 days after surgery. Gentle physical therapy to keep the other joints in the foot supple may begin at this time. X-rays may be taken to check that alignment has not changed. During the first few weeks after surgery, swelling and pain will increase when the foot is below the heart for extended periods of time. Mild amounts of swelling and pain when the foot is below the heart for long periods of time may persist for months, but will gradually improve over time.
After sufficient time has passed, patients slowly begin placing weight on their ankle using a walking boot. X-rays may be obtained to confirm that the ankle is fusing well. Physical therapy will aid in this transition. After 10 to 12 weeks, the ankle fusion is typically sturdy enough to allow walking out of the plastic boot and a gradual return to more vigorous activity.
There are complications that relate to surgery in general. These include the risks associated with anesthesia, infection, damage to nerves and blood vessels, and bleeding or blood clots.
A specific risk associated with ankle arthrodesis is nonunion. This is failure of the ankle bones to fuse together. The ankle bones successfully fuse in more than 90 percent of operations, so the risk is relatively low. If nonunion does occur, a second operation to place bone graft in the ankle and place new hardware may be needed.
Loss of motion in the ankle after a fusion causes the other joints in the foot to bear more stress than they did prior to the surgery. This can lead to an increased rate of arthritis in those other joints. This typically takes several years to develop and may or may not be symptomatic.
Frequently Asked Questions
Will I lose all motion in my foot?
The ankle joint is responsible for the majority of up-and-down motion. Ankle fusion decreases this movement, but the movement of the subtalar joint and the other joints of the foot remains. This allows the heel to move from side to side and the middle of the foot to move up and down. A fused ankle does not typically result in a fully rigid foot. Ankle arthrodesis does change how a person walks. However, with proper shoe wear most patients do not limp.
Are there activities I should avoid with an ankle arthrodesis?
Once the ankle has fused, it is quite durable. Many patients work physically demanding jobs, walk long distances, hike, cycle and ski on fused ankles. The fused ankle will never function exactly like a normal ankle, however. Patients are encouraged to discuss specific hopes for return to activity with their physicians. Running and similar activities are not recommended.
Do I need to have the plates or screws removed?
No. Occasionally the plates and screws may be removed if they are close to the skin and cause irritation. They may also need to be removed if an infection develops. Otherwise hardware is not typically removed. There is usually not enough hardware in place to set off metal detectors.
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