Open ankle fusion, also known as ankle arthrodesis, may be considered for patients who have an ankle disorder or deformity and who suffer severe pain and impaired function.
Ankle fusion keeps the ankle joint from moving during walking and other activities, so the remaining joints in the foot need to be normal and have good mobility for the surgery to be successful.
The surgeon must also take into account foot positioning with regard to overall limb alignment and function.
Ankle fusion can be performed using several techniques. When good surgical technique is used for the right patient, ankle fusion can correct any deformity and dysfunction and relieve pain.
“Fusion rates ranging from 80% to 100% have been reported in the literature, along with patient satisfaction rates over 80%.” (Department of Orthopaedic Surgery Faculty Papers, 2008)
Ankle fusion is especially helpful in patients who are young and active. However, the surgery is not without risks, which are discussed below.
When Is Open Ankle Fusion Appropriate?
Open ankle fusion is often recommended for patients who have a history of ankle arthritis that is causing persistent pain, loss of function, or deformity of an ankle joint.
The procedure is only considered after non-surgical treatments (such as corticosteroid injections, ankle foot orthoses, anti-inflammatory medications, custom orthotics, and ankle braces) have been tried. Some conditions that may warrant open ankle fusion are:
- Arthritis (post-traumatic or rheumatoid arthritis)
- Avascular necrosis (secondary to trauma or metabolic disease states)
- Congenital ankle deformities
- Failed ankle implant
- Lateral ankle instability (after failure of operative and nonoperative treatment)
- Neuromuscular disorders
- Neuropathic Arthropathy (Charcot deformity)
- Sepsis or severe infection
Preparing for Open Ankle Fusion
Osteonecrosis of the talus and smoking are known risk factors for nonunion. Before open ankle fusion can be considered, your doctor must examine the foot and rule out any osteonecrosis. Cessation of smoking is important to improve the chances that your surgery will be successful.
In preparation for open ankle fusion, you will undergo a complete physical examination. This will include blood work and a modified Allen test and/or Doppler to evaluate foot vasculature. Your doctor will check the external rotation of the ipsilateral hip.
The findings will help determine proper foot positioning, which is important for good function after surgery. The mobility of the rest of the foot will be reviewed to ensure that all unaffected foot joints are working normally. You will also undergo radiographic studies, which may include x-rays and CT or MRI scans.
The Open Ankle Fusion Procedure
Open ankle fusion takes about one to two hours and is usually performed under general anesthesia. The purpose of the surgery is to remove all the remaining cartilage from the ankle joint and the underlying hard bony surface.
Then the joint is screwed together to immobilize it and allow the bones to fuse. The foot will be positioned at a right angle to the floor.
An incision is made on the side of the ankle, usually over the outer side, although an incision may be made in the front or inner side of the ankle if there is an associated deformity that prevents going through the outer side.
Chisels are used to remove cartilage and the hard underlying bone. When the joint has been prepared, two screws will be placed across the ankle joint. The tissues are then stitched and a below-knee half cast is applied.
Other ankle fusion techniques include:
- Arthroscopic ankle fusion — This technique produces minimal soft tissue disruption and generally results in the mildest and shortest-lived post-operative pain.
- Fusion of the ankle with an Ilizarov frame — This procedure allows the greatest degree of correction and does not require the use of screws. It has an advantage when infection is present, because screws placed across the infected site tend to encourage the persistence of local infection.
The main advantage of open ankle fusion versus an arthroscopic technique is that greater degrees of fixed deformity around the ankle joint can be corrected with the open approach. An open approach may also be performed with compression and internal fixation. Open ankle fusion with a fibular-sparing technique has also been done.
After Open Ankle Fusion
For the first 72 hours after surgery, it is important to rest and keep your foot elevated (even in bed) to prevent swelling and pain. The swelling gradually resolves but can persist six months after surgery. Some patients may continue to have minor swelling, particularly at the end of the day.
You will be given a prescription for pain medication at discharge and will be referred to a physiotherapist, who will show you how to use crutches. You should not put any weight on the foot for at least two weeks. The foot will be immobilized for 12 weeks.
At your first follow-up appointment about two weeks after surgery, your dressing will be changed and the sutures removed.
A cast is applied to allow you to start putting weight on the foot. You doctor will probably want to see you six weeks after surgery, at which time an x-ray may be taken to evaluate healing, and then again at 12 weeks after surgery to remove the cast.
Driving is not recommended during the first 12 weeks after surgery. When you can return to work depends on the physical demands of your job.
Office workers may be able to return after two weeks. Those with more physical occupations may not be able to return for three to six months. Full recovery generally takes about six months to a year.
Risks of Open Ankle Fusion To Be Aware Of
Aside from the usual risks of surgery (infection, blood clots, nerve damage, scar sensitivity), open ankle fusion is associated with two major complications:
- Pseudarthrosis (false joint): This results when the bones do not fuse. “A nonunion rate as high as 40% has been reported” (Journal of the American Academy of Orthopaedic Surgeons, 2000)
- Malaligned fusion: When the fusion position is incorrect, function will be impaired. Patients may have difficulty in walking and gait problems can occur.
Patients with these complications may require further surgery.