Total Ankle Replacements vs Ankle Fusion: Choosing the Right Option
Introduction to Ankle Arthritis and Surgical Options
Arthritis is a well-known condition that leads to degeneration of the articular cartilage in our joints, leading to pain, swelling and stiffness. The ankle joint is a unique joint in its anatomic, mechanical, and biological characteristics compared to other joints in the body.
Unlike the hip and knee, which are prone to develop primary osteoarthritis, the ankle joint develops arthritis predominantly after a traumatic event, such as a fracture or the sequelae of chronic sprains and instability of the ankle ligaments.
Even if you lead a healthy lifestyle, arthritis usually progresses over time and causes a significant impact on mobility and quality of life. If you have been diagnosed by your orthopedic physician with ankle arthritis and have failed conservative, non-operative treatments, surgical intervention may have been offered to you.
Currently, the surgical options for end-stage arthritis are Ankle Fusion and Total Ankle Replacement. Both surgical options are great choices for the pain relief for which patients are searching.
What is Total Ankle Replacement Surgery (TAR)?
A total ankle replacement involves removing the damaged cartilage and a limited amount of underlying bone from the joint. Then a prosthetic implant is inserted into the joint. The implants are typically two metal components that are attached to the bone surfaces with a piece of plastic (polyethylene) interposed between the metal surfaces.
Similar to other joint replacements, the motion of the ankle joint is retained, or even improved, after replacement surgery. A patient can expect to increase the ankle motion by about 10-15 degrees from levels before the surgery. Although this improvement may be considered nominal, it is in stark contrast to a fusion procedure, which completely sacrifices all motion of the ankle.
What is Ankle Fusion Surgery (Arthrodesis)?
Undergoing an ankle fusion (otherwise known as ankle arthrodesis) is another option to address ankle arthritis. An ankle fusion is a surgical procedure that involves removing the remaining and damaged cartilage in the joint. The bone surfaces are then prepared for fusion, which leads to the bleeding of the opposing bone surfaces. Removing the cartilage from the joint surfaces allows the bone surfaces to heal like a fracture. Orthopedic hardware is inserted to compress the bone surfaces together. This bone bridges the gap where the joint cartilage used to exist. The fusion essentially removes the joint and the two opposing bones grow together.
Total Ankle Replacement Surgery (TAR) vs Ankle Fusion Surgery (Arthrodesis)
The main difference between an ankle fusion and replacement is that the ankle fusion sacrifices any remaining motion of the joint. Usually, an arthritic ankle may not have a significant amount of motion at baseline before the surgery. After an ankle fusion a patient may not notice too much of a difference in the function of the ankle. Therefore, a patient may be able to ambulate and perform activities similar to those before surgery. Studies have shown that there are mechanical changes to a patient’s gait and function of the foot and ankle.
Factors Influencing Treatment Selection
When considering a Total Ankle Replacement, patients with uncontrolled diabetes, especially in the presence of diabetic neuropathy, have been shown to have a higher risk of complications after total ankle replacement. Additionally, during your physical examination, if you are found to have a very high arch or a severe flat foot deformity in the affected ankle, you may require additional procedures at the time of your ankle replacement surgery; or may be better suited to an ankle fusion surgery.
Ankle fusions can be performed for arthritis with severe deformities of the ankle. Also, ankle fusions are preferred in the younger patient—usually below age 50. Additionally, there are no activity restrictions placed on a patient after fusion surgery.
Finally, poor skin condition or history of skin grafts, or problems with blood flow to the foot and ankle from vascular disease can cause major complications after both total ankle replacement and ankle fusion surgery.
Highly active, younger patients, and people with physically demanding jobs may benefit more from having ankle fusion surgery. This is due to the high stress placed on the ankle joint with physical activity. This high stress would lead a younger, more active patient to wear out an ankle replacement sooner than expected.
Risks and Complications of Ankle Surgery
After ankle replacement surgery, a patient should expect a significant improvement in quality of life and function. However, the unique mechanical characteristics of the ankle continue after surgery and there are strict, long-term activity limitations after total ankle replacement. Due to the high forces across the relatively small ankle joint surfaces, a patient is unable to run at a fast speed, perform repetitive jumping activities, and participate in high-impact exercises and/or high-level athletics. Even a very physically demanding job can be an impediment to undergoing an ankle replacement.
Ankle fusion surgery provides very good pain relief for patients. However, there are potential drawbacks and complications of an ankle fusion procedure. These include nonunion (a process in which the bone does not heal completely), hardware complications and loosening, and development of arthritis in surrounding joints.
Other potential risks possible with both surgeries include infection and incisional healing. Delayed wound healing may require repeat surgery to close a non-healing wound to avoid a deeper infection. This is due to the precarious blood supply to the front of the ankle, which is the most common approach to perform these surgeries. Pre-surgical antibiotics, proper preoperative testing, and high-level expertise and good surgical techniques are used to help mitigate these complications.
Recovery and Rehabilitation
Ankle replacement and Ankle fusion have a similar recovery. Both procedures involve a period of non-weight-bearing in a splint, usually for about two weeks. Transition to a removable Cam boot walker is then done after suture removal.
Depending on surgeon preference and the patient’s bone quality, weight-bearing with a total ankle replacement may begin anywhere from 2-4 weeks from surgery.
Ankle fusion surgery requires approximately 6 weeks of non-weight-bearing. Physical therapy usually begins after weight-bearing is initiated.
Long-term Outcomes and Success Rates
In general, patients have a high satisfaction rate of about 90% after total ankle replacement in recently reported studies [1]. Implant survival, which is the percentage of ankle replacements still functioning well in a patient, is 80-90% at 10 years from surgery.
Usually, if a patient avoids early complications after ankle fusion, the procedure has a high satisfaction rate for pain relief. A patient’s gait is affected by the fusion of the ankle joint, and this has shown to produce arthritis in surrounding joints, but may take up to 20-30 years to occur.
If you are experiencing ankle pain from arthritis or another chronic condition, please schedule an appointment with myself or another one of my skilled Rothman orthopedic foot and ankle surgeon colleagues, to determine the most suitable surgical option based on your individual diagnosis, expectations, and lifestyle.
Citations
- Lee MS, Mathson L, Andrews C, Wiese D, Fritz JM, Jimenez AE, Law B. Long-term Outcomes After Total Ankle Arthroplasty: A Systematic Review. Foot Ankle Orthop. 2024 Nov 8;9(4):24730114241294073. doi: 10.1177/24730114241294073. PMID: 39525891; PMCID: PMC11544666.
