An artificial ankle joint, also called an ankle replacement, is a surgical treatment for arthritis in the ankle. The outcome of this procedure depends greatly on the surgeon’s experience. On this page, you’ll find helpful information as well as selected specialists and centers for ankle replacement surgery.
The ankle joint connects the leg to the foot. It includes the bones and soft tissues responsible for flexing and extending the foot. The ankle is the most heavily loaded joint in the human body. With every step, it may carry up to seven times a person’s body weight.
When the ankle joint is replaced with an artificial joint, it is called an artificial ankle joint or ankle prosthesis.
Illustration of the different bones in the ankle joint © bilderzwerg | AdobeStock
Osteoarthritis, or joint wear-and-tear, can also affect the upper ankle joint (UAJ). It is especially common in older adults who participate in sports that put stress on the lower limbs. In advanced age, ankle osteoarthritis often develops. Sports that increase risk include:
The most common fractures in the lower limb occur at the UAJ. After ankle fractures, up to one in two cases may develop arthritis years later. This can happen regardless of how precisely the fracture was surgically repaired.
These discouraging short- and long-term outcomes are caused by the very sensitive biomechanics of the ankle joint. For example, if a step of just 1 to 2 mm remains in the bone after surgery, it can reduce the contact surface between the bones of the lower leg and the foot by 30 to 60 percent.
This leads to overloading of the remaining joint surface, which permanently increases the risk of arthritis. Even small cartilage injuries can, over time, trigger degenerative changes.
The most frequent sports injury also occurs in the upper ankle joint. It is estimated that a lateral ligament tear happens up to 1,000 times daily in Germany.
People under age 35, especially teens between 15 and 20, are most often affected. About 15 percent of them will later develop wear-related ankle problems.
Before deciding on an ankle replacement, a thorough physical examination including an X-ray of the ankle joint is necessary. An MRI (magnetic resonance imaging) may also be required in certain cases.
Not every patient is suitable for an ankle prosthesis. Bone quality plays an especially important role: the talus bone must have good structural quality. Severe osteoporosis around the joint is a contraindication.
Infections in the joint area must be ruled out. If an infection occurred, it must have been fully treated and at least one year in the past.
Other limitations include:
Contraindications for ankle replacement include:
In most cases of ankle arthritis, conservative treatments are tried first. These may relieve symptoms for years.
If conservative options no longer help, there are two surgical treatments available:
The ankle typically reacts to wear with:
These are signs of progressive cartilage loss. Eventually, stiffness develops, resulting in full-blown arthritis.
In the past, the only option at this stage was fusion surgery. This surgical immobilization usually provided pain relief.
However, in about one out of five patients, fusion fails because the bones do not fully heal. In such cases, pain persists and another surgery is needed.
If fusion succeeds, the ankle is “locked” and cannot move anymore. Pain goes away, but lost mobility must be compensated by neighboring joints.
This extra strain can cause problems. A feared long-term complication is “adjacent joint arthritis,” which develops in nearby joints due to overuse. Up to 28 percent of surrounding joints can be affected later on.
Lifestyle factors also influence the outcome. Poor healing after surgery is more common with:
In recent years, ankle prostheses have become a good alternative to fusion.
Artificial ankle joints have been used since around 1970. Early expectations were not fulfilled—prostheses loosened after only a few years. The design and fixation methods of first-generation implants were inadequate.
Today, modern total ankle replacements show much better long-term results. They usually consist of three components:
Stability is adjusted using the height of the polyethylene insert.
A major advancement is cement-free fixation of the talus and tibia components. A special coating (such as titanium/calcium phosphate) allows the bone to grow directly into the implant.
Ankle replacement is a technically demanding procedure. It should only be performed by surgeons experienced in this field.
Outcomes are not yet fully comparable to hip replacements, but modern implants show similar durability.
If loosening occurs, usually only one component is affected. Complete loosening is rare and mostly linked to infection. There are no universal surgical solutions; the surgeon’s experience determines the best approach.
In cases of aseptic loosening, the implant may be partially or completely replaced. Mixing components from different manufacturers may be possible depending on the bone condition and extent of loosening.
Unlike in hip or knee replacements, there are no standardized revision models for the ankle. Revision surgeries are still rare and done on a case-by-case basis. If a prosthesis fails completely, fusion surgery remains the treatment of choice.
In Europe, the five-year survival rate after ankle replacement is about 89 percent, and the ten-year survival rate is about 76 percent.
Although ankle replacement is still debated, the number of surgeries is increasing. In Germany, about 1,500 procedures were performed annually in 2009, compared with about 800 in the UK.
Early revision rates are around 7 percent, only slightly better than fusion (9 percent). The main cause of revision is premature loosening (28 percent), often linked to the surgeon’s learning curve.
Typical errors during ankle replacement include:
With growing experience and improved techniques, revision surgeries are becoming less frequent.
Fusion is still performed ten times more often than ankle replacement. However, it does not consistently offer better outcomes or fewer complications.
Immediately after surgery, the operated leg is placed in a removable Vacoped® splint.
If recovery goes well, patients can stand with assistance the day after surgery. On day two, the leg is carefully tested with full weight in the splint to secure the implant in place.
From the second day on, walking exercises begin with the splint. For six weeks, the leg may bear up to 20 kg of partial weight. At the same time, gentle mobilization of the ankle is started with simple up-and-down foot movements.
Additional therapies include passive motion exercises, manual lymph drainage, and elevation to reduce swelling.
Sutures are usually removed on day 12 after the wound has healed.
Further physical therapy can take place either:
After six weeks, the splint is removed. Full weight-bearing is encouraged as soon as possible. Rehabilitation usually takes about 12 weeks.
The first X-ray is taken immediately after surgery. Further X-rays are done:
As with any surgery, complications may occur.
A fracture of the inner or outer ankle bone during or shortly after surgery must be stabilized surgically.
Wound healing problems and other soft tissue issues may require extended care, and sometimes plastic surgery.
Some patients may need additional surgeries due to:
Occasionally, implant parts must be replaced or fusion surgery performed. With modern prostheses, bone loss is minimal, so fusion remains a viable backup option.
After successful implantation, patients can realistically expect pain-free mobility in the ankle joint.
Ankle replacement is a strong alternative to fusion, but results still depend heavily on the surgeon’s experience.
Compared with fusion, prostheses offer shorter rehabilitation. Extended immobilization, such as plaster casts, is usually unnecessary.
After a successful procedure, walking is pain-free and mobility is close to normal. Regular shoes can be worn without issues, though high heels are not recommended.
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