Ankle replacement surgery

Ankle replacement surgery is indicated primarily to treat an arthritic ankle when the cartilage covering the joint has suffered considerable wear and tear.

Historically, knee and hip joints were the first to benefit from prosthetic implants in the 1970s. Little by little, other materials and designs have appeared allowing the implantation of prostheses in areas such as the shoulder and ankle.

Arthrodesis, which is the permanent blocking of a joint, was for many years the only option in cases of painful arthritis. Although this surgery is still applicable in many cases, the development of the ankle prostheses now offer other options for the treatment of ankle arthritis.

Concept and benefits

Implanting a prosthesis consists of replacing the affected joint by a synthetic implant. In the ankle, this means replacing the joint between the tibia and the talus (astragalus).

In common with any manufactured product, a range of different prosthetic designs is available on the market; however, their design is often identical. A metal structure is anchored in the bone on each side of the joint and is separated in its centre by a polyethylene (plastic) interface. The mobility of the ankle is achieved by these implants sliding one over the other.

Ankle replacement (Tornier©)

Prosthesis implanted in the ankle.

The obvious advantage of the prosthesis compared to blocking the ankle (arthrodesis) is retaining the mobility of the joint. However, it is worth stating that an ankle replacement does not equate to a full recovery of movement. The mobility after surgery depends mainly on the degree of mobility before surgery. However, ankle arthritis quickly results in joint stiffness and mobility is generally extremely reduced when the arthritis becomes sufficiently severe to justify the implantation of a prosthesis. A partial recovery of movement is therefore an expected outcome of this surgery. It is also expected that pain should decrease substantially or completely disappear.

Preserving the mobility of the ankle can also protect the neighbouring joints from arthritis, unlike an arthrodesis, which accelerates the process. Patients suffering from foot joint injuries other than those affecting ankle joint are excellent candidates for surgery.

Finally, the life expectancy of a prosthesis depends on its use, the quality of his placement and more complex factors. It is preferable to offer a replacement to a patient who is not very active and sedentary rather than to a young patient who does sport.
Limits and difficulties

Although the sole indication for a prosthesis is painful arthritis of the ankle, it is subject to conditions. The following situations are strict or relative contraindications:

Young and active patient or manual worker

An active patient will quickly wear down the prosthetic components and the life expectancy of the prosthesis, which is normally around 10-20 years, may be shortened by a few years. The risk is that the prosthesis may detach from the bone, otherwise called “prosthetic loosening”. Changing an ankle prosthesis involves complex and major surgery and is not always possible.

Unstable ankle

The stability of the ankle is very important for the sustainability of the prosthesis. Any instability must be corrected during the procedure or the surgery will be contraindicated.

Infection

Infection of the ankle or even at another site is an absolute contraindication to the implantation of any prosthesis. In fact, bacteria will attach themselves to synthetic implants and often require the removal of the prosthesis.

Poor bone quality

It is important that the prosthesis is attached to strong and stable bone. When this is not the case (necrosis, etc.) there is a major risk that the prosthesis may move which can result in serious consequences (even the loss of the implant).

An ankle replacement must be carried out after due consideration of the implications. In the presence of risk factors, arthrodesis is often preferred and remains an excellent surgical option. Sport and physical activities carried out should be reasonable and must certainly change in order to protect the prosthesis.

Finally, it should be noted that the placement of an ankle prosthesis is a delicate procedure that requires an excellent knowledge of foot surgery and considerable experience in prosthetic ankle surgery.
Conclusion

A replacement is an excellent alternative to arthrodesis in cases of advanced ankle arthritis. It is a procedure that has been performed successfully for decades in very many patients and is a growing trend. The implantation of a prosthesis is, however, subject to conditions that must be known and researched. Equally, the placement of a prosthesis involves complex surgery that must be performed by an experienced team. When all these conditions are met, it allows patients to retrieve ankle mobility and stay pain free.

Ankle arthritis

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Ankle replacement surgery

Concept and benefits

Limits and difficulties

Conclusion

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