Total ankle replacement (TAA), also known as total ankle arthroplasty, refers to a surgical procedure during which damaged bone and cartilage from the ankle joint are removed and replaced with new artificial components. A total ankle replacement procedure may be considered when chronic ankle pain and disability from arthritis have not responded to conservative treatment and interfere with normal daily activities. The replacement prosthetic ankle joint surfaces are made of low friction materials that are able to glide freely against each other and thus restore mobility and function to the joint.
The ankle joint is formed where the two bones of the lower leg (the tibia and fibula) meet the ankle bone (the talus). This junction is referred to as the true ankle joint. It is a hinge joint and is responsible for the up and down motion of the foot. The side-to-side motion of the foot is facilitated by a joint that is located between the bottom of the ankle bone and the top of the heel bone (the calcaneus).
The complex design of the ankle and its supporting tissues makes it a very stable joint. It is so strong that it can withstand 1.5 times an individual’s body weight when walking, and up to eight times the body weight when running. The ankle working in conjunction with the foot provides support, cushioning, balance, and other functions that are essential for motion. A smooth and effortless gait depends on the normal function of the ankle joint.
There are several forms of arthritis and related conditions that can affect the ankle joint and cause problems like pain, stiffness and swelling. Arthritis in the ankle may involve any or all the bones in the joint. End stage arthritis in the ankle is characterized by pain as well as a loss of function and mobility that severely limits normal activity. At this point in time any conservative and non-surgical forms of treatment have been exhausted.
Traditionally advanced arthritis in the foot has been managed with a surgery called arthrodesis or ankle fusion. In this procedure the ankle joint, where the ends of the lower leg bones and the talus meet, are fused into one bone. This fusion fixes the joint in the correct position, eliminating motion and reducing pain from the arthritic ankle. While this procedure continues to be helpful and is the treatment of choice in certain cases, a more recent alternative known as total ankle replacement offers pain relief with the added benefit of retaining ankle motion. Total ankle replacement also does not produce significant additional stress on the surrounding joints that might lead to future degenerative changes.
The best candidate for an ankle replacement is a relatively healthy individual with ankle arthritis who has either no deformity or misalignment of the ankle or very minimal ones. Previous ankle joint infections as well as some medical problems that increase the risk of complications may prevent an individual from being selected for this particular procedure. Ankle replacements can wear out over time and may require a revision surgery or conversion to an ankle fusion. Additional procedures to address other sources of pain in the ankle and foot may also need to be performed for a better outcome.