Surgical Options: Ankle Replacement Surgery
Dr. Borgini wrote an informative overview of joint replacement surgery including information on the most common types of joint replacement surgery, the various materials used for the replacement joints, and the benefits and risks of joint replacement surgery.
Although total ankle replacement surgery has been in existence and researched since the 1970s, it has never progressed to the same level of use as hip and knee replacement. This may be because of technical design difficulties related to the weight, pressure and motion that the ankle joint must bear. In the 1980s, there was a very high long-term failure rate for pain control and joint function, and the procedure was basically shunned in favor of ankle arthrodesis (joint fusion). Since then, researchers have been working to develop more successful and longer-lasting ankle joint replacements including types offering either more stability or more flexibility and those using either cement fixation or cementless fixation.
It appears that there are now two types of ankle replacements approved by the FDA and available on the U.S. market. The first is the Agility Ankle Revision Prosthesis, approved by the FDA in May 2002. It is intended to be used with cement fixation and only in patients who have had a failed previous ankle replacement. The other is the Topez Total Ankle Replacement System, made by DePuy, Inc., which was approved in November 2005. It is also intended for use with cement fixation in patients who have failed previous ankle replacements. Three other types of ankle replacements (the STAR device- Scandanavian Total Ankle Replacement, the Beuchel-Pappas device and the TNK ankle) are under investigation, but are not yet approved by the FDA.
The surgery basically consists of cutting the tibia and fibula (the bones that make up the socket of the ankle joint) and then cutting away the lower bone (the talus) connecting the foot to the leg bones. The new joint implant is inserted into both the leg bones and the talus bone and held in place with screws and maybe a bone graft to allow the bones to fuse and heal to the implant.
In situations where a total ankle replacement is not the optimal solution for a patient, other options are available such as an ankle arthrodesis or fusion. Both procedures are intended to reduce pain in the joint. The main difference is that an ankle fusion, just like fusions of other joints, makes the joint much more stable, but the patient will lose mobility. Joint replacements tend to be more mobile, but stability is the trade off. Also, if the ankle replacement joint is not properly aligned, it can cause the patient to walk abnormally over time, which can cause hip and knee problems.
It appears that ankle replacement surgery is still considered investigational or unproven because there are few long term studies that show a relatively high rate of long-term effectiveness. The studies that have been done over the last decade tend to show that while the success rate may be in the 70% area, a significant portion around 30% of the ankle replacements require a second surgery to revise or replace them. Overall, they do reduce pain for a while, but have a lower success rate overall than the more common knee and hip replacements. Patients considering either ankle fusion or total ankle replacement surgery should discuss all options with their physician. Surgery time, healing time, and time in rehabilitation are all significant factors that should be considered.