Over the last 40 years, ankle joint replacements have gone through three generations of implant design and materials. In this article, a group of orthopedic surgeons review the history of total ankle arthroplasty (TAA) and bring us up to date on this treatment approach for ankle arthritis.
Early designs were stable but the implants often loosened up or sank down into the bone. The first TAAs had a high failure rate and were removed from the market. Since then, many improvements have been made. Today's implants allow the patient to keep ligaments needed for stability and avoid removing so much bone.
Porous-coated titanium or chromium alloy materials allow for bone ingrowth around the implant. It's possible to hold the implant in place without cement. Various designs are in clinical trials or being considered by the FDA for use with the public. Short-term and medium-term results are available but long-term (10 to 15 years or more) studies of the newer implants are not yet possible.
Patient selection and surgeon experience seem to be two important keys to success. Although patient age doesn't seem to be a factor, the ratio of patient weight-to-implant size does make a difference. And patients with changes in soft tissue alignment and altered joint mechanics may not be good candidates for TAA.
Complications are three times more likely in cases where surgeons are doing their first 10 cases. Poor wound healing and bone fractures are common problems that decline with increased surgeon experience.
Care must be used to avoid putting too much tension on the soft tissues with self-retaining retractors during the procedure. Sutures that are too tight or a foot positioned improperly are examples of technical errors made that can be corrected with practice. Choosing the wrong size implant can also create many postoperative problems.
There's still much we don't know about ankle implants. Studies are needed to compare outcomes using different implant designs. Results of the same prosthesis but by different surgeons should be compared. Changes in design and implant materials will continue to improve bone ingrowth and prevent wear-related problems.Loretta B. Chou, MD, et al. Osteoarthritis of the Ankle: The Role of Arthroplasty. In Journal of the American Academy of Orthopaedic Surgeons. May 2008. Vol. 16. No. 5. Pp. 249-259.