Surgeons know that replacing the ankle joint (a procedure called total ankle arthroplasty or TAA) is more successful for some patients than for others. This particular operation requires selecting patients carefully for the best outcomes.

There are all kinds of potential reasons why one patient would be a good candidate for an ankle joint replacement while another is rejected as a "poor" candidate. Factors such as age, sex (male versus female), body-mass index (BMI), and general health may make a difference. Some studies show results are compromised most often when the patient has rheumatoid arthritis.

In this study, the orthopedic surgeons were interested in narrowing down risk factors associated with complications following total ankle arthroplasty. They specifically focused just on wound infection of the incision used to open the ankle up. By doing a retrospective (looking back) chart review of 106 patients, they were able to see who had problems and why.

The authors collected, compared, and analyzed data recorded in the patients' charts. For example, they looked at implant size, the use of medications, smoking (tobacco use) status, and type of sutures used to close the wound. They also separated the patients into three basic groups based on severity of complications. They compared the presence of each of these factors based on which group the patients were in.

The first group had no wound complications or only mild/minor problems with the healing incision. Group two had minor complications that could be easily treated with local care and possibly some oral (taken by mouth, usually in pill form) antibiotics. The most difficult and severe group (group number three) had major complications that meant having another operation.

As it turns out, the main difference between the groups with no complications or only mild complications and the group with major complications was the presence of diabetes mellitus. The biggest threat to healing without complications was the presence of rheumatoid arthritis (RA). In fact, patients with RA were 14 times more ikely to develop severe enough complications at the incision site to require another operation.

Why is rheumatoid arthritis such a big problem? It is an inflammatory condition that is often treated with medications that suppress (decrease) the immune system's response. So any bacteria present at the surgical site aren't always taken care of by the immune system. They can quickly mount an attack on the body. With limited immune capability, the body can't fend off the growing bacteria and a full-blown infection breaks out.

The authors concluded that rheumatoid arthritis is not only a risk factor for infection inside the joint, it is also the number one risk factor for infection and complications at the wound (incision) site.

What can be done to prevent this from happening? Until we know how to work around the rheumatoid arthritis, surgeons are restricted from choosing a total ankle replacement for these patients.

This is especially true for anyone with rheumatoid arthritis who has poor circulation, is overweight (obese), and/or who smokes (uses tobacco products). Patients with any of these factors present at the time of the surgical evaluation are simply at too high a risk to consider for a total ankle arthroplasty.

The authors provide three caveats -- the proverbial "yes, but" or "beware" of this study. First, it was a fairly small number of patients to base any firm recommendations off of. Second, they only evaluated patients with one type of ankle joint implant (DePuy Orthopaedics Agility Total Ankle System). The results might be different with another type. And third, follow-up was short-term (six months). The long-term survival of the joint and/or the start of a second infection later on was not evaluated.

Reference: Steven M. Raikin, MD, et al. Risk Factors for Incision-Healing Complications Following Total Ankle Arthroplasty. In The Journal of Bone and Joint Surgery. September 15, 2010. Vol. 92-A. No. 12. Pp. 2150-2155.