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Friday, February 25, 2005

TAA has positive results in intermediate term

Although ankle arthrodesis remains the standard surgical treatment for disabling ankle arthritis, total ankle arthroplasty (TAA) offers the potential of preserved joint motion in select patients, according to presenters of Paper 124 yesterday.

During the past decade, the interest in TAA has increased, particularly as second-generation implant designs have been developed. Researchers conducted a retrospective review of the intermediate-term results of TAA in 41 consecutive patients (43 ankles). Evaluation included preoperative and postoperative questionnaires, physical examination, and radiographs.

At the time of follow-up, 38 patients (40 ankles) were available for review. The most common preoperative diagnoses included post-traumatic arthritis (60 percent) and rheumatoid arthritis (20 percent). The average age of patients at surgery was 63 years old (range: 32 to 85 years old); average follow-up was 44.5 months (range: 26 to 64 months). All patients received the Agility (DePuy, Warsaw, Ind.) total ankle replacement system.

Patients completed a preoperative ankle-hindfoot questionnaire developed by the American Orthopaedic Foot and Ankle Society (AOFAS) at the initial office visit; the average score was 33.6. After the surgery, patients completed a similar AOFAS questionnaire as well as a Medical Outcomes Study Short Form-36 (SF-36) survey. The postoperative AOFAS ankle-hindfoot scores averaged 83.3, a significant improvement (p<0.001). Post-operative SF-36 Physical Component Summary averaged 49.5, with an average score of 56.1 for the postoperative SF-36 Mental Component Summary.

Although 34 of the 40 ankles demonstrated radiographic lucency, the degree of involvement varied. Five tibial and 11 talar components demonstrated evidence of subsidence or migration. Fifteen ankles required additional surgical procedures subsequent to the index operation, including one revision TAA. Overall, 37 of the 38 patients were satisfied with the outcome of their surgery and would undergo the same procedure under similar circumstances.

Based on this information, researchers concluded that the Agility TAA results in a favorable clinical outcome and patient satisfaction in the majority of patients. TAA is, however, associated with potential complications and the need for subsequent surgical treatment.

Researchers found that "areas of radiographic lucency or lysis around the ankle prosthesis were very common…areas of lucency, defined as a radiolucent line of 2 mm in width or less, were stable throughout the follow-up period, [while] areas of lysis appeared slowly progressive." They also noted that using the revision talar component, which was introduced in 2001, for primary TAA provides a theoretic biomechanical advantage and may yield more favorable results.

In conclusion, researchers found that radiographic follow-up commonly reveals periprosthetic lucency and component migration, but this does not appear to adversely affect the intermediate-term clinical outcome. The long-term consequences of such radiographic findings are concerning, and surgeons and patients choosing this procedure need to be cautious.

Researchers included Franz Kopp, MD of San Diego, Calif.; Mihir Patel, MD of Zionsville, Ind.; and Jonathan Deland, MD, and Martin O'Malley, MD, both of New York City.

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