According to data presented at the 2012 American Orthopaedic Foot & Ankle Society (AOFAS) Annual Meeting, functional outcomes for patients who underwent either total ankle replacement (TAR) or ankle fusion
were roughly equivalent 5 years after surgery. The report on the multicenter study, conducted by Timothy R. Daniels, MD, and the Canadian Orthopaedic Foot and Ankle Society (COFAS) ankle arthritis research group, was the 2012 recipient of the AOFAS Roger A. Mann Award.

The 388 patients initially enrolled in the study constitute a subgroup of the COFAS Prospective Ankle Reconstruction Database, which includes information on all patients with symptomatic end-stage ankle arthritis who had undergone unsuccessful nonsurgical treatment and who then received either TAR or ankle fusion. Patients showed significant improvement after either intervention.

The primary outcome measure was the total score of the Ankle Osteoarthritis Scale (AOS), a self-reported, ankle-specific functional outcome measure. Secondary outcome measures included the AOS pain and disability subscales; the physical component summary (PCS) and mental component summary (MCS) scores from the SF-36, a generic measure of general health status; and the need for revision of each surgical procedure.

Of the original 388 patients, 107 underwent ankle fusion and 281 underwent TAR. Baseline AOS and SF-36 (PCS and MCS) scores were similar for both groups. At final follow-up, both the AOS and SF-36 PCS scores improved significantly from preoperative values for both groups (P < 0.001); SF-36 MCS scores did not change.

Different procedures, different patients
As the authors noted, indications for TAR and ankle fusion are not the same. In general, fusion is the preferred procedure for younger patients; patients with isolated ankle arthritis, physically demanding jobs, compromised soft tissues around the ankle, or previous infection; and patients involved in physically demanding sports. TAR is the preferred procedure for older patients and those with more extensive arthritis or less strenuous physical demands.

By allowing variability in the surgical approach and type of implant used, said the authors, the study reflects “actual clinical use of these procedures, based on what was felt to be most appropriate following consultation with the patient. In so doing, it represents the outcomes for fusion and TAR when used in a setting where each procedure is felt to be the option most likely to provide the best clinical outcome. It is therefore not surprising that both procedures produced large improvements in clinical outcome scores.”

The authors pointed out that after equalizing the groups with respect to multiple variables—including age, sex, operated side, inflammatory arthritis, smoking status, diabetes, body mass index, preoperative outcome score, and surgeon—the midterm outcomes were nearly equivalent for the two procedures.

Although revision rates were higher in the TAR cohort—approximately double those observed in the fusion group—the authors noted a trend toward better outcome scores following TAR. “As prosthesis designs continue to improve, there is a potential to reduce revision rates following TAR,” they wrote.

They concluded that “functional outcomes are equivalent in TAR and ankle fusion at a mean of 5 years postoperatively when these procedures are performed by sub-specialty trained foot and ankle orthopaedists who carefully selected the procedure felt to be most appropriate for a given patient.

“When the surgeon and patient make a good decision, it leads to good results. Both operations have the capacity of providing good results in patients where appropriate selection has been made.”

Co-authors with Dr. Daniels (Carticept, Biomimetic, Integra, Canadian Orthopaedic Association, AOFAS) are Alastair S. E. Younger, MD (Biomimetic, ConMed Linvatec, Wright Medical Technology, Synthes, Integra Life Sciences and Foundation, Carticept, BioSET, Acumed, Arthrex), Murray J. Penner, MD (Arthrex, Biomimetic, ConMed Linvatec, Synthes, Wright Medical Technology, Cartiva), Mark Glazebrook, MD (ConMed Linvatec, Smith & Nephew, Zimmer, Arthrex, Biomimetic, Bioset, Cartiva, Clinical Orthopaedics and Related Research, Foot and Ankle International, Journal of Bone and Joint Surgery–American, Journal of Bone and Joint Surgery–British, AOFAS, Canadian Orthopaedic Association, OFAS, Canadian Orthopedic Research Society), Kevin J. Wing, MD (Biomimetic, ConMed Linvatec, DePuy, Synthes, Wright Medical Technology, Acumed), Peter J. Dryden, MD (no conflicts reported), and Hubert Wong, PhD (no conflicts reported).

Terry Stanton is senior science writer for AAOS Now. He can be reached at tstanton@aaos.org

Bottom Line

• A multicenter Canadian study examined outcomes at 5-year follow-up for a large cohort of patients receiving either ankle fusion or TAR for end-stage ankle arthritis.
• Although the raw data appeared to show better results with TAR, analysis that accounted for variables found both groups had statistically similar outcomes.
• The TAR cohort had revision rates that were approximately double those in the fusion group, but improved prosthetic designs could reduce revision rates.
• When more than one procedure can be used to treat a condition, an informed decision by the patient and surgeon on the most appropriate procedure can yield good results.