Risks of Ankle Arthroplasty Failure Quantified

Surgeons should discuss the high risk of failure of total ankle arthroplasty (TAA) with patients who have moderate to severe coronal plane deformity, researchers say.

“Addressing coronal plane deformity when performing a total ankle arthroplasty remains a topic of controversy. While surgeons have become bolder in correcting deformity, long-term follow-up is sparse regarding maintenance of correction and viability of the prosthesis,” wrote the authors of the study, “Long-Term Follow up of Correction of Moderate to Severe Coronal Plane Deformity With the Star Ankle Prosthesis,” published in the Vol 7 No. 5 issue of the International Journal of Orthopaedics.

The researchers assessed the long-term follow up of the correction of moderate to severe coronal plane deformity with the use of a mobile bearing prosthesis.

The study included 130 consecutive patients who underwent total ankle arthroplasty between 2000 and 2009. Forty-three of the patients (44 ankles) had at least 100 of tibiotalar coronal plane deformity, with 25 of them having between 100 and 200 of deformity and 18 having greater than 200.

The average age at time of the surgery was 66 years (range 41-79). The initial deformity was 17.90 (range 10-290) in the entire cohort.

All of the patients underwent intraarticular deformity correction with intraoperative soft-tissue balancing as indicated utilizing the STAR prosthesis. For those patients who needed it, realignment osteotomies were performed in a staged fashion before the total ankle arthroplasty.

Only seven of the patients were available for long-term follow up with retention of the original prosthesis. Two of the seven had an initial deformity greater than 200. The average final tibiotalar deformity was 4.90, with a mean correction of 130 (p = 0.0001).

Eleven patients were deceased at the time of the study due to unrelated conditions and five patients experienced failed total ankle arthroplasty. The data shows that two were converted to arthrodesis, two underwent component revision and one patient had a polyethylene fracture. They weren’t included in the long-term follow-up and neither were 20 other patients who had declined to participate or were unable to participate because of their health status.

The authors concluded, “While the low follow-up rate limits the overall generalizability of the results, enduring correction of moderate and severe coronal plane deformity with a mobile bearing prosthesis can be achieved in a cohort of patients traditionally regarded as high-risk. One must be cautious when discussing with patients the utilization of TAA in the setting of moderate and severe coronal plane deformity given the risk of failure.”

They added, “However, provided a well-balanced ankle can be achieved intraoperatively, long-term mobile bearing prosthesis survivorship is achievable.”