Studies Examine Impact of Obesity on Total Ankle Replacement Outcomes

Total Ankle Replacement (TAR), also known as total ankle arthroplasty, is a surgical procedure used to treat ankle arthritis. In the procedure, the ankle joint is removed and replaced with an artificial implant made of metal and plastic. TAR aims to provide pain relief while preserving ankle motion so the patient has less pain and better function during activity. Foot and ankle orthopedic surgeons continue to investigate the factors that contribute to the success or failure of the procedure, including the impact of obesity. 
 
In a recent study published in Foot & Ankle International (FAI), Duke University researchers reviewed the impact of obesity on patient-reported outcomes and complication rates after TAR procedures. A study titled, “Total Ankle Arthroplasty: Does Obesity Matter?” reviewed data from 1,093 patients who underwent TAR at Duke University between 2001 and 2020. Patients were grouped by body mass index (BMI) including a control group, an obesity class I with a BMI from 30-34.9, and an obesity class II with a BMI of 35 and over.  
 
Study author Albert T. Anastasio, M.D., of Duke University, said the researchers did not see any increase in complication rates or failure rates across all three obesity classes after the TAR procedures. This is one of the largest single-institution studies to date examining the effect of obesity on outcomes after TAR.
 
Yet, results from other studies have shown that obesity does impact the procedure’s success. In a separate study published in FAI, United Kingdom researchers analyzed various risk factors for TAR failure in a retrospective registry-based study of 5,562 patients. They reported that increased BMI significantly increased the risk of TAR failure.
 
Both studies used larger data samples for their evaluations, yet they had very different findings. In an expert commentary in FAI, independent researchers reviewed these results.
 
“I was surprised that two studies with large sample sizes came to different conclusions regarding complication rates in obese patients that have undergone a TAR,” said Timothy R. Daniels, M.D., chief of the Division of Orthopaedic Surgery at St. Michael’s Hospital in Toronto, Canada, who co-authored the commentary. “These conflicting outcomes suggest that a more in-depth analysis is required in order to identify the reasons for this disparity.”
 
“Dr. Daniels’ commentary is a fantastic interpretation of the literature,” Anastasio stated. “Simply, we do not yet know the answer on whether obese patients fare worse after the TAR procedure. The data is clearer with other forms of total joint replacement like hip and knee replacement—we are still learning a lot about ankle replacements. My take-home point would be to offer folks hope that TAR can be as successful in patients with elevated BMIs. We really saw an impressive reduction in pain and improvements in function in both normal BMI and elevated BMI patients in our study.”
 
Anastasio and Daniels agree that future studies with larger samples are required to fully understand the impact of obesity after TAR.

The American Orthopaedic Foot & Ankle Society (AOFAS) mobilizes foot and ankle orthopadic surgeons to improve patient care through education, research, and advocacy. As the premier global organization for foot and ankle care, AOFAS delivers events and resources for continuous education, funds and promotes research, and broadens patient understanding of foot and ankle conditions and treatments. AOFAS inspires increasing levels of professional performance leading to improved patient outcomes.