Patients with obesity who underwent total ankle replacement had long-term outcomes comparable to those of patients without obesity in a retrospective Level III cohort study with more than a decade of follow-up.

The study included 515 total ankle replacements in 482 patients treated between 2002 and 2014 at a quaternary center by a single high-volume surgeon. Procedures were categorized by body mass index (BMI), with obesity defined as BMI of 30 kg/m² or greater.

Of the total cohort, 236 procedures were performed in patients with obesity and 279 in patients without obesity. Following exclusions for death, loss to follow-up, conversion to fusion, below-knee amputation, and dementia, 310 procedures were available for minimum 10-year patient-reported outcome analysis.

Outcomes and Functional Improvement

Primary outcomes included the Ankle Osteoarthritis Scale (AOS) and the 36-Item Short Form Health Survey (SF-36). At a mean follow-up of about 13 years, improvements in pain, disability, and physical health scores did not differ significantly between groups.

Mean AOS pain improvement was 26 points in patients with obesity vs 21 points in patients without obesity. Disability improved by 26 points vs 19 points, respectively. Physical component scores on the SF-36 improved by about 5 points in both groups.

Although these differences were not statistically significant, patients with obesity demonstrated numerically greater improvements in both pain and disability.

Patients with obesity had worse preoperative disability scores but achieved postoperative disability levels similar to those of patients without obesity, indicating a larger absolute functional gain.

Clinically meaningful improvement rates were also similar between groups:

• AOS pain: 48.7% (obesity) vs 45.2% (nonobesity)

• AOS disability: 46.6% (obesity) vs 38.8% (nonobesity)

Given that the obesity group started with significantly worse baseline disability, this gap may be clinically meaningful even without statistical significance.

Reoperations and Complications

Secondary procedures were analyzed across the full procedural cohorts (229 nonobese and 189 obese total ankle replacements), including patients later lost to follow-up to avoid undercounting complications.

Overall rates were similar, occurring in 34% of procedures in patients with obesity and 38% in those without obesity. Procedures for major complications—including implant failure, infection, and revision—occurred in approximately 17% in each group.

Seventeen total ankle replacements were converted to fusion (10 in patients with obesity and 7 in patients without obesity). Four patients underwent below-knee amputation, including three in the obesity group and one in the nonobesity group; two of the amputations in patients with obesity were unrelated to the ankle replacement.

Patient Selection and Generalizability

The findings apply to selected surgical candidates. Patients were excluded if they had active infection, severe bone loss, soft tissue compromise, neuromuscular disease, or significant neuropathy. Patients with diabetes were included only if glycemic control was adequate (HbA1c <7%).

The study did not stratify outcomes by obesity class. The mean BMI in the obesity group was approximately 35 kg/m², suggesting the findings primarily reflect class I and II obesity rather than more severe obesity.

Three implant systems were used, most commonly Hintegra (79%), with smaller proportions of Scandinavian Total Ankle Replacement and Mobility implants, which may affect generalizability across practice settings.

Mental health scores declined slightly over time in both groups, which the researchers attributed to aging and comorbidities rather than the procedure itself.

Limitations

The retrospective design limits causal inference. As a single-surgeon series at a high-volume referral center, results may not generalize to lower-volume settings.

Selection bias is also likely, as healthier patients with obesity may have been preferentially selected for surgery, potentially overestimating outcomes in broader clinical practice.

Interpretation

For physicians, the findings suggest that obesity alone may not preclude total ankle replacement when patients are appropriately selected and optimized, including careful assessment of neuropathy and glycemic control.

“These findings challenge the perception of obesity as a relative contraindication to TAR and support its use in appropriately selected obese patients,” wrote lead study author Zakir Haider, MBBS, of Unity Health Toronto–St. Michael’s Hospital, and colleagues.

Disclosure forms were provided with the published article.

Source: JB&JS Open Access