Total Ankle Arthroplasty: Does Obesity Matter?

Abstract

Background: There is limited data evaluating the effect of obesity on outcomes following total ankle arthroplasty (TAA), especially in adequate sample sizes to detect impacts on patient-reported outcomes (PROs). The purpose of this study was to assess the effect of obesity on complication rates and PROs. Methods: This was a single-institution, retrospective study of 1093 primary TAA performed between 2001 and 2020. Minimum follow-up was 2 years. Patients were stratified by body mass index (BMI) into control (BMI = 18.5-29.9; n = 615), obesity class I (BMI = 30.0-34.9; n = 285), and obesity class II (BMI > 35.0; n = 193) groups. Patient information, intraoperative variables, postoperative complications, and PRO measures were compared between groups using univariable statistics. Multivariable Cox regression was performed to assess risk for implant failure. Mean follow-up was 5.6 years (SD: 3.1). Results: Compared to control and class I, class II patients had the lowest mean age ( P = .001), highest mean ASA score ( P < .001), and greatest proportion of female sex ( P < .001) and Black/African American race ( P = .005). There were no statistically significant differences in postoperative complications (infection, implant failure, or impingement) across the BMI classes ( P > .05). Preoperatively, class II had lower (worse) mean scores for Foot and Ankle Outcome Score pain and ADL subscales than controls (post hoc pairwise P < .001 for both). At final follow-up, both class II and class I had lower (worse) mean Short Musculoskeletal Function Assessment (post hoc pairwise P < .001 and P = .030, respectively) and 36-Item Short Form Health Survey scores (post hoc pairwise P < .001 and P = .005, respectively) than controls. Conclusion: At midterm follow-up, obesity was not associated with increased rates of complications after TAA. Patients with obesity reported worse musculoskeletal function and overall quality of life after TAA but there was no differential improvement in PROs across BMI classes. To our knowledge, this is the largest single-institution study to date examining the effect of obesity on outcomes after primary TAA. Level of Evidence: Level III, retrospective comparative study.

Does Obesity Affect Total Ankle Replacement Outcomes?

“…They found that obese patients did not experience increased rates of complication, revision, or infection after TAR. 9 In addition, patients with obesity reported, on average, worse pre-and postoperative function, pain, and general health status; however, the magnitude of the change in PRO scores was similar across the BMI groups. More broadly, Jennison et al 8 analyzed various risk factors for failure of TAR in a retrospective UK registry-based study of 5562 patients.…”

“…In this issue of FAI , 2 articles provide important insights into the effect of body mass index (BMI) on TAR outcomes. 8,9 Kim et al 9 evaluated the effect of obesity on complication rates and patient-reported outcome (PRO) measure scores in a single-institution, retrospective comparative study of 1093 primary TARs. They found that obese patients did not experience increased rates of complication, revision, or infection after TAR.…”

“…The importance of Kim et al 9 and Jennison et al 8 is primarily their large sample size, follow-up length, and treatment of potential confounders. Simply, previous studies may not have been powered sufficiently to detect differences.…”

“…Moreover, both studies adjust for potential confounders to improve the accuracy and validity of their findings. Kim et al 9 adjust for age, sex, and ASA score, whereas Jennison et al 8 adjust for age, sex, indication, laterality, ASA score, Charlson Comorbidity Index score, surgeon grade, deformity, plantar and dorsal range of motion, and subtalar joint. The conflicting results are frustrating, but may be due to the confounders considered or not considered by each study, or how confounders were defined or measured.…”

Obesity and Ankle Prosthesis Revision: A Systematic Review and Meta-analysis

“…12,21,54 However, the role of excess weight or obesity as a prognostic factor for TAA is still under debate. 20,31,33,37…”