Factors Associated With Nonunion and Infection Following Ankle Arthrodesis Using a Large Claims Database: Who Has Elevated Risk?

Abstract

Background: Complications such as nonunion and infection following ankle arthrodesis can lead to increased patient morbidity and financial burden from repeat operations. Improved knowledge of risk factors can improve patient selection and inform post–ankle arthrodesis surveillance protocols. Methods: This is a large retrospective, database study with structured query of a national insurance claims database (PearlDiver Technologies) for patients treated with ankle arthrodesis from 2015 to 2019 as identified by International Classification of Diseases, Tenth Revision ( ICD-10), codes. Patients with any operation 1 year prior to or following ankle arthrodesis were excluded from analysis to prevent attributing complications to another operation. Likelihoods of nonunion and infection within 1 year and 3 years following ankle arthrodesis were analyzed using Kaplan-Meier estimations. Patient characteristics associated with the identified complications following ankle arthrodesis were analyzed using multivariable logistic regression analyses. Results: Our query yielded 2463 patients in the 5-year period who underwent ankle arthrodesis. Nonunion occurred in 11% (95% CI 10-12) of patients within 1 year of ankle arthrodesis and 16% (95% CI 14-17) of patients within 3 years. Infection occurred in 3.9% (95% CI 3.1-4.7) of patients within 1 year of ankle arthrodesis and in 6.2% (95% CI 5.1-7.2) of patients within 3 years. Obese patients increased odds of nonunion on multivariable analysis (OR 1.6, 95% CI 1.3-2.0; P < .001). On multivariable analysis, diabetes (OR 1.7, 95% CI 1.2-2.6; P = .010) and each 1-unit increase in Elixhauser Comorbidity Index scores (OR 1.1, 95% CI 1.1-1.2; P < .001) contributed to increased odds of infection after ankle arthrodesis. Conclusion: Nonunion and infection following ankle arthrodesis have a 3-year probability of 16% and 6%, respectively. More than one-quarter of patients with nonunion following ankle arthrodesis experience a delay in diagnosis beyond 1 year. The risk of post–ankle arthrodesis nonunion is highest in patients with obesity; the risk of post–ankle arthrodesis infection is highest in patients with diabetes or an elevated Elixhauser Comorbidity Index score. Level of Evidence: Level III, prognostic study.

Association of Preexisting Triple Fusion and Arthroscopic Ankle Arthrodesis nonunion

“…Analysis of a large administrative claims database of 2463 patients identified that nonunion occurred in 14% of patients following ankle arthrodesis, and the odds of nonunion were higher among patients with a smoking record compared to patients without (18.0% vs 12.8%). 38 A recent systematic review and meta-analysis of ankle arthrodesis studies has also identified smoking (OR 2.89, 95% CI 1.23-6.76) as a factor associated with nonunion. 30 In our study, other patient variables such as concomitant steroid use and history of inflammatory arthropathy had relatively high impact on the OR in the univariate analysis without a significant P value.…”

“…The only study to identify obesity as a risk factor for nonunion was the analysis of a large administrative claims database mentioned above that identified that odds of nonunion were higher in obese patients compared with nonobese patients (17.1% vs 9.5%). 38 One case series of open ankle fusions found nonunion was associated with varus ankle alignment. 5 Two further case series of AAA found no difference in union rates associated with preoperative varus/valgus ankle deformity of >15 degrees.…”

“…Of these, nonunion is recognized as one of the most important 1171077F AIXXX10.1177/10711007231171077Foot & Ankle InternationalWoods et al research-article2023 1 Nuffield Orthopaedic Centre, Oxford, UK 2 Horton General Hospital, Banbury, UK complications, with rates of 8% to 13% reported in systematic reviews. 3,25 There is often a delay in diagnosis and treatment, 38 requiring long and complex revision surgery, further periods of nonweightbearing, immobilization, and complications with added financial burden to the health care system. 11 For these reasons, nonunion following AAA can have significant repercussions for the patient.…”

“…Previous studies of open ankle arthrodesis cases, or a mixture of arthroscopic and open cases, have identified smoking, 17,30,38 vitamin D deficiency, 34 obesity, 38 male gender, 30 clinical varus ankle alignment, and previous subtalar joint (STJ) fusion 5 as risk factors for nonunion. Those studies that included only AAA were either small case series and/or limited in sample size (ie, fewer than 80 patients).…”

Patient-related risk factors associated with poorer outcomes following total ankle arthroplasty

“…11,[32][33][34] It is also likely that some of the factors identified, particularly comorbidities, are general operative risk factors which may similarly influence the outcome of alternative operative treatments such as ankle arthrodesis. [35][36][37] Therefore, rather than using individual identified factors as contraindications, clinicians should incorporate a holistic assessment of patient risk factors, evaluating the presence and number of these to aid in both clinical decision-making and informing patient expectations. Future research should continue to aid this process, ensuring that adequate statistical techniques are used to control for confounding factors when attempting to identify independent risk factors for poorer outcome.…”