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Objectives and questions: Metabolic syndrome (MetS) and paradoxical malnutrition (PM) are risk factors for surgical site infection and increased mortality after primary total joint arthroplasty. With the growing prevalence of metabolic disorders and the rise in re-revision surgeries, understanding their impact on surgical outcomes is crucial. However, no study has yet examined the role of MetS and PM in re-revision arthroplasty. Therefore, we aimed to evaluate their influence on re-revision risk.

Material and methods: We retrospectively analyzed patients who underwent hip or knee revision arthroplasty between March 2010 and August 2023. Propensity score matching was used to create comparable groups for MetS and PM based on age, sex, previous surgeries, joint, and revision indication (septic or aseptic) before Kaplan-Meier analysis. After matching, 246 patients per group were included in the MetS analysis, and 55 per group in the PM analysis. Periprosthetic joint infections (PJI) were diagnosed per EBJIS criteria. MetS was defined by IDF 2009 criteria, and PM by BMI > 30 and albumin < 3.5 g/dl. Fine-Gray analysis assessed competing risks. All calculations were performed in R at a significance level of 0.05.

Results: Kaplan-Meier analysis showed no significantly higher overall failure rate in patients with MetS (p=0.55) or PM (p=0.55). When assessing aseptic failure, survival times were not significantly shorter in patients with MetS (p=0.24) or PM (p=0.13). However, in cases of septic failure, patients with MetS had significantly worse survival (p=0.023), whereas those with PM again showed no significant difference (p=0.55). Fine-Gray analysis, incorporating the factors from propensity score matching along with the factors included in MetS and PM definitions (hypertension, diabetes, obesity, elevated triglycerides, reduced HDL-C, and albumin), identified the number of previous revisions (p<0.0001) and BMI over 30 (p=0.0023) as significant risk factors for failure from any cause.

Discussion and conclusions: Our findings indicate that MetS is associated with a higher risk of septic failures after revision arthroplasty. Both MetS and PM encompass multiple metabolic factors, however, Fine-Gray analysis revealed that obesity (BMI > 30) and the number of previous revisions were the most significant risk factors associated with failure for any cause, suggesting that BMI plays a central role in surgical outcomes, rather than the broader metabolic syndrome or paradoxical malnutrition classifications. This emphasizes the need to focus on BMI rather than other metabolic factors in preoperative risk assessment and patient optimization.