Low prognostic nutritional index is highly associated with periprosthetic joint infection in revision arthroplasty: a 14-year retrospective cohort study.

BACKGROUND: The relationship between preoperative nutritional status and periprosthetic joint infection (PJI) remains unclear in patients undergoing revision arthroplasty. This study aimed to investigate (1) whether preoperative nutritional status influences the risk of PJI in these patients, and (2) to determine the optimal threshold for risk stratification. METHODS: A retrospective cohort study involved 1,117 patients who underwent hip or knee revision between January 2011 and September 2024. Prognostic nutritional index (PNI) was calculated based on serum albumin and lymphocyte counts. Multivariate logistic regression, propensity score matching (PSM), restricted cubic spline (RCS) modeling, and Kaplan-Meier analysis were used to assess the association between PNI and PJI. RESULTS: Among 1,117 patients, 40 (3.58%) developed PJI. Low levels of preoperative PNI (< 45.00) were significantly associated with an increased risk of re-revision due to PJI (adjusted odds ratio = 7.40, 95% CI: 3.49 ~ 15.72, P < 0.001). The incidence of re-revision for PJI was significantly higher in patients with lower preoperative PNI (8.31% vs. 1.21%, p < 0.001). Propensity score matching further confirmed these findings. The optimal threshold for preoperative PNI control was identified as 45.00, below which the risk of re-revision for PJI increased significantly. CONCLUSION: Lower PNI is independently associated with increased re-revision for PJI risk after revision arthroplasty. Maintaining preoperative PNI above 45.00 may help reduce the risk of re-revision for PJI.