The Geriatric Nutritional Risk Index Is an Independent Predictor of Prosthesis Aseptic Loosening in Patients Undergoing Total Joint Arthroplasty

ABSTRACT Background The geriatric nutritional risk index (GNRI) is a simple index for evaluating malnutrition, but whether it contributes to the development of prosthesis aseptic loosening (PAL) after total joint arthroplasty (TJA) is controversial. The aim of this study was to determine whether the GNRI is independently associated with PAL. Methods We retrospectively analyzed the medical data of 13,265 patients who underwent primary TJA at our institution between 2012 and 2023. After matching the patients to one another at a 1:2 ratio on the basis of clinical demographic variables, we compared the GNRI and other nutritional data in 205 patients who experienced PAL and 410 patients who did not experience PAL. We also compared common risk factors associated with PAL between the two groups. Multiple logistic regression was performed to analyze the relationship between the preoperative GNRI and PAL, and the predictive ability of the GNRI was assessed using the receiver operating characteristic (ROC) curves. Results The occurrence of malnutrition (defined by the GNRI) was significantly greater among PAL patients in the total hip arthroplasty (THA) group (38.3 vs. 9.0%, p < 0.001) and in the total knee arthroplasty (TKA) group (20.9% vs. 5.8%, p = 0.009). Multivariate regression analysis revealed that a low GNRI independently predicted a greater risk of PAL in the THA group (OR 1.091, 95% CI 1.041 to 1.145, p < 0.001) and in the TKA group (OR 1.240, 95% CI 1.060 to 1.451, p = 0.007). The ROC curves revealed an AUC of 0.729 for the GNRI in the THA group and 0.844 for the GNRI in the TKA group, which was greater than the AUC values for other common indicators. Conclusion A low GNRI is an independent risk factor for PAL after primary TJA, and the GNRI is more effective at predicting such risk than other commonly used indicators among elderly patients.