Geriatric Nutritional Risk Index is a risk factor for long-term decreases in patient-reported outcome measures following total knee arthroplasty

Purpose: Total knee arthroplasty (TKA) is an effective treatment for alleviating pain and improving function in patients with end-stage knee osteoarthritis. However, factors influencing long-term patient-reported outcome measures (PROMs) remain underexplored. This study aimed to evaluate the relationship between preoperative nutritional status, specifically the Geriatric Nutritional Risk Index (GNRI), and the long-term decline in PROMs following TKA. Methods: We conducted a retrospective cohort study including patients who underwent TKA between 2000 and 2009. PROMs were assessed using the Knee Society Score (KSS) at two time points: an initial evaluation in 2012 (median postoperative 4 years) and a follow-up in 2023 (median 13 years). Preoperative GNRI, body mass index (BMI), and other demographic and clinical data were collected from medical records. Statistical analysis included paired t-tests and multivariate logistic regression to identify independent risk factors for long-term decline in KSS scores. Results: A total of 75 patients completed follow-up assessments. Over the 11-year follow-up period, there was a significant decrease in the KSS functional activity scores (p < 0.001), with 47 patients experiencing a decline exceeding the minimal clinically important difference. A multivariate analysis revealed low preoperative GNRI (p = 0.0043) as a significant risk factor for long-term decline in PROMs. Conclusion: Preoperative malnutrition, as indicated by a low GNRI, is a significant risk factor for long-term decline in functional outcomes following TKA. These findings highlight the importance of preoperative nutritional interventions and rehabilitation for improving the long-term outcomes of patients undergoing TKA. Level of Evidence: Level III, retrospective cohort study.