Preoperative Malnutrition Is Associated With Increased Rates of Periprosthetic Fractures in Total Knee Arthroplasty.

Background: Periprosthetic fractures (PPFx) after total knee arthroplasty (TKA) are associated with high morbidity and mortality. While previous studies have shown the potential role of malnutrition as a predictor of PPFx in total hip arthroplasty, no studies have evaluated malnutrition as a risk factor for PPFx in TKA patients. This study aims to evaluate the relationship between preoperative nutrition status and PPFx after TKA. Methods: We conducted a retrospective cohort study using data from the TriNetX Registry to identify patients who underwent primary TKA or revision TKA (rTKA) from 2005 to 2025. Preoperative nutrition status was assessed using albumin levels within 3 months prior to TKA based on prior arthroplasty and nutrition literature. Hypoalbuminemia was defined as < 3.5 g/dl. The primary outcome was PPFx occurring at least 1 day after TKA surgery, thereby excluding intraoperative PPFx. Cox proportional hazard models were used to determine hazard ratios (HRs) for each cohort. Results: There were 176,662 TKA patients and 1301 (0.74%) patients with subsequent PPFx during this study period. Preoperative malnutrition was identified in 19,500 patients (11.5%) in the primary TKA group and 1138 patients (17.9%) in the rTKA group. Both primary TKA (hazard ratio [HR] = 1.37, 95% confidence interval [CI], 1.23-1.52, P ≤ 0.001) and rTKA patients (HR = 1.20, 95% CI, 1.03-1.41, P = .022) with preoperative hypoalbuminemia were at an increased risk of PPFx while albumin levels of greater than 3.5 g/dl were protective against PPFx ((HR = 0.73, 95% CI, 0.58-0.93, P = .009) and (HR = 0.72, 95% CI, 0.53-0.97, P = .029) for primary TKA and rTKA respectively). Other nutritional labs including increased prealbumin and higher lymphocyte percentage were statistically significantly associated with a decreased risk for PPFx. Independent risk factors for PPFx following TKA included diabetes, obesity, female sex, and increased age. Conclusions: Our study shows that poor preoperative nutrition status is associated with statistically significant increased risks of PPFx following TKA in both primary TKA and rTKA. Optimization of nutrition may help prevent PPFx following TKA.