Can the Preoperative Prognostic Nutrition Index (PNI) Predict Surgical Site Infection Following Primary Total Knee Arthroplasty?

Background: Malnutrition is reported as one of the risk factors for surgical site infection (SSI). The prognostic nutritional index (PNI) is a simple method for nutritional evaluation. However, few studies have discussed the effectiveness of PNI as a nutritional assessment in predicting SSI after primary total knee arthroplasty (TKA). The aim of this study is to investigate the relationship between SSI and malnutrition as identified by the PNI scores following TKA. Methods: : A retrospective analysis of 483 patients (SSI vs. non-SSI group: 19 vs. 464; follow-up period: at least 1 year) was performed to confirm the risk factors, including the PNI, associated with SSI after primary TKA using both univariate and multivariate analyses. Results: : Postoperatively, nineteen patients (19/483, 3.9%) experienced SSI (deep vs. superficial SSI: 12 vs. 7), and periprosthetic joint infection was observed in all deep SSI cases. Univariate analysis showed that male sex, body weight, body mass index (BMI), diabetes mellitus, steroid usage, operative time and PNI differed between the SSI and non-SSI groups (P<0.05). Multivariate logistic regression analysis identified that the preoperative PNI (odds ratio [OR]: 0.859; 95% confidence interval [CI]: 0.762-0.969; cutoff [CV]: 49.27), operative time (OR: 1.005; 95% CI: 1.000-1.010; CV: 131.0 min), male sex (OR: 4.127; 95% CI: 1.165-14.615), diabetes mellitus (OR: 6.133; 95% CI: 2.067-18.193) and steroid usage (OR: 6.034; 95% CI: 1.521-23.935) were independently associated with SSI (P<0.05). Conclusions: : A low preoperative PNI associated with malnutrition was demonstrated to be an independent risk factor for SSI following primary TKA. Patients with preoperative low PNI should be cautioned and provided with adequate nutritional intervention to reduce postoperative SSI.