Prognostic nutritional index as a risk factor for aseptic wound complications after total knee arthroplasty

Background: Patients with malnutrition have a high risk of postoperative complications in total knee arthroplasty (TKA). Previously, serum albumin and total lymphocyte count were considered preoperative nutritional assessment measures. Prognostic nutritional index (PNI) is calculated by a combination of serum albumin and total lymphocyte count. This study aimed to identify the risk factors for postoperative complications after TKA, including preoperative nutritional assessment, and evaluated preoperative PNI as a predictor of postoperative complications.

Methods: One-hundred and sixty patients (234 knees) who underwent primary TKA were enrolled consecutively from 2010 to 2018. The serum albumin (g/dL) and total lymphocyte count (/mm3) were examined within 3 months before TKA; thereafter, the PNI was calculated. Postoperative aseptic wound problems, such as skin erosion and dehiscence within 2 weeks and periprosthetic joint infection after TKA were examined.

Results: Periprosthetic joint infections occurred in 14 knees (6.0%). Postoperative aseptic wound problems within 2 weeks were significant risk factors of periprosthetic joint infection (odds ratio; 5.10, 95% confidence interval [CI]; 1.438-18.093, p = 0.012). No significant differences were noted in the patient demographics, such as age, sex, body mass index (BMI), and comorbidities between the positive and negative groups for periprosthetic joint infection, except for the rate of aseptic operative wound problems. Furthermore, postoperative aseptic wound problems were influenced by high BMI (odds ratio; 1.270, 95% CI; 1.111-1.453, p = 0.000) and low PNI (odds ratio; 0.858, 95% CI; 0.771-0.955, p = 0.015).

Conclusions: Preoperative nutritional status, indicated by PNI and BMI, was associated with postoperative wound problems within 2 weeks. Periprosthetic joint infection after TKA was associated with early postoperative aseptic wound problems.