Prognostic nutrition index (PNI) level in predicting surgical incision complications following medial opening-wedge high tibial osteotomy (MOWHTO) for knee osteoarthritis (KOA): A retrospective cohort study

Malnutrition is prevalent among hospitalized patients and has been shown to predict postoperative adverse events. This study aims to examine the relationship between malnutrition indicated by prognostic nutrition index (PNI) and surgical incision complication (SIC) following medial opening-wedge high tibial osteotomy (MOWHTO) for unicompartmental knee osteoarthritic (KOA). This was a retrospective study of patients who had undergone MOWHTO for varus KOA from January 2021 to June 2024 in 2 hospitals. Baseline data and laboratory test results were collected by reviewing the inpatient medical records. The outcome, incidence of SIC within 30 days postoperatively, was identified by reviewing the inpatient medical records and post-discharge outpatient follow-up records. The restricted cubic spline curve, receiver operating characteristic curve, univariate tests and multivariate logistic regression models were employed to identify the relationship between PNI and SIC. 528 patients were enrolled, comprising 190 males and 338 females, with an average age of 56.2 ± 6.5 years. Within the 30 days postoperatively, 48 (rate, 9.1%; 95% confidence interval (CI) = 6.6%-11.5%) patients developed SICs. The adjusted restricted cubic spline models demonstrated a significant inverted "J-shaped" nonlinear relationship (P < .05). The receiver operating characteristic curve analysis revealed a cutoff value for PNI of 47.0, accordingly categorizing patients into low PNI (n = 141) and high PNI (n = 387) groups. The multivariate models, using different adjustment methods, indicated a significant relationship between PNI < 47.0 and an increased risk of SICs, odds ratio of 4.86 (95% CI = 2.12 to 11.11) for the "enter" method and of 4.12 (95% CI = 2.23 to 7.61) for the "backward elimination" method. This study elucidates the significant relationship between PNI and SICs following MOWHTO for varus KOA. These findings emphasize the need for early nutritional assessment to improve patient safety and enhance surgical results.