Risk factors for early infection following hemiarthroplasty in elderly patients with a femoral neck fracture.

Periprosthetic joint infections (PJI) after hemiarthroplasty for geriatric femoral neck fractures are a devastating complication that results in serious morbidity and increased mortality. Identifying risk factors associated with early infection after HA for hip fractures may offer an opportunity to address and prevent this complication in many patients. The aim of this study was to evaluate preoperative risk factors for early PJI after HA in hip fracture patients. From January 2010 to December 2015, 312 femoral neck fractures (AO/OTA 31-B) in 305 patients were included in this single-center, retrospective study. PJI was defined according to the Centers for Disease Control (CDC) definition of deep incisional surgical site infection. Early infection referred to a postoperative period of 4 weeks. Binary univariable and multivariable regression analysis with backward elimination was applied to identify predictors of PJI. Median age of all patients was 83.0 (IQR 76-89) years. We identified 16 (5.1%) early PJI which all required surgical revision. Median length of in-hospital stay (LOS) was 20.0 (IQR 10-36) days after PJI compared to 10.0 (8-15) days without deep wound infection. In-hospital mortality was 30.8 vs. 6.6%, respectively. Preoperative CRP levels (OR 1.009; 95% CI 1.002-1.018; p = 0.044), higher BMI (OR 1.092; 95% CI 1.002-1.189; p = 0.044) and prolonged surgery time (OR 1.013; 95% CI 1.000-1.025; p = 0.041) were independent risk factors for PJI. Excluding infection following major revision due to mechanical complications identified preoperative CRP levels (OR 1.012; 95% CI 1.003-1.021; p = 0.007) and chronic glucocorticoid therapy (OR 6.314; 95% CI 1.223-32.587; p = 0.028) as risk factors, a clear trend was seen for higher BMI (OR 1.114; 95% CI 1.000-1.242; p = 0.051). A cut-off value at CRP levels ≥ 14 mg/l demonstrated a sensitivity of 69% and a specificity of 70% with a fair accuracy (AUC 0.707). Preoperative serum CRP levels, higher BMI and prolonged surgery time are independent predictors of early PJI. Excluding PJI secondary to major revision surgery revealed chronic glucocorticoid use as a risk factor apart from preoperative CRP levels.