RISK FACTORS FOR THE DEVELOPMENT OF DEEP INFECTION FOLLOWING HIP FRACTURE SURGERY: ANALYSIS OF 2822 CONSECUTIVE PATIENTS
Aim This study aimed to identify risk factors for development of deep periprosthetic joint infection (PJI) in patients following surgical treatment of neck of femur fracture. Method This study identified a consecutive series of 2,822 (2,052 female, 73% patients who underwent either hemiarthroplasty (n=1,825, 65% or fixation (DHS) (n=997, 35% for fractured neck of femur performed between January 2009 and June 2015 at our institution. Full patient demographics, co morbidity and peri operative complication data were determined. The majority of patients were either ASA 2 (n=663, 23% or ASA 3 (n=1,521, 54% mean age 81.3 years (SD 10.3) All patients were followed up post operatively by a dedicated surgical site infection (SSI) monitoring team in order to identify patients who developed a PJI within 1 year. A stepwise multivariable logistic regression model was used to identify patient and surgical factors associated with increased risk of infection. Predictors with a p value of <0.20 in the univariate analysis were included in the multivariate analysis. Results Thirty nine (39) cases of deep periprosthetic infection were identified (hemiarthroplasty n=35, DHS n=4) representing an overall deep infection rate of 1.4% (hemiarthroplasty 1.9% DHS 0.4% The most common infecting pathogen was a pure growth of coagulase negative Staphylococcus (n=9, 23% followed by a pure growth of Staphylococcus aureus (n=7, 18% An increased risk of PJI was observed in patients who underwent hemiarthroplasty compared to those treated by fixation (odds ratio (OR) 6.50, 95%CI 2.26 18.7, p=0.001) Of patient factors, only blood transfusion within 30 days (OR 3.51, 95%CI 1.72 7.13, p=0.001) and the presence or development of pressure sores on or during admission (OR 2.99, 95%CI 1.24 7.19, p=0.015) were significantly associated with an increased risk of development of PJI. Use of high dose dual antibiotic cement (gentamicin and clindamycin) was associated with a two fold reduction in the risk of PJI (OR 0.39, 95%CI 0.20 0.76, p=0.005) vs standard dose gentamicin antibiotic cement. Conclusions This study found: 1) a deep infection rate similar to that reported earlier from large number studies from the UK, 2) a six fold higher deep infection rate in hemiarthroplasties, compared to internal fixations, and 3) a three fold higher infection rate in patients who suffer concomitant pressure sores or receive a blood transfusion up to 30 days post operatively.