Advanced age, obesity and continuous femoral nerve blockade are independent risk factors for inpatient falls after primary total knee arthroplasty.

We asked whether femoral nerve blockade (FNB) was an independent risk factor for inpatient post-operative falls after total knee arthroplasty (TKA). Data on 2197 primary TKAs were collected from our institution between 2003 and 2010. Patient demographics, type and duration of blocks were considered predictors of falls in a logistic regression model. Among 60 (2.7%) falls, the odds ratio was 1.04 (1.0-1.07; p=0.008) for each 1 year of increased age above the mean (66 years), 2.4 (1.3-4.5; p=0.005) for BMI >30 kg/m(2) and 4.4 (1.04-18.2; p=0.04) for continuous FNB. Single-shot FNB did not increase risk. No fall resulted in operative morbidity. The use of continuous FNB should be cautioned, especially in patients with other risk factors such as obesity and advanced age.