title: The association between lower extremity continuous peripheral nerve blocks and patient falls after knee and hip arthroplasty.
abstract: BACKGROUND
  Continuous peripheral nerve blocks (CPNB) may induce muscle weakness, and multiple recently published series emphasize patient falls after postarthroplasty CPNB. However, none have included an adequate control group, and therefore the relationship between CPNB and falls remains speculative.
  
  
  METHODS
  We pooled data from 3 previously published, randomized, triple-masked, placebo-controlled studies of CPNB involving the femoral nerve after knee and hip arthroplasty.
  
  
  RESULTS
  No patients receiving perineural saline (n = 86) fell (0%; 95% confidence interval [CI] = 0%-5%), but there were 7 falls in 6 patients receiving perineural ropivacaine (n = 85; 7%; 95% CI = 3%-15%; Fisher's exact test P = 0.013).
  
  
  CONCLUSIONS
  Our analysis suggests that there is a causal relationship between CPNB and the risk of falling after knee and hip arthroplasty.
authors.affiliation: Department of Anesthesiology, University of California San Diego, San Diego, California, USA. bilfeld@ucsd.edu
authors.forename: Brian M
authors.initials: BM
authors.lastname: Ilfeld
authors.forename: Kimberly B
authors.initials: KB
authors.lastname: Duke
authors.forename: Michael C
authors.initials: MC
authors.lastname: Donohue
mesh_terms: D000058:Accidental Falls; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D035002:Lower Extremity; D008297:Male; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D018908:Muscle Weakness / Q000209:etiology; D018482:Muscle, Skeletal / Q000294:innervation*; D009407:Nerve Block / Q000009:adverse effects*; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D016896:Treatment Outcome