title: MR imaging after hip and knee replacement.
abstract: BACKGROUND
  Diffusion-weighted (DW) imaging abnormalities often develop in patients after invasive procedures associated with cerebral microembolism. Cerebral microembolism has recently been shown during orthopedic surgery. We here examine the effects of intraoperative microembolism on acute magnetic resonance(MR) imaging in patients undergoing hip and knee replacement.
  
  
  METHODS
  We enrolled 24 patients, at least 65 years old, requiring elective knee or hip replacement surgery. MR with DW and axial fluid-attenuated inversion recovery (FLAIR) imaging was performed pre- and postoperatively. All patients were monitored intraoperatively for microemboli.
  
  
  RESULTS
  The mean age of patients was 74 years. All patients had intraoperative microemboli. The mean number of emboli detected was 9.9 +/- 18 per surgery. MR imaging was obtained a mean of 3.5 days postoperatively. No DW imaging abnormalities were found after surgery. One patient had new findings on postoperative FLAIR imaging.
  
  
  CONCLUSIONS
  Intraoperative microembolism occurred universally, but did not lead to acute DW imaging abnormalities following knee and hip replacement. Acute imaging abnormalities on FLAIR imaging are rare but may occasionally occur after joint surgery.
authors: Department of Neurology, Miller School of Medicine, University of Miami, Miami, FL, USA. skoch@med.miami.edu
authors: Sebastian
authors: S
authors: Koch
authors: Alejandro
authors: A
authors: Forteza
authors: Carlos
authors: C
authors: Lavernia
authors: Jose G
authors: JG
authors: Romano
authors: Nelly
authors: N
authors: Campo
authors: Rita
authors: R
authors: Bhatia
authors: Iszet
authors: I
authors: Campo-Bustillo
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D020766:Intracranial Embolism / Q000175:diagnosis* / Q000209:etiology*; D008297:Male; D011183:Postoperative Complications / Q000175:diagnosis; D018709:Statistics, Nonparametric