After the approval of institutional review board and the provision of informed consent , 80 patients over 70 years old , undergoing acute replacement of femoral head under combined spinal and epidural anesthesia and midazolam sedation at Qingdao Municipal Hospital and Qingdao Hiser Medical Center from January 2011 to May 2012 , were randomly assigned into control group ( group C , n = 40 ) and parecoxib group ( group P , n = 40 ) .