A systematic review studying the outcomes after Total Hip Arthroplasty concluded that when compared with systemic analgesia the use of femoral nerve block was on unclear benefit.(15) Separate analysis of the two studies included showed that in the Biboulet study, ultrasound was not used to perform the blocks, and pain with activity was not evaluated in the first 24 hours after surgery, time in which the maximum benefit of blocks is observed.(16) In the second study by Singelyn et al. with continuous femoral nerve block, the authors found similar pain relief than with IV Patient Controlled Analgesia morphine with fewer side effects.(17)