After ethical committee approval, eligible patients scheduled to have a fast-track total hip arthroplasty are screened during preoperative evaluation clinic. Informed written consent will be obtained from all patients during pre-anesthesia visit the day before surgery (J-1). Consenting patients will be randomized the day of surgery (J0) to undergo QLB with ropivacaine ("ropivacaine group") or normal saline ("saline group").