Inclusion Criteria:  Patients, aged 21-75 years American Society of Anesthesiologists (ASA) physical status I-III Scheduled to undergo unilateral total hip replacement surgery.  Exclusion Criteria:  Patient refusal. Known hypersensitivity to local anesthetics. Body mass index > 35 kg /m2. Uncooperative or psychiatric patients. Infection at the injection site. Coagulation disorder. Major cardiac, renal, or hepatic diseases