Ninety patients undergoing THA were randomized to receive fascia iliaca compartment block (FICB) with ropivacaine + methylene blue (MB) (n=45) or ropivacaine alone (n=45). The primary outcome was VAS pain (rest and activity), with the 48 h VAS prespecified as primary. Secondary outcomes included hs‑CRP, procalcitonin, neutrophil‑to‑lymphocyte ratio, heart rate/mean arterial pressure, supplemental analgesia, early mobilization (out‑of‑bed counts and first‑walk distance), and adverse events. Outcomes were assessed pre‑block and at 2, 6, 12, 24, and 48 h; inflammatory markers were measured on postoperative days 1 and 2. Overall, the results revealed lower VAS at 24 and 48 h with MB + ropivacaine, reduced inflammatory markers, fewer patients requiring rescue analgesia, and greater early activity and walking distance, without excess adverse events. These findings suggest adding low‑dose MB to ropivacaine FICB modestly prolongs analgesia and supports early recovery after THA.