Postoperative pain relief after total hip arthroplasty: a randomized, double-blind comparison between intrathecal morphine and local infiltration analgesia.

BACKGROUND Postoperative pain after total hip arthroplasty (THA) can delay mobilization. This was assessed after intrathecal morphine (ITM) compared with local infiltration analgesia (LIA) using a non-inferiority design. METHODS Eighty patients were recruited in this randomized, double-blind study. ITM 0.1 mg (Group ITM) or periarticular local anaesthetic (ropivacaine 300 mg)+ketorolac 30 mg+ epinephrine 0.5 mg (total volume 151.5 ml) (Group LIA) were compared. After 24 h, 22 ml of saline (Group ITM) or ropivacaine (150 mg)+ketorolac (30 mg)+epinephrine (0.1 mg) (Group LIA) were injected via a catheter. After operation, rescue analgesic consumption, pain intensity, and home-readiness were measured. RESULTS Morphine consumption was equivalent, median difference 0 mg (95% confidence interval -4 to 4.5) between the groups at 0-24 h. During 24-48 h, it was lower in Group LIA (3 mg, 0-60 mg, median, range) compared with Group ITM (10 mg, 0-81 mg) (P=0.01). Lower pain scores were recorded at rest at 8 h in Group ITM (P<0.01), but in Group LIA on standing and mobilization, at 24-48 h (P<0.01). Paracetamol and tramadol consumption was lower in Group LIA (P=0.05 and 0.05, respectively) as was pruritus, nausea, and vomiting (P<0.05). CONCLUSION Lower pain intensity was recorded early after surgery in ITM group but later, analgesic consumption, pain intensity on mobilization, and side-effects were lower in patients receiving LIA. LIA is a good alternative to ITM in patients undergoing THA.