A randomized clinical trial comparing six techniques of postoperative analgesia for elective total hip arthroplasty under subarachnoid anesthesia with opioids

BACKGROUND: Optimal control of acute postoperative pain and prevention of chronic persistent pain in total hip arthroplasty (THA) remain a challenge. The main hypothesis was that peripheral nerve blocks improve postoperative analgesia.METHODS: Immediate postoperative pain (24 hours) was evaluated every hour in 510 patients using a verbal rating 11-point scale for patient self-reporting of pain (VRS-11). All patients received subarachnoid anesthesia (SA) and were randomly allocated in six groups: SA with morphine 0.1 (SA0.1) or 0.2 mg (SA0.2), fascia iliaca compartment block with dexamethasone 4 mg + levobupivacaine 0.375% 20 (FICB20) or 30 mL (FICB30), lateral femoral cutaneous nerve block with levobupivacaine 0.25% 5 mL (LFCNB) and FICB20+LFCNB. Standardized analgesia included intravenous metamizole magnesium, dexketoprofen and rescue with paracetamol and morphine, and/or regional rescue (FICB, LFCNB, femoral and sciatic nerve blocks).RESULTS: About 37.5% of patients had at least one episode of pain, 31.3% of them needed rescue analgesia while the remaining 6.2% did not request analgesia. There were no significant differences between the groups in paracetamol, morphine and rescue nerve blocks requirements. There was pain only in 5.4% of the total PACU pain records: 3.1% mild pain, 1.7% moderate pain and 0.6% severe pain.CONCLUSIONS: combined with a multimodal analgesic approach, infra-inguinal FICB and LFCNB did not improve immediate postoperative analgesia for THA in our hospital. Other options and longer-term studies should be more extensively investigated to determine the role of peripheral blocks in postoperative pain treatment protocols.