Pain Management for Total Knee Arthroplasty: Single-Injection Femoral Nerve Block versus Local Infiltration Analgesia

BACKGROUND Pain is one of the major concerns of patients underwent Total Knee Arthroplasty (TKA); appropriate pain management is a key factor in patient's early physical fitness to move, physiotherapy, and most importantly, patient satisfaction. OBJECTIVES In this study the analgesic effect of single injection femoral nerve block (SFNB) was compared with local infiltration analgesia (LIA). PATIENTS AND METHODS Forty patients who underwent TKA under spinal anesthesia were randomized to receive single femoral nerve block (group F) or intra-periarticular infiltration (group I). Group F received single injection 20cc ropivacaine (10mg/cc) and in group I, a combination of 300mg ropivacaine, 30mg ketorolac and 0.5mg epinephrine diluted to a volume of 150cc and locally injected in and around the knee joint in 3 stages. Postoperative pain intensity measured by Visual Analog Scale (VAS). Morphine consumption, mobilization time and patients' satisfaction evaluated as well. RESULTS Group I had significantly lower morphine consumption in the first postoperative day (10 vs. 12.5mg, P-value < 0.05). Within 6 hours postoperatively, VAS score was statistically lower in group I compared to group F (3 vs. 4, P-value < 0.05). However, within 12 hours it was statistically higher in group I than group F (6 vs. 5, P-value < 0.05). Other parameters were not statistically different in two groups. CONCLUSIONS Both methods LIA and SFNB provided excellent pain relief and lower morphine consumption following TKA. LIA is a surgeon-controlled analgesic technique, which can be used to enhance patients' satisfaction and reduce the pain in the very early postoperative period by surgeon independently.