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.