Evaluation of Postoperative Pain When Adding a Tibial Nerve Block to the Femoral Nerve Block for Total Knee Arthroplasty.

Background : The aim of this study was to compare the postoperative analgesic efficacy when a tibial nerve block was added to the femoral nerve block for total knee arthroplasty (TKA). Methods : A total of 60 patients were randomly assigned to the experimental group (EG) or the control group (CG) in a 1:1 ratio. The thirty patients who formed the CG underwent an ultrasound-guided femoral nerve block together with neuraxial anaesthesia and the administration of opioids and NSAIDs through an intravenous elastomeric pump for the management of the postoperative pain; the other thirty, who formed the EG, underwent neuraxial anaesthesia together with femoral and tibial nerve blocks. The efficacy of the analgesic effect was evaluated based on the numerical pain rating scale (NPRS) and on the need for analgesic rescue at different time intervals within 48 h after surgery. Results : At 24 h, the mean NPRS score in the EG and CG at rest was 1.50 ± 1.19 and 1.63 ± 1.60 [ U = 443.5, p = 0.113], respectively. With joint movement, the mean NPRS score was 2.80 ± 1.49 and 3.57 ± 1.79 [ U = 345, p = 0.113], respectively. Ten patients in the EG [33.3%] and 24 in the CG [80%] required rescue analgesia [Phi = 0.471, p < 0.001]. At 48 h, the mean NPRS score in the EG and CG at rest was 0.33 ± 0.60 and 0.43 ± 0.72 [ U = 428, p = 0.681], respectively. With movement, the mean NPRS score was 1.03 ± 0.99 in the EG and 1.60 ± 1.07 in the CG [ U = 315, p = 0.038]. No patient in the EG group required rescue analgesia, while three patients in the CG [10%] did [Phi = 0.229, p = 0.076]. The mean opioid dosage in the CG was 300 mg, whereas in the EG it was 40 mg ± 62.14 [ U < 0.05, p < 0.001]. Conclusions : Adding a tibial nerve block to the femoral nerve block in TKA may achieve the same analgesic efficacy within 48 h after surgery and would reduce the systematic use of opioids.