Analgesic Effects of Different Local Infiltration Anesthesia Techniques Combined with Femoral Nerve Block in Patients Undergoing Total Knee Arthroplasty: A Randomized Controlled Clinical Trial

Objective: Pain after total knee arthroplasty (TKA) remains an unresolved problem. Femoral nerve block (FNB) could relieve pain; however, it alone is insufficient. The local infiltration anesthesia technique (LIA) has been suggested as a supplement to FNB. This study aimed to evaluate the analgesic effects of different LIA combined with FNB in TKA patients.Methods: The femoral nerve was blocked with 0.375% ropivacaine 20mL, and all patients routinely received general anesthesia. The primary indicator was the proportion of patients who did not receive post-operative remedial analgesia. Seventy-eight patients were randomly assigned to PAI (periarticular injection combined with FNB), IAI (intra-articular injection combined with FNB), or control (FNB alone) groups. All patients underwent FNB under general anesthesia. The primary outcome was the proportion of patients who did not receive additional postoperative analgesia within the first 48 h after surgery.Results: Compared with the PAI and control groups, the IAI group had a higher proportion (69.23%) of patients who did not receive remedial analgesia within 48 hours after surgery (P = 0.009; P = 0.009), a lower consumption of diclofenac sodium lidocaine (P = 0.021; P < 0.001), and an earlier time of walking with a walker (P < 0.001; P < 0.001). The time of first need for remedial analgesia postoperatively in IAI group was longer than the PAI group (P = 0.008) and IAI group has a shorter hospital stay than the control group (P = 0.008). The maximum NRS during the first 48 hours postoperatively and NRS 24 hours after surgery in the IAI group were lower than those in the control and PAI groups. The incidences of POD and PONV were similar among the three groups (P = 0.610; P = 0.264).Conclusion: When combined with FNB, intra-articular injection offers a superior analgesic effect and favorable recovery compared to periarticular injection and separate application of FNB.