Visualized Saphenous Nerve Block Distal To The Adductor Canal Through Minimally Invasive Far Medial-Subvastus Approach In Total Knee Arthroplasty

Objective To report the method of visualized saphenous nerve block(VSNB)distal to the adductor canal through minimally invasive far medial-subvastus approach in total knee arthroplasty(TKA),and investigate the effect of VSNB in this way on postoperative pain relief.Methods A total of 100 patients with knee osteoarthritis were prospectively included from June 2018 to October 2019,29 males and 71 females,aged 50～87(70±8)years.All patients undergoing TKA through minimally invasive far medial-subvastus approach were randomized to visualized saphenous nerve block combined with periarticular infiltration analgesia group(Group VSNB+PIA)or only periarticular infiltration analgesia group(Group PIA),50 cases in each group.Outcome evaluations included visual analogue scale(VAS)scores in resting and active state at 4,8,12,24,48,72 hours after operation and the proportion of patients receiving parecoxib within 72 hours after operation.Results The postoperative VAS scores of Group VSNB+PIA at 4,8,12,24 hours at resting state were 1.26±0.75,1.42±0.67,1.74±0.75,3.08±0.75 respectively,which were all significantly lower than those of Group PIA(1.62±0.90,1.80±0.81,2.32±0.89,3.58±0.79)(P<0.05).The postoperative VAS scores of Group VSNB+PIA at 4,8,12,24 hours at active state were 1.96±0.83,2.24±0.74,2.72±0.61,3.70±0.68 respectively,which were all significantly lower than those of Group PIA(2.34±0.77,2.72±0.73,3.28±0.81,4.42±0.70)(P<0.05).Fourteen percent of patients(7/50)in VSNB+PIA group accepted parecoxib within 72 hours after surgery,which was significantly lower than that in PIA group(34%,17/50)(P<0.05).We record one case of superficial wound infection in each group,with smooth recovery without other complications.Conclusion It is easy to expose the saphenous nerve distal to the adductor canal through minimally invasive far medial-subvastus approach.The combination therapy of VSNB+PIA is more effective than the simple periarticular infiltration analgesia in providing pain relief after total knee arthroplasty.