Complementary Saphenous Nerve Block to Intra-Articular Analgesia Reduces Pain After Total Knee Arthroplasty: A Prospective Randomized Controlled Trial.

Background: Numerous strategies exist for pain management after total knee arthroplasty (TKA), with a fast recovery and early ambulation required for full function. Currently, there is no universal standard of care to facilitate this management. We assessed pain management safety and efficacy after TKA, using intra-articular infiltration associated with peripheral saphenous nerve block (SNB) vs intra-articular infiltration alone.

Methods: We performed a controlled, double-blinded, and randomized trial to evaluate postoperative pain in TKA. One group was treated with intra-articular analgesia associated with SNB, whereas a second group received the same intra-articular cocktail, associated with placebo. Efficacy was evaluated according to average pain, pain-free time, and morphine rescue indices. Safety was assessed by intervention complications and surgery.

Results: About 70 patients were recruited. At time 0 (immediately postoperative), 51.43% of the intra-articular analgesia + placebo group presented pain <3, whereas in the intra-articular analgesia + SNB group, 8.82% (P = .001) presented with pain. This difference was maintained at 6, 12, and 24 hours, postoperatively. After 24 hours, the placebo group received an average 0.66 morphine rescues (standard deviation, 0.86), when compared with the SNB group that received 0.14 rescues (standard deviation, 0.43), (P = .002). We recorded a paresis of the external popliteal sciatic nerve, with spontaneous recovery without other complications.

Conclusion: Complementary SNB to intra-articular analgesia was more effective in reducing average pain and the amount of pain-free time in the first 24 hours after TKA, with fewer requests for morphine rescue analgesia.