Saphenous nerve block versus femoral nerve block in enhanced recovery after knee replacement surgery under spinal anaesthesia

Abstract Background Inadequate pain management after total knee replacement (TKR) prolongs recovery time and increases the risk of postoperative complications. Peripheral nerve fibres blockade has been used as a mode of analgesia after TKR. Femoral nerve block (FNB) is often used to provide postoperative analgesia after TKR. However, FNB causes quadriceps muscle weakness leading to delayed ambulation, patient discomfort and prolonged hospital stay. Nowadays, saphenous nerve block is a relatively new alternative being superior to FNB for providing pure blockage of sensory nerve fibres with preserving quadriceps muscle strength. Results Results of this study showed that leg raising test percentages were significantly higher in group S compared to group F (86.7% versus 43.3% respectively), whereas, time up and go (TUG) test values were significantly lower in group S compared to group F (Mean ±SD values were 22.47 ± 4.93 versus 44.6 ± 4.18 respectively with a p-value < 0.0001). Numerical rating score (NRS) for pain scoring was measured at 30 min after admission to PACU, 3, 6, 12 and 24hrs postoperatively showed no significant differences in both groups F & S (1;(0-2), 1;(1-2), 2;(1-2), 2;(1-2), 2;(2-2) versus 1;(0-2), 1;(1-2), 2;(1-3), 2;(1-2), 2;(2-3) respectively with a p-value 0.42, 0.1, 0.1, 0.49, 0.67). Also, both groups showed no significant difference in cumulative 1st 24hrs Nalbuphine consumption (Mean ±SD were 15.33 ± 7.3 for F group versus 14.33 ± 6.26 for S group with a p-value 0.57). Conclusions Despite the excellent analgesic effect of FNB, saphenous nerve block could be a favorable choice as a mode of analgesia after TKR, as it preserves quadriceps motor strength and promotes early mobilization compared to FNB.