Similar early functional recovery after total knee replacement comparing single shot versus continuous saphenous nerve block: A randomised, double-blind trial

Purpose: Total knee replacement (TKR) is associated with post-operative pain. Femoral nerve block can relieve the pain but also affects the post-operative mobility. Saphenous nerve block (SNB) can improve analgesia without interfering mobilisation. However, there is no consensus on the ideal mode of administration of SNB. We aim to compare the effects of single shot versus continuous SNB on patients undergoing TKR. Methods: Patients were randomised into two groups: single shot and continuous SNB groups. Post-operative rehabilitation and mobilisation were assessed by blinded physiotherapists, and preoperative and post-operative American knee scores were recorded by blinded specialised nurse. Post-operative analgesics usage was recorded by blinded pain nurses and anaesthetists. Results: Sixty-four patients were recruited; 6 patients withdrew with 29 patients in each group. There is no significant difference in early mobilisation and rehabilitation comparing both groups. The mean of the range gained on day 2 when compared to day 1 in single-shot SNB group was 17.41 +/- 19.67 degrees versus continuous SNB group was 23.45 +/- 19.18 degrees (p= 0.149). The mean of the range gained on day 3 when compared to day 1 in single-shot group was 27.24 +/- 22.66 degrees versus continuous SNB group was 29.31 +/- 21.57 degrees (p= 0.6). The mean of maximum flexion achieved by day 3 in single-shot SNB group was 92.41 +/- 9.6 degrees versus continuous SNB was 91.90 +/- 7.95 degrees (p= 0.84). The day of reaching maximum flexion and the goal of 40 m showed no significant difference. Length of stay (LOS), difference in post-operative American Knee Society knee score at 3 months and analgesics usage showed no significant difference. Conclusion: There is no significant difference in comparing the effect on mobilisation, LOS, early clinical outcome, analgesics usage in the single-shot group and the continuous SNB group.