Value of single-injection or continuous sciatic nerve block in addition to a continuous femoral nerve block in patients undergoing total knee arthroplasty: a prospective, randomized, controlled trial

Continuous femoral nerve block in patients undergoing total knee arthroplasty (TKA) improves and shortens postoperative rehabilitation. The primary aim of this study was to investigate whether the addition of sciatic nerve block to continuous femoral nerve block will shorten the time-to-discharge readiness. Ninety patients undergoing TKA were prospectively randomized to 1 of 3 groups: patient-controlled analgesia via femoral nerve catheter alone (F group) or combined with a single-injection (Fs group) or continuous sciatic nerve block (FCS group) until the second postoperative day. Discharge readiness was defined as the ability to walk and climb stairs independently, average pain on a numerical rating scale at rest lower than 4, and no complications. In addition, knee function, pain, supplemental morphine requirement, local anesthetic consumption, and postoperative nausea and vomiting (PONV) were evaluated. Median time-to-discharge readiness was similar: F group, 4 days (range, 2-16 days); Fs group, 4 days (range, 2-7 days); and FCS group, 4 days (range, 2-9 days; P = 0.631). No significant differences were found regarding knee function, local anesthetic consumption, or postoperative nausea and vomiting. During the day of surgery, pain was moderate to severe in the F group, whereas Fs and FCS groups experienced minimal pain (P < 0.01). Patients in the F group required significantly more supplemental morphine on the day of surgery and the first postoperative day. Until the second postoperative day, pain was significantly less in the FCS group (P < 0.01). A single-injection or continuous sciatic nerve block in addition to a femoral nerve block did not influence time-to-discharge readiness. A single-injection sciatic nerve block can reduce severe pain on the day of the surgery, whereas a continuous sciatic nerve block reduces moderate pain during mobilization on the first 2 postoperative days