Ultrasound-guided single-injection femoral nerve block provides effective analgesia after total knee arthroplasty up to 48 hours.

OBJECTIVES

The purpose of this study is to evaluate the effects of ultrasound (US) guided single-injection femoral nerve block (FNB) spinal anesthesia on pain control, morphine consumption, adverse effects, and patient satisfaction during the postoperative 48-hour period in patients undergoing total knee arthroplasty (TKA).

METHODS

One hundred four ASA physical status I-III patients undergoing single TKA for degenerative joint disease were enrolled in this clinical study. Patients were randomly distributed into two groups: US-guided single-injection FNB with 40 ml of 0.5% bupivacaine and 1:200,000 epinephrine was administered to Group F (n=51) patients. Preservative-free saline was injected in Group P (n=53) patients using the same method as Group F. Pain scores, morphine consumption, incidences of adverse events, and patient satisfaction were assessed over the course of 48 hours.

RESULTS

Group F used significantly less morphine compared with Group P (18.7 mg vs. 39.6 mg) during the first 48 hours after surgery (p<0.001). When compared with group P, the VRS scores both at rest and during movement were significantly lower in Group F at 4, 8, 12, 24, and 48 hours after TKA (for all comparisons p<0.001). In addition, patient satisfaction was better in Group F than Group P.

CONCLUSION

This study suggests that a US-guided single-injection femoral nerve block following TKA improves patient satisfaction and reduces consumption of morphine during the first 48 hours.