Obturator versus femoral nerve block for analgesia after total knee arthroplasty.
BACKGROUND
Both femoral and obturator nerve blocks have been suggested to be useful in relieving pain after total knee arthroplasty (TKA). We sought to compare their efficacy.


METHODS
Sixty patients undergoing elective unilateral TKA under spinal anesthesia received in a randomized, double-blind manner a femoral, obturator, or sham nerve block at the end of surgery. Blocks were performed using nerve stimulation and 20 mL bupivacaine 0.5% containing epinephrine 5 microg/mL. Patient-controlled IV analgesia with fentanyl, celecoxib 100 mg PO bid, and acetaminophen 650 mg PO every 6 h were started on arrival in the recovery room. Pain (0-10 numeric rating scale, NRS) at rest and with movement, analgesic use, and side effects were recorded for 48 h. Maximum knee flexion and total days in hospital were recorded as functional outcomes.


RESULTS
There were no significant differences in the obturator block group and the control group in any outcome variable. With baseline pain scores subtracted, femoral block resulted in less pain at rest compared with control (NRS difference from baseline 2.1 +/- 0.4 sem vs 3.4 +/- 0.4, respectively; P = 0.02) and less pain with movement (NRS difference 2.6 +/- 0.6, 4.3 +/- 0.6, P = 0.05) at recovery room discharge. Neither block had a significant effect on opioid use, functional outcome, or side effects. Only one (5%) patient with femoral block developed obturator motor block.


CONCLUSIONS
Femoral nerve blocks rarely block the obturator nerve. Single-injection femoral nerve block improved multimodal analgesia after spinal anesthesia for TKA, but this effect did not persist beyond the day of surgery. Obturator nerve block alone was of no benefit.
Kardash
Ken
K
Department of Anesthesia, Jewish General Hospital, McGill University, Montreal, Canada.
Hickey
Don
D
Tessler
Michael J
MJ
Payne
Stacey
S
Zukor
David
D
Velly
Ana Miriam
AM
D000082:Acetaminophen / Q000627:therapeutic use; D000368:Aged; D000698:Analgesia / Q000379:methods*; D016058:Analgesia, Patient-Controlled; D018712:Analgesics, Non-Narcotic / Q000627:therapeutic use; D000701:Analgesics, Opioid / Q000627:therapeutic use; D000779:Anesthetics, Local; D019645:Arthroplasty, Replacement, Knee; D002045:Bupivacaine; D000068579:Celecoxib; D016861:Cyclooxygenase Inhibitors / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D005267:Femoral Nerve; D005283:Fentanyl / Q000627:therapeutic use; D006801:Humans; D007717:Knee / Q000503:physiopathology / Q000601:surgery; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D009407:Nerve Block; D009776:Obturator Nerve; D010147:Pain Measurement; D010149:Postoperative Pain / Q000503:physiopathology / Q000517:prevention & control*; D011720:Pyrazoles / Q000627:therapeutic use; D020127:Recovery of Function; D013449:Sulfonamides / Q000627:therapeutic use; D013997:Time Factors; D016896:Treatment Outcome
D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D016861:Cyclooxygenase Inhibitors; D011720:Pyrazoles; D013449:Sulfonamides; D000082:Acetaminophen; D000068579:Celecoxib; D005283:Fentanyl; D002045:Bupivacaine