Correspondence  |   September 2015
In Reply
Author Notes
  • Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada (R.B.).
  • (Accepted for publication March 5, 2015.)
    (Accepted for publication March 5, 2015.)×
Article Information
Correspondence   |   September 2015
In Reply
Anesthesiology 9 2015, Vol.123, 723. doi:
Anesthesiology 9 2015, Vol.123, 723. doi:
We thank Dr. Merman for her comments regarding the novelty of our study,1  the duration of analgesia provided by a single-shot sciatic block, and the safety concerns associated with using a distal sciatic block in the setting of knee arthroplasty.
Although the work published in 2004 by Ben-David et al.2  may signal a benefit to sciatic block in treating posterior knee pain after knee arthroplasty, any conclusions drawn from this trial are significantly undermined by its observational design and limited sample size of only 12 patients. In the 2005 randomized trial by Pham Dang et al.,3  neither the patients nor the assessors were blinded, and the authors did not specifically examine the effect of sciatic block on posterior knee pain. Therefore, neither of these two earlier studies can be considered definitive.
We agree with Dr. Merman that a continuous catheter-based perineural infusion can prolong the duration of analgesia associated with sciatic nerve block; however, the clinical importance of prolonged sensory blockade may be offset by a delay in mobilization, a critical requirement in the contemporary clinical pathways that emphasize early ambulation.
Finally, we aimed to definitively quantify the analgesic benefits of sciatic nerve block after knee arthroplasty, and our results suggest that both proximal and distal sciatic nerve blockade similarly improve analgesic outcomes. Our study was not sufficiently powered to demonstrate differences in the rate of block-related nerve injury. Although Dr. Merman’s comments regarding the safety of tourniquet use in the immediate vicinity of a perineural injection around the popliteal sciatic nerve may seem reasonable, these concerns remain speculative.
Competing Interests
The authors declare no competing interests.
Faraj W. Abdallah, M.D., Richard Brull, M.D., F.R.C.P.C. Toronto Western Hospital, University of Toronto, Toronto, Ontario, Canada (R.B.).
Abdallah, FW, Chan, VW, Gandhi, R, Koshkin, A, Abbas, S, Brull, R The analgesic effects of proximal, distal, or no sciatic nerve block on posterior knee pain after total knee arthroplasty: A double-blind placebo-controlled randomized trial.. Anesthesiology. (2014). 121 1302–10 [Article] [PubMed]
Ben-David, B, Schmalenberger, K, Chelly, JE Analgesia after total knee arthroplasty: Is continuous sciatic blockade needed in addition to continuous femoral blockade?. Anesth Analg. (2004). 98 747–9 [Article] [PubMed]
Pham Dang, C, Gautheron, E, Guilley, J, Fernandez, M, Waast, D, Volteau, C, Nguyen, JM, Pinaud, M The value of adding sciatic block to continuous femoral block for analgesia after total knee replacement.. Reg Anesth Pain Med. (2005). 30 128–33 [Article] [PubMed]