Correspondence  |   February 2018
In Reply
Author Notes
  • University of Virginia, Charlottesville, Virginia (A.S.T.).
  • (Accepted for publication October 27, 2017.)
    (Accepted for publication October 27, 2017.)×
Article Information
Correspondence   |   February 2018
In Reply
Anesthesiology 2 2018, Vol.128, 421-422. doi:
Anesthesiology 2 2018, Vol.128, 421-422. doi:
Webb et al. note our conclusion that “the combination of femoral and sciatic nerve blocks provides the best analgesia”1  and assert that it is “not surprising that anesthetizing multiple nerves is superior to blocking a single nerve.” In fact, it was hardly a forgone conclusion that sciatic nerve blocks are necessary, because femoral nerve blocks alone work fairly well and might have proven sufficient, especially when combined with supplemental nonopioid systemic analgesics. Our results clearly show that sciatic nerve blocks significantly augment the benefit of femoral nerve blocks, and—importantly—quantify the effect magnitude.
Webb et al. comment that the incidence of transient peroneal nerve palsy was high in combined femoral-sciatic nerve blocks (7.6%). It is important to recognize that this fragile estimate was based on only six episodes in the femoral-sciatic group and was nearly the same as after periarticular infiltration (6.4%). Given how infrequently peroneal nerve palsy was reported in our underlying studies and the transient nature of the condition, it seems ill-advised to select analgesic strategy based on this minor and rare outcome.
Adding sciatic blocks to femoral blocks might slightly increase the incidence of falls, especially when a continuous infusion is used (we reported an incidence of 2.3%). However, it is important to recognize that falls are common (about 3%) even when patients are not given nerve blocks, presumably because of difficulty bearing weight on the painful joint. Patient and staff education might be more important than whether a block is used. For example, Clarke et al.2  report that a simple patient education program almost eliminates postarthroplasty falls. Webb et al. suggest substituting adductor canal blocks for femoral nerve blocks to reduce the risk of falls. Quadriceps strength is generally preserved with adductor canal blocks, but it remains unclear whether these blocks reduce the risk of falls after knee arthroplasty3  and whether they speed discharge readiness4  compared to femoral nerve block.
When we conducted our study, there were no randomized clinical trials that evaluated combinations of peripheral nerve block with periarticular injection. There is thus little evidence to support the assertion of Webb et al. that combining peripheral nerve blocks with periarticular injection offers advantages over other modalities. In fact, the reference they provide to support their assertion is a review article rather than original research.5 
We restricted our rehabilitation analyses to passive range of motion because it was the only functional outcome reported sufficiently often to be analyzed. We agree that there are probably better methods of assessing functional recovery, and this point was conceded in the limitations section of our discussion. That said, it remains unknown which “newer” rehabilitation outcomes best predict good long-term recovery.
Including multiple analgesic approaches in recovery pathways is prudent and increasingly routine; however, it is also clear that peripheral nerve blocks substantially reduce the need for systemic analgesics and should be included in multimodal pathways when practical. For example, a recent cohort study found that patients given peripheral nerve blocks (including major plexus and femoral nerve blocks) for knee arthroplasty had shorter hospital stays and fewer readmissions, with no differences in emergency department visits or falls.6 
Our network meta-analysis included multiple sensitivity analyses, such as excluding low-quality studies. It was based on the balance of pain control, opioid use, and passive range of motion of the prosthetic joint throughout the initial 72 postoperative hours and not at just at 72 h or any single time point.1  We were thus able to strongly conclude that “the combination of femoral and sciatic nerve block appears to be the overall best approach,” whereas “rehabilitation parameters remain markedly understudied.”
Competing Interests
The authors declare no competing interests.
Abdullah Sulieman Terkawi, M.D., Edward C. Nemergut, M.D., Daniel I. Sessler, M.D. University of Virginia, Charlottesville, Virginia (A.S.T.).
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Clarke, HD, Timm, VL, Goldberg, BR, Hattrup, SJ . Preoperative patient education reduces in-hospital falls after total knee arthroplasty. Clin Orthop Relat Res 2012; 470:244–9 [Article] [PubMed]
Elkassabany, NM, Antosh, S, Ahmed, M, Nelson, C, Israelite, C, Badiola, I, Cai, LF, Williams, R, Hughes, C, Mariano, ER, Liu, J . The risk of falls after total knee arthroplasty with the use of a femoral nerve block versus an adductor canal block: A double-blinded randomized controlled study. Anesth Analg 2016; 122:1696–703 [Article] [PubMed]
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