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October 13, 2018
10/13/2018 2:00:00 PM - 10/13/2018 4:00:00 PM
Room North, Hall D, Area B
Preoperative Sciatic Nerve Blocks for Total Ankle Arthroplasty Confer Advantages Over Those Placed Postoperatively
Ava Alamdari, M.B.,B.S., Paul I. Bhalla, M.B.,Ch.B., Ramesh Ramaiah, M.B.,B.S., Sanjay M. Bhananker, M.B.,B.S.
University of Washington, Harborview Medical Center, Seattle, Washington, United States
Disclosures: A. Alamdari: None. P.I. Bhalla: None. R. Ramaiah: None. S.M. Bhananker: None.

Peripheral nerve blocks are often used for management of postoperative pain, as well as minimizing opioid use during and following orthopedic surgery. The preference of the surgeons in our institution is for sciatic nerve blocks to be placed postoperatively following total ankle arthroplasty (TAA) or revision TAA, due to their concerns about operating room turnover times. We audited the timing of nerve block placement and the effects on quantifiable metrics described below to provide data driven guidance on our practice.


We retrospectively reviewed the charts of patients that underwent TAA or revision TAA with a sciatic peripheral nerve catheter between January 1, 2015 and May 30, 2017. All sciatic nerve catheters were placed under ultrasound guidance by dedicated regional anesthesia personnel. Preoperative nerve blocks were placed in awake or lightly sedated patients in the preoperative holding area and postoperative nerve blocks were placed in anesthetized patients in the post-anesthesia care unit (PACU). The outcomes were: opioid use in the operating room (OR) and post-operative care unit (PACU) calculated, via the hospital pharmacy conversion table, in morphine equivalents (ME) in mg; PACU length of stay (LOS); use of medications to treat opioid side effects (i.e. nausea, vomiting, itching and respiratory depression); and hospital LOS. The outcomes between the two groups were compared using appropriate statistical tests (two sample t-test, Pearson’s chi-squared or Wilcoxon run-sum tests) with p<0.05 for statistical significance.


A total of 223 patients underwent TAA or revision TAA with a sciatic nerve block in the study period (Table 1). Mean OR opioid use was reduced in the preoperative group by a significant proportion (19.29 ± 8.2 ME vs 26.17 ± 11.3 ME p<0.001). A reduction was also noted in the PACU opioid use (3.23 ± 5.8 ME vs 4.69 ± 8.9 ME p=0.39). This amounted to a 28% decrease in total opiate use for patients receiving a preoperative nerve block (22.52 ± 11.3 ME vs 31.4 ± 15.7 ME p=0.004). Mean PACU LOS was reduced by nearly half for the preoperative group at 66.6 ± 27 minutes compared to 117 ± 43.2 minutes for those receiving the nerve block postoperatively (p<0.001). There was no significant difference noted in hospital LOS or medication use for opioid side-effects between the two groups.


Preoperative sciatic nerve blocks for TAA reduced mean perioperative opioid use by 28%, and mean PACU LOS by 50 minutes compared to postoperative blocks. The significant reduction in opioid use suggests a pre-emptive effect of early nerve blockade, although data on opioid use beyond the perioperative period would be needed to confirm this. Given the high cost of PACU time (approximately $1130/half hour at our institution) the reduction in PACU LOS is both clinically and fiscally significant. Additionally, with increased PACU LOS, the risk of bottlenecks in patient flow increases, potentially leading to delayed or cancelled operations and further increased costs. Further prospective studies are needed to confirm these findings.


We thank the Perioperative & Pain initiatives in Quality Safety Outcome (PPiQSO) group at the University of Washington, Seattle for providing data extraction services.
Figure 1

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