Peripheral nerve block (PNB) anesthesia was associated with a better postoperative pain profile vs spinal anesthesia (SA) in patients who underwent acute ankle fracture surgery, but PNB anesthesia may be associated with intense rebound pain, according to a study in the British Journal of Anaesthesia.

In this randomized, 2-center trial, 150 patients scheduled to undergo primary ankle fracture surgery were randomly assigned to either PNB (n=77) or SA (n=73). In the PNB group, patients received ultrasound-guided popliteal sciatic and saphenous blocks with ropivacaine, while patients in the SA group received hyperbaric bupivacaine.

All patients in the trial received paracetamol (known in the United States as acetaminophen), ibuprofen, and patient-controlled intravenous morphine to manage pain after the operation.

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Change in the 27-hour Pain Intensity and Opioid Consumption (PIOC) score comprised the primary endpoint. Additional secondary endpoints included long-term pain scores, morphine consumption, and recovery quality as assessed by the Danish QoR-15 score.

For the SA and PNB procedures, the mean duration of effect was 3.5 hours (95% CI, 3.2-3.9) and 16.5 hours (95% CI, 15.8-17.3 hours), respectively. The PIOC score was significantly lower with PNB anesthesia compared with SA (median, -26.5% vs +54.3%, respectively; P <.001). Additionally, the effect size probability of a better PIOC score with PNB vs SA was 74.8% (95% CI, 67.0-82.6).

The use of PNB was associated with better postoperative pain scores (median, 37.5 vs 72.0; P <.001) and lower morphine consumption (median, 20.0 mg vs 32.5 mg; P =.001). In spite of these benefits, PNB was associated with substantial rebound pain following its use.

While quality of recovery scores were comparable between groups, approximately 99% who had PNB and 90% who had SA said they would choose the same anesthesia again (P =.03).

Limitations of this study included its lack of blinding, differences in initial postoperative care between the perianesthesia care unit and orthopedic unit, as well as the relatively small sample size.

The investigators noted that these findings indicate “that rebound pain after PNB can be severe and warrants attention in clinical practice.”


Sort R, Brorson S, Gögenur I, et al. Peripheral nerve block anaesthesia and postoperative pain in acute ankle fracture surgery: the AnAnkle randomised trial. Br J Anaesth. Published online February 2, 2021. doi:10.1016/j.bja.2020.12.037