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Adductor Canal Block With 10 mL Versus 30 mL Local Anesthetics and Quadriceps Strength: A Paired, Blinded, Randomized Study in Healthy Volunteers
  1. Pia Jæger, MD, PhD*,
  2. Zbigniew J. Koscielniak-Nielsen, MD, DMSc, FRCA*,
  3. Karen Lisa Hilsted, RN*,
  4. Maria Louise Fabritius, MD* and
  5. Jørgen B. Dahl, MD, DMSc, MBEx
  1. From the *Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet; and †Department of Anaesthesia, Bispebjerg and Frederiksberg Hospitals, Copenhagen University Hospital, Copenhagen, Denmark
  1. Address correspondence to: Pia Jæger, MD, PhD, Department of Anaesthesia 4231, Centre of Head and Orthopaedics, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark (e-mail: pia.therese.jaeger{at}


Background and Objectives Adductor canal block (ACB) is predominantly a sensory nerve block, but excess volume may spread to the femoral triangle and reduce quadriceps strength. We hypothesized that reducing the local anesthetic volume from 30 to 10 mL may lead to fewer subjects with quadriceps weakness.

Methods We performed a paired, blinded, randomized trial including healthy men. All subjects received bilateral ACBs with ropivacaine 0.1%; 10 mL in 1 leg and 30 mL in the other leg. The primary outcome was the difference in number of subjects with quadriceps strength reduced by more than 25% from baseline in 2 consecutive assessments. Secondary outcomes were quadriceps strength as a percentage of baseline at predefined time points, functional outcome assessed by the 30-Second Chair Stand Test (1 leg at a time), and sensory block. Identifier: NCT01981746.

Results We included and analyzed 26 subjects. For either volume, 2 subjects had a reduction in quadriceps strength by more than 25% from baseline (difference, 0%; 95% confidence interval, −13 to 13; P > 0.999). Similarly, we found no significant differences between volumes in quadriceps strength at any of the predefined time points or in sensory block. The only statistically significant difference between volumes was found in the 30-Second Chair Stand Test at 2 hours (P = 0.02), but this difference had disappeared at 4 hours (P = 0.06).

Conclusions Varying the volume of ropivacaine 0.1% used for ACB between 10 and 30 mL did not have a statistically significant or clinically relevant impact on quadriceps strength.

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  • P.J. has received speaker’s honoraria from Smiths Medical USA, and Z.J.K.N. occasionally receives speaker’s honoraria from B. Braun Medical, Melsungen, Germany. The other authors declare no conflict of interest.

    Support was provided solely from institutional and departmental sources.

    The department and institution to which the work should be attributed: Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.

    Abstract was presented at the Danish Society of Anaesthesiology and Intensive Care Medicine’s Annual Meeting, Copenhagen, Denmark, November 2014 and at the European Society of Regional Anaesthesia and Pain Therapy 33rd Annual Congress 2014, Seville, Spain.

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