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The Effect Of Dexmedetomidine As Adjuvant To Ropivacaine 0.1% For Femoral Nerve Block On Strength Of Quadriceps Muscle In Patients Undergoing Total Knee Arthroplasty: A Double-Blinded Randomized Controlled Trial

Authors Yang X, Kang W, Xiong W, Lu D, Zhou Z, Chen X, Zhou X, Feng X

Received 27 May 2019

Accepted for publication 31 October 2019

Published 17 December 2019 Volume 2019:12 Pages 3355—3363


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 2

Editor who approved publication: Dr E Alfonso Romero-Sandoval

Xiaoyu Yang,1,* Wenbin Kang,1,* Wei Xiong,1 Dihan Lu,1 Zhibin Zhou,1 Xi Chen,2 Xue Zhou,1,3 Xia Feng1

1Department of Anesthesiology, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, People’s Republic of China; 2Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, Tianjin, People’s Republic of China; 3MGH Center for Translational Pain Research, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA

*These authors contributed equally to this work

Correspondence: Xue Zhou; Xia Feng
Department of Anesthesiology, First Affiliated Hospital of Sun Yat-Sen University, No. 58 Zhongshan 2nd Road, Guangzhou, Guangdong 510080, People’s Republic of China
Tel +86-20-87332200-8273
Fax +86-020-873355766

Background: Femoral nerve block (FNB) has been considered as an excellent analgesic modality in total knee arthroplasty (TKA) pain control. However, relatively high concentration of ropivacaine could lead to quadriceps muscle weakness and increase the risk of postoperative falls.
Objective: This double-blinded randomized controlled study was designed to investigate the effect of a combination of dexmedetomidine with a lower concentration of ropivacaine on quadriceps muscle strength and analgesic effect in FNB.
Methods: A total of 90 patients scheduled for TKA were randomized to receive continuous FNB postoperatively using 0.2% ropivacaine (H group), 0.1% ropivacaine (L group) or 0.1% ropivacaine combined with 2 μg/kg dexmedetomidine (LD group). Meanwhile, intravenous patient-controlled analgesia with morphine was administered to patients. The primary endpoint was the strength of quadriceps muscle evaluated by manual muscle testing (MMT) and Timed Up and Go test (TUG). The secondary endpoint was the pain scores and morphine consumption among different groups.
Results: For MMT, LD group showed higher quadriceps muscle strength than the other two groups (P<0.05) at 12 hrs postoperatively. TUG test was conducted to measure the walking ability, and showed that scores were significantly better in LD group than those in H group and L group (P<0.05) at 24 and 48 hrs postoperatively. There was no significant difference between H and LD group in the numeric rating scales (NRS) scores both at rest and at 45° flexion. The total morphine consumption in L group was significantly higher than in H or LD group (P<0.001).
Conclusion: Collectively, the addition of dexmedetomidine 2 μg/kg to 0.1% ropivacaine preoperatively would preserve quadriceps muscle strength with satisfactory analgesia in patients undergoing TKA. (This study was registered at, identifier NCT03658421).

Keywords: femoral nerve block, dexmedetomidine, total knee arthroplasty, postoperative pain, muscle strength

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