Effect of adductor canal block versus femoral nerve block on quadriceps strength, mobilization, and pain after total knee arthroplasty: a randomized, blinded study.
OBJECTIVE
Total knee arthroplasty (TKA) is often associated with severe pain. Different regional anesthetic techniques exist, all with varying degrees of motor blockade. We hypothesized that pain relief provided by the adductor canal block (ACB) could increase functional muscle strength.


METHODS
We included 50 TKA patients with severe movement-related pain; defined as having visual analog scale pain score of greater than 60 mm during active flexion of the knee. The ACB group received an ACB with ropivacaine 0.2% 30 mL and a femoral nerve block (FNB) with 30 mL saline. The FNB group received an ACB with 30 mL saline and an FNB with ropivacaine 0.2% 30 mL. We compared the effect of the ACB versus FNB on maximum voluntary isometric contraction of the quadriceps muscle relative to a postoperative baseline value. Secondary end points were differences between groups in ability to ambulate and changes in pain scores (Clinicaltrials.gov identifier NCT01922596).


RESULTS
After block, the quadriceps maximum voluntary isometric contraction increased to 193% (95% confidence interval [CI], 143-288) of the baseline value in the ACB group and decreased to 16% (95% CI, 3-33) in the FNB group with an estimated difference of 178% (95% CI, 136-226), P < 0.0001. Pain scores were similar between groups. Before block, 2 of 25 patients in each group were unable to perform the Timed-Up-and-Go test; after block, this number increased to 7 of 25 in the FNB group and decreased to 0 of 25 in the ACB group.


CONCLUSIONS
Adductor canal block provides a clinically relevant and statistically significant increase in quadriceps muscle strength for patients in severe pain after TKA.
From the *Department of Anaesthesia and Intensive Care Medicine, Copenhagen University Hospital, Gentofte Hospital, Gentofte; †Section of Acute Pain Management, Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen; and ‡Department of Orthopaedic Surgery, Copenhagen University Hospital, Gentofte Hospital, Gentofte; and §Department of Anaesthesia, Centre of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.
Ulrik
U
Grevstad
Ole
O
Mathiesen
Laura Staun
LS
Valentiner
Pia
P
Jaeger
Karen Lisa
KL
Hilsted
Jørgen B
JB
Dahl
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000779:Anesthetics, Local / Q000008:administration & dosage; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000639:trends*; D001340:Autonomic Nerve Block / Q000379:methods*; D005260:Female; D005267:Femoral Nerve / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D053580:Muscle Strength / Q000187:drug effects / Q000502:physiology*; D010149:Postoperative Pain / Q000175:diagnosis / Q000517:prevention & control*; D011446:Prospective Studies; D052097:Quadriceps Muscle / Q000187:drug effects / Q000502:physiology; D016037:Single-Blind Method; D016896:Treatment Outcome
D000779:Anesthetics, Local