J Korean Orthop Assoc.  2018 Jun;53(3):243-247. 10.4055/jkoa.2018.53.3.243.

A Comparison of the Results from Femoral Nerve Block Using Different Concentration of Ropivacaine after Total Knee Arthroplasty

Affiliations
  • 1Department of Orthopedic Surgery, Busan Medical Center, Busan, Korea. jun4128@naver.com

Abstract

PURPOSE
Peripheral nerve block is one of the many options available to reduce pain after total knee arthroplasty. Among the various kinds of peripheral nerve block procedure, femoral nerve block (FNB) using ropivacaine is a very effective method for reducing pain. However, it has been known to cause weakness in the quadriceps femoris, resulting in an increased risk of fall during ambulation after surgery. The purpose of this study was to compare the effectiveness of FNB on pain and muscle strength with different concentrations of ropivacaine.
MATERIALS AND METHODS
Our study was performed on 120 patients with knee osteoarthritis who had undergone total knee arthroplasty between January 2016 and December 2016. Patients were divided to 3 groups depending on the concentration of ropivacaine: Group 1 received 0.125% ropivacaine 6 ml FNB; group 2 received 0.2% ropivacaine 6 ml FNB; group 3 received normal saline 6 ml FNB. FNB with 1% lidocaine 10 ml and 0.75% ropivacaine 10 ml was performed to all groups at 3 hours after surgery. From the day after surgery, each group of patients were injected 4 times with FNB on their own designated concentration of ropivacaine with an interval of 6 hours. The severity of pain was estimated by visual analogue scale (VAS) and the strength of quadriceps femoris was measured using medical research council (MRC) grade and knee extension angle.
RESULTS
VAS score in group 3 was significantly higher compared to other groups; MRC grade in group 2 was significantly lower than in other grades, and knee extension angle in group 2 was significantly lower than in other groups at 6 pm on the day of and at 6 am on the day after surgery. VAS score, MRC grade, and extension angle of all groups showed no significantly difference at other times.
CONCLUSION
FNB with 0.125% ropivacaine after total knee arthroplasty shows effective reduction of pain without inducing quadriceps femoris weakness.

Keyword

total knee arthroplasty; femoral nerve block; 0.125% ropivacaine; quadriceps femoris power

MeSH Terms

Arthroplasty, Replacement, Knee*
Femoral Nerve*
Humans
Knee
Lidocaine
Methods
Muscle Strength
Osteoarthritis, Knee
Peripheral Nerves
Quadriceps Muscle
Walking
Lidocaine
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