The Effect of Local Anesthetic Volume Within the Adductor Canal on Quadriceps Function Evaluated by Electromyography

Ulrik Grevstad

Status and phase: Completed; Phase 4

Conditions: Knee Arthroplasty, Total

Treatments: Drug: Saline; Drug: Lidocaine

Study type: Interventional

Funder types: Other

Identifiers

NCT02344589

SM-UG-14

Details and patient eligibility

About

Our aim is to investigate which components of the quadriceps femoris muscle are affected following an ACB with different volumes (10, 20 and 30 ml) of 1% lignocaine evaluated by electromyography. Both a placebo treatment (20ml saline) and the femoral nerve block (20ml lignocaine 1%) as an active comparative will be used for model control. Further, we want to investigate the effect of volume on motor block. This will be evaluated by measuring the Maximum Voluntary Isometric Contraction (MVIC) of the quadriceps femoris muscle.

Full description

The ACB has a well-proven analgesic effect after TKA, but we do not know which nerves that are affected by the block. Aside being a motor nerve, the nerve to the vastus medialis of the quadriceps femoris muscle, contains the second largest sensory contribution from the femoral nerve. It is probable that some of the analgesic effect of the ACB arises from blocking this nerve.

Even though the ACB is mainly a sensory nerve block, a study in healthy volunteers showed a small decline by 8% in quadriceps muscle strength(10). It is speculated that the decline in muscle strength was caused by the spread of local anesthetic to the nerve supplying the vastus medialis of the quadriceps femoris muscle. Three out of eleven of the volunteers experienced an even larger decline of 25 % in quadriceps muscle strength. It has been argued that this decline likely was caused by a proximal spread of the local anesthetic to the femoral triangle thereby resulting in an affection of the femoral nerve. In this study, a volume of 30 ml of local anesthetic was used.

We do not know the optimal volume for the ACB and we find it relevant to investigate to what extent and which parts of the quadriceps muscle gets affected when different volumes of a local anesthetic are injected into the adductor canal. Selective affection of the different components of the femoral quadriceps muscle can be assessed by non-invasive EMG recordings. Further, the quadriceps femoris muscle strength will be evaluated by measuring the MVIC following the different volumes. The EMG recordings will be voluntary (vEMG) measured during MVIC and stimulated (sEMG). sEMG is measured during transcutaneous electrical stimulation of the femoral nerve.

Enrollment: 20 patients

Sex: Male

Ages: 18+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Age > 18 years old
• Subjects who gave their written informed consent to participating in the study after having fully understood the contents of the protocol and re-strictions.
• ASA 1
• Male
• BMI 18-30
• Physical exercise 1-3 hours/week

Exclusion criteria

• Subjects who cannot cooperate with the study.
• Subjects who cannot understand or speak Danish.
• Subjects with allergy to the medicines used in the study.
• Subjects suffering from alcohol and/or drug abuse - based on the investi-gator's opinion.
• Pathology or previous surgery or trauma to the lower limb.
• Intense exercise 24 h before the tests
• Intake of any analgesics 24 h prior to baseline measurements.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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20 participants in 5 patient groups, including a placebo group

ACB 10

Experimental group

Description:

ACB in right leg with 10ml of lidocaine 10mg/ml. Subject and assessor blinded, randomized. given on day 1, 2 or 3

Treatment:

Drug: Lidocaine

ACB 20

Experimental group

Description:

ACB in right leg with 20ml of lidocaine 10mg/ml. Subject and assessor blinded, randomized. given on day 1, 2 or 3

Treatment:

Drug: Lidocaine

ACB 30

Experimental group

Description:

ACB in right leg with 30ml of lidocaine 10mg/ml. Subject and assessor blinded, randomized. given on day 1, 2 or 3

Treatment:

Drug: Lidocaine

FNB

Active Comparator group

Description:

FNB in left leg with 20ml of lidocaine 10mg/ml on day 1. Unblinded arm, used for model control

Treatment:

Drug: Lidocaine

Placebo

Placebo Comparator group

Description:

ACB in left leg with 30ml of isotonic saline on day 2. Unblinded arm used for model control

Treatment:

Drug: Saline