The purpose of this study is to investigate whether there is quantitative motor-sparing of the quadriceps muscles following adductor canal nerve block versus femoral nerve block. Patients will be randomly placed into one of three treatment groups: 1) Femoral nerve block, 2) Adductor canal nerve block - low volume, or 3) Adductor canal nerve block - high volume. Quadriceps function will be assessed in the operating room using a skin patch and electrical stimulation. Follow up visits with the patients will continue over the course of 2 days during patient's stay at the hospital. A total of 60 patients will be enrolled for the study.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
33
Adductor canal block performed in the distal thigh (1/3 of the total distance between the superior border of the patella and the femoral crease, cephalad to the patella) utilizing an injectate volume of 30 mL 0.25% bupivacaine/ epinephrine
Adductor canal block performed in the distal thigh (1/3 of the total distance between the superior border of the patella and the femoral crease, cephalad to the patella) utilizing an injectate volume of of 10 mL 0.75% bupivacaine/ epinephrine
Femoral nerve block with 10 mL 0.75 % bupivacaine/epinephrine
Hospital for Special Surgery
New York, New York, United States
Quadriceps function as assessed by non-invasive transcutaneous nerve stimulation of the femoral nerve
After CSE effect, but prior to peripheral block, quadriceps function will be assessed by non-invasive transcutaneous nerve stimulation of the femoral nerve by placing an ECG electrode over the femoral location (determined by U/S) in the inguinal groove. The threshold amperage that produces patellar motion in response to electrical stimulation will be recorded. This threshold amperage will serve as a baseline value. Following the peripheral nerve block, transcutaneous stimulation will be repeated and, if still possible to elicit quadriceps contractions in response to electrical stimulation, the resulting new threshold amperage will be measured. The new threshold amperage will be expressed as a percentage of the baseline value and serve as a quantitative functional indication of the extent of quadriceps paresis resulting from the peripheral nerve block. The primary outcome will be quadriceps paralysis - yes/no.
Time frame: 15 minutes after the placement of the peripheral nerve block (femoral or adductor canal)
Threshold amperage as a percentage of the baseline value
Following the peripheral nerve block, transcutaneous stimulation will be repeated and, if still possible to elicit quadriceps contractions in response to electrical stimulation, the resulting new threshold amperage will be measured. The new threshold amperage will be expressed as a percentage of the baseline value and serve as a quantitative functional indication of the extent of quadriceps paresis resulting from the peripheral nerve block.
Time frame: 15 minutes after the placement of the peripheral nerve block
Analgesic adequacy
Analgesic adequacy as determined by pain scores (0-10) at spinal resolution (on average 2 hours post-op), 24 hours post-op and 48 hours post-op and daily epidural patient controlled analgesia consumption
Time frame: Resolution of the spinal anesthetic (2 hours post-op), 24 and 48 hours post-op
Ability to complete a straight leg lift
Ability to complete and hold (for 3 seconds) a straight leg lift (from supine position) against gravity as evidence of meaningful quadriceps function - performed in holding area (baseline), at spinal resolution (on average 2 hours post-op), 24 hours post-op and 48 hours post-op
Time frame: Holding area (baseline), at spinal resolution (2 hours post-op), 24 hours post-op and 48 hours post-op
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