Questions · Femoral Nerve Block and Adductor Canal Block
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Recall — derived from a kept point
A systematic review of eight randomised trials in 655 patients having arthroscopic anterior cruciate ligament reconstruction compared adductor canal block with femoral nerve block. The trials did not all agree. Describe what the review could and could not conclude, and say what happened to strength at six months.
Answer: The outcome measures were heterogeneous enough that no meta-analysis could be performed, so the review reports the trials rather than pooling them. Three trials found the adductor canal block preserved quadriceps strength, measured by straight-leg raise, for the first 12 to 24 hours after surgery; three others found no difference between the blocks. Analgesia, opioid consumption and complications were mostly the same in both. At six months there was no difference in isokinetic strength between the groups. So the defensible statement is a short-term motor advantage on some measures and no demonstrated long-term difference — not a lasting functional benefit.
"Heterogeneity precluded meta-analysis" is a finding, not a footnote. It means the effect is not consistent enough across trials to be summarised as a single number, and quoting one favourable trial as if it were the answer misrepresents the literature.
Source claim: Across eight randomised trials with 655 patients undergoing arthroscopic anterior cruciate ligament reconstruction, heterogeneity of outcome measures precluded meta-analysis; three trials found adductor canal block preserved quadriceps strength on straight-leg raise for the first 12 to 24 hours while three found no difference, no difference in isokinetic strength was reported at six months, and the majority of studies reporting opioid consumption, pain scores and complications found no differences between the blocks.
Edwards MD et al., Effect of Adductor Canal Block Versus Femoral Nerve Block on Quadriceps Strength, Function, and Postoperative Pain After Anterior Cruciate Ligament Reconstruction: A Systematic Review of Level 1 Studies, Am J Sports Med 2020
recall · CA-1 · phrased by llm
A meta-analysis of 12 randomised trials compared adductor canal block with femoral nerve block after total knee arthroplasty. Summarise what it found on the motor side and on the analgesic side, and explain why that combination is what drives the choice of block on an enhanced-recovery pathway.
Answer: On the motor side the adductor canal block was clearly better: quadriceps maximum voluntary isometric contraction was significantly higher than after femoral nerve block, and the same direction held when strength was graded on a manual muscle scale. Range of motion was also better. On the analgesic side there was no cost — at every follow-up time the adductor canal block was not inferior to the femoral nerve block for pain control or for opioid consumption. That is what settles the choice: you are buying quadriceps function and earlier knee recovery without giving up analgesia, and on a pathway whose whole aim is early ambulation, an equal-analgesia block that leaves the quadriceps working is the one to pick.
When two blocks are equal on the outcome you were measuring, the decision moves to the outcome you were not — here, whether the patient can lift the leg and get out of bed.
Source claim: Pooling 12 randomised trials of total knee arthroplasty, quadriceps maximum voluntary isometric contraction was significantly higher after adductor canal block than after femoral nerve block, a result consistent with quadriceps strength assessed on a manual muscle strength scale, range of motion was better, and the adductor canal block was not inferior to the femoral nerve block for pain control or opioid consumption at any follow-up time; the authors conclude that the adductor canal block is superior to the femoral nerve block for sparing quadriceps strength and for faster knee function recovery.
Wang D et al., Adductor canal block versus femoral nerve block for total knee arthroplasty: a meta-analysis of randomized controlled trials, Sci Rep 2017
recall · CA-1 · phrased by llm
This randomized trial found that for knee arthroscopy, intra-articular local anesthetic provided significantly lower pain scores than an adductor canal block at 1, 2, and ___ hours postoperatively, with no difference in total narcotic consumption.
Answer: 4
This randomized trial found that for knee arthroscopy, intra-articular local anesthetic provided significantly lower pain scores than an adductor canal block at 1, 2, and 4 hours postoperatively, with no difference in total narcotic consumption.
Adductor Canal Nerve Block versus Intra-articular Anesthetic in Knee Arthroscopy: A Single-Blinded Prospective Randomized Trial · PMID 36807102
recall · CA-1 · phrased by derived
This network meta-analysis of adults undergoing primary total knee arthroplasty found that a single-shot adductor canal block provides better ___-hour functional recovery but higher pain scores and opioid consumption compared with a continuous femoral nerve block.
Answer: 24
This network meta-analysis of adults undergoing primary total knee arthroplasty found that a single-shot adductor canal block provides better 24-hour functional recovery but higher pain scores and opioid consumption compared with a continuous femoral nerve block.
Adductor Canal Block Versus Femoral Nerve Block in Total Knee Arthroplasty: Network Meta-Analysis · PMID 38561898
recall · CA-1 · phrased by derived
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