Por Vicente Roques :
However, there may be a third option. All of the pain control with the duration of the single shot, at the least; the continuous adductor canal block.
So what’s wrong with the single shot adductor canal block? In my (humble) opinion, the problem is partly the position and partly the effect.
Consider this. Placing your local anesthetic solution at mid-thigh means that the tourniquet will be placed almost exactly over the injection site. External pressure like that will spread the local solution along the canal and the spread will increase the surface area of the solution bolus, an increase in surface area will increase the rate of absorption shortening the duration of the block.
Secondly, pursuant to the goal of the approach, the patient is up and ambulating early. Walking and therefore working the quadriceps will obviously put the thigh through a series of repeated compressions and relaxations, a pumping effect. That and the attendant increase in bloodflow and movement of interstitial fluid will cause the patient to “walk off” the block more quickly.
This may seem hyper-critical or nit-picking, but it’s not; you can cut hours off of a single-shot nerve block with active movement.
In order for this block to last through the first 24 hours post-operatively I think you should leave a catheter in place after the initial single shot bolus. Then either use a medication pump or periodically bolus the catheter with local.
More information on the Adductor Canal block is found here. May 25, 2013