Ultrasound Evaluation of Subsartorial Spread Following Adductor Canal Block: A Case Series.

Adductor canal block is a widely used regional anesthesia technique for total knee arthroplasty that helps in reducing post-surgical pain and opioid use. Anatomically, the adductor canal extends from the apex of the femoral triangle proximally to the adductor hiatus distally and is roofed by the sartorius and vasto-adductor fascia. All these serve as a potential path for the spread of the local anesthetic when it is injected inside the adductor canal during the block. Subsartorial space is of unique interest as it lies between the sartorius and vasto-adductor fascia, carrying the subsartorial plexus that can provide additional analgesia to the knee when the adductor canal block injectate spreads into it. While the spread can be variable, ultrasound can be a useful tool to evaluate this spread. This is a case series of patients who underwent total knee arthroplasty under spinal anesthesia and adductor canal blocks. We present the findings of ultrasound evaluation of the injectate spread following adductor canal blocks and evaluation of their analgesia effects.