The purpose of this technical note is to present a microinvasive percutaneous ultrasound-guided release of the lacertus fibrosus of the biceps brachii for lacertus syndrome, i.e., median nerve entrapment at the elbow.

Using the Walant technique (wide awake local anesthesia and no tourniquet), the entry point is made with a 19G needle to introduce the hook distally from the distal border of the lacertus fibrosus. The hook is then slid along the pronator teres fascia to the proximal border of the lacertus fibrosus. The cut is ultrasound-guided from proximal to distal. The cut is effective when the back of the force is observed in the 3 targeted muscles (flexor carpi radialis, flexor pollicis longus and flexor digitorum profundus).

This minimally invasive surgical procedure is efficient in terms of lacertus fibrosus sectioning. Real-time ultrasound monitoring may improve safety. The technique could be considered as a new ultrasound-guided alternative to open surgery.

When performed superficially to the pronator teres muscle under WALANT anesthesia and percutaneously, ultrasound-guided lacertus fibrosus release may be an effective treatment for lacertus syndrome in the interventional ultrasound unit.