The Supra-iliac Anterior Quadratus Lumborum Block: a Cadaveric Study and Case Series

Purpose: The local anesthetic injectate spread with fascial plane blocks and corresponding clinical outcomes may vary depending on the site of injection. We developed and evaluated a supra-iliac approach to the anterior quadratus lumborum (QL) block and hypothesized that this single injection might successfully block the lumbar and sacral plexus in cadavers and provide analgesia for patients undergoing hip surgery.

Methods: Ultrasound-guided bilateral supra-iliac anterior QL blocks were performed with 30 mL of India ink dye in six fresh adult cadavers. Cadavers were subsequently dissected to determine distribution of the dye. In five patients undergoing hip surgery, a unilateral supra-iliac anterior QL block with 25 mL ropivacaine 0.5% followed by a continuous catheter infusion was performed. Patients were clinically assessed daily for block efficacy.

Results: The cadaveric injections showed consistent dye involvement of the majority of the branches of the lumbar plexus, including the femoral nerve, lateral femoral cutaneous nerve, ilioinguinal nerve, and iliohypogastric nerve. The majority of cadaveric specimens (83%) also exhibited thoracic paravertebral spread of dye to the T10 level. No specimens showed L5 or sacral nerve root staining or caudal spread below L5. All patients had effective analgesia for total hip surgery and a T11-L3 sensory level following the initial bolus of local anesthetic as well as during the period of continuous catheter infusion.

Conclusion: This cadaveric study and case series show that a supra-iliac approach to the anterior QL block involved T10--L3 nerve territories and dermatomal coverage with no sacral plexus spread. This technique may have clinical utility for analgesia in hip surgery.