Ultrasound guided 4 in 1 block – a newer, single injection technique for complete postoperative analgesia for knee and below knee surgeries

Abstract

Introduction: The demand for better outcome with increased incidence of lower limb surgeries have increased interest in advanced techniques which, reduce complications and lower perioperative morbidity and mortality. The regional analgesia techniques, which provide better outcome, for knee and below knee surgeries provide excellent options for perioperative care for every age group of patients. The combination of the femoral nerve block with sciatic nerve block has provided adequate analgesia with lower consumption of perioperative opioids and rescue analgesia, for knee and below knee surgeries. We describe a novel and single injection technique for the combined 4-in-1 block (saphenous nerve, obturator nerve, nerve to vastus medialis and sciatic nerve) with a single injection point.
Relevant Anatomy: The adductor canal consists of the femoral vessels (vein and artery) along with the branches of the femoral nerve namely the femoral cutaneous nerves, the saphenous nerve and the Nerve to vastus medialis. The posterior division of the obturator nerve enters the popliteal fossa through the adductor hiatus. The knee is innervated by the genicular branches from the nerve to vastus medialis, saphenous nerve, sciatic nerve and the posterior division of obturator nerve. The skin around the knee is supplied by the cutaneous branches from the femoral nerve and the saphenous nerve. The nerve supply of the leg and foot is from the sciatic nerve, except the skin in the medial aspect is supplied by the sensory saphenous nerve.
Methodology: We describe the functional anatomy of the nerve supply to the lower limb, especially the knee joints and below knee areas. We describe the proposed ‘4 in one’ nerve block technique for adequate postoperative analgesia of the body parts under discussion.
Description of Technique: The patient was kept in supine position with the ipsilateral leg kept in Frog leg position. The medial femoral condyle was marked. A linear high frequency Ultrasound probe (6-13Hz) was used. The probe was kept over the femoral condyle and vastus medialis muscle and the Vastus and sartorius intersection (antero-medial intermuscular septum) was identified and the probe was slid proximally till the superficial femoral artery appeared in the Adductor Hiatus. The probe was slid slowly proximally till the descending genicular artery branching from superficial femoral artery was visualized in the hiatus. This point was the injection point.