Introduction: The demand for better outcome following lower limb surgeries has led to increased interest in advanced techniques which can reduce complications and lower perioperative morbidity and mortality. The regional analgesia techniques, which provide better outcome, for knee and below knee surgeries provided 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 adductor hiatus and into the popliteal fossa. 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.
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 medial femoral condyle and slid proximally till Vastus and sartorius intersection (antero-medial intermuscular septum) was identified and 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. The point of injection was just proximal to it.
Discussion: The epidural analgesia was considered gold standard for postoperative analgesia for knee and below knee surgeries but the peripheral nerve block has given comparable analgesia to epidural analgesia with lower side effects. Various studies have concluded that the combination of sciatic with femoral nerve block improves the postoperative analgesia significantly. The adductor canal block has been proven to be non-inferior to femoral nerve block in providing analgesia and also provides better quadriceps strength. A single injection technique to block all the nerves can provide ease of practice and better postoperative care. Runge et al in 2017, performed a cadaver study where they described the spread of drug to sciatic nerve when injected in the distal adductor canal. Wong et al also compared the cadaver studies and analyzed the location of adductor canal using ultrasound and concluded that injection of drug in the distal part of the adductor canal spreads drug into the popliteal fossa blocking the sciatic nerve also.
Conclusion: The positional and technical difficulties with the blocks being performed can be overcome by using a single injection, 4 in 1 block, technique described by us with ease, adequacy and surety.
Key words: 4 in 1 block, adductor canal, adductor block, knee block, knee surgery, leg surgery, leg block, distal adductor, usg knee block, usg adductor block, usg 4 in 1 block, dr R roy, dr G agarwal, Dr C S Pradhan, Dr D Kuanar, Dr D Mallick
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