Comparison Of The Analgesic Efficacy Of IPACK (Interspace Between The Popliteal Artery And Capsule Of The Posterior Knee) Block Alone And IPACK Block Combined With Genicular Block In Patients Planned For Total Knee Arthroplasty

Chronic knee pain, observed in the range of 7-33% in the society, is often caused by osteoarthritis. The knee joint consists of four bones: the femur, tibia, the largest sesamoid bone called the patella, and the fibula, although it does not directly join the joint. It is divided into three compartments called the medial tibiofemoral, lateral tibiofemoral, and patellofemoral, which share a common synovial cavity. Additionally, the knee joint is composed of the patellofemoral and tibiofemoral joints. The knee joint is supported by ligaments that provide stability and muscles and tendons that maintain its dynamic structure.

The superomedial quarter of the anteromedial aspect of the knee joint is innervated by the nervus vastus medialis, the medial branch of the nervus vastus intermedius, and the superior medial genicular nerve. The inferomedial quarter is innervated by the infrapatellar branch of the saphenous nerve and the inferior medial genicular nerve. The superolateral quarter of the anterolateral aspect is innervated by the nervus vastus lateralis, the lateral branch of the nervus vastus intermedius, the superior lateral genicular nerve, and the articular branches of the common fibular nerve. The inferolateral portion is innervated by the inferior lateral genicular nerve and the recurrent fibular nerve. The posterior sensation of the knee is provided by the popliteal plexus. Due to the dense innervation of the knee joint, approximately 60% of patients undergoing knee prostheses experience severe pain, while 30% describe a moderate level of pain.

The IPACK (interspace between the popliteal artery and capsule of the posterior knee) block is a regional anesthesia technique in which a local anesthetic is infiltrated under ultrasound guidance between the popliteal artery and the capsule of the posterior knee. This technique blocks the branches of the obturator nerve, the common peroneal nerve, and the tibial nerve in the popliteal region. In the context of knee arthroplasty, the application of the IPACK block has been associated with lower scores for ambulatory pain, lower scores for resting pain, and reduced morphine consumption .

The genicular nerves, including the superomedial, inferomedial, superolateral, inferolateral genicular nerves, and the infrapatellar branch of the saphenous nerve, comprise the five main innervation branches of the knee. Clinically, they play an important role in the anterior sensory innervation of the knee. GNB (genicular nerve block) and radiofrequency ablation techniques are utilized in the treatment of chronic osteoarthritis and have recently gained popularity in postoperative pain management following knee surgeries.

In our study, the investigators aimed to prospectively, double-blind, and randomly compare the postoperative analgesic efficacy of combined IPACK block and genicular block with the sole application of IPACK block in patients undergoing total knee arthroplasty (TKA). The investigators hypothesized that in blocks performed with equal volumes, there might be a spread of the local anesthetic solution from the IPACK block area to the genicular block area, and the investigators investigated this hypothesis.