Genicular vs IPACK Block for Analgesia in Knee Arthroplasty

Total knee arthroplasty (TKA) is one of the most frequently performed orthopedic procedures, and with the aging population, the global number of TKA cases is expected to increase sixfold within the next decade. Postoperative pain following TKA is often severe and difficult to manage, which may increase the risk of developing chronic pain. Effective pain control is therefore a major concern, and multimodal analgesia is recommended to enhance analgesia, reduce opioid consumption, and minimize opioid-related side effects.

Peripheral nerve blocks (PNBs) are an integral part of multimodal regimens. Among them, the adductor canal block (ACB), which provides analgesia to the anteromedial aspect of the knee while preserving motor function, is widely used. The optimal analgesic strategy for TKA should not only ensure adequate pain relief but also maintain quadriceps strength to allow early mobilization. Motor-sparing blocks combined with multimodal analgesia have become increasingly popular because they facilitate early rehabilitation, decrease opioid requirements, and improve recovery outcomes.

The knee joint has a complex innervation, receiving contributions from the femoral, sciatic, and obturator nerves. For this reason, combining different PNBs may provide superior analgesia compared to a single block (2). The genicular nerves, consisting of branches from the femoral, common peroneal, saphenous, tibial, and obturator nerves, innervate the knee capsule. Genicular nerve block specifically targets these branches and has been used to manage postoperative pain in TKA patients.

Another motor-sparing option is the interspace between the popliteal artery and posterior capsule of the knee (IPACK) block, which provides analgesia to the posterior aspect of the knee. Using ultrasound guidance, local anesthetic is deposited between the posterior capsule and the popliteal artery. This approach spares the main trunks of the tibial and common peroneal nerves while effectively blocking the terminal branches innervating the posterior capsule, including the genicular nerves and the popliteal plexus.

However, there are no studies in the literature directly comparing IPACK and genicular blocks. With this study, the investigators aim to compare the efficacy of these two blocks in patients undergoing TKA.