Analgesic Effect of Adductor Canal Block, IPACK Block, and Genicular Nerve Block

Total knee arthroplasty (TKA) is a surgical procedure performed on patients with severe pain and severely limited range of motion in the knee joint due to knee osteoarthritis, when traditional conservative treatments have failed. Fifty-eight percent of patients who undergo TKA experience moderate or severe pain in the postoperative period. Inadequate pain control leads to complications such as venous thrombosis, coronary ischemia, myocardial infarction, and pneumonia, and increases morbidity. In addition, failure to control postoperative pain negatively affects physical therapy procedures. This situation prolongs the rehabilitation and hospital stay of patients, thus increasing care costs. Therefore, it is of great importance to reduce the patient's pain after TKA.

Femoral nerve block (FNB) has traditionally been a critical component of multimodal analgesia in TKA due to its high analgesic efficacy. However, FNB limits physical therapy by causing motor limitations in the quadriceps muscle. This situation causes delays in ambulation and discharge. Due to the difficulties in rehabilitation observed in patients undergoing FNB due to quadriceps muscle weakness, different techniques were sought and the Adductor canal block (ACB) emerged. AKB is a sensory block that blocks the saphenous nerve, a sensory nerve that courses in the adductor canal in the thigh, thus preserving motor function. It is an alternative block to FNB by providing adequate analgesia to the anterior compartment of the knee.

Genicular nerves include branches of the femoral, common peroneal, saphenous, tibial and obturator nerves that innervate the knee capsule. It is known that the superolateral, superomedial and inferomedial branches of the genicular nerve are close to the periosteum of the tibia and femur and play a role in sensory innervation of the anterior part of the knee joint. Genicular nerve block (GNB) is used in chronic osteoarthritis pain and has been used in recent years to relieve postoperative pain in TKA.

Infiltration between Popliteal Artery and Capsule of the Knee (IPACK block) is performed by infiltrating local anesthetic (LA) between the popliteal artery and the knee capsule under USG guidance. The sciatic nerve has an important function in the motor and sensory innervation of the posterior leg. In the IPACK block application, the LA spreads along the popliteal fossa and proximal sciatic nerve involvement does not occur. Thus, the sensory nerve network innervating the posterior part of the knee is blocked. Since IPACK block provides only sensory block without causing motor block, it is a new method recommended for analgesia in knee surgery as an alternative to sciatic nerve block, which causes motor block.

Method:

Exclusion criteria from the study were: patient refusal to participate in the study, patients with ASA physical classification 4-5, revision TKA, simultaneous bilateral TKA, patients younger than 18 years and older than 80 years, BMI >40, allergy to the local anesthetic used, DM, hepatic and renal failure, alcohol and drug addiction, high-dose opioid drug use within 3 days before surgery, peripheral nerve disease, patients who could not score pain with the VAS system, patients with contraindications to spinal anesthesia and peripheral nerve block.

Adductor canal block procesure: Before the procedure, the patient will be informed about the technique and a signed consent will be obtained from the patient. The patient's hip will be slightly externally rotated and the ultrasonography linear probe will be placed on the medial aspect of the thigh, at the midpoint of the patella and vastus medialis. After the femoral artery is visualized at a depth of approximately 3-4 centimeters (cm) from the distal short axis angle, if the artery cannot be identified, the femoral artery, which is visualized in the inguinal region, can be followed distally starting from the proximal and the pulsatile flow of the artery will be seen in the doppler mode. After the vastus medialis and sartorius muscles are visualized, the superficial femoral artery is centered at the midpoint of the sartorius muscle. At this point, the roof of the adductor canal can be visualized. After the saphenous nerve and vastus medianus nerve are seen as small round hyperechoic structures, the needle is inserted with the in plane technique and advanced towards the anterolateral aspect of the superficial femoral artery. Then, 5-20 milliliters (mL) of LA is administered into the adductor canal.

Genicular Nerve Block: Before the procedure, the patient is informed about the technique and approval is obtained from the patient. A pillow is placed in the popliteal fossa of the patient lying in the supine position and the knee is slightly flexed. For superior lateral Genicular nerve blockade; the linear USG probe is placed on the lateral epicondyle of the femur in the coronal plane and moved proximally to visualize the metaphysis of the bone. At this level, the superolateral genicular artery can be seen between the deep fascia of the vastus lateralis and the femur. With the in-plane or out-of-plane technique, the peripheral block needle is advanced from the side of the artery until it touches the bone surface and 4-5 mL of LA medication is injected. For superior medial Genicular nerve blockade; the linear USG probe is placed on the medial epicondyle of the femur in the coronal direction and moved proximally to visualize the metaphysis of the bone in front of the adductor tubercle. The superior medial Genicular artery is seen between the femur and the deep fascia of the vastus medialis muscle. The peripheral block needle is inserted from the side of the artery until it touches the bone surface with an in-plane or out-of-plane technique and 4-5 ml of LA drug is injected. A linear USG probe placed coronally on the medial condyle of the tibia is moved distally to visualize the bone metaphysis. The inferomedial genicular artery can be seen under the medial collateral ligament. The peripheral block needle is inserted from the side of the artery until it touches the bone surface with an in-plane or out-of-plane technique and 4-5 ml of LA drug is injected. A negative aspiration test is performed before injecting LA drug in all blocks.

IPACK Block: Before the procedure, the patient is informed about the technique and written consent is obtained from the patient. The patient lies in the prone position. The linear USG probe is placed approximately 2-3 cm above the popliteal fossa and scanned distally to identify the femoral shaft and popliteal artery. If the femoral condyles are initially visualized, the probe is moved until the condyles disappear and the femoral shaft is identified as a straight line and hyperechoic. Color doppler can be used to identify the popliteal vessels. The peripheral block needle is advanced between the femoral shaft and the popliteal artery. After negative aspiration control, 15-20 mL of LA medication is injected here.