Comparison of the Effectiveness of "Sciatic Nerve", "Biceps Femoris Short Head (BiFeS)" and "Interspace Between the Popliteal Artery and the Capsule of the Posterior Knee (IPACK)" Blocks Added to the Adductor Canal Block for Postoperative Pain Control in Patients Undergoing Primary Total Knee Arthroplasty: A Prospective, Randomized Controlled Clinical Trial

The study was designed as a prospective, single-center, double-blind, randomized controlled trial to be conducted in the operating rooms of Erzincan Binali Yıldırım University Mengücek Gazi Training and Research Hospital. The study will begin after obtaining approval from the Erzincan Binali Yıldırım University Ethics Committee and written informed consent from all participants. A minimum of 102 patients (based on G-Power analysis), aged 18-75 years, scheduled for elective unilateral primary total knee arthroplasty by the Orthopedics and Traumatology Department and classified as American Society of Anesthesiologists (ASA) physical status I-III, will be included.

Patients with ASA ≥ IV, those undergoing revision total knee arthroplasty, bilateral arthroplasty, neuromuscular disease, cognitive dysfunction, drug allergies, a history of local anesthetic systemic toxicity, neurological deficits, bleeding diathesis, pregnancy, or those who decline participation will be excluded. The study will be conducted over a 12-month period between November 1, 2025 and November 1, 2026.

All patients will be informed about the study protocol and procedures one day before surgery, and written consent will be obtained. Upon arrival to the operating room, standard monitoring will be applied. As per routine practice, spinal anesthesia will be performed. Nasal oxygen at 2 L/min will be administered. During surgery, standard hemodynamic parameters (SpO₂, blood pressure, heart rate) will be recorded.

Spinal anesthesia will be conducted according to standard regional anesthesia protocols for total knee arthroplasty using a 25-gauge pencil-point spinal needle at the L3-L4 interspace in the sitting position. A total of 15 mg (3 mL) of 0.5% hyperbaric bupivacaine and 20 mcg (0.4 mL) fentanyl will be administered. Surgery will commence once a T10 sensory block level is achieved. Motor block will be assessed using the Modified Bromage Scale, and sensory block using pinprick or cold tests to determine dermatomal level.

At the end of surgery, under sterile conditions and ultrasound (USG) guidance, patients assigned to Group I will receive a Mid-Adductor Canal block with 20 mL (10 mL 0.25% bupivacaine + 10 mL 0.9% NaCl) and a Sciatic nerve block with 20 mL of the same local anesthetic solution. Group II patients will receive a Mid-Adductor Canal block and a BiFeS (Biceps Femoris Short Head) block using identical volumes and concentrations. Group III patients will receive a Mid-Adductor Canal block and an IPACK (Interspace Between the Popliteal Artery and the Capsule of the Posterior Knee) block with the same solution. All blocks will be performed by a single anesthesiologist with at least 3 years of experience in peripheral nerve blocks. Anesthesia technicians, operating room nurses, and postoperative assessors will be blinded to group allocation.