BiFeS vs. iPACK in Postoperative Knee Arthroplasty Analgesia
Comparison of Postoperative Analgesic Effects of Two Different Anesthesia Techniques in Knee Arthroplasty: Nerve Blocks Named BiFeS and iPACK
Amasya University
88 participants
Apr 20, 2026
INTERVENTIONAL
Summary
The Biceps Femoris Short Head (BiFeS) block is a new fascial plane block technique targeting the sensory innervation of the posterolateral capsule of the knee while preserving motor function. The aim of this study is to evaluate the postoperative analgesic efficacy of the BiFeS block combined with the adductor canal block (ACB) in patients undergoing total knee arthroplasty, compared to ACB + iPACK block. The study is planned as a prospective, randomized, double-blind, parallel two-group trial. Patients will be randomized in a 1:1 ratio to receive ACB + iPACK (Group A) or ACB + BiFeS (Group B). Postoperative pain scores (VAS), opioid consumption, early mobilization, and quality of recovery (QoR-15) outcomes will be compared.
Eligibility
Inclusion Criteria2
- Scheduled for unilateral total knee arthroplasty
- Classified as ASA physical status I-III
Exclusion Criteria8
- Scheduled for revision arthroplasty or bilateral surgery
- Allergy to local anesthetics or contraindication to regional blocks
- Neurological disorders, peripheral neuropathy, or conditions affecting lower extremity muscle strength
- Coagulopathy or receiving anticoagulant therapy
- History of severe liver, kidney, or heart failure
- Chronic opioid use or history of substance abuse
- Patients experiencing intraoperative complications (e.g., excessive bleeding)
- Cases in which adequate sensory blockade is not achieved after the block
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Interventions
Under ultrasound guidance, the fascial plane between the short head of the biceps femoris and the semimembranosus muscles will be identified. The needle will be advanced into this plane using a lateral approach, and 20 mL of 0.25% bupivacaine will be injected. This injection area forms an anatomical corridor encompassing the terminal sensory branches of the common peroneal nerve, the popliteal extension of the posterior femoral cutaneous nerve, and the lateral genicular nerve branches. Thus, a broad sensory block is achieved along the posterolateral capsule of the knee without affecting motor fibers.
Under ultrasound guidance, the posterior aspect of the popliteal artery at the distal femur, at the level of the femoral condyles, will be targeted. The needle will be advanced using a medial approach, and 20 mL of 0.25% bupivacaine will be injected into the potential space between the artery and the posterior capsule of the knee. This technique blocks the terminal genicular nerve branches innervating the posterior capsule while sparing motor fibers.
The block will be performed under ultrasound guidance at the distal femoral triangle, just below the apex of the femoral triangle. This level lies deep to the sartorius muscle and represents the lower boundary of the vastoadductor membrane and the beginning of the adductor canal. The ultrasound probe will be placed transversely on the medial thigh to visualize the femoral artery, and the saphenous nerve running lateral to the artery will be targeted. A total of 20 mL of 0.25% bupivacaine will be slowly injected beneath the sartorius muscle and lateral to the femoral artery to allow spread along the adductor canal. This injection at this level affects both the saphenous nerve and the motor branch of the vastus medialis, providing an effective sensory block of the anterior and medial aspects of the knee joint.
Locations(1)
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NCT07360392