Femoral Triangle Block vs Adductor Canal Block on Early Quadriceps Function After Total Knee Arthroplasty

Postoperative Effects of Femoral Triangle Block Versus Adductor Canal Block on Early Quadriceps Function After Total Knee Arthroplasty Under a Multimodal Analgesia Protocol: A Randomized Double-Blind Controlled Trial

The goal of this clinical trial is to compare the effects of femoral triangle block (FTB) and adductor canal block (ACB) on early quadriceps function after total knee arthroplasty (TKA).

The main question it aims to answer is whether FTB causes more early quadriceps functional impairment than ACB under a standardized multimodal analgesia protocol.

Researchers will compare FTB and ACB using a composite binary functional outcome measured 6 hours after block completion. Quadriceps functional impairment is defined as the inability to perform a structured straight leg raise or quadriceps muscle strength <50% of the preoperative baseline.

Participants will be randomly assigned to receive ultrasound-guided FTB or ACB. All participants will also receive a popliteal plexus block and standardized multimodal analgesia.

This is a single-center, randomized, parallel-group clinical trial designed to compare the postoperative effects of femoral triangle block (FTB) and adductor canal block (ACB) on early quadriceps function after primary unilateral total knee arthroplasty (TKA). A total of 136 adult participants are planned for enrollment at Daiyukai General Hospital.

Participants will be randomly assigned to receive ultrasound-guided FTB or ultrasound-guided ACB as part of a standardized multimodal analgesia protocol. In all participants, a popliteal plexus block will also be performed to standardize posterior knee analgesia.

The primary outcome is quadriceps functional impairment at 6 hours after block completion, assessed using a composite binary functional outcome defined as the inability to perform a structured straight leg raise or normalized isometric quadriceps muscle strength <50% of the preoperative baseline.

Secondary outcomes include quadriceps functional impairment at 24 hours after block completion using the same composite definition, postoperative pain intensity, rescue analgesic consumption, early mobilization and rehabilitation-related measures, active knee range of motion, time to achieve active knee flexion of at least 120 degrees, and ultrasound-assessed local anesthetic spread.

The study aims to determine whether FTB results in greater early motor impairment than ACB under a standardized multimodal analgesia protocol while maintaining clinically appropriate postoperative analgesia.

Inclusion Criteria:

1. Adult patients (≥ 20 years of age) are scheduled to undergo primary unilateral TKA.
2. American Society of Anesthesiologists (ASA) physical status I-III.
3. Ability to ambulate independently prior to surgery.
4. Ability to understand the study procedures and provide written informed consent.
5. Planned perioperative anesthesia management including regional anesthesia as part of standard clinical care.
6. Ability to extend the knee below 30 degrees preoperatively (no knee extension contracture)

Exclusion Criteria:

1. Known allergy or contraindication to local anesthetic agents used in this study.
2. Pre-existing neurological or neuromuscular disorders affect lower limb strength or motor control.
3. Severe cognitive impairment or psychiatric conditions interfere with study participation or assessment.
4. History of revision knee arthroplasty on the operative side.
5. Severe preoperative quadriceps weakness that precludes reliable baseline strength assessment.
6. Any condition deemed by the investigator to make participation inappropriate.