Comparing femoral triangle and adductor canal nerve blocks for early quadriceps function after knee replacement

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

This test compares two nerve blocks — femoral triangle block and adductor canal block — to see which causes less early quadriceps weakness in adults having a single knee replacement.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 136 (estimated)
• Ages: 20 Years and up
• Sex: All
• Sponsor: Social Medical Corporation Daiyukai (Academic / other)
• Locations: 1 site (Ichinomiya, Aichi-ken)
• Trial ID: NCT07524387 on ClinicalTrials.gov

What this trial studies

This single-center, randomized, parallel-group study will assign 136 adults undergoing primary unilateral total knee arthroplasty to receive either an ultrasound-guided femoral triangle block (FTB) or an adductor canal block (ACB) as part of standardized multimodal analgesia. All participants will also receive a popliteal plexus block to standardize posterior knee analgesia and perioperative pain management. The primary outcome is a composite binary measure of quadriceps functional impairment at 6 hours after block completion, defined as inability to perform a structured straight leg raise or normalized isometric quadriceps strength <50% of the preoperative baseline. Secondary outcomes include the same functional measure at 24 hours, postoperative pain intensity, rescue analgesic consumption, early mobilization and rehabilitation milestones, active knee range of motion and time to achieve 120 degrees of active knee flexion, and ultrasound-assessed local anesthetic spread.

Who should consider this trial

Good fit: Adults aged 20 or older scheduled for primary unilateral total knee arthroplasty who are ASA physical status I–III, able to ambulate independently and extend the knee adequately, and able to provide informed consent are ideal candidates.

Not a fit: Patients with pre-existing neurological or neuromuscular disorders affecting the lower limb, severe preoperative quadriceps weakness, prior revision knee arthroplasty on the operative side, allergy to local anesthetics, or severe cognitive impairment are unlikely to benefit or be eligible.

Why it matters

Potential benefit: If successful, the results could identify a nerve-block approach that preserves early quadriceps strength while maintaining good pain control, enabling safer and earlier mobilization after knee replacement.

How similar studies have performed: Prior comparisons of adductor canal block versus femoral nerve block have generally shown better short-term quadriceps preservation with adductor canal approaches, but the femoral triangle block is a newer variant and direct evidence comparing FTB to ACB is limited.

Eligibility criteria

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.

Where this trial is running

Ichinomiya, Aichi-ken

• Department of Anesthesiology, Daiyukai General Hospital — Ichinomiya, Aichi-ken, Japan (Recruiting)

Study contacts

• Principal investigator: Norihiro Sakai, MD, PhD — Department of Anesthesiology, Daiyukai General Hospital
• Study coordinator: Norihiro Sakai, MD, PhD

Conditions Total Knee Arthroplasty; Total Knee Arthroplasty Recovery; Total Knee Arthroplasty Postoperative Pain; Postoperative Pain; Peripheral Nerve Block; Postoperative Recovery