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.

Study Overview

• Status: Recruiting
• Conditions: Total Knee Arthroplasty; Total Knee Arthroplasty Recovery; Total Knee Arthroplasty Postoperative Pain
• Intervention / Treatment: Procedure: Femoral Triangle Block (FTB) Group; Procedure: Adductor Canal Block (ACB) Group

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Estimated): 136
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Norihiro Sakai, MD, PhD; Phone Number: +81-586-72-1211; Email: dykmasui@gmail.com
• Study Contact Backup: Name: Tomohiro Michino, MD, PhD; Phone Number: +81-586-72-1211; Email: dykmasui@gmail.com

Study Locations

• Japan
  • Aichi-ken
    • Ichinomiya, Aichi-ken, Japan, 491-8511
      • Recruiting
      • Department of Anesthesiology, Daiyukai General Hospital
      • Contact: Norihiro Sakai, MD, PhD; Phone Number: +81-586-72-1211; Email: dykmasui@gmail.com
      • Contact: Tomohiro Michino, MD, PhD; Phone Number: +81-586-72-1211; Email: dykmasui@gmail.com
      • Sub-Investigator: Tomohiro Michino, MD, PhD
      • Sub-Investigator: Aya Seki, MD
      • Sub-Investigator: Chieko Taruishi, MD
      • Sub-Investigator: Yuki Uematsu, MD
      • Sub-Investigator: Tomoko Sudani, MD
      • Sub-Investigator: Hiroki Yoshida, MS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Femoral Triangle Block (FTB) Group; Ultrasound-guided femoral triangle block with standardized multimodal analgesia including popliteal plexus block.	Procedure: Femoral Triangle Block (FTB) Group; Ultrasound-guided femoral triangle block performed as part of a standardized multimodal analgesia protocol for total knee arthroplasty. A total of 10 mL of 0.25% levobupivacaine is injected in the femoral triangle to achieve sensory blockade of the saphenous nerve, the nerve to vastus medialis, and surrounding structures. The injection is performed at the distal femoral triangle under ultrasound guidance, targeting the perineural space adjacent to the relevant nerve branches. In all participants, a popliteal plexus block using 15 mL of 0.25% levobupivacaine is additionally performed to standardize posterior knee analgesia.
Active Comparator: Adductor Canal Block (ACB) Group; Ultrasound-guided adductor canal block with standardized multimodal analgesia including popliteal plexus block.	Procedure: Adductor Canal Block (ACB) Group; Ultrasound-guided adductor canal block performed as part of a standardized multimodal analgesia protocol for total knee arthroplasty. A total of 10 mL of 0.25% levobupivacaine is administered in a divided manner within the proximal adductor canal, targeting both the saphenous nerve within the canal and the nerve to vastus medialis running adjacent to the canal. The injection is performed under ultrasound guidance to achieve selective sensory blockade while minimizing motor involvement. In all participants, a popliteal plexus block using 15 mL of 0.25% levobupivacaine is additionally performed to standardize posterior knee analgesia.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participants with quadriceps functional impairment at 6 hours after block completion	Composite binary functional outcome defined as the inability to perform a structured straight leg raise (SLR) or normalized isometric quadriceps muscle strength <50% of the preoperative baseline. The outcome will be reported as the percentage of participants with quadriceps functional impairment.	6 hours after block completion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participants with quadriceps functional impairment at 24 hours after block completion	Composite binary functional outcome defined as the inability to perform a structured SLR or normalized isometric quadriceps muscle strength <50% of the preoperative baseline. The outcome will be reported as the percentage of participants with quadriceps functional impairment.	24 hours after block completion
Participants able to perform a structured straight leg raise at 6 and 24 hours after block completion	Ability to perform a structured straight leg raise (SLR), assessed using the predefined study procedure. The outcome will be reported as the percentage of participants able to perform the structured SLR.	6 and 24 hours after block completion
Normalized isometric quadriceps muscle strength at 6 and 24 hours after block completion	Normalized isometric quadriceps muscle strength, expressed as a percentage of the preoperative baseline (%MVIC). Higher values indicate greater preservation of quadriceps strength.	6 and 24 hours after block completion
Postoperative pain intensity at rest on the Numeric Rating Scale	Pain intensity at rest assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst pain imaginable; higher scores indicate worse pain. Pain will be assessed postoperatively after patient awakening.	1, 2, 3, 6, 12, 18, and 24 hours after surgery
Postoperative pain intensity during active knee movement on the Numeric Rating Scale	Pain intensity during active knee movement assessed using the Numeric Rating Scale (NRS), ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst pain imaginable; higher scores indicate worse pain. Pain will be assessed postoperatively after patient awakening.	1, 2, 3, 6, 12, 18, and 24 hours after surgery
Participants requiring any rescue analgesic during the first 24 postoperative hours	Proportion of participants who receive at least one rescue analgesic during the first 24 postoperative hours. Rescue analgesia is permitted when the Numeric Rating Scale (NRS) pain score is 5 or higher or when the participant requests additional analgesia. Allowed rescue analgesics include loxoprofen, acetaminophen, diclofenac suppository, and intramuscular pentazocine. The choice of rescue agent is left to the treating clinical team, and no fixed sequence of rescue analgesics is mandated.	Within the first postoperative 24 hours
Number of rescue analgesic administrations during the first 48 postoperative hours	Total number of rescue analgesic administrations per participant during the first 48 postoperative hours. Rescue analgesia is permitted when the Numeric Rating Scale (NRS) pain score is 5 or higher or when the participant requests additional analgesia. Allowed rescue analgesics include loxoprofen, acetaminophen, diclofenac suppository, and intramuscular pentazocine. The choice of rescue agent is left to the treating clinical team, and no fixed sequence of rescue analgesics is mandated.	Within the first postoperative 48 hours
Time to first mobilization	Time from block completion to the first documented mobilization attempt.	Within 24 hours after block completion
Ability to stand during the first postoperative rehabilitation session	Proportion of participants able to complete supported standing during the first routine postoperative rehabilitation session, as assessed and documented by a physical therapist.	Postoperative day 1
Walking distance during routine postoperative rehabilitation	Distance ambulated in meters during supervised postoperative rehabilitation sessions, as assessed and documented by a physical therapist.	From postoperative days 1 to 7
Active knee flexion angle of the operated knee	Active knee flexion angle of the operated knee, measured in degrees by rehabilitation staff using a goniometer during routine postoperative rehabilitation assessment. Higher values indicate greater knee flexion.	Postoperative days 1, 2, 3, and 7
Active knee extension deficit angle of the operated knee	Active knee extension deficit angle of the operated knee, measured in degrees by rehabilitation staff using a goniometer during routine postoperative rehabilitation assessment, where 0 degrees indicates full knee extension and higher values indicate greater residual extension limitation.	Postoperative days 1, 2, 3, and 7
Time to achieve active knee flexion of at least 120 degrees	Number of days required to achieve active knee flexion of the operated knee of at least 120 degrees, based on routine postoperative rehabilitation assessment by rehabilitation staff using a goniometer.	Up to postoperative day 7
Cranial spread of local anesthetic from the injection point	Cranial spread of local anesthetic from the injection point, measured in centimeters on ultrasound immediately after block completion. Higher values indicate greater cranial spread of the injectate.	Immediately after block completion
Caudal spread of local anesthetic from the injection point	Caudal spread of local anesthetic from the injection point, measured in centimeters on ultrasound immediately after block completion. Higher values indicate greater caudal spread of the injectate.	Immediately after block completion

Collaborators and Investigators

• Sponsor: Social Medical Corporation Daiyukai
• Investigators: Principal Investigator: Norihiro Sakai, MD, PhD, Department of Anesthesiology, Daiyukai General Hospital

Study record dates

Study Major Dates

• Study Start (Actual): April 13, 2026
• Primary Completion (Estimated): March 15, 2029
• Study Completion (Estimated): March 31, 2029

Study Registration Dates

• First Submitted: March 29, 2026
• First Submitted That Met QC Criteria: April 6, 2026
• First Posted (Actual): April 13, 2026

Study Record Updates

• Last Update Posted (Actual): April 16, 2026
• Last Update Submitted That Met QC Criteria: April 13, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Postoperative Pain; Total Knee Arthroplasty; Peripheral Nerve Block; Postoperative Recovery
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Population Characteristics; Demography; Population Groups
• Other Study ID Numbers: DGH-2025-022

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: There are no plans to make individual participant data available to other researchers.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No