The Effect of Single-leg 20-degree Squats Combined With Conventional Training on the Biomechanical Characteristics of Gait After Anterior Cruciate Ligament Reconstruction Surgery

NCT07308431 | Not Yet Recruiting

• 1 other identifier: M20250156
• Study Type: interventional
• Target: 48
• Locations: 0 countries
• Sites: N/A

Brief Summary

Anterior cruciate ligament (ACL) tears are one of the most common sports injuries, with an ACL injury rate as high as 20.9% in the general population . Currently, the primary treatment for ACL tears is arthroscopic reconstruction surgery to restore knee stability and function . Following ACL injury, abnormal gait biomechanical characteristics persist, even after ACL reconstruction surgery (ACLR) and evidence-based rehabilitation therapy. These abnormal gait biomechanical characteristics remain unresolved, with the lower limbs exhibiting insufficient loading and stiffness, which are associated with quadriceps muscle dysfunction. Interventions for quadriceps atrophy following ACLR should be initiated early to prevent worsening of early knee pain, swelling, and abnormal gait. Additionally, since ACL reconstruction results in different biomechanical characteristics at various stages and gait phases, it is important to adopt more targeted and precise rehabilitation measures to correct biomechanical abnormalities and improve gait function in patients.

Conditions

Anterior Cruciate Ligament Injuries

Outcome Measures

Primary Outcomes (6)

• Knee joint kinematics during walking

  Kinematic angles (flexion, rotation, and adduction) of the knee joint in the sagittal, frontal, and horizontal planes during walking.

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months）

• Knee joint kinetics during walking

  The moment generated at the knee joint during walking.

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months)]

• Gait-Synchronized Electromyographic Signals

  Outcome Measure 1: Raw electromyographic (EMG) activity Raw EMG signals of the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, and semitendinosus muscles during specified movements. Outcome Measure 2: Integrated electromyographic (IEMG) activity The integrated EMG (IEMG) of the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, and semitendinosus muscles during specified movements. Outcome Measure 3: Average electromyographic (AEMG) amplitude The average EMG amplitude (AEMG) of the rectus femoris, vastus lateralis, vastus medialis, biceps femoris, and semitendinosus muscles during specified movements.

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months)]

• Isokinetic muscle strength

  Quadriceps isokinetic strength test: Isokinetic biomechanical test and trainer (CON-TREX, MJ; Germany), conducted by the same tester on a constant velocity device. Three complete movements need to be collected, with an interval of 90 seconds between each test to avoid fatigue. The quadriceps muscle was tested for isokinetic and eccentric peak torque (PT) at 60°/s.

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months)

• Anterior cruciate ligament stress distribution and peak.

  * Joint flexion, rotation and adduction angles of the knee joint in the sagittal, frontal and horizontal planes during walking and squatting at 20°. * measured during squatting at 12 weeks post-anterior cruciate ligament reconstruction surgery. Stress and strain distribution in the anterior cruciate ligament at a 20-degree squat angle were calculated using ANSYS.

  Completed through study, averaging 3 months.

• Anterior cruciate ligament stress distribution and peak.

  * the moment generated during movement, and the tibial displacement during squats at 20°. * measured during squatting at 12 weeks post-anterior cruciate ligament reconstruction surgery. Stress and strain distribution in the anterior cruciate ligament at a 20-degree squat angle were calculated using ANSYS.

  "through study completion, an average of 3 month".

Secondary Outcomes (3)

• Lysholm Knee Scoring Scale

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months)]

• International Knee Documentation Committee Subjective Knee Form

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months）

• Thigh circumference measurement

  Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months)

Study Arms (2)

experimental group

EXPERIMENTAL

Both groups underwent conventional training. In addition, the experimental group underwent single-leg 20° squat training. Participants were required to stand for the exercise and hold onto a stable surface with their hands, while the unaffected lower limb hip joint was extended and the knee joint flexed to 90°. Participants were then instructed to bend the affected knee to 20° and hold this position for 10 seconds. They then fully extended the knee and rested in that position for 3-4 seconds. The load form can be dumbbells.

Behavioral: single-leg 20° squat training

control group

ACTIVE COMPARATOR

In the 1-8 week rehabilitation program, the goal is to strengthen the muscle strength of the affected knee joint and gradually introduce functional movement exercises, while avoiding forceful flexion and extension of the knee. The specific rehabilitation program includes: prone leg curl exercises, quadriceps resistance band training, hamstring progressive resistance exercises, backward lunge exercises, in-place small jumps, knee joint flexion with appropriate cushioning, in-place squat jumps, landing and immediately squatting for stability, repeated 15 times, each lasting 2-3 seconds, performed 2-3 sets per week, totaling 3 sessions; Wall-supported static squat exercises, repeated 5 times, performed 2-3 sets per week, totaling 3 sessions.

Behavioral: regular training

Interventions

single-leg 20° squat training BEHAVIORAL

Both groups underwent conventional training. In addition, the experimental group underwent single-leg 20° squat training. Participants were required to stand for the exercise and hold onto a stable surface with their hands, while the unaffected lower limb hip joint was extended and the knee joint flexed to 90°. Participants were then instructed to bend the affected knee to 20° and hold this position for 10 seconds. They then fully extended the knee and rested in that position for 3-4 seconds. The load form can be dumbbells.

experimental group

regular training BEHAVIORAL

In the 1-8 week rehabilitation program, the goal is to strengthen the muscle strength of the affected knee joint and gradually introduce functional movement exercises, while avoiding forceful flexion and extension of the knee. The specific rehabilitation program includes: prone leg curl exercises, quadriceps resistance band training, hamstring progressive resistance exercises, backward lunge exercises, in-place small jumps, knee joint flexion with appropriate cushioning, in-place squat jumps, landing and immediately squatting for stability, repeated 15 times, each lasting 2-3 seconds, performed 2-3 sets per week, totaling 3 sessions; Wall-supported static squat exercises, repeated 5 times, performed 2-3 sets per week, totaling 3 sessions.

control group

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Clinical diagnosis of unilateral Anterior Cruciate Ligament (ACL) rupture.
• Aged between 18 and 45 years.
• Scheduled for primary unilateral ACL reconstruction at our hospital.
• Presence of quadriceps atrophy, defined as the bilateral difference in quadriceps strength is \>10% of the contralateral unaffected limb.
• The operated knee has no significant redness, swelling, pain, inflammation, or limitations in range of motion and has essentially restored basic joint mobility.
• No or only minor (Grade I) injury to the posterior cruciate ligament, medial collateral ligament, or lateral collateral ligament.

You may not qualify if:

• Severe injury (Grade II or III) to the posterior cruciate ligament, medial collateral ligament, or lateral collateral ligament in the affected knee.
• Concomitant severe meniscal tear(s) in the affected knee.
• History of significant prior trauma or surgery to the affected knee.
• Presence of other knee joint diseases (e.g., osteoarthritis, tumors, rheumatoid arthritis, tuberculosis).
• Poor subject compliance or anticipated inability to complete the entire study protocol.Subject withdrawal of informed consent.
• Any reason the subject proposes to terminate the study or is unable to complete the trial.
• In the investigator's judgment, continued participation would adversely affect the subject's physical condition.
• Decision by the Ethics Review Committee to terminate the study.

Sponsors & Collaborators

• Peking University Third Hospital: lead

MeSH Terms

Conditions

Anterior Cruciate Ligament Injuries

Condition Hierarchy (Ancestors)

Knee Injuries; Leg Injuries; Wounds and Injuries

Central Study Contacts

Hongshi Huang

CONTACT

+8619861171626; z19861171626@163.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 1, 2025
• First Posted: December 29, 2025
• Study Start: January 10, 2026
• Primary Completion: April 10, 2026
• Study Completion: April 10, 2026
• Last Updated: December 29, 2025

Record last verified: 2025-09

Data Sharing

• IPD Sharing: Will not share