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Anterior Cruciate Ligament InjuriesNCT07308431

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

A study testing single-leg 20° squat training and regular training in people with Anterior Cruciate Ligament Injuries, run by Peking University Third Hospital.

Not yet recruiting

Opening soon. The study is approved but enrolment has not started yet. Sites may already take enquiries.

Sites and contacts
Official record
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Trial 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 . Read more about this study

Who is it for?
Ages 18 to 45 yearsHealthy volunteers can take part
Conditions the study is for
Anterior Cruciate Ligament Injuries
What is being tested?
single-leg 20° squat training and regular training
Could I receive a placebo?
No, everyone receives an active treatment
How many people
48 participants
Where
No sites listed yet
Study dates
10 Jan 2026to 10 Apr 2026
Phase
Interventional
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 to 45 years
  • All sexes
  • Healthy volunteers accepted
  • Adult

Who may be able to join

  • 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.

Who cannot join

  • 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.

Trial locations and contacts

No sites are listed yet. Contact the study team or a site near you to ask about taking part.

About this study

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.

Read the detailed description

Research Background: The anterior cruciate ligament (ACL) is one of the important anatomical structures in the knee joint, maintaining knee stability and preventing anterior displacement of the tibia. Following ACL injury, abnormal gait biomechanical characteristics persist, even after ACL reconstruction surgery (ACLR) and evidence-based rehabilitation therapy, with abnormal gait biomechanics failing to fully recover. Quadriceps atrophy is a common cause of abnormal gait biomechanics and persists long-term postoperatively. The quadriceps are closely related to knee joint function and contribute most significantly to knee joint stability and movement control. Therefore, intervention for quadriceps atrophy following ACLR should be initiated early to prevent worsening of early knee pain, swelling, and abnormal gait. Post-ACLR rehabilitation aims to protect the graft, promote its biological remodeling, and limit the extent of muscle atrophy while facilitating muscle strength recovery. Additionally, since ACL injury and reconstruction exhibit different biomechanical characteristics at various stages and gait phases, it is essential to adopt more targeted and precise rehabilitation measures to correct biomechanical abnormalities and improve gait function. Research methods: This study plans to recruit 48 patients 12 weeks post-ACL reconstruction surgery, divided into an experimental group and a control group. The experimental group will undergo single-leg mini squat (SLMS) training in addition to conventional training, with kinematic and dynamic data collected simultaneously using a three-dimensional motion capture system and force plate system; electromyographic signals will be collected from patients during gait testing. Additionally, three-dimensional finite element modeling will be used to calculate the stress distribution and peak stress on the ACL graft during SLMS. Expected Study Outcomes: This study anticipates that after 8 weeks of SLMS training, the knee flexion angle during the stance phase of walking, knee extension torque, and activity of the medial femoral muscle during walking will increase. Additionally, the study aims to confirm that SLMS training keeps stress on the ACL graft within a safe range.

Being tested
single-leg 20° squat training, regular training
Medical subject headings
Anterior Cruciate Ligament Injuries

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • single-leg 20° squat trainingBehavioural

    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.

  • regular trainingBehavioural

    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.

Study groups in NCT07308431
Study groupRoleWhat they receive
experimental groupExperimentalBoth 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.
Receives: Behavioral: single-leg 20° squat training
control groupActive comparatorIn 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.
Receives: Behavioral: regular training

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Knee joint kinematics during walking

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

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

  2. Knee joint kinetics during walking

    The moment generated at the knee joint during walking.

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

  3. 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.

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

  4. 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.

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

  5. 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.

    Measured: Completed through study, averaging 3 months.

  6. 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.

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

Secondary outcomes (3)
  1. Lysholm Knee Scoring Scale

    The Lysholm Knee Scoring Scale, a patient-reported outcome measure assessing knee function. Scores range from 0 to 100, where higher scores indicate a better outcome.

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

  2. International Knee Documentation Committee Subjective Knee Form

    The International Knee Documentation Committee Subjective Knee Form, a patient-reported outcome measure assessing symptoms, function, and sports activity. Scores range from 0 to 100, where higher scores indicate a better outcome.

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

  3. Thigh circumference measurement

    The circumference of the thigh, measured at a standardized anatomical location, to assess muscle atrophy or swelling. A smaller circumference indicates a worse outcome (greater atrophy or reduced swelling).

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

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted29 Dec 2025
  2. Study start10 Jan 2026 (estimated)
  3. Primary completion10 Apr 2026 (estimated)
  4. Study completion10 Apr 2026 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Treatment
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
48 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07308431
Sponsor's protocol ID
M20250156
Status last verified
Sep 2025
First submitted
1 Sep 2025
Last updated
29 Dec 2025
Results posted
No
Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A study testing single-leg 20° squat training and regular training in people with Anterior Cruciate Ligament Injuries, run by Peking University Third Hospital.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 6 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: opening soon, as of the sponsor's last update on 29 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Hongshi Huang (+8619861171626, z19861171626@163.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Knee joint kinematics during walking (time frame: Assessed at 12 weeks post-operation and again after 8 weeks of intervention (total assessment period of 2 months)). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 Dec 2025.

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