Anterior Cruciate Ligament InjuriesNCT07145606
Effects of Early Rehabilitation Using Blood Flow Restriction and/or Surface Electromyography Biofeedback on Quadriceps Activation and Strength After Anterior Cruciate Ligament Reconstruction: A Multicenter Randomized Controlled Trial
A study testing Standard Rehabilitation, Blood Flow Restriction (BFR) Training and sEMG Biofeedback in people with Anterior Cruciate Ligament Injuries and Knee Injuries, run by Haute Ecole ARC Sante at 4 sites in 2 countries.
Trial summary
Many patients experience quadriceps inhibition after anterior cruciate ligament (ACL) reconstruction, delaying strength recovery, hindering return to sport, and potentially increasing the risk of re-injury. Read more about this study
- Who is it for?
- Ages 18 to 35 years
- Conditions the study is for
- Anterior Cruciate Ligament Injuries, Knee Injuries, Muscle Weakness
- What is being tested?
- Standard Rehabilitation, Blood Flow Restriction (BFR) Training and sEMG Biofeedback
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 200 participants
- Where
- 4 sitesin 2 countries
- Study dates
- 2 Jan 2026to 2 Jan 2031
- 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 35 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Adults aged 18-35 years.
- First-time anterior cruciate ligament (ACL) reconstruction.
- Pre-injury activity level Tegner ≥ 6.
- Marx activity scale ≥ 12.
- Body mass index < 35.
- With or without associated meniscal injury.
Who cannot join
- Revision ACL surgery.
- Concurrent repair of other knee ligaments.
- Neurological or systemic musculoskeletal disorders.
- Contraindications to blood flow restriction (BFR) or surface EMG monitoring/biofeedback.
- Pregnancy or lactation.
- Language barrier or cognitive impairment preventing valid informed consent; vulnerable populations not enrolled.
Trial locations and contacts
4 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
4 sites in 2 countries
Switzerland3 sites
Movare
Bulle
Loic Bel, MSc, +41792749573, bel.loic.pt@gmail.com
Centre de l'Appareil Locomoteur et du Sport, Hôpitaux Universitaires de Genève (HUG)
Geneva
Anna Stitelmann, MSc, +4122372 33 11, anna.stitelmann@outlook.com
Exotherapie
Geneva
Maxime Gard, +41796518623, m.gard@exotherapie.ch
France1 site
Orthosport
Domont
Ayrton Moiroux -- Sahraoui, +33634099012, ayrton.moirouxsahraoui@gmail.com
About this study
Many patients experience quadriceps inhibition after anterior cruciate ligament (ACL) reconstruction, delaying strength recovery, hindering return to sport, and potentially increasing the risk of re-injury. Two rehabilitation strategies-low-load blood flow restriction (BFR) training and surface electromyography (sEMG) biofeedback-aim to enhance neuromuscular activation and strength while limiting joint load. However, comparative and combined evidence in pragmatic, multicenter settings remains limited.
AMIRACL is a multicenter, prospective, randomized, controlled, parallel-group trial with four arms enrolling 200 adults (18-35 years) undergoing a first-time ACL reconstruction. Participants are randomized with center stratification; outcome assessors are blinded to allocation. The four groups are: (1) standard rehabilitation; (2) standard + early BFR; (3) standard + early sEMG biofeedback; and (4) standard + combined BFR and sEMG biofeedback. Interventions begin about 2 weeks postoperatively, are delivered over 6 weeks at three supervised sessions per week, and are integrated into contemporary ACL rehabilitation. BFR uses individualized, auto-regulated cuff pressure during low-load isometric and then dynamic exercises. sEMG biofeedback provides real-time visual and/or auditory feedback to optimize quadriceps recruitment during targeted tasks. The combined arm receives both modalities concurrently.
Read more
The primary objective is to compare quadriceps activation (sEMG) and maximal isometric knee extensor strength between groups at 3 and 6 months. Secondary objectives include return-to-sport readiness and patient-reported function (e.g., ACL-RSI, IKDC), broader knee outcomes (e.g., KOOS, Lysholm), adherence and adverse events across arms, and ACL re-injury (ipsilateral graft rupture or contralateral ACL injury) within 2 years. Longer-term patient-reported quality of life is explored up to 5 years.
Key eligibility criteria include age 18-35 years, first ACL reconstruction, and preinjury sport participation; major exclusions include revision ACL surgery, concomitant multi-ligament repair, neuromuscular disorders, and contraindications to BFR or sEMG. The planned sample size is 200 (50 per arm), powered to detect a clinically meaningful between-group difference in quadriceps activation. Analyses will follow the intention-to-treat principle using mixed-effects models for repeated measures. The study is conducted under Good Clinical Practice and applicable Swiss regulations; all participants provide written informed consent. Overall, AMIRACL will determine whether early BFR, sEMG biofeedback, or their combination meaningfully improves quadriceps activation, strength, and clinical recovery after ACL reconstruction compared with standard rehabilitation alone.
- Being tested
- Standard Rehabilitation, Blood Flow Restriction (BFR) Training, sEMG Biofeedback
- Keywords
- Anterior Cruciate Ligament, ACL Reconstruction, Knee Injuries, Rehabilitation, Quadriceps Muscle, Quadriceps Activation, Muscle Strength, Arthrogenic Muscle Inhibition, Blood Flow Restriction Training, Surface Electromyography, Biofeedback, Return to Sport
- Medical subject headings
- Anterior Cruciate Ligament Injuries, Knee Injuries, Muscle Weakness
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Standard RehabilitationBehavioural
Standardized postoperative ACL rehabilitation only. Begins ~2 weeks after surgery; supervised ~3 sessions/week for 6 weeks. Includes progressive range of motion, quadriceps activation/strengthening, functional drills, and return-to-activity progressions delivered per protocol.
Blood Flow Restriction (BFR) TrainingBehavioural
Low-load resistance exercises performed with individualized limb occlusion pressure (LOP) determined each session; target %LOP per protocol. Progresses from isometric to dynamic open/closed-chain tasks. Delivered under supervision ~3 sessions/week for 6 weeks; monitoring of tolerance and adverse events per safety LOP.
sEMG BiofeedbackBehavioural
Real-time surface electromyography biofeedback to optimize quadriceps recruitment during targeted tasks (e.g., isometric contractions, straight-leg raise, sit-to-stand, mini-squat, gait drills). Visual and/or auditory feedback with progressive targets. Supervised ~3 sessions/week for 6 weeks; outcome assessors remain blinded.
| Study group | Role | What they receive |
|---|---|---|
| Standard Rehabilitation | Active comparator | Participants receive the standardized postoperative ACL rehabilitation program only. Sessions are supervised approximately 3 times per week for 6 weeks, starting about 2 weeks after surgery. Content includes progressive range of motion, quadriceps activation and strengthening, functional tasks, and return-to-activity progressions delivered per protocol. Receives: Behavioral: Standard Rehabilitation |
| Standard Rehabilitation + Blood Flow Restriction (BFR) | Experimental | Participants receive the standardized postoperative ACL rehabilitation plus low-load BFR training. BFR is applied with individualized limb occlusion pressure during prescribed isometric and then dynamic exercises. Sessions are supervised ~3 times per week for 6 weeks beginning ~2 weeks postoperatively. Receives: Behavioral: Blood Flow Restriction (BFR) Training |
| Standard Rehabilitation + sEMG Biofeedback | Experimental | Participants receive the standardized postoperative ACL rehabilitation plus surface EMG biofeedback to optimize quadriceps recruitment during targeted tasks (e.g., isometric contractions and functional movements). Real-time visual and/or auditory feedback is provided during supervised sessions ~3 times per week for 6 weeks starting ~2 weeks after surgery. Receives: Behavioral: sEMG Biofeedback |
| Standard Rehabilitation + Combined BFR and sEMG Biofeedback | Experimental | Participants receive the standardized postoperative ACL rehabilitation with both adjuncts delivered concurrently: individualized low-load BFR training and sEMG biofeedback during targeted tasks. Sessions are supervised ~3 times per week for 6 weeks beginning ~2 weeks postoperatively. Receives: Behavioral: Blood Flow Restriction (BFR) Training; Behavioral: sEMG Biofeedback |
What is being measured
The primary outcome is the main question the study is designed to answer.
Quadriceps neuromuscular activation (surface EMG)
Mean normalized surface electromyography (sEMG) activity of the quadriceps during standardized voluntary isometric knee extension; higher values indicate greater activation. Primary analysis compares groups at 3 and 6 months; baseline and post-intervention values are collected to describe trajectories.
Measured: 3 months and 6 months after ACL reconstruction
Maximal isometric knee extensor strength (traction dynamometry)
Peak voluntary isometric knee extension strength recorded with a traction dynamometer under standardized positioning; primary analysis compares groups at 3 and 6 months; baseline and post-intervention values are collected to describe trajectories.
Measured: 3 months and 6 months after ACL reconstruction
Secondary outcomes (5)
ACL-RSI (Return to Sport after Injury)
Patient-reported readiness and psychological response to return to sport using the ACL-RSI questionnaire; higher scores indicate greater readiness.
Measured: 3 months and 6 months after ACL reconstruction
IKDC (International Knee Documentation Committee) subjective knee form
Patient-reported knee symptoms, function, and sports activity; higher scores indicate better status.
Measured: 3 months and 6 months after ACL reconstruction
ACL re-injury/recurrence rate
Proportion of participants with ipsilateral graft rupture or contralateral ACL injury within 2 years, assessed via structured telephone interview and medical record verification when available.
Measured: 24 months after ACL reconstruction (telephone follow-up)
KOOS (Knee injury and Osteoarthritis Outcome Score)
Patient-reported outcomes across KOOS subscales (Symptoms, Pain, ADL, Sport/Rec, QoL); higher scores indicate better status.
Measured: 5 years after ACL reconstruction
Lysholm Knee Scoring Scale
Patient-reported knee function; higher scores indicate better status.
Measured: 5 years after ACL reconstruction
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Aug 2025
- Study start2 Jan 2026 (estimated)
- Primary completion2 Apr 2026 (estimated)
- Study completion2 Jan 2031 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Anterior Cruciate Ligament InjuriesStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Haute Ecole ARC Sante
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Forelli Florian, Haute Ecole ARC Sante
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07145606
- Sponsor's protocol ID
- AMIRACL
- Status last verified
- Aug 2025
- First submitted
- 21 Aug 2025
- Last updated
- 28 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data (IPD) underlying the primary and secondary outcomes (baseline, Week 8, Month 3, Month 6, and 24-month re-injury status) will be shared, together with a data dictionary and variable codebook. Free-text notes, direct identifiers, and potentially identifying combinations will be removed or masked. Dates will be offset or converted to study days. sEMG raw signals will be shared in anonymized form where feasible.
Study at a glance
From the registry record, last updated by the sponsor on 28 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Early Rehabilitation Using Blood Flow Restriction and/or Surface Electromyography Biofeedback on Quadriceps Activation and Strength After Anterior Cruciate Ligament Reconstruction: A Multicenter Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07145606
- Acronym / sponsor ID
- AMIRACL
- Keywords
- Anterior Cruciate Ligament, ACL Reconstruction, Knee Injuries, Rehabilitation, Quadriceps Muscle, Quadriceps Activation, Muscle Strength, Arthrogenic Muscle Inhibition
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- Haute Ecole ARC SanteUniversity, hospital or other
- Study start
- 2 Jan 2026 (estimated)
- Primary completion
- 2 Apr 2026 (estimated)
- Study completion
- 2 Jan 2031 (estimated)
- First posted
- 28 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Many patients experience quadriceps inhibition after anterior cruciate ligament (ACL) reconstruction, delaying strength recovery, hindering return to sport, and potentially increasing the risk of re-injury. Two rehabilitation strategies-low-load blood flow restriction (BFR) training and surface electromyography (sEMG) biofeedback-aim to enhance neuromuscular activation and strength while limiting joint load. However, comparative and combined evidence in pragmatic, multicenter settings remains limited.
AMIRACL is a multicenter, prospective, randomized, controlled, parallel-group trial with four arms enrolling 200 adults (18-35 years) undergoing a first-time ACL reconstruction. Participants are randomized with center stratification; outcome assessors are blinded to allocation. The four groups are: (1) standard rehabilitation; (2) standard + early BFR; (3) standard + early sEMG biofeedback; and (4) standard + combined BFR and sEMG biofeedback. Interventions begin about 2 weeks postoperatively, are delivered over 6 weeks at three supervised sessions per week, and are integrated into contemporary ACL rehabilitation. BFR uses individualized, auto-regulated cuff pressure during low-load isometric and then dynamic exercises. sEMG biofeedback provides real-time visual and/or auditory feedback to optimize quadriceps recruitment during targeted tasks. The combined arm receives both modalities concurrently.
The primary objective is to compare quadriceps activation (sEMG) and maximal isometric knee extensor strength between groups at 3 and 6 months. Secondary objectives include return-to-sport readiness and patient-reported function (e.g., ACL-RSI, IKDC), broader knee outcomes (e.g., KOOS, Lysholm), adherence and adverse events across arms, and ACL re-injury (ipsilateral graft rupture or contralateral ACL injury) within 2 years. Longer-term patient-reported quality of life is explored up to 5 years.
Key eligibility criteria include age 18-35 years, first ACL reconstruction, and preinjury sport participation; major exclusions include revision ACL surgery, concomitant multi-ligament repair, neuromuscular disorders, and contraindications to BFR or sEMG. The planned sample size is 200 (50 per arm), powered to detect a clinically meaningful between-group difference in quadriceps activation. Analyses will follow the intention-to-treat principle using mixed-effects models for repeated measures. The study is conducted under Good Clinical Practice and applicable Swiss regulations; all participants provide written informed consent. Overall, AMIRACL will determine whether early BFR, sEMG biofeedback, or their combination meaningfully improves quadriceps activation, strength, and clinical recovery after ACL reconstruction compared with standard rehabilitation alone.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Standard Rehabilitation | Active comparator | Behavioral: Standard RehabilitationParticipants receive the standardized postoperative ACL rehabilitation program only. Sessions are supervised approximately 3 times per week for 6 weeks, starting about 2 weeks after surgery. Content includes progressive range of motion, quadriceps activation and strengthening, functional tasks, and return-to-activity progressions delivered per protocol. |
| Standard Rehabilitation + Blood Flow Restriction (BFR) | Experimental | Behavioral: Blood Flow Restriction (BFR) TrainingParticipants receive the standardized postoperative ACL rehabilitation plus low-load BFR training. BFR is applied with individualized limb occlusion pressure during prescribed isometric and then dynamic exercises. Sessions are supervised ~3 times per week for 6 weeks beginning ~2 weeks postoperatively. |
| Standard Rehabilitation + sEMG Biofeedback | Experimental | Behavioral: sEMG BiofeedbackParticipants receive the standardized postoperative ACL rehabilitation plus surface EMG biofeedback to optimize quadriceps recruitment during targeted tasks (e.g., isometric contractions and functional movements). Real-time visual and/or auditory feedback is provided during supervised sessions ~3 times per week for 6 weeks starting ~2 weeks after surgery. |
| Standard Rehabilitation + Combined BFR and sEMG Biofeedback | Experimental | Behavioral: Blood Flow Restriction (BFR) Training, Behavioral: sEMG BiofeedbackParticipants receive the standardized postoperative ACL rehabilitation with both adjuncts delivered concurrently: individualized low-load BFR training and sEMG biofeedback during targeted tasks. Sessions are supervised ~3 times per week for 6 weeks beginning ~2 weeks postoperatively. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Adults aged 18-35 years.
- First-time anterior cruciate ligament (ACL) reconstruction.
- Pre-injury activity level Tegner ≥ 6.
- Marx activity scale ≥ 12.
- Body mass index < 35.
Key exclusion criteria (6 listed)
- Revision ACL surgery.
- Concurrent repair of other knee ligaments.
- Neurological or systemic musculoskeletal disorders.
- Contraindications to blood flow restriction (BFR) or surface EMG monitoring/biofeedback.
- Pregnancy or lactation.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Standard RehabilitationStandardized postoperative ACL rehabilitation only. Begins ~2 weeks after surgery; supervised ~3 sessions/week for 6 weeks. Includes progressive range of motion, quadriceps activation/strengthening, functional drills, and return-to-activity progressions delivered per protocol. | Behavioural | Standard Rehabilitation |
| Blood Flow Restriction (BFR) TrainingLow-load resistance exercises performed with individualized limb occlusion pressure (LOP) determined each session; target %LOP per protocol. Progresses from isometric to dynamic open/closed-chain tasks. Delivered under supervision ~3 sessions/week for 6 weeks; monitoring of tolerance and adverse events per safety LOP. | Behavioural | Standard Rehabilitation + Blood Flow Restriction (BFR), Standard Rehabilitation + Combined BFR and sEMG Biofeedback |
| sEMG BiofeedbackReal-time surface electromyography biofeedback to optimize quadriceps recruitment during targeted tasks (e.g., isometric contractions, straight-leg raise, sit-to-stand, mini-squat, gait drills). Visual and/or auditory feedback with progressive targets. Supervised ~3 sessions/week for 6 weeks; outcome assessors remain blinded. | Behavioural | Standard Rehabilitation + Combined BFR and sEMG Biofeedback, Standard Rehabilitation + sEMG Biofeedback |
Primary outcome
Quadriceps neuromuscular activation (surface EMG)
Time frame: 3 months and 6 months after ACL reconstruction
Mean normalized surface electromyography (sEMG) activity of the quadriceps during standardized voluntary isometric knee extension; higher values indicate greater activation. Primary analysis compares groups at 3 and 6 months; baseline and post-intervention values are collected to describe trajectories.
Maximal isometric knee extensor strength (traction dynamometry)
Time frame: 3 months and 6 months after ACL reconstruction
Peak voluntary isometric knee extension strength recorded with a traction dynamometer under standardized positioning; primary analysis compares groups at 3 and 6 months; baseline and post-intervention values are collected to describe trajectories.
5 secondary outcomes
ACL-RSI (Return to Sport after Injury)
Time frame: 3 months and 6 months after ACL reconstruction
IKDC (International Knee Documentation Committee) subjective knee form
Time frame: 3 months and 6 months after ACL reconstruction
ACL re-injury/recurrence rate
Time frame: 24 months after ACL reconstruction (telephone follow-up)
KOOS (Knee injury and Osteoarthritis Outcome Score)
Time frame: 5 years after ACL reconstruction
Lysholm Knee Scoring Scale
Time frame: 5 years after ACL reconstruction
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Aug 2025.
- Individual participant dataSharing planned: Yes. De-identified individual participant data (IPD) underlying the primary and secondary outcomes (baseline, Week 8, Month 3, Month 6, and 24-month re-injury status) will be shared, together with a data dictionary and variable codebook. Free-text notes, direct identifiers, and potentially identifying combinations will be removed or masked. Dates will be offset or converted to study days. sEMG raw signals will be shared in anonymized form where feasible.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
4 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Standard Rehabilitation, Blood Flow Restriction (BFR) Training and sEMG Biofeedback in people with Anterior Cruciate Ligament Injuries and Knee Injuries, run by Haute Ecole ARC Sante at 4 sites in 2 countries.
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 6 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 28 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 4 sites in Switzerland, France. Whether a site is taking part right now should be confirmed with that site. See every site.
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 Florian Forelli, PhD (0041329301654, florian.forelli@he-arc.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Quadriceps neuromuscular activation (surface EMG) (time frame: 3 months and 6 months after ACL reconstruction). The study lists 2 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 28 Aug 2025.