An interventional study of Standard Rehabilitation and Blood Flow Restriction (BFR) Training in Anterior Cruciate Ligament Injuries, Knee Injuries and Muscle Weakness, sponsored by Haute Ecole ARC Sante. Not yet recruiting at 4 sites in 2 countries. Open to participants aged 18 Years to 35 Years. Per ClinicalTrials.gov, last updated 2025-08-28.
Sponsored by Haute Ecole ARC Sante · Not applicable, Interventional, and Treatment
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.
625 studies on the registry are indexed under Anterior Cruciate Ligament Injuries; 192 are open to participants now.
This study's planned enrollment of 200 is above the median of 56 across 458 interventional studies indexed under Anterior Cruciate Ligament Injuries.
Browse Anterior Cruciate Ligament Injuries studies →Haute Ecole ARC Sante is the lead sponsor of 4 studies on the registry; 2 are open to participants now.
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First-time anterior cruciate ligament (ACL) reconstruction.
Pre-injury activity level Tegner ≥ 6.
Marx activity scale ≥ 12.
\< 35.
With or without associated meniscal injury.
Exclusion Criteria:
Concurrent repair of other knee ligaments.
Neurological or systemic musculoskeletal disorders.
to blood flow restriction (BFR) or surface EMG monitoring/biofeedback.
Pregnancy or lactation.
Language barrier or cognitive impairment preventing valid ; vulnerable populations not enrolled.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Behavioral: Standard Rehabilitation
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.
Behavioral: Blood Flow Restriction (BFR) Training
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.
Behavioral: sEMG Biofeedback
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.
Behavioral: Blood Flow Restriction (BFR) Training · Behavioral: sEMG Biofeedback
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.
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.
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.
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.
Time frame: 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.
Time frame: 3 months and 6 months after ACL reconstruction
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 5 years after ACL reconstruction
Lysholm Knee Scoring Scale
Patient-reported knee function; higher scores indicate better status.
Time frame: 5 years after ACL reconstruction
Quadriceps neuromuscular activation (sEMG) at end of intervention
Normalized sEMG activity measured immediately after the 6-week intervention phase to characterize early neuromuscular changes.
Time frame: Week 8 (post-intervention)
Maximal isometric knee extensor strength at end of intervention
Peak isometric knee extension strength measured with traction dynamometry after the 6-week intervention phase to characterize early strength changes.
Time frame: Week 8 (post-intervention)
Adverse events related to rehabilitation and/or BFR/sEMG procedures
Number and proportion of participants experiencing adverse events potentially related to the study interventions; categorized by severity (mild/moderate/severe) and seriousness per protocol definitions; events recorded at each supervised session and follow-up visit.
Time frame: Throughout the 6-week intervention and up to Month 6 follow-up
Plan to share: 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.
Supporting information: Study protocol, Statistical analysis plan, Informed consent form
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This study is not yet recruiting, as verified in Aug 2025. You cannot join it, but the record below documents what was studied.
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