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
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Standard Rehabilitation, Blood Flow Restriction (BFR) Training, sEMG Biofeedback.
- Who it may be relevant to
- Registry conditions: Anterior Cruciate Ligament Injuries, Knee Injuries, Muscle Weakness. Basic parameters: 18 years — 35 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- France, Switzerland
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Overview
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.
Interventions
- Behavioral Standard Rehabilitation
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. - Behavioral Blood Flow Restriction (BFR) Training
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. - Behavioral sEMG Biofeedback
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.
Primary outcome measures
- Quadriceps neuromuscular activation (surface EMG) [Time frame: 3 months and 6 months after ACL reconstruction]
- Maximal isometric knee extensor strength (traction dynamometry) [Time frame: 3 months and 6 months after ACL reconstruction]
Secondary outcome measures (5)
- 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]
Eligibility criteria
Inclusion criteria
- 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.
Exclusion criteria
- 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.
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Allocation
- Randomized
- Model
- Parallel assignment
- Masking
- Single blind
- Primary purpose
- Treatment
Study locations
Switzerland · 3 centers
- Movare — Bulle
- Centre de l'Appareil Locomoteur et du Sport, Hôpitaux Universitaires de Genève (HUG) — Geneva
- Exotherapie — Geneva
France · 1 center
- Orthosport — Domont
Identifiers
NCT: NCT07145606 · AMIRACL