NCT Number: NCT07145606
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.
Trial opening soon.
Get Notified18 year–35 year
All sexes
Interventional
Not applicable
Orthosport, Domont, France
Healthy volunteers accepted: No
Only the study team can determine whether someone qualifies for participation.
Inclusion criteria
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
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.
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.
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.
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.
Time frame: 3 months and 6 months after ACL reconstruction
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
Patient-reported knee symptoms, function, and sports activity; higher scores indicate better status.
Time frame: 24 months after ACL reconstruction (telephone follow-up)
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: 5 years after ACL reconstruction
Patient-reported outcomes across KOOS subscales (Symptoms, Pain, ADL, Sport/Rec, QoL); higher scores indicate better status.
Time frame: 5 years after ACL reconstruction
Patient-reported knee function; higher scores indicate better status.
Time frame: Week 8 (post-intervention)
Normalized sEMG activity measured immediately after the 6-week intervention phase to characterize early neuromuscular changes.
Time frame: Week 8 (post-intervention)
Peak isometric knee extension strength measured with traction dynamometry after the 6-week intervention phase to characterize early strength changes.
Time frame: Throughout the 6-week intervention and up to Month 6 follow-up
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.
Contact information is provided by the study sponsor or research team.
Haute Ecole ARC Sante
Other
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View the official ClinicalTrials.gov record (opens in a new tab)This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.
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