Eccentric Phase Biomechanics of the Countermovement Jump After Anterior Cruciate Ligament Reconstruction (DECAL)

Analysis of Biomechanical Alterations During the Eccentric Phase of the Countermovement Jump in Patients After Anterior Cruciate Ligament Reconstruction

Purpose: This study aims to better understand how force is produced during a vertical jump in individuals approximately six months after anterior cruciate ligament reconstruction compared with healthy individuals. After this type of knee surgery, many patients recover well clinically but may still present strength differences between the operated and non-operated leg. These differences are not always visible during routine clinical testing but may influence performance and potentially increase the risk of reinjury. By analyzing how force is generated during a standardized countermovement jump, this study seeks to identify whether biomechanical alterations persist at this stage of recovery and to improve decision-making related to rehabilitation and return to sport.

Study Design: This is an observational comparative study. Participants who have undergone anterior cruciate ligament reconstruction using a hamstring tendon graft will be assessed between five and seven months after surgery. Their results will be compared with those of healthy recreationally active individuals without a history of recent knee injury. No experimental treatment or modification of rehabilitation will be introduced as part of this study.

Procedures: Participants will complete a brief standardized warm-up followed by three maximal vertical countermovement jumps performed on a force platform. During the test, participants will keep their hands on their hips and will be instructed to jump as quickly and as high as possible. The force platform measures ground reaction forces from each leg separately, allowing detailed analysis of the lowering phase (when the body bends before jumping) and the push-off phase (when the body propels upward). The entire testing session lasts only a few minutes and reflects movements commonly used in rehabilitation and sports settings.

Measurements: The primary measurements include jump height and the mean force produced by each leg during both the eccentric (lowering) and concentric (push-off) phases of the jump. The study will also calculate limb symmetry indices to determine the degree of difference between the operated and non-operated legs. These measurements provide objective information about neuromuscular recovery and functional performance after surgery.

Risks: The procedures involve physical activity comparable to exercises already performed during standard rehabilitation. The risks are minimal and similar to those encountered during routine physical training. Participants may stop the test at any time if they experience discomfort.

Potential Benefits: Participants may not receive direct personal benefit from taking part in the study. However, the results may contribute to improving rehabilitation strategies, refining criteria used for return-to-sport decisions, and enhancing long-term functional outcomes after anterior cruciate ligament reconstruction. A better understanding of persistent biomechanical alterations may ultimately help reduce the risk of secondary injury and optimize recovery pathways.

Study Overview

• Status: Completed
• Conditions: Anterior Cruciate Ligament Injury; Anterior Cruciate Ligament Reconstruction Rehabilitation
• Intervention / Treatment: Other: Countermovement Jump Force Platform Assessment; Other: Isokinetic Test

• Study Type: Observational
• Enrollment (Actual): 100

Contacts and Locations

Study Locations

• Switzerland
  • Delémont, Switzerland
    • Haute Ecole ARC

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

The study population includes adults aged 18 to 40 years. The post-anterior cruciate ligament reconstruction cohort consists of individuals who underwent primary reconstruction using a hamstring tendon autograft and are evaluated between 5 and 7 months after surgery, following completion of standard rehabilitation and medical clearance for functional testing. The healthy control cohort includes recreationally active individuals with no history of anterior cruciate ligament injury, no prior lower limb surgery, and no lower extremity injury within the past 12 months. All participants must be able to perform maximal effort jumping and isokinetic strength testing.

Description

Inclusion Criteria:

• Post-Anterior Cruciate Ligament Reconstruction Cohort:

Age between 18 and 40 years

Primary anterior cruciate ligament reconstruction using a hamstring tendon autograft

Assessment performed between 5 and 7 months post-surgery

Completion of standard postoperative rehabilitation

Medical clearance for functional testing

Ability to perform maximal effort jumping and strength testing

Healthy Control Cohort:

Age between 18 and 40 years

Recreationally active (minimum two sessions of physical activity per week)

No history of anterior cruciate ligament injury

No lower limb surgery

No lower extremity injury within the past 12 months

No current knee pain or functional limitation

Exclusion Criteria:

• Previous anterior cruciate ligament reconstruction on either knee (except the index surgery for the ACL group)

Concomitant ligament reconstruction (e.g., posterior cruciate ligament, medial collateral ligament, lateral collateral ligament)

Symptomatic meniscal repair limiting full participation in testing

Neurological disorders affecting lower limb function

Inflammatory joint disease

Pregnancy

Inability to perform maximal effort testing

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
ACLR; Individuals aged 18-40 years who underwent primary anterior cruciate ligament reconstruction using a hamstring tendon graft and are assessed between 5 and 7 months after surgery. Participants must have completed standard rehabilitation and be cleared for functional testing at the time of evaluation.	Other: Countermovement Jump Force Platform Assessment; Participants perform three maximal countermovement jumps on a calibrated force platform after a standardized warm-up. Hands are kept on the hips during testing. The platform records ground reaction forces from each limb separately during the eccentric (lowering) and concentric (push-off) phases of the jump. Jump height and limb symmetry indices are calculated. This procedure is used for biomechanical and functional assessment only and does not modify standard rehabilitation.; Other: Isokinetic Test; isokinetic dynamometry is performed to assess concentric quadriceps and hamstring strength at standardized angular velocities. Peak torque values and limb symmetry indices are calculated for quadriceps and hamstring
Healthy; Recreationally active individuals aged 18-40 years with no history of anterior cruciate ligament injury, no lower limb surgery, and no musculoskeletal injury affecting the lower extremities within the past 12 months. Participants must be physically active and free from current knee pain at the time of testing.	Other: Countermovement Jump Force Platform Assessment; Participants perform three maximal countermovement jumps on a calibrated force platform after a standardized warm-up. Hands are kept on the hips during testing. The platform records ground reaction forces from each limb separately during the eccentric (lowering) and concentric (push-off) phases of the jump. Jump height and limb symmetry indices are calculated. This procedure is used for biomechanical and functional assessment only and does not modify standard rehabilitation.; Other: Isokinetic Test; isokinetic dynamometry is performed to assess concentric quadriceps and hamstring strength at standardized angular velocities. Peak torque values and limb symmetry indices are calculated for quadriceps and hamstring

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Eccentric Mean Force	3 and 6 months

Secondary Outcome Measures

Outcome Measure	Time Frame
Concentric Mean Force	3 and 6 months
Jump Height	3 and 6 months
Quadriceps and Hamstring Peak Torque	3 and 6 months

Collaborators and Investigators

• Sponsor: Haute Ecole ARC Sante

Publications and helpful links

General Publications

• Ricupito, R., Bravi, M., Santacaterina, F., Campardo, G., Guarise, R., Castellucci, R., Alaoui, I. B., & Forelli, F. (2025). Biomechanical Alterations in the Unweight Phase of the Single-Leg Countermovement Jump After ACL Reconstruction. Journal of functional morphology and kinesiology, 10(3), 296. https://doi.org/10.3390/jfmk10030296
• Forelli, F., Moiroux-Sahraoui, A., Mazeas, J., Ly, W., Bialy, M., Douryang, M., Hewett, T. E., & De Fontenay, B. P. (2025). Evaluation of eccentric and concentric force during vertical jump after anterior cruciate ligament reconstruction: a comparative study. BMC sports science, medicine & rehabilitation, 17(1), 259. https://doi.org/10.1186/s13102-025-01301-4
• Forelli, F., Moiroux-Sahraoui, A., Nekhouf, B., Bouzekraoui Alaoui, I., Vandebrouck, A., Duffiet, P., Ratte, L., Bialy, M., Bjerregaard, A., Mazeas, J., Douryang, M., & Rambaud, A. (2025). Is Deceleration the Key Element in Vertical Jump Performance to Return to Sport After Anterior Cruciate Ligament Reconstruction With Hamstring Graft? A Preliminary Study. International journal of sports physical therapy, 20(9), 1321-1329. https://doi.org/10.26603/001c.142878

Study record dates

Study Major Dates

• Study Start (Actual): March 2, 2022
• Primary Completion (Actual): March 31, 2025
• Study Completion (Actual): March 31, 2025

Study Registration Dates

• First Submitted: February 25, 2026
• First Submitted That Met QC Criteria: February 25, 2026
• First Posted (Actual): March 4, 2026

Study Record Updates

• Last Update Posted (Actual): March 4, 2026
• Last Update Submitted That Met QC Criteria: February 25, 2026
• Last Verified: March 1, 2022

More Information

Terms related to this study

• Keywords: Anterior Cruciate Ligament Reconstruction; Return to Sport; Countermovement Jump; Knee Biomechanics
• Additional Relevant MeSH Terms: Wounds and Injuries; Leg Injuries; Knee Injuries; Anterior Cruciate Ligament Injuries
• Other Study ID Numbers: DECAL ACL

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No