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NCT Number: NCT07259083

Psychological and Physiological Parameters for Return-to-sport After ACL Reconstruction

Injuries to the anterior cruciate ligament are common and are usually treated with reconstruction and subsequent rehabilitation. Many people succeed in return to sport (RTS), but not to the original level. Muscle strength factors can be assessed using isokinetic strength measurements, while the psychological readiness to return to sport can be assessed using the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) questionnaire. In this study, isokinetic strength testing and psychological testing with the ACL-RSI questionnaire 1 to 4 years after ACL reconstruction will be assessed. The study will be conducted at the Institute of Physical Medicine & Rehabilitation at the Kepler University Hospital. The Biodex System Pro™, a medical device for measuring and training muscle strength, will be used for the isokinetic measurements. The research question is as follows: Is there a correlation between the results of the ACL RSI questionnaire and the results of isokinetic strength testing on the Biodex System 4 Pro™ in test subjects following ACL reconstruction?

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Key information

Conditions

ACL Reconstruction Anterior Cruciate Ligament Injuries Knee Injuries Leg Injuries Wounds and Injuries

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Kepler University Clinic, Dept. of Physical Medicine & Rehabilitation

Linz, 4021, Austria

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Primary unilateral ACL reconstruction 1 to 4 years prior testing
  • Physically active
  • 18-50 years
  • Medical approval for maximum loads

Exclusion criteria

  • Bilateral Knee injury
  • Pregnancy
  • Acute pain (VAS ≥ 3)
  • Extremely limited mobility
  • Extreme joint instability
  • Acute injuries
  • Inflammation
  • Fever

Treatment and study plan

Primary outcomes

  1. Peak torque (Nm) - Isokinetic dynamometry (Biodex System 4)

    Time frame: Day 1 (1 to 4 years after ACL reconstruction)

    The isokinetic dynamometer measures concentric strength in extension and flexion.

    Isokinetic strength testing at a ROM (range of motion) of 0-90° knee flexion at 3 different speeds. Test protocol at angular velocities of 60°/sec, 180°/sec and 240°/sec.

  2. ACL-RSI questionnaire (Anterior Cruciate Ligament-Return to Sport after Injury)

    Time frame: Day 1 (1 to 4 years after ACL reconstruction)

    The ACL-RSI is a measure of psychological readiness to return to sport. It contains 12 questions and examines 3 components related to readiness to return to sport: emotions (5 questions), confidence in one's own performance (5 questions) and risk assessment (2 questions). The questions relate to the psychological effects of returning to sport. The respondents answer each question by giving their assessment in steps of ten on a Likert scale from 0 to 100 points. Low scores indicate a negative psychological assessment and high scores indicate a positive psychological assessment. The cut-off value for distinguishing between returnees and non-returnees is 51.3 points. A German version of the questionnaire is used.

Secondary outcomes

  1. Isokinetic dynamometry (Biodex System 4)

    Time frame: Day 1 (1 to 4 years after ACL reconstruction)

    The isokinetic dynamometer measures concentric strength in extension and flexion including following parameters:

    Average peak torque (Nm), time to peak torque (sec), angle of peak torque (deg), torque at 30°, torque at 0.18 seconds, max. repetitions to total work, work/body weight, total work, work first third, work last third, work fatique, avg. power, acceleration time (msec), ROM (range of motion, deg), agonist/antagonist ratio (%), hamstring/quadriceps (H/Q) ratio, LSI (limb symmetry index)

    Isokinetic strength testing at a ROM of 0-90° knee flexion at 3 different speeds. Test protocol at angular velocities of 60°/sec, 180°/sec and 240°/sec.

  2. Sports activity

    Time frame: Day 1

    Sports activity before and after surgery in minutes/week

Other outcomes

  1. Time since ACL surgery

    Time frame: Day 1

    Time in months since ACL surgery

  2. Height

    Time frame: Day 1

    Height of the participant in cm

  3. Weight

    Time frame: Day 1

    Weight of the participant in kg

  4. Body Mass Index

    Time frame: Day 1 (1 to 4 years after ACL reconstruction)

    Relation of body weight to the square of body height

  5. Age

    Time frame: Day 1

    Age of the participant in years

Sponsors and collaborators

Lead sponsor

Johannes Kepler University of Linz

Other

Collaborators

  • University of Salzburg

Registry information

Official study title

Long-term Correlation of Functional and Psychological Parameters for the Return-to-sport Decision After Anterior Cruciate Ligament Reconstruction

Acronym: ACL-RTS

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Dec 2, 2025
Registry last updated
Apr 20, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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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