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Completed

NCT Number: NCT03209531

Conditioning Brain Responses to Improve Thigh Muscle Function After Anterior Cruciate Ligament Reconstruction

The purpose of this study is to examine if thigh muscle weakness and the lack of muscle activation that accompanies ACL injury can be improved through a form of mental coaching and encouragement, known as operant conditioning.

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Key information

Conditions

Anterior Cruciate Ligament Injury Anterior Cruciate Ligament Injuries Knee Injuries Leg Injuries Wounds and Injuries

Age range

18 year–45 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Michigan

Ann Arbor, Michigan, 48108, United States

About this study

Thigh muscle weakness is a common result after anterior cruciate ligament (ACL) injury and reconstruction surgery. Therefore, reducing thigh muscle weakness after ACL injury and reconstructive surgery is important as the quadriceps muscles act as shock absorbers that protect the knee joint. If significant weakness is present in the quadriceps, the knee is exposed to increased forces and often results in degeneration of the structures in the joint leading to osteoarthritis. Thus, it is important to investigate activation and strength rehabilitation methods for the quadriceps muscles. This research study is being done to learn if thigh muscle weakness and the lack of muscle activation that accompanies ACL injury can be improved by conditioning brain responses (elicited by non-invasive transcranial magnetic stimulation) using a form of training called as operant conditioning.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • aged 18-45 years
  • suffered an acute, complete ACL rupture
  • have undergone ACL reconstructive surgery
  • willingness to participate in testing and follow-up as outlined in the protocol

Exclusion criteria

  • have suffered a previous ACL injury;
  • have undergone previous major surgery to either knee;
  • have a history of recent significant knee injury (other than ACL) or lower-extremity fracture;
  • have a history of uncontrolled diabetes or hypertension;
  • be pregnant or plan to become pregnant;
  • have metal implants in the head;
  • have electronic devices in their ear or heart (e.g., cochlear implants or cardiac pacemakers);
  • have unexplained recurrent headaches;
  • have a recent history of seizures;
  • be taking drugs that reduce seizure threshold;
  • have a history of repeated fainting spells;

Treatment and study plan

Operant Conditioning

Behavioral

Active encouragement and feedback to increase motor evoked response when stimulated.

Control

Behavioral

Absence of active encouragement and feedback to increase motor evoked response when stimulated.

Single Pulse Transcranial Magnetic Stimulation

Device

Transcranial magnetic stimulation to elicit a motor evoked response from the quadriceps muscles.

Primary outcomes

  1. Changes in Quadriceps muscle strength

    Time frame: Approximately 8 weeks after the start of intervention

    Quadriceps strength will be measured using an isokinetic dynamometer. Improvements in quadriceps strength from baseline to the end of intervention will be assessed and compared between groups.

Secondary outcomes

  1. Changes in voluntary activation

    Time frame: Approximately 8 weeks after the start of intervention

    Voluntary activation will be measured using an electrical superimposition technique. Improvements in voluntary activation from baseline to the end of intervention will be assessed and compared between groups.

Other outcomes

  1. Changes in mid-point quadriceps muscle strength

    Time frame: Approximately 4 weeks after the start of intervention (mid-time point evaluation)

    Quadriceps strength will be measured using an isokinetic dynamometer. Improvements in quadriceps strength from baseline to the mid-point of intervention will be assessed and compared between groups.

  2. Changes in mid-point voluntary activation as measured by percentage activation deficit

    Time frame: Approximately 4 weeks after the start of intervention (mid-time point evaluation)

    Voluntary activation will be measured using an electrical superimposition technique. Improvements in voluntary activation from baseline to the mid-point of intervention will be assessed and compared between groups.

  3. Changes in motor cortical excitability measures

    Time frame: Approximately after 8 weeks after the start of intervention

    Motor cortical excitability will be measured using single- and paired-pulse transcranial magnetic stimulation protocols. Improvements in motor cortical excitability from baseline to the end of intervention will be assessed and compared between groups.

  4. Changes in Knee Injury and Osteoarthritis Outcome Score

    Time frame: Approximately after 8 weeks after the start of intervention

    Knee Injury and Osteoarthritis Outcome Score (KOOS) will be measured using the KOOS questionnaire, which is a self-administered survey of knee function across five domains: pain, symptoms, activities of daily living, sport and recreation function, and knee related quality of life (scores range from 0 to 100, with 0 indicating extreme symptoms and 100 indicating no symptoms). The improvements in KOOS from baseline to the end of intervention will be assessed and compared between groups.

  5. Changes in International Knee Documentation Committee Score

    Time frame: Approximately after 8 weeks after the start of intervention

    International Knee Documentation Committee (IKDC) score will be measured using the IKDC subjective knee evaluation form, which is a survey of self-reported level of knee functioning across different domains (scores range from 0 to 100, with 0 indicating extreme symptoms and 100 indicating no symptoms).The improvements in IKDC score from baseline to the end of intervention will be assessed and compared between groups.

  6. Changes in Lysholm Knee Score

    Time frame: Approximately after 8 weeks after the start of intervention

    Lysholm knee score will be measured using the Lysholm Knee Scoring Scale, which is a questionnaire that assesses knee function after conservatively or surgically treated knee ligament injuries based on activities that require knee movement (scores range from 0 to 100, with 0 indicating extreme symptoms and 100 indicating no symptoms). The improvements in Lysholm score from baseline to the end of intervention will be assessed and compared between groups.

  7. Changes in Tegner Activity Score

    Time frame: Approximately after 8 weeks after the start of intervention

    Tegner activity score will be measured using the Tegner Activity level scale, which is a self-reported measure of activity level (scores range from 0 to 10, with 0 indicating no activity because of knee problems and 10 indicating extremely active in competitive sports). The improvements in Tegner activity score from baseline to the end of intervention will be assessed and compared between groups.

  8. Changes in Marx Activity Rating Score

    Time frame: Approximately after 8 weeks after the start of intervention

    Marx activity rating score will be measured using the Marx Activity Rating Scale, which is a self-reported rating scale designed to measure a subject's level of physical activity in four different categories: running, cutting, deceleration and pivoting (scores range from 0 to 16, with 0 indicating very low activity [< one time in a month] because of knee problems and 16 indicating very high activity [> 4 times in a week] in the four categories). The improvements in Marx activity score from baseline to the end of intervention will be assessed and compared between groups.

Sponsors and collaborators

Lead sponsor

University of Michigan

Other

Collaborators

  • Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
  • Medical University of South Carolina
  • National Center of Neuromodulation for Rehabilitation

Registry information

Official study title

Operant Conditioning of Motor Evoked Responses to Improve Quadriceps Function in Individuals With Anterior Cruciate Ligament Reconstruction

Important dates

Study start
2017
Primary completion
2025
Study completion
2025
First posted
Jul 6, 2017
Registry last updated
Nov 26, 2025

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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