Functional Connectivity After Anterior Cruciate Ligament Reconstruction (FCACLR)

Background: Despite surgical reconstruction and rehabilitation, individuals after a primary anterior cruciate ligament injury have a significantly increased risk of relapse. The mechanisms for this increased risk may go beyond mere physiological and biomechanical changes of the reconstructed anterior cruciate ligament. The loss of ligamentous mechanoreceptors can affect sensory feedback and consequently result in a disrupted afferent input to the central nervous system. However, research on the neuroplasticity of the central nervous system after anterior cruciate ligament injury and more specifically on the cooperation between different brain areas (=functional connectivity) in motor execution and performance is limited. Research purpose: To investigate the changes in terms of functional connectivity in the brain after sustaining an anterior cruciate ligament injury and associated reconstruction? Population: Patients after anterior cruciate ligament reconstruction Healthy controls Protocol: First, all participants are required to complete several questionnaires regarding the level of anxiety and the functioning of the knee in daily activities and sports. In addition, during the baseline testing, participants will be required to perform an experiment while electrical brain activity is recorded by means of an electroencephalography (EEG) measurement. During this experiment, the participants will have to successively perform the following exercises: 10x knee extension from sitting (left and right), 10x bipodal squat from standing, 5x 30 seconds unipodal standing (left and right). The above protocol will be administered to the patient group for the first time 8 weeks after the anterior cruciate ligament reconstruction. When the patients do not need further rehabilitation, they will be invited a second time to execute the same protocol again. The control group will only have to carry out the above protocol once. Finally, for one year after the last test, the patient group will be contacted monthly to monitor return to sport and the occurrence of injuries.

EEG measurement to evaluate functional connectivity in the brain during 3 motor tasks: Knee extension while sitting (10x left - right) Bipodal squatting (10x) Unipodal stance (5x30 seconds left-right)

Change in functional connectivity in the brain in patients following anterior cruciate ligament reconstruction

Electroencephalography (EEG) will be recorded from a 128 Sn surface electrode cap during 3 motor tasks. Functional connectivity will be analyzed.

Experimental group: 8 weeks postoperative and at the end of the rehabilitation (on average 9-12 months postoperative) / Control group: baseline

Change in subjective knee functionality measured by the Knee injury and Osteoarthritis Outcome Score (KOOS) - Questionnaire

Assess the patients opinion about their knee and associated problems. Each item is given a score between 0 and 4, then the total score is converted to a scale of 0-100. A higher score indicates less disfunction.

Experimental group: 8 weeks postoperative and at the end of the rehabilitation (on average 9-12 months postoperative) / Control group: baseline

This questionnaire consists of 17 questions and evaluates the extent to which patients experience kinesiophobia. Each item is given a score between 0 and 4. A higher score indicates more kinesiophobia.

Experimental group: 8 weeks postoperative and at the end of the rehabilitation (on average 9-12 months postoperative) / Control group: baseline

To evaluate the confidence of patients in their operated knee, expressed as a percentage relative to the nonoperated side (0-100%). A lower score indicates less confidence.

Experimental group: 8 weeks postoperative and at the end of the rehabilitation (on average 9-12 months postoperative) / Control group: baseline

This questionnaire consists of 16 questions and evaluates the extent to which patients are concerned Each item is given a score between 1 and 5. The total scores range from 16 to 80 with higher scores indicative of higher levels of trait worry.

Experimental group: 8 weeks postoperative and at the end of the rehabilitation (on average 9-12 months postoperative) / Control group: baseline

Change in athletes' emotion, confidence, and risk appraisal when returning to sports after an anterior cruciate ligament reconstruction measured by the ACL-Return to sport after injury (ACL-RSI) - Questionnaire

This questionnaire consists of 12 questions divided into three main sections: athletes' emotion, confidence, and risk assessment when returning to sport after an ACL injury and/or reconstructive surgery. Each item is given a score between 0 and 100, after which the total score is converted to a scale of 0-100. A lower score indicates more concerns about return to sport.

Experimental group: 8 weeks postoperative and at the end of the rehabilitation (on average 9-12 months postoperative) / Control group: baseline

PATIENT GROUP Inclusion Criteria: Older than 18 years of age. Primary anterior cruciate ligament rupture and reconstruction Exclusion Criteria: Major knee surgery in the past. Diagnosed with any knee pathology at this moment. Have any muscle or nerve related conditions that affect the functioning of the lower limbs. CONTROL GROUP Inclusion Criteria: - Older than 18 years of age. Exclusion Criteria: Major knee surgery in the past. Diagnosed with any knee pathology at this moment. Have any muscle or nerve related conditions that affect the functioning of the lower limbs.