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

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.

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;