Anterior cruciate ligament (ACL) injury leads to early-onset osteoarthritis. Quadriceps weakness is a consequence of ACL injury and is considered to result from arthrogenic inhibition (AMI). AMI is the neurological "shutdown" of muscles surrounding an injured joint, preventing full activation, reducing strength, and promoting atrophy. As quadriceps function is critical for energy absorption, its dysfunction may contribute to posttraumatic osteoarthritis.