Knee Injuries and The Brain

Some joint function is often permanently lost after anterior cruciate ligament (ACL) reconstruction, and re-injury is common even with intensive physical therapy, but it has been unclear as to why.

The ACL injury risk has been reported to be higher in elite sports versus non-elite sports.

Female athletes are 3-6X more likely to sustain a sports-related noncontact ACL injury than male athletes in comparable high-risk sports.

The incidence of female to male knee injuries is 3.5X greater in basketball and 2.8X greater in soccer.

Injuries to the knee’s anterior cruciate ligament are one of the most common knee injuries. Unfortunately, when the ACL tears, it not only damages the ligament, but also damages the nerve endings within the ligament. Once the nerve endings are gone, they do not regrow. A recent study from the University of Michigan School of Kinesiology has examined how ACL nerve damage affects the brain.  The study’s conclusions provide important clues about how to recover from joint injuries.

Lindsey Lepley, and colleague Adam Lepley, took MRI brain scans of 10 ACL-reconstructed patients. The scans showed that part of the corticospinal tract (the pathway that transmits messages from brain to muscles) had atrophied in the patients. “In essence, the brain not only alters the way it communicates with the rest of the body, joints, muscles, etc., but the structural makeup of the basic building blocks of the brain are also changed after ACL injury,” Adam Lepley said. “We think that this is a protective mechanism, in which our body is trying to limit unwanted movement around a joint injury … and can be applied to not just ACL injuries, but other musculoskeletal injuries as well.”

Once the constant flow of information from the ACL’s nerves has been cut off by the injury, the brain may send fewer signals back to the surrounding muscles thus you end up using more parts of your brain to produce simple motion. Eventually, this could result in muscle atrophy, or altered function of the knee joint.

The bottom line for patients and clinicians is that a knee injury is not just about knees -- other areas, like the brain structure, are negatively impacted, too. On the positive side, the brain has the ability to develop an alternate path in response to injury called neuroplasticity,’ which means that our brains can change.

A similar injury pattern has been noted after concussion injuries. There is an increase in knee and other lower body injuries in the first 6 months after recovery from a concussion injury. This 2-4x increase in injuries demonstrates that a strong link exists between the brain and injuries to other parts of the body.

"It means that during treatment, a systemic approach should be taken not just to improve range of motion or swelling at the injured joint, but also consider other impairments like poor movement patterns and muscle activation in order to get better outcomes," Lindsey Lepley said. "There is evidence of using visual retraining, different motor learning modalities like external focus of attention and biofeedback, which can help 'rewire' the brain to help the body adapt to a new normal." 

At Honsberger Physio+ we have found that injury prevention and rehabilitation linking the body and brain have been very effective in injury management. Honsberger Physio+ offers comprehensive rehabilitation treatment that incorporates both a physical and neurocognitive approach using our full suite of sports performance vision training equipment including NeurotrackerX, Dynavision D2, FitLight, PlayAttention and Cambridge Brain Sciences.

If you are suffering from lingering concussion symptoms or fall in to the 'at risk' groups mentioned above, please talk to us about validated preventative programs to help reduce the incidence of knee injuries in running and jumping sports such a basketball, volleyball and soccer, and especially for female athletes. These programs utilize DorsaVi movement analysis, as well as sports specific testing and conditioning to minimize knee injury risk.

Book your appointment with Efan today!


Written by: 
Registered Physiotherapist, Retired Athletic Therapist
Manaing Clinical Director of the Markham Clinic 

B.H.SC. (PT)


Orthopedic Rehabilitation
105-675 Cochrane Drive, Markham, ON L3R 0B8 P (905) 940-2627 F (905) 940-3136 HONSBERGER@HONSBERGERPHYSIOPLUS.COM
81 Temperance Street, Aurora, ON L4G 2R1 P (905) 841-0411 F (905) 841-7311 AURORA@HONSBERGERPHYSIOPLUS.COM