More than a knee injury: ACL tears cause harmful changes in our brain structure

It’s known that some joint function is often permanently lost after anterior cruciate ligament reconstruction, and re-injury is common even with intensive physical therapy, but it’s unclear why.

Adam Lepley, assisant professor of kinesiology in residence, left, and Elisa Medeiros, technician, prepare a model patient for functional MRI testing to assess brain activation during a knee flexion and extension task at the Phillips Communication Sciences Building on July 17, 2017. Peter Morenus, UConn Photo

Laura Bailey, University of Michigan January 28, 2020

New research from the University of Michigan School of Kinesiology shows structural changes in the brains of patients who underwent ACL reconstruction. These changes hinder recovery and may contribute to performance deficits and re-injury, says study co-author Lindsey Lepley, U-M assistant professor of athletic training.

Computer recreation of patient MRI scans, abnormalities are undetectable with the naked eye. Red depicts the right side corticospinal tract, blue depicts the left. Adam Lepley

Lindsey Lepley and colleague Adam Lepley, clinical assistant professor of athletic training, took MRI brain scans of 10 ACL-reconstructed patients. The scans showed that part of the corticospinal tract—the pathway that scuttles messages from brain to muscles—had atrophied in the patients.

The corticospinal tract runs from front to back through both hemispheres of the brain. The side of the tract that controls the ACL-reconstructed knee was about 15% smaller than on the uninjured side, the researchers say.

Think of the altered corticospinal tract as a traffic tunnel that narrows, letting fewer cars pass through, they say. In the ACL reconstructed patients, less information gets from the brain to the muscle because less information can travel along the smaller tract.

Adam Lepley, assisant professor of kinesiology in residence, prepares a model subject for transcranial magnetic stimulation at the Phillips Communication Sciences Building on July 17, 2017. Peter Morenus, UConn

“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.”

Another recent study shows that downstream neural activity in the quadriceps is impaired during sport-like movements after ACL surgery, which suggests that poor brain structure and communication can lead to reduced functioning, the researchers say.

Elisa Medeiros, observes a functional MRI test in the fMRI at the Phillips Communication Sciences Building on July 17, 2017. Peter Morenus, UConn Photo

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.

“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.”

Contact Laura Bailey  baileylm@umich.edu

Source University of Michigan

  References

Corticospinal tract structure and excitability in patients with anterior cruciate ligament reconstruction: A DTI and TMS study, Lepley AS, Ly MT, Grooms DR, Kinsella-Shaw JM, Lepley LK. Neuroimage Clin. 2019 Dec 27;25:102157. doi: 10.1016/j.nicl.2019.102157. [Epub ahead of print] Full text

  Further reading

Quadriceps muscle function following anterior cruciate ligament reconstruction: systemic differences in neural and morphological characteristics, Lepley AS, Grooms DR, Burland JP, Davi SM, Kinsella-Shaw JM, Lepley LK. Exp Brain Res. 2019 May;237(5):1267-1278. doi: 10.1007/s00221-019-05499-x. Epub 2019 Mar 9.

Quadriceps Neuromuscular Function in Patients With Anterior Cruciate Ligament Reconstruction With or Without Knee Osteoarthritis: A Cross-Sectional Study, Norte GE, Hertel J, Saliba SA, Diduch DR, Hart JM. J Athl Train. 2018 May;53(5):475-485. doi: 10.4085/1062-6050-102-17. Epub 2018 Jun 12. Full text

Neuroplasticity following anterior cruciate ligament injury: a framework for visual-motor training approaches in rehabilitation, Grooms D, Appelbaum G, Onate J. J Orthop Sports Phys Ther. 2015 May;45(5):381-93. doi: 10.2519/jospt.2015.5549. Epub 2015 Jan 10. Review.

Contributions of neural excitability and voluntary activation to quadriceps muscle strength following anterior cruciate ligament reconstruction, Lepley AS, Ericksen HM, Sohn DH, Pietrosimone BG. Knee. 2014 Jun;21(3):736-42. doi: 10.1016/j.knee.2014.02.008. Epub 2014 Feb 16.

Quadriceps activation following knee injuries: a systematic review, Hart JM, Pietrosimone B, Hertel J, Ingersoll CD. J Athl Train. 2010 Jan-Feb;45(1):87-97. doi: 10.4085/1062-6050-45.1.87. Review. Full text

Also see
Research Finds Brain Changes, Needs To Be Retrained After ACL Injury in Ohio State University Wexner Medical Center

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