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Knee Injuries Hurt the Brain

15 April, 2019

Knee Injuries Hurt the Brain

Approximate reading time: 3 minutes

Not only are knee injuries disabling, they also change your brain.

Neuroplasticity, also called brain plasticity, is the brain’s ability to change - physically & chemically rewiring. It is fundamental for learning and memory as well as performing complex behaviours.

Unfortunately, the reserve is also true. The brain remembers injuries and pain, detrimentally changing the brain’s structure and function. Chronic pain has long been known to change the brain’s activation patterns making it difficult to treat and frustrating for sufferers.

New research now shows that our brain rewires with an anterior cruciate ligament (ACL) injury.

Traditional knee rehabilitation approaches include muscle strength, balance and powerful plyometric training with little consideration for the brain changes. The high re-rupture rates after surgical repair may indicate that this approach is not enough. Additionally, only around half of reconstructed ACL patients return to their competitive level of sport again (Ardern et al 2014).

Although this recent study targeted knee injuries, similar changes have been seen elsewhere in the body such as lower back pain.

What brain changes are seen after a knee injury?

Neto and his colleagues did a review of the scientific research last year (2019). They specifically looked at ACL injuries and the brain changes measured with functional brain imaging.

They found that there were more slow brain waves in the front part of the brain. In technical terms, increased frontal theta activation. Frontal theta activity is involved in working memory.

What does working memory have to do with an ACL reconstruction?

Well, we know that rehabbed ACL injuries can achieve the same muscular force patterns as healthy knees. However, they require more brain energy to do it. Their brains have to think more.

Information is sent from the knee to the brain - what angle is the joint at, what muscles are activated, how much force are the muscles using. The brain compares this to what the brain expects to be happening at the knee - the long term memory of the knee.

After an ACL reconstruction, the messages from the knee to the brain different to the long term memory expectations. This requires more energy for the brain to figure out what is really happening. This is your working memory in action.

How can you target the brain after an injury?

Take a full body approach.

More research is suggesting that the knee and the brain’s control of the knee need to be targeted.

This requires a thorough assessment of the joints, muscles and movement patterns of the knee. In addition, the brain’s control the body - called motor learning - needs to be looked at.

Treatment should involve home exercises tailored specifically to your body & brain. For our brain to change, it requires repetition so these brain-based exercises are a vital component in addition to traditional musculoskeletal rehabilitation and treatments.

Appointments available in Moonee Ponds or online.


  • Neuroplasticity is the brain's ability to change to learn but also in reaction to pain
  • ACL injuries rewire the brain with more frontal theta brainwaves
  • After ACL injuries, the brain has to think more to control the knee
  • Rehabilitation should include traditional strength training as well as brain-based exercises

About the Author

Dr Cassie Atkinson-Quinton - Chiropractor, Pilates Instructor and Perinatal Yoga & Pilates Instructor

With 10 years experience treating musculoskeletal conditions, Cassie uses a range of therapies including gentle adjustments, specific massage techniques, laser therapy and home rehabilitation plans incorporating Pilates & yoga. She regularly treats headaches, migraines, back pain and sports injuries.

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  • Ardern CL, Taylor NF, Feller JA, Webster KE (2014). Fifty-five percent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta analysis including aspects of physical functioning and contextual factors. Br J Sports Med. 2014;48(21):1543–52.
  • Baumeister J, Reinecke K, Schubert M & Weiß M (2011). Altered electrocortical brain activity after ACL reconstruction during force control. J. Orthop. Res., 29: 1383-1389. Doi:10.1002/jor.21380
  • Gokeler A, Neuhaus D, Benjaminse A, Grooms DR & Baumeister J (2019). Principles of Motor Learning to Support Neuroplasticity After ACL Injury: Implications for Optimizing Performance and Reducing Risk of Second ACL Injury. Sports Medicine. Doi:10.1007/s40279-019-01058-0 
  • Grooms D, Appelbaum G, Onate J (2015). Neuroplasticity Following Anterior Cruciate Ligament Injury: A Framework for Visual-Motor Training Approaches in RehabilitationJournal of Orthopaedic & Sports Physical Therapy. Published 2015. Doi: 10.2519/jospt.2015.5549
  • Hotz-Boendermaker S, Marcar VL, Meier ML, Boendermaker B, Humphreys BK (2016). Reorganization in Secondary Somatosensory Cortex in Chronic Low Back Pain Patients. Spine: June 1, 2016 - Volume 41 - Issue 11 - p E667-E67. Doi: 10.1097/BRS.0000000000001348
  • Neto T, Sayer T, Theisen D & Mierau A (2019). Functional Brain Plasticity Associated with ACL Injury: A Scoping Review of Current Evidence. Neural Plast. 2019; 2019: 3480512.Published online 2019 Dec 27. Doi: 10.1155/2019/3480512
  •  Miao X, Huang H, Hu X, Li D, Yu Y & Ao Y (2017). The characteristics of EEG power spectra changes after ACL rupture. PLoS One. 2017;12(2, article e0170455). Doi: 10.1371/journal.pone.0170455.