How Does Your Brain Affect ACL Rehabilitation?

A torn ACL is one of the most common injuries among athletes of all ages. More than 200,000 ACL tears occur each year in the United States alone.1These injuries are treated surgically 76.6% of the time.After undergoing surgery for an ACL reconstruction, physical therapy is extremely important when attempting to return to participation in sport, or whatever it is your goal may be. Your physical therapist will work with you to recover your strength, power, range of motion, and balance in the injured knee in order for you to make a full recovery.

There are also many other impairments that occur after sustaining an ACL injury. Research has shown that after an ACL injury, individuals have decreased proprioception in their affected knee3. Proprioception is the ability for your brain to recognize joint position and detect movement. This can lead to difficulties with movement and balance, which a skilled physical therapist will provide patients with exercises for in order to return an individual to their previous level of function.

New research is also emerging that shows how the brain adapts when an individual suffers an injury to their ACL. Research has shown that different regions of the brain are activated to a greater or lesser degree with active movement of the knee after an injury to the ACL. This likely occurs as a method of compensating for the injury. An example is more activation in the region of the brain responsible for vision, which likely means that the brain is compensating for a decreased sense of proprioception by relying on the visual system to aid with movement, and position sense.3

There is also an increased risk of a second ACL injury in individuals who have previously torn their ACL. Research has shown that you are 15 times more likely to tear your ACL if you have done so in the past.4 Some factors that have been proven to increase the likelihood of this occurring include abnormal mechanics while landing from a jump, and decreased postural stability4. These are variables that a physical therapist will focus on throughout the course of rehabilitation from an ACL tear, in order to allow patients to safely return to unrestricted participation in sports and other recreational activities.


  1. Prodromos CC, Han Y, Rogowski J, et al. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy.2007;23:1320-1325. E1326.
  2. Joseph,Allan M, Comstock, R et al. A Multisport Epidemiologic Comparison of Anterior Cruciate Ligament Injuries in High School Athletics. J Athl Train. 2013 Nov-Dec; 48(6): 810–817.doi:10.4085/1062-6050-48.6.03
  3. Kapreli E, Athanasopoulos S. Anterior Cruciate Ligament Deficiency Causes Brain Plasticity: A Functional MRI Study. Am J Sports Med 2009 37: 2419 DOI: 10.1177/0363546509343201
  4. Paterno M, Hewett E. Biomechanical Measures During Landing and Postural Stability Predict Second Anterior Cruciate Ligament Injury After Anterior Cruciate Ligament Reconstruction and Return to Sport. Am J Sports Med 2010 38: 1968 originally published online August 11, 2010. DOI: 10.1177/0263546510376053