Knee ACL Injury May Change Brain Function After Rehab


ACL Basics

A common and debilitating knee injury is a tear of the Anterior Cruciate Ligament, or ACL. This important structure holds the tibia bone of the shin in place, preventing it from shifting forward. during movement. The ACL is responsible for roughly 90 percent of knee stability in adults. Because torn ligaments cannot repair themselves, they often require surgical reconstruction when the tear in severe. Most ACL injuries are sustained while playing agility sports that require rapid directional changes, sudden stopping, rapid deceleration, twisting and jumping. While men sustain more ACL injuries overall, female athletes are at higher risk, being two to four times more likely to sustain an ACL injury during sports.

Reconstruction and Rehab

In general, a torn ACL means reduced knee stability and increased risk of injury when an athlete returns to play. While reconstructive knee surgery can resolve some of the stability issues, full recovery demands extensive high level ACL rehabilitation, dedicated training and ongoing maintenance. Even after a complete battery of ACL injury treatment and therapy, there is evidence to suggest there may be some alterations in brain processes after injury, specifically motor, sensory and sensory-visual-spacial processing that govern functional movement.

Brain Function and Athletic Performance

Athletes who return to play after ACL reconstruction are 30 to 40 times more likely to incur a second ACL injury than athletes with no history of ACL injury. In a recent study, Grooms et al. (2016) sought to explain alterations in athletes’ movement mechanics unrelated to physiological or biological changes after ACL reconstruction and rehab.

The researchers suspected that ACL injury led to neuroplastic changes due to the loss of ACL mechanoreceptors, and to compensation in neuromuscular control. They used MRI imaging to assess the brain function of athletes post-ACL reconstruction during a motor task of unilateral knee flexion and extension. Their findings suggest that brain activation during knee movement after ACL reconstruction shifts to a visual-motor strategy rather than a sensory motor strategy.

Implications for ACL Rehab Treatment

An interesting and important finding that emerged from this study is that traditional ACL rehabilitation treatment may be in part responsible for changes in brain activation patterns. This is because traditional therapy encourages focused attention on the knee with visual and cognitive position control during movement. The authors suggest that shifting the focus of the brain to the external environment rather than the knee during rehab could reduce the neuroplastic adaptations seen after knee reconstruction.

Cutting Edge Treatment in NYC

When it comes to ACL injury treatment, the sports medicine specialists at NYDNR are on top of their game. Not only do we keep current with the latest research, but we embrace newly emerging approaches to therapy, to give our patients the very best treatment and care. If you have sustained an ACL tear or knee reconstruction, you can trust the sports medicine team at NYDNR to provide you with the best rehabilitation and treatment in NYC.


Grooms, DR et al.(2016). Neuroplasticity associated with anterior cruciate ligament reconstruction. Journal of Orthopaedic and Sports Physical Therapy, 47(3), 180-189.


In this instance, an athlete was originally diagnosed with minor quadriceps muscle strain and was treated for four weeks, with unsatisfactory results. When he came to our clinic, the muscle was not healing, and the patients’ muscle tissue had already begun to atrophy.

Upon examination using MSUS, we discovered that he had a full muscle thickness tear that had been overlooked by his previous provider. To mitigate damage and promote healing, surgery should have been performed immediately after the injury occurred. Because of misdiagnosis and inappropriate treatment, the patient now has permanent damage that cannot be corrected.

The most important advantage of Ultrasound over MRI imaging is its ability to zero in on the symptomatic region and obtain imaging, with active participation and feedback from the patient. Using dynamic MSUS, we can see what happens when patients contract their muscles, something that cannot be done with MRI. From a diagnostic perspective, this interaction is invaluable.

Dynamic ultrasonography examination demonstrating
the full thickness tear and already occurring muscle atrophy
due to misdiagnosis and not referring the patient
to proper diagnostic workup

Demonstration of how very small muscle defect is made and revealed
to be a complete tear with muscle contraction
under diagnostic sonography (not possible with MRI)


Complete tear of rectus femoris
with large hematoma (blood)


Separation of muscle ends due to tear elicited
on dynamic sonography examination

Buy now 3D Gait
Payment Success
Request TelehealthRequest Telehealth Request in office visit Book now