Is Your Old ACL Injury Causing Pain and Dysfunction?

Benefits of Real-Time Feedback for Enhanced Sports Performance

Physically active people can have a plethora of injuries over the course of a lifetime, and as much as they hurt at the time, many injuries are forgotten, once the pain subsides and function returns. ACL injuries and tears are especially common for young athletes, dancers and fitness lovers, and even with reconstructive surgery and rehab, they can come back to haunt you, years down the road.

Why Old Knee Injuries Cause Problems

Because of the knee joint’s location and function in the body’s lower kinetic chain, a knee injury can affect joints above and below. A knee that is not fully rehabbed after injury, or that deteriorates over time, can alter the way body weight is distributed over the ankle and foot, causing misalignment that leads to ankle instability, which in turn affects gait and balance, and increases injury risk during physical activity.

In the same way, a dysfunctional knee can translate upward, affecting the hip and misaligning the spine. This can lead to hip pain and instability, groin pain, pelvic instability and back pain. While many people write these issues off as the consequences of aging, they are in reality a consequence of injury.

The good news is that physical therapy can help improve knee function, even years after an injury, and dramatically reduce pain, dysfunction and instability throughout the body.

Why Old Knee Injuries Cause Problems

What the Research Says About Old ACL Injuries

New research about the long-term consequences of knee injury is shedding light on the extent of the initial damage done to the tissues surrounding the knee, and how immediate treatment affects long-term outcomes.

  • A study by Hettrich et al. (2013) evaluated 1,000 people, with a median age of 23 at the time of injury, for six years post-ACL reconstruction. Six years later, 9 percent had required at least one additional surgery on the same knee, and 10 percent needed surgery on the other knee, Of those, 6.4 percent were for ACL injury. The research team concluded that patients who had ACL surgery in their youth were more likely to need additional surgery later on.
  • A 2012 study by Potter et al. ran MRIs for 11 years on 40 patients, with a total of 42 earlier ACL ruptures. Fourteen of the patients had rehabbed their knee without surgery, and 28 had undergone reconstructive surgery. The MRIs revealed that ACL tears had affected the surrounding cartilage, which had deteriorated over time, with cartilage loss in the lower femur up to 50 times greater than baseline. Cartilage loss to the knee cap itself was 30 times greater than baseline. The researchers concluded that progressive cartilage damage occurred to areas surrounding the knee that were not impacted by the initial ACL injury.
What the Research Says About Old ACL Injuries
  • A more recent study by Lohmander et al. (2020) surveyed patients with old ACL and meniscus injuries,10 to 20 years afterward. They found that 50 percent of the study participants had developed knee osteoarthritis that caused pain and dysfunction, and that knee injury survivors make up a substantial percent of the osteoarthritis population.
  • In a final study (Lepley et al., 2020), researchers documented brain changes in patients who had undergone ACL reconstruction, and noted that those changes impacted performance and the risk of reinjury. The study involved MRI brain scans of 10 post-reconstruction patients, and discovered that the portion of the corticospinal tract that controlled the injured knee was 15 percent smaller than that on the uninjured side. They concluded that changes to the brain after ACL reconstruction can negatively impact the recovery of motor function.

Physical Therapy for Old Knee Injuries

If you have an old ACL rupture or knee injury from younger, more active years, having a thorough gait and biomechanical analysis now could help prevent future problems.

At NYDNRehab, we go beyond treating the knee and its surrounding structures after an ACL injury. We take rehab to the next level by reestablishing the relationship between the muscles and the brain, to ensure fully restored function.

Physical Therapy for Old Knee Injuries
  • Diagnostic ultrasonography to identify changes in the structures surrounding the knee and monitor treatment results
  • Top-of-the-line 3D gait analysis system to identify gait anomalies and retrain correct gait mechanics
  • Zebris instrumented treadmill to measure ground reaction forces and pressure, and compare them on both sides of the body
  • C.A.R.E.N (computer assisted rehab environment) system to analyze kinematic joint angle data and dynamic stability, and to provide virtual reality feedback training to restore knee function
  • Surface EMG to analyze muscle firing patterns and identify compensation mechanisms and correct them
  • DD Robotech training equipment powered by artificial intelligence, for neuromuscular and neurocognitive training to restore brain-muscle control of the knee and lower kinetic chain

ACL and Knee Pain Treatment in NYC

The team at NYDNRehab has rehabilitated over 100 patients with torn ACLs over the past six years. All had ACL tear treatment without surgery using our meticulous approach and advanced modern technology. Our results closely reflect those of various research studies. Only 20 of our patients were unable to return to sports, and subsequently went for surgical ACL repair.

At NYDNRehab, we go beyond treating symptoms of pain and dysfunction. Our advanced technologies and innovative treatment methods enable us to identify the underlying causes, collect baseline data, and develop rehabilitation protocols that restore neuromuscular and neurocognitive function. Our end goal is to eliminate pain and dysfunction, so our patients can enjoy the very best quality of life.

Range of Available Unique Physical Therapy Treatments at Nydnrehab


  • Hettrich CM, Dunn WR, Reinke EK, MOON Group, Spindler KP. The rate of subsequent surgery and predictors after anterior cruciate ligament reconstruction. Am J of Sports Med. 2013; 41(7):1534-1540. DOI: 10.1177/0363546513490277.PMID: 23722056.
  • Lepley, Adam S., et al. “Corticospinal tract structure and excitability in patients with anterior cruciate ligament reconstruction: A DTI and TMS study.” NeuroImage: Clinical 25 (2020): 102157.
  • Lohmander, L. Stefan, et al. “The long-term consequence of anterior cruciate ligament and meniscus injuries: osteoarthritis.” The American journal of sports medicine 35.10 (2007): 1756-1769.
  • Potter HG, Jain SK, Ma Y, Black BR, Fung S, Lyman S. Cartilage injury after acute, isolated anterior cruciate ligament tear: immediate and longitudinal effect with clinical/MRI follow-up. Am J Sports Med. 2012 Feb;40(2):276-85. doi: 10.1177/0363546511423380. Epub 2011 Sep 27. PubMed PMID: 21952715.

About the Author

Dr. Lev Kalika is clinical director of NYDNRehab, located in Manhattan. Lev Kalika is the author of multiple medical publications and research, and an international expert in the field of rehabilitative sonography, ultrasound guided dry needling and sports medicine Dr. Kalika works with athletes, runners, dancers and mainstream clients to relieve pain, rehabilitate injuries, enhance performance and minimize the risk of injuries. His clinic features some of the most technologically advanced equipment in the world, rarely found in a private clinic.


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

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