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Knee Injuries and Prevention


Not everyone knows what the letters A.C.L stand for, but any sports participant or avid sports fan has likely heard them before, which is usually followed by the thought of “that athlete’s season is over or, in professional sports, possibly their career”. The anterior cruciate ligament (ACL) is an important ligament in the middle of the knee, which prevents forward translation or sliding of the tibia (shin bone) on the femur (thigh bone) and provides great stability to the knee joint. ACL injuries can occur from a direct blow to the knee (contact) or without any contact (non-contact) such as jumping, landing, pivoting, or cutting. Deficits to the ACL ligament results in poor knee stability and often requires surgical intervention. Common symptoms of a torn ACL are swelling, “buckling” of the leg, and a feeling like the knee is slipping.

Knee injuries account for about 10-25% of all sports-related injuries and an estimated 250,000 ACL-related injuries occur annually in the United States. The rate of non-contact ACL injuries has dramatically increased over the years. Those involved in sports that require jumping, cutting, and pivoting have an increased risk of serious knee injuries, specifically non-contact ACL tears. Non-contact means their is no collision with another person and the only outside force acting on the knee is that of the individual’s own body. An example of this would be an athlete sprinting and then suddenly stopping or pivoting. Unfortunately, female athletes are at an even greater risk of ACL injuries; they are 5-8 times more likely to injure their ACL when compared to their male counterparts.

These injuries commonly occur during the deceleration phase of a sport-specific movement such as landing a jump, decelerating to a stop, or a change of direction. There are many factors that contribute to ACL injuries such as biomechanical dysfunction, anatomical abnormalities that differ between male and female, hormone influence, etc. However, the biomechanical factors have been heavily studied and these factors are modifiable, unlike their counterparts.


Common biomechanical risk factors that can be modified are increased dynamic knee valgus (knee moving inward across midline), decreased hip and knee flexion, decreased hip internal rotation and ankle dorsiflexion, lack of or abnormal timing of quadriceps activation, and lack of core control, just to name a few.

These risk factors can be identified using functional movement screening tools and video analysis during sport-specific movements. At Wright Physical Therapy, we offer a Dynamic Movement Assessment (DMA), which is a research based performance and movement assessment exam. It contains a set of essential athletic movements applicable across multiple sports that allows objective identification of faulty or uncontrolled movement patterns. Common
athletic movements assessed during a functional movement screen include but are not limited to: squats, step-ups, single leg squats, drop jumps, single leg hops, planks, shuffling, decelerations, and cutting. Poor biomechanics during these movements can be identified and will guide further training to improve functional deficits and correct faulty movement patterns that increase the risk for injury. Although we cannot control most contact injuries or direct blows to the knee, we can directly influence these modifiable factors associated with non-contact knee injuries.


The decision of an athlete returning to sport should be a collaborative effort between the athlete, parents, coach, and surgeon. Athletes tend to get antsy when return to sport (RTS) is becoming a reality. In addition to collaboration, ultimately the RTS decision needs objective functional testing in order to confidently return an athlete to prior level of sport.

RTS is multi-factorial and can often take 1-2 years to feel comfortable in the proper return. Most are not functionally ready to return to their sport even though they are cleared by their physician. It seems in the industry of medicine, that “time” is falsely used as the number one decision maker versus specific criteria that include functional tests of strength, power and endurance. In a recent research article by renowned ACL researcher Tim Hewett, it showed that at 6 months, 2 patients (3.2%) passed all RTS criteria. At 9 months, seven patients (11.3%) passed all RTS criteria. Twenty-nine patients (46.8%) did not pass the strength criterion on an Isokinetic test at 60°/s at 9 months after ACL reconstruction (ACLR). These are eye opening results and supports our clinical experience over the last 10 years that ACLR athletes are usually not ready to return to sport under 9 months post-surgery. The research also shows that athletes who did not meet all RTS criteria before returning to their sport had a 4x greater risk of sustaining an ACL graft rupture compared with those who met all RTS criteria (Isokinetic testing at 60 deg, running T-Test, Single Leg Hop, triple hop, triple crossover hop tests, knee psychological exam, and running mechanics).

At Wright Physical Therapy, we understand the obstacles that exist from when therapy is complete to when an athlete is ready to return to sport after injury. Although the actual rehabilitation typically does not extend past 12 weeks, it is after rehab that the real strength, power, endurance and agility activities should really start taking shape. Unfortunately, a lot of patients are left to fend for themselves on what the next steps are in the RTS process, without the necessary guidance. At Wright Physical Therapy, we have created a specific RTS program through our Human Performance division, SCiATHLETE. Through collaboration with our doctors of physical therapy and licensed Human Performance Specialists, we address the biomechanical risk factors through proper stretching, strengthening/resistive training, neuromuscular training, agility/balance training, plyometric training, and running techniques. This program closes the gap between skilled physical therapy and an athlete being physically and mentally ready to return to sport.

Research also provides adequate evidence that this type of program is successful in reducing non-contact knee injuries. In 2015 Donnell-Fink et al determined the effectiveness of knee and ACL injury prevention programs significantly reduced the risk of knee injuries by 27% and ACL injuries by 51%.


The doctors of physical therapy at Wright Physical Therapy are movement specialists trained to identify the biomechanical risk factors that increase an athlete’s risk for knee injuries. They will identify these risk factors by conducting a one on one Dynamic Movement Assessment. The results of this assessment will guide the RTS program that is specifically needed for the athlete in order to return back to their sport, both safely and quickly. In order to do so, there needs to be intense focus on the athlete being mentally and physically ready as determined through proper testing against specific RTS criteria.

In the medical world at large, we are missing critical factors regarding RTS after ACLR. The amount of time from surgery as sole criteria for RTS will have very dire consequences. The data suggests that these athletes need to stay out of their sport for at least 9 months until all RTS criteria have been met. Take the guess work out of the RTS decision and join our RTS program that is tailored specifically to the athlete’s injury. Please call us today at one of our clinic locations and schedule an appointment to get back to your game. I am available via email for questions at tyler@wrightpt.com