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Return to Sport (RTS) For An ACL Athlete


Recently, a lot of attention has been paid to re-injury and return to sport following anterior cruciate ligament reconstruction (ACLR). Unfortunately the results continue to be less than exceptional.

We are often asked by athletes, “When can I return to my Sport after an ACL repair?” NFL running back, Adrian Petersen, has been a model of phenomenal healing that many athletes cross-reference their return to sport against. Adrian returned to full participation as a running back within 6 months and had one of the most memorable stat lines in all the NFL that year. This anomaly of rapid and explosive return to sport at 6 months after ACLR is very rare and can be a misleading measuring stick.


In a recent study by Grindem et al, BJSM 2016, those who returned to level 1 sports had 4.32 x higher ACL re-injury rate than those who did not. They also found that re-injury rates reduced by 51% for each month RTS was delayed until 9 months. For every month after 6 months with these same athletes, ACL tear risk reduced by 24%

Along with these staggering statistics we remind the athletes that they are not Adrian Petersen. Go youtube some of this guys workouts and the things that he is able to do, he is an athletically blessed specimen. Our bodies come in all shapes, sizes, and type of tissue (fast twitch and slow twitch). Secondly, we have to educate the athlete about allowing the ACL graft time to heal. In numerous studies regarding ACL reconstructions, it takes a minimum of 9 months for solid healing to occur with the new ACL. Father time is a criterion based parameter that has to be respected and can not be accelerated. “Ligamentization” takes time as it goes through the biological process and angiogenesis in order for the ACL to fully heal. Whether it is hamstring or patellar tendon grafts, both processes exceed the often cited 6-month return to sport criteria.

In 1966, songwriter Paul Simon wrote, “slow down – you move too fast,” maybe it’s time we follow his advice.


A case series of elite collegiate athletes who suffered ACL injuries prior to and during their college careers continually found difficulty returning to sports participation (Kamath et al., 2014). Of the 35 athletes who had undergone ACLR prior to enrollment in college, the rate of re-operation on the involved limb was 51.4%, the rate of re-rupture of the ACL graft was 17.4%, and contralateral ACL rupture was 20.0% within this population of athletes. Similarly, those who underwent ACLR during college had a 20.4% re-operation rate, 1.9% suffered re-rupture of the ACL graft, and 11.1% of these athletes underwent ACLR on the contralateral limb.

Unfortunately, these findings are not isolated to collegiate athletes; professional (Busfield et al., 2009) and high school athletes (McCullough et al., 2012) alike have similar statistics. Considering these numbers, it points to inadequate or premature return to athletic participation, which may be because we are overlooking important aspects of athletic competition.


Like with any injury, it cannot be blamed on one thing. Injuries are multi-factorial as well as non-preventable. Injuries will always happen. The only thing that we can do is to decrease the frequency or incidence of them. Luckily, as we continue to learn more about the mechanism of injury, we have developed some strategies to reduce your chance of ACL injuries.

Let’s look at what factors have been shown to predispose these athletes to injury. Hewett et al after screening 205 female collegiate athletes with a drop-jump task, 9 athletes went on to suffer an ACL injury during the following season. The 9 athletes in this study had several important factors in common in comparison to those who did not suffer an injury:
• Knee abduction angle at landing was 8° or greater
• Knee abduction moment was 2.5 times greater
• Ground reaction force was 20% higher
• Female athletes – 4-5 x more likely to tear and ACL compared to their male counterpart.


Prior to returning to sport, most athletes should undergo functional testing, but do these tests, done under optimal circumstances, tell the full story or are we missing something?

More specific to patients following ACLR, Webster et al conducted a study comparing the response to neuromuscular fatigue between uninjured control subjects and athletes following ACLR. This study once utilized an anticipated drop-landing task with data collected pre and post fatigue. Fatigue led to:
• Reduced flexion in the lower limb
• Reduced knee joint moments
• Increased hip and knee abduction
• Increased knee rotation

This shows an obvious decline in movement quality following fatigue, which may place both post-ACLR patients and uninjured controls at risk for injury.

This data should be used to further evolve our testing procedures to account for these potentially injurious movement patterns secondary to neuromuscular fatigue.

Albert Einstein is often quoted for saying, “The definition of insanity is to continually do the same thing over and over expecting a different result”. If we are to improve these return to sport and re-injury numbers, fatigue cannot be overlooked and must be included in our clinical decision making process.


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 discussions start occurring. Over the many years of testing athletes, we have seen that this collaboration is crucial in the return to sport decision. RTS decisions should be based off objective performance testing criteria that must met by the athlete.

We have recently updated our ACL Return to Sport (RTS) Exam that takes the athlete through research based physical and functional testing items that have high specificity. The rules of this exam are: Athlete must be 9 months post-op to be eligible, Surgeon must sign off on the exam, and every test item needs to be a “Yes” to be considered a “Pass”.

Their are three sections in this RTS exam: Physical Exam, Functional Testing, and Results.


Section 1 – Physical Exam :
• Special Tests – Negative Lachman’s test and Thessaly’s (meniscus) are required to ensure healing has occurred.
• Knee AROM – Bilateral Symmetry of motion that is pain-free is required for passing score. If the non-involved LE has 3 degrees of hyperextension so must the involved ACLR knee. Asymmetry in motion leads to much higher rate of re-injury.
• Cybex Testing – Passing criteria is no more than 10% deficit compared to contralateral LE on Quad Peak Torque and Hamstring to Quad ratio.
• Running – Rhythmic foot strike patterns without gross asymmetries when running without pain are required.

Section 2 – Functional Testing 
• Complete Fatigue Protocol Prior to Testing – As was explained earlier, if we want to improve athletes returning to sport we must incorporate fatigue into the equation to expose biomechanical issues that could lead to further injury. This is a specific protocol that takes the athlete through a progressive sequence of exercises that mimics sporting activity.
• Single Limb Hop Tests – No less than 10% deficit as compared to the contralateral LE to qualify for RTS. 3 different hop tests are involved and are compared to the opposite LE.
• 45 Degree Single Leg Squat Test (10 Reps) – Looks for biomechanical flaws that lead to ACL tears, the ability to eccentrically control body weight while stabilizing the hip.
• Modified T – Agility Test – timed test that challenges the athletes ability to cut, shuffle, sprint, and change direction. All these are crucial in sporting activity.

Section 3 – Results
• Overall Clearance from the DPT – If all test items are a “Yes” the form is then faxed to the surgeon for final approval.
• Overall Clearance from the Surgeon – Vital in return to sport is having both the clearance from both DPT and Surgeon. This will also play a huge role in the confidence of the athlete during sport.


The decision to return an athlete before 9 months may be an aggressive move that could be costly in the end. Time component for optimal grafting is a significant consideration in the RTS decision. Through communications with orthopedic surgeon experts, sophisticated protocols and research, 9 months post-op for safe return to sport is a minimum time requirement, and is based on extent of damage as well as tissue quality.

The RTS decision should rely minimally from subjective eyeballing and alternatively rely more heavily on objective physical and functional testing criteria. These objective criteria will likely expose concerns with the ACLR knee. Before functional testing occurs on the RTS Exam, a fatigue protocol should not be overlooked in creating a realistic environment for analysis. Equally important in the RTS decision is the collaboration of the DPT, Surgeon, Athlete, Coach, and Parent.

Failing to follow a criteria based exam for RTS could lead to what Grindem et al found in their research. In summary of those findings, of the athletes that did not meet the specific objective criteria, 38% of them re-tore their ACL.

Please email tyler@wrightpt.com or call us at any of our 6 Magic Valley locations with any questions you may have regarding ACL rehabilitation and return to sport decision making. We look forward to collaborating with you in helping your athletes return safely and swiftly to their sport.