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Tyler Golden
MSAT 6500
Dr. Herzog
July 25, 2014
ACL Rupture
This paper will be discussing the many aspects that can accompany the ACL rupture
pathology. This painful injury used to be considered a death sentence for anyone engaging in an
active lifestyle. When this injury occurred to an athlete it almost marked the end of their career1,
but thanks to advances in medicine we now have better protocols and treatments for this injury.
The ACL ligament also known as the anterior cruciate ligament is one of four critical ligaments
in the knee. The ligament is a very strong ligament because of its role in knee stability. It is
made up of a thick dense amount of fibrous tissue that can withstand forces up to 500 pounds of
pressure2. Because of its job in knee stability this ligament, when damaged, can lead to a very
debilitating time.
The ACL ligament is located in the knee and helps form the dynamic knee joint that
consists of the femur and tibia. It’s located on the posterior aspect of the femur and the anterior
portion of the tibia. Its location in the center aspect of the knee allows its main function to be
stabilization the knee by preventing forward or anterior movement of the tibia as well as
rotational stability2. When it comes to what structures are involved in an ACL rupture the main
damage occurs to the ligament itself. In some cases though when an individual tears their ACL
they can damage other structures in the knee joint as well. Any time an individual damages the
ACL you can see issues with damage of the menisci. In extreme cases with an ACL tear you can

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incur what is called the unhappy triad. The unhappy triad consists of a knee injury involving not
only the ACL but the MCL and meniscus as well3. Being diagnosed with this injury can be very
discouraging to a patient it is something clinicians need to be aware of.
After discussing the function of the ACL and what can be damaged when an ACL rupture
occurs the next step is to understand what causes the injury. The mechanisms of injury for an
ACL tear can be many and wide-ranging but most ACL occurs with axial and rotational forces4,2.
These are the types of forces needed in order to have this injury occur without contact4. This is
that classic athlete plants and pivots type of action that we see as clinicians. One that comes to
mind is when Wes Welker tore his ACL in 2010. You can clearly see in the play that as he goes
to evade the defender he plants (axial) and pivots (rotational) causing the ACL to tear. Another
reason this is a common injury in athletics is because when someone cuts they transfer all of
their body weight onto the leg which is too much to handle5. This injury can occur with contact
as well, normally when an athlete foot is planted and after contact the body rotates while the foot
stays. More often than not though this injury occurs without contact, when looking at female
NCAA soccer athletes more than 63% had an ACL injury without contact 6. Previously there
were other theories of why the ACL would be injured. One of the early thoughts the injury was
that the intercondylar notch would pinch the ACL4. Another theory regarding ACL injuries is
that the quadriceps group being as powerful as they are compared to the hamstring group would
pull the tibia anteriorly causing the ACL to be overstretched and rupture4. This can make some
sense one of the special tests used to possibly diagnose an ACL tear requires flexion of the
quads. The quads which insert at the tibial tuberosity will pull the tibia forward and if the ACL
has been comprised you can have abnormal anterior movement of the tibia. Other mechanisms

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that can define if an ACL can be damaged are ground reaction forces. Ground reaction forces are
those forces that were mentioned earlier where the foot plants and transfers the force up through
the body4. These forces can increase when an athlete lands flat footed as compared to when they
land softly4. These types of landings also increase the chance of injury without contact. As you
can see even though the injury can occur in a variety of ways they are mostly predicated on
forces that overload the joint with compressive and rotational forces. This is why proper
instruction when it comes to landing techniques plays a vital role in the health of people with
active lifestyles.
Now after understanding how this injury can occur in most cases, clinicians need to
understand what can make someone more susceptible to the forces. Looking back to the
previous paragraph of what was thought to cause injury we can look to see which people have
anatomical or functional tendencies that lead to ACL injuries. One of the previous theories
suggested that tears of the ACL occurred when the intercondylar notch pinched the ligament.
This would suggest that if an individual has a smaller notch that would increase the chances of
the ACL being injured. One journal studied men and women and found that those with
intercondylar notches were more at risk at sustaining an ACL injury7. The study also found that
women on average tend to have smaller notches than there male counterparts7. This fact is one
of many that lead to women being more susceptible to having an ACL injury. Another risk factor
is the measure of the Q-Angle. The Q-Angle is a measurement consisting of aspects of the hip,
patella, and tibia. More specifically it measures from anterior superior iliac spine (ASIS) to the
midpoint of the patella and finally to the tibial tuberosity. Women whose hips are wider due to
their ability to bear children naturally having a higher Q-angles than men. Because of this

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anatomical defect it causes more stress on the medial aspect of the knee known as genu valgum.
This genu valgum alignment increases the amount of ground reaction forces naturally making the
amount of compressive force necessary to damage the ACL lower4. Basically this amounts to the
fact that when you have this condition and you try to make a cut versus someone who doesn’t
you are already stressing a ligament that is at stretch and any increase will likely result in
damage to the ACL. This unfortunate anatomical difference between men and women is another
factor that leads women to be at higher risk for an ACL tear. Because of the increased risk
factors for women studies looked at if there were any physiological factors that can also affect
women. One study looked at female hormones between women who had ruptured ACLs and
those who didn’t what they found was women who had lower levels of testosterone were more
likely to have an ACL tear than those who had higher levels8. The also found that lower levels of
progesterone may also be a risk factor for those trying to avoid ACL injuries8. As the studies
show women are more susceptible to ACL injuries compared to men for several reasons most of
which are out of their control.
The next of the ACL rupture injury is to look at the prevalence of it. One study
conducted with the New Zealand population found about a 37% injury rate out of 100,000
people. This shows that this injury occurs a fair amount in a population and as such needs to be
of concern to clinicians9. Another aspect of this injury to look at its occurrence in active
populations this will give us a much more accurate understanding of how often this injury
occurs. One study looked at ACL injury occurrence among wakeboarders. Wakeboarding is
sport most common in the summer months. It is like snowboarding on water and is becoming
increasingly popular. This study surveyed wakeboarders of all levels and returned 123 responses

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with a percentage of 42.3% reporting that while they were wakeboarding they suffered an ACL
injury10. This number shows that in active populations we should be concerned with the chance
of an individual sustaining this injury. This same study also looked at treatment patterns, and
return to wakeboarding stats. The study reported that 71.1% of people were unable to wakeboard
again until they treated the injury with reconstruction and 78.85% had the ACL repaired
surgically10. We may not see this as athletic trainers though because it may be a fringe sport that
may not be as popular as some sports around the world. The next study looked at the incidence
of ACL injuries occurring in the elite Italian soccer league Serie A. To be more specific it looked
at how many of these athletes were treated with ACL reconstructions. The Serie A league is a
top-notch league when it comes to the international soccer scene. This study found out that 10%
of players in the 2002-2003 study had to undergo at least one ACL reconstruction in their
career11. This is a decent amount of the population and shows that even those who are at the
peak levels of fitness and strength are still vulnerable to this debilitating injury. The same study
found that most of the people who underwent the procedure were older individuals in the
league11. Also if players had a reconstruction surgery once before they would be more likely to
have another ACL injury11. To look at the incidence of injury after reconstruction is another
aspect of this injury clinicians need to be aware of. More specifically what occurs when
someone reinjures a previous reconstruction? One study found that when someone reinjures a
graft they tend to have torn the ACL in a different part of the ligament then original12. It found
that the tears occurred in the middle of the anterior-medial functioning part of the ACL
ligament12. Another unique aspect of this study was the length of time after each of the tears.
They found the longer a person went with the reconstructed graft it was more likely to resemble

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the original injury, those who had reinjured the graft sooner damaged the graft in a different
aspect of the ligament12. The concerns clinicians in the fact that we need to pay attention to the
mechanisms and risk factors of those with previous ACL ruptures. These studies show that in the
active population we are more likely to see an ACL injury occur which is a red flag for clinicians
dealing with the active population.
After looking at mechanisms, risk factors, and epidemiological aspects of the injury its
best to describe how go about evaluating and diagnosing this injury. There are many ways to go
about trying to discern whether an individual has the injury. There are some physical tests
clinicians can use as well radiological tools to find out if an individual has sustained an ACL
injury. One of the most commonly used physical special tests is the Lachman test. Of all the
physical test the Lachman is the one that has the highest level of accuracy9. The accuracy of the
Lachman test hovers right around 85% according to one study13. This physical test consists of
manipulating the two bones that the ACL ligament attaches together. By doing this you check
the amount of movement anteriorly you get by checking against what would be the uninjured leg.
Another reliable test using radiology would be the MRI. The levels of sensitivity and specificity
for the use of the MRI test is 94%13. The use of this tool is most common in helping confirm
what the physical exam suggest and is most commonly used here in America9. The other benefit
of using a MRI is will also allow the clinician to see if any other of the structures in the knee
have been involved9. To be absolutely positive about what may be seen or felt between the two
other tests clinicians may schedule an arthroscopic surgery to look at what is going on exactly
inside of the joint5. More often than not this technique will be used only when the surgeon is
looking to repair any damage previously found. There are two other physical tests that are

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sometimes used but are not as reliable which would be the anterior drawer test and pivot shift5.
Another test that has just come around is the Lelli test but not enough research has been to
confirm how solid this test is. But the physical capabilities needed to perform this test are less
demanding than some other physical tests.
The final aspect of the ACL rupture would be to look at what happens after we do have a
patient with a injured knee. There are two approaches that clinicians can take for this injury, one
approach is conservative and the other is to surgically repair the knee. There is no clear deciding
factor that states whether a patient needs a surgery or not. A key factor that can help decide
which route would be better for the patient would be there activity level13,2. The people who
choose the conservative route will probably be placed on a course of physical therapy work, a
change in their level of activity, and finally if the patient is still active they should be fitted with a
brace to help with stability2. When it comes to the conservative the route the main goal is gain
stabilization of the knee joint via the neuromuscular route14. Those patients who where
participating in contact sports had a decline in their activity levels which affected there quality of
life measurements as well14. To conclude for those choosing to not operate to repair the ACL
ligament they should focus on open-chain exercises, balance exercises that help with
proprioception, and if the patient still feels instability they may need the use of a brace13. The
other option is taken is a surgical approach with restoring the ligament to resemble what it used
to be. The reason someone might choose the surgical route maybe because of their high activity
level, they may have damaged more than the ACL structure, and if conservative measures are not
working5. When it comes to the surgical route a patient has three options that are available to
them, the three options available to a patient to choose from are an autograft (coming from their

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own body), an allograft (the same tissue but from a source outside of their body), and finally a
synthetic graft. To begin with the autograft is replacing the ACL with a part of the patients own
flesh. The two sources used in the autograft choice are usually a patellar tendon or the hamstring
tendon13. Between the two choices of the autograft there is no significant differences when it
comes to the amount of stability each provides13. There is more reported anterior knee pain with
the patellar graft though13. The allograft route is when the new ACL comes from a source that
isn’t part of the patient. Taken from cadavers this option gives no significant difference when it
comes to stability measurements compared to the autograft13. In a review of studies conducted
some of the issues that come with the allograft route can be when using a radiated allograft they
have a tendency to fail more13. The other issue of course whenever there is a tissue transplant is
the risk of infection from the previous owner. But benefits of allograft include less invasive
techniques as well preventing damage to another aspect of the patients body5. The other option
is a synthetic graft but this option is not used very often due to its high failure rate5,13. After the
patient chooses their option they start the process of rehabilitating the knee joint. Similar to the
conservative route the main goals of rehabbing the reconstructed knee is to regain functional
stability, a solid functional level, and to reduce the chance of injuring the reconstructed ACL15.
Most rehab programs performed these days involve trying to regain range of motion quicker after
surgery then previous techniques15. The next phase of rehab should include strengthening the
musculature, this will allow the patient to return quicker13. As the patient continues to get
stronger we need to be mindful of when to allow them to return to physically demanding
activities. A review in the literature suggested that physical demanding work and return to sport
should not be performed in the first 3 months of surgery13. But after awhile the patient and

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clinician can both be getting antsy to try and return, but this needs to accomplished in a efficient
manner to prevent complications in rehab. As clinicians we should allow light activities for the
patient if they can perform it safely15. The more criteria that the patients achieves allows
clinicians to allow for more advanced workloads maybe even return to sport in the 4-6 month
range15. The most complete way to decide whether a patient is ready to return to play is by
looking a the combination of several factors including strength, ROM, stability, psychological
factors and maybe some social factors as well15. In the end when making a decision as a
clinician you need to look at all factors involved with patient and make the decision with their
best interests in mind.
To conclude this we have discussed the many different aspects of the ACL rupture. The
literature has shown us what some of the main mechanism of injury and how these mechanisms
of injury can be compounded with inherent risk factors especially in those in the female
population. We looked at how often this injury occurs and what can happen to the quality of life
of the patient after suffering this injury. After reviewing the literature we identified special test
physical and radiological that can be used by clinicians to diagnose an ACL rupture. Finally
review of the literature gives clinicians an idea of how to treat, repair, and rehabilitate patients
suffering from this injury.
1. Kvist J. Rehabilitation Following Anterior Cruciate Ligament Injury: Current
Recommendations for Sports Participation. Sports Med. 2004; 34(4): 269-280.
2. ACL_Tear.pdf. Available at: http://www.scottgudemanmd.com/images/uploads/
ACL_Tear.pdf. Accessed July 24, 2014.
3. Unhappy Triad - Understanding Your Knee Injury. Available at: http://
www.unhappytriad.org/. Accessed July 25, 2014.

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4. Unlocking the mechanisms of ACL injury. Available at: http://www.aaos.org/news/
aaosnow/sep10/clinical10.asp. Accessed June 18, 2014.
5. The Steadman Clinic Vail, CO | Sports Medicine & Orthopedic Surgery | Steadman
Hawkins. Available at: http://thesteadmanclinic.com/acl/overview.asp. Accessed July 25,
2014.
6. Arendt EA, Agel J, Dick R. Anterior Cruciate Ligament Injury Patterns Among Collegiate
Men and Women. J Athl Train. 1999; 34(2): 86-92.
7. Chung SC, Chan W, Wong S. Lower limb alignment in anterior cruciate ligament-deficient
versus -intact knees. J Orthop Surg Hong Kong. 2011;19(3):303-308.
8. Stijak L, Kadija M, Djulejić V, et al. The influence of sex hormones on anterior cruciate
ligament rupture: female study. Knee Surg Sports Traumatol Arthrosc. 2014:1-8. doi:
10.1007/s00167-014-3077-3.
9. Anterior Cruciate Ligament Injury: Diagnosis, Management, and Prevention - American
Family Physician. Available at: http://www.aafp.org/afp/2010/1015/p917.html. Accessed
July 24, 2014.
10. Starr HM, Sanders B. Anterior Cruciate Ligament Injuries in Wakeboarding: Prevalence
and Observations on Injury Mechanism. Sports Health Multidiscip Approach. 2012;4(4):
328-332. doi:10.1177/1941738112443364.
11. Roi GS, Nanni G, Tavana R, Tencone F. Prevalence of anterior cruciate ligament
reconstructions in professional soccer players. Sport Sci Health. 2006;1(3):118-121. doi:
10.1007/s11332-006-0021-z.
12. Van Eck CF, Kropf EJ, Romanowski JR, et al. ACL graft re-rupture after double-bundle
reconstruction: factors that influence the intra-articular pattern of injury. Knee Surg Sports
Traumatol Arthrosc. 2011;19(3):340-346.
13. Meuffels DE, Poldervaart MT, Diercks RL, et al. Guideline on anterior cruciate ligament
injury. Acta Orthop. 2012;83(4):379-386. doi:10.3109/17453674.2012.704563.
14. Delincé P, Ghafil D. Anterior cruciate ligament tears: conservative or surgical treatment? A
critical review of the literature. Knee Surg Sports Traumatol Arthrosc. 2012;20(1):48-61.
doi:10.1007/s00167-011-1614-x.
15. Kvist J. Rehabilitation Following Anterior Cruciate Ligament Injury: Current
Recommendations for Sports Participation. Sports Med. 2004;34(4):269-280.

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