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ACL Injury ACL Injury
ACL or anterior cruciate ligament injuries are among the most common knee injuries. In the US, there are approximately 150,000 ACL injuries every... ACL Injury

by Kimberly Allen, RN

ACL or anterior cruciate ligament injuries are among the most common knee injuries.  In the US, there are approximately 150,000 ACL injuries every year, most of which are suffered by athletes.  Female athletes are up to eight times more likely to suffer an ACL injury than their male counter parts, especially if they participate in sports like skiing,  basketball or soccer.  A recent study by the WNBA found that European-American women have a higher chance of ACL injury than women of Asian, Hispanic or African-American decent.  Also, once you’ve suffered one ACL injury your chances of suffering another increases.winter injury
There are 2 types of ligaments that control your knee movement, the collateral ligaments and the cruciate ligaments.  The collateral ligaments are located on the sides of your knee controlling the sideways movements of your knee.  They also brace it against movements that are not normal.  The cruciate ligaments are located inside the knee.  There are 2 cruciate ligaments, they cross and make an “X” in the middle of the knee with the ACL crossing in front and the PCL or posterior cruciate ligament crossing in the back.  These ligaments are responsible for controlling the back and forth motion of the knee.  The ACL also keeps the tibia, one of the bones in your lower leg, from sliding out in front of your thigh bone or femur.  It also gives your knee rotational stability.
Research has found that ACL injuries occur because of both external and internal factors.  External factors include things like if your knee gets twisted, bent backward or to the side.  Most ACl injuries are non-contact injuries occurring when you jump and land “wrong” or if your running and try to change direction quickly.  Sports that have a lot of “stop and go” type movements have a higher incidence of ACL injuries.  The internal factors involve the differences in anatomy between males and females, for example women have a wider pelvis which affects how they move and land after jumping.  Females also tend to have knee’s that are more flexible than males which puts more force on the ligaments during movement.  Hamstring muscles in the back of the leg are more flexible but have less strength in females than males which affects how the knee reacts to movement.  Also, estrogen, the female hormone has been shown to relax the ACL allowing it to stretch increasing the chance of injury in women.
Most people that injure their AcL know immediately that something is wrong.  Most of the time you’ll either hear or feel a “pop” in your knee when the injury occurs.  there will be a burning pain immediately that you’ll notice on the outside behind your knee.  Your knee will swell especially in the first few hours after the injury.  The degree of pain and swelling usually depends on the severity of the injury.  Most people are unable to bear weight on their knee after an ACL injury.
When treating ACL injuries the first priority is to reduce the swelling and pain in your knee.  Then the goal of treatment focuses on strengthening the muscles that surround your knee and regaining normal movement.  Depending on the severity of the injury and the type of activity you wish to pursue the Dr may recommend surgery to reconstruct the ligaments to prevent further injury.  You will need physical therapy regardless of whether or not you have surgery.  In the early stages of rehabilitation you’ll need to use crutches and usually a knee brace to stabilize the knee.  Then you’ll need to do range of motion exercises as well as strengthening and stability exercises in order to regain full motion of your knee.

Preventing ACL injuries

As more and more children and teens are participating in sports the incidence of ACL injury is on the rise, especially in girls.  For this reason preventing ACL injuries has been the focus of research in sports injuries.  The result of this research is several prevention programs aimed at reducing the number of non-contact ACL injuries.  Research has indicated that by focusing on correct muscle/nerve control of your knee you can reduce your chances of suffering an ACL injury.  The focus of all these programs is on balance, and strengthening/stability exercises as well as plyometrics.
While plyometric exercises are used by many athletes as well as trainers to not only improve on their coordination speed and build power, it’s important to remember they are specialized exercises.  Plyometrics involves high intensity exercise techniques that produce explosive muscular contractions.  These contractions are aimed at initiating the stretch reflex which stretches the muscle before it starts to contract which allows the muscle to contract with more force.  The most common exercise in plyometrics involves various jumps and bounding movements as well as different hops.  One of the most common plyometric exercises involves jumping off a small box and as soon as the balls of your feet touch the floor you jump up onto another taller box.  There are a wide array of opinions on this type of exercise.  Some experts say they can actually increase your chances of suffering an ACL injury if not done correctly and safely.  However, both the National Strength and Conditioning Association and The American Council on Fitness recommend plyometrics, when done correctly and abiding by certain safety precautions.  Always receive instruction from someone that is certified in athletic training.

It’s also important to remember a good warm up and cool down are a crucial part of any exercise program including plyometrics.  Warming up gets your body ready for exercise.  You can significantly reduce your chance of injury when you warm your muscles up first.  There are a variety of stretches and exercises that can be used to get you warmed up depending on which program you prefer.  In addition to warming up it’s important to include exercises that improve your balance and agility.  Strengthening your hamstring muscles is especially important for females.  However, strengthening exercises for both the quadriceps as well as the hamstring muscles is important in reducing ACL injuries in both  male and female athletes.  In addition to participating in an ACL injury prevention exercise program it’s also important to use proper techniques when moving.  For example, if you play basketball it’s important to learn how to jump and then land correctly or if you’re a skier it’s important to learn how to slide the skis to turn correctly.

Now that research has proven that prevention works, the problem is going to be convincing coaches in all sports at all levels of the value of adding these programs  to their practices, many of which only take 15 minutes to complete.  One of the fundamental problems that exists is time.  As one coach said “if you only have an hour or so to spend with your team are you going to put them through strength and conditioning routines or have them learn plays?”  Another big problem especially in high school is getting facility time as well as accessibility to qualified trainers.  However, the experts continue to argue that not taking prevention seriously is extremely short sighted and in many ways plays Russian Roulette with the athletes health and safety.

Kimberly Allen is a registered nurse with an AND in nursing. She has worked in ACF, LCF and psychiatric facilities, although she spent most of her career as a home health expert. She is now a regular contributor to, dispensing advice and knowledge about medical issues and questions. You can reach her with any comments or questions at