ACL Injury and Anterior Cruciate Ligament Sprain

Prevent ACL injury and recover quickly from an ACL tear or sprain with these prevention and treatment tips.

by Brad Walker | First Published April 20, 2005 | Updated March 25, 2020
The knee joint is susceptible to a range of injuries, including sprains, strains and dislocations. So, what is an ACL Injury?

An ACL (Anterior Cruciate Ligament) injury (also referred to as an ACL sprain or tear), is a common injury that affects the knee joint. An injury occurs when the Anterior Cruciate Ligament is stretched or torn. The ACL is injured in about 70% of all serious knee injuries, which makes it the most common injury affecting the knee joint.

ACL Injury and Anterior Cruciate Ligament Sprain

How is the ACL Injured?

As with any sprain, an ACL injury is the result of excessive stretching or tearing of the anterior cruciate ligament. The severity of the injury can range from a slight stretching to a complete tear or rupture. An ACL injury most commonly results from:

  • A sudden stop or change of direction.
  • A twisting motion at the knee joint.
  • A blow or sudden impact to the front of the knee.

Athlete’s involved in sports that require a lot of running and change of direction and speed; (especially contact sports) are most susceptible to ACL injury. Sports that involve the highest risk are soccer, basketball, skiing, hockey and gymnastics.

Anatomy of the Knee

The anterior cruciate ligament is located within the joint capsule of the knee and connects the femur (thigh bone) to the tibia (shin bone). It’s responsible for preventing excessive forward movement of the tibia and limiting rotational movement at the knee joint.

The picture shows the side-on view of the bones and ligaments that make up the knee joint. In the middle of each picture is a ligament called the “Anterior Cruciate Ligament.” It is this ligament, most commonly referred to as the ACL, which is sprained or torn in an ACL injury.

Anterior Cruciate Ligament (ACL) Anatomy

What are the Signs and Symptoms of an ACL Injury?

The severity of the symptoms tends to correlate with the severity of the injury. In other words, the worse the injury, the worse the symptoms. The most common symptom of an ACL injury is pain, swelling and instability at the knee joint. Sometimes a popping sound can be heard at the moment of injury.

Immediate Treatment for ACL Injury

A minor ACL injury is just like any other soft tissue injury and should be treated accordingly. This involves the application of R.I.C.E.R. (R) rest, (I) ice, (C) compression, (E) elevation and obtaining a (R) referral for appropriate medical treatment. The following two points are of most importance.

  • Rest & Immobilization: Once an ACL injury is diagnosed it is important that the affected area be rested immediately. Any further movement or stress will only aggravate the condition and prolong recovery. It is also important to keep the injured area as still as possible.
  • Ice: By far the most important part. The application of ice will have the greatest effect on reducing bleeding, swelling and pain. Apply ice as soon as possible after the injury has occurred or been diagnosed.

The most common recommendation is to apply ice for 20 minutes every 2 hours for the first 48 to 72 hours. These figures are a good starting point, but remember they are only a guide. My personal recommendation is that people should apply ice for as long as it is comfortable. Obviously, there will be a slight discomfort from the cold, but as soon as pain or excessive discomfort is experienced, it is time to remove the ice. It is much better to apply ice for 3 to 5 minutes a couple of time an hour, than not at all.

During the first 24 to 72 hours be sure to avoid any form of heat at the injury site. This includes heat lamps, heat creams, spas, Jacuzzi’s and saunas. Avoid all movement and massage of the injured area. Also, avoid excessive alcohol. All these things will increase the bleeding, swelling and pain of your injury.

ACL Surgery

For major ACL injuries, including a complete tear of the ligament, surgery will be necessary. The specific procedures for each surgery varies according to the degree of damage done, the age of the patient, the activity level of the patient and if there are any other injuries to the knee joint.

There are a number of tests your doctor or physical therapist can perform to help determine the extent of the damage of the ACL. Depending on certain factors your doctor may also choose to perform an x-ray and MRI, but these are not always necessary.

As it is not possible to repair the ACL by simply reconnecting the torn ends, in most cases, surgery will involve using a segment of another healthy ligament to replace the damaged ACL.

After surgery, expect to be on crutches for one to three weeks. Full recovery, using a comprehensive rehabilitation program will generally take about three to four months and athletes involved in high demand sports can be back on the field in about six to eight months.

ACL Injury Prevention

Although it is important to be able to treat ACL injury, prevention should be your first priority. So what are some of the things you can do to help prevent an ACL injury?

  • Warm Up properly: A good warm up is essential in getting the body ready for any activity. A well structured warm up will prepare your heart, lungs, muscles, joints and your mind for strenuous activity.
  • Avoid activities that cause pain: This is self-explanatory, but try to be aware of activities that cause pain or discomfort, and either avoid them or modify them.
  • Rest and Recovery: Rest is very important in helping the soft tissues of the body recover from strenuous activity. Be sure to allow adequate recovery time between workouts or training sessions.
  • Balancing Exercises: Any activity that challenges your ability to balance, and keep your balance, will help what is called, proprioception: – your body’s ability to know where its limbs are at any given time.
  • Footwear: Be aware of the importance of good footwear. A good pair of shoes will help to keep your knees stable, provide adequate cushioning, and support your knees and lower leg during the running or walking motion.
  • Strapping: Strapping or taping can provide an added level of support and stability to weak or injured knees.
  • Stretch and Strengthen: To prevent ACL injury, it is important that the muscles around the knee be in top condition. Be sure to work on the strength and flexibility of all the muscle groups in the leg.

While the recommendations on this page are a good place to start, you'll get a lot more benefit when you add the right stretches to your training program. With the Ultimate Guide to Stretching & Flexibility you'll...

  • The Stretching Handbook, DVD & CD-ROMDo away with stiff, tight muscles and joints;
  • Improve your freedom of movement;
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  • Take your flexibility to the next level.

You'll get 135 clear photographs and 44 video demonstrations of unique stretches for every major muscle groups in your body. Plus, the DVD includes 3 customized sets of stretches (8 minutes each) for the Upper Body; the Lower Body; and the Neck, Back & Core. And the Handbook will show you, step-by-step, how to perform each stretch correctly and safely. Plus, you'll also learn the 7 critical rules for safe stretching; the benefits of flexibility; and how to stretch properly.

If you want to improve your flexibility and loosen up stiff, tight muscles fast, check out the Ultimate Guide to Stretching & Flexibility for yourself.

Research and References

Brad Walker - AKA The Stretch CoachAbout the Author: Brad Walker is often referred to as the "Stretch Coach" and has even been called the Stretching Guru. Magazines such as Runners World, Bicycling, Triathlete, Swimming & Fitness, and Triathlon Sports have all featured his work. Amazon (author page) has listed his books on five Best-Seller lists. Google cites over 100,000 references to him and his work on the internet. And satisfied customers from 122 countries have sent 1,000's of verified customer reviews. If you want to know about stretching, flexibility or sports injury management, Brad Walker is the go-to-guy.

Disclaimer: The health and fitness information presented on this website is intended as an educational resource and is not intended as a substitute for proper medical advice. Please consult your physician or physical therapist before performing any of the exercises described on this website, particularly if you are pregnant, elderly or have any chronic or recurring muscle or joint pain.

Finally, an amazingly effective way to loosen up stiff muscles fast, even if you feel like your muscles are made of rock!
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