The anterior cruciate ligament (ACL) joins the upper leg bone with the lower leg bone to help keep the knee stable. 1 out of every 3000 people will have an ACL injury per year and approximately 100,000 will choose to have reconstruction surgery to repair it. 

Mechanism of Injury

• Hyperextension (the leg straightens too far), the knee “gives out”.
• Direct blows to the knee.
• A stress to the outside of the knee.
• A stress from an outside rotation of the knee.
• “Unhappy triad” is combination of an outside force, bend in the knee and outside rotation applied to the knee while the foot is planted.

Signs and Symptoms

• Rapid swelling and hemarthrosis (bleeding in the joint) within 12 hours.
• Severe pain.
• You will feel that: “My knee gave way when I attempted to bear weight”.
• Difficult for the trainer to go through a complete exam right after the injury.
• Special tests for joint stability (from ACL) are all positive.

On-Site Management
P.R.I.C.E.

PROTECT the area from further injury by avoiding exercises that produce pain.

REST the knee from weight-bearing activities to allow the swelling to settle.

ICE your knee for 10-20 minutes every 1.5 to 2 hours for the first 2 to 3 days or until the pain goes away. 

COMPRESS the area by using an ace wrap; this helps decrease swelling and bleeding.

ELEVATION is important to encourage blood flow to the heart for healing.

Medical Referral. When there is a severe sprain or complete rupture of the ACL it is important that you seek medical attention for possible surgery. A doctor may prescribe anti-inflammatory medication to help with pain and swelling. You should get a medical referral for a therapist to direct you to proper treatment and strengthening activities for either preparation of surgery and/or return to play.

When is ACL Surgery Required?
The decision on whether to operate is based on a number of factors, including the athletes age; lifestyle; sporting involvement; occupation; degree of knee instability and any other associated injuries.
A younger, fit person who regularly plays sport and would be more likely to complete a complex rehabilitation program is more likely to be offered surgery.

What does ACL surgery involve?
Surgery involves either repairing or reconstructing the ACL.
With a repair, the existing damaged ligament is stitched back together if the tear is in the middle.
If the ligament has detached from the bone (avulsed) then the bony fragment is reattached.
Surgical reconstruction of the ACL is performed using either a structure outside the knee joint (i.e. hamstring tendon) or a structure inside the knee joint (i.e. patellar tendon) to replace the ACL.

Rehabilitation. The physician may request very gradual weight-bearing exercise immediately after the initial ACL injury. Braces can be used early after the injury as conservative treatment of the ligament tear (ex: straight immobilizer and hinged brace). This brace can also be used after surgery for the injured ACL along with crutches while you gradually work towards full weight-bearing. As the swelling in and around the joint decreases and weight-bearing progresses, mild strengthening exercises are started.

Quadriceps sets are one example of strengthening exercises at this stage. With the knee almost straight you work on contracting your front thigh muscles. Some things to look for are seeing the muscle work and your foot moving upwards as you straighten your leg. Hold this position for a count of 6-10 seconds and repeat 10 times. You should do this several times throughout the day.

The most important part of the rehabilitation program is to increase the range of motion of the knee. This helps to avoid joint stiffness and muscle tightness.
Heel slides are one example of stretching exercises at the initial stage. While sitting up with your legs straight out in front of you slide the heel of the injured leg towards your buttock until a gentle stretch is felt. Hold this stretch for 10 to 20 seconds and repeat 10 times, several times a day.

Return to Activity. There are many tests that your doctor and therapist can choose from to determine if you are ready to return to play. The tests that are used will be both general and specific for your sport.

Prevention. An alternative program that focuses on stretching, strengthening and improving balance and movements may help reduce the risk of ACL.
The PEP program, developed by the Santa Monica (California) Orthopedic and Sports Medicine Research Foundation, is an example of a specific program designed for female athletes. It uses a good warm-up, stretching, strengthening and sport-specific agility exercises. This program can be done without additional equipment or extensive training that may be required by other prevention programs.

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