the shin bone from sliding out in front of the thigh bone. It also provides roughly 90 percent of
stability in the knee joint.
HOW ACL INJURIES OCCUR
Most ACL tears do not occur from player-to-player contact (approximately 70 percent)*. The most
common causes of noncontact ACL injury include:
change of direction or cutting maneuvers combined with sudden stopping
landing awkwardly from a jump
pivoting with the knee nearly fully extended when the foot is planted on the ground
ACL injuries often occur with other injuries. An ACL tear usually occurs along with tears to the MCL
and the shock-absorbing cartilage in the knee (lateral & medial meniscus). Most ACL tears are in
the middle of the ligament or the ligament is pulled off the bone. This injury does not heal on its
own.
SYMPTOMS
a "popping" sound at the time of injury
knee swelling within 6 hours of injury
pain, especially when you try to put weight on the injured leg
loss of full range of motion
tenderness along the joint line
discomfort while walking
In a mild injury the knee might just feel unstable or seems to "give way" when using it. It is also
possible with this type of injury that blood vessels are damaged. If the foot is cool and blue after a
knee injury, the knee joint may be dislocated, and blood vessels to the foot may be injured. This is
a medical emergency that requires immediate professional help.
TYPES OF DAMAGE
The funny thing is the way the severity of the injury is labeled. Injured ligaments are considered
"sprains" and are graded – one, two and three.**
Grade 1 Sprains. The ligament is mildly damaged. It has been slightly stretched, but is still
able to help keep the knee joint stable.
Grade 2 Sprains. Stretches the ligament to the point where it becomes loose. This is often
referred to as a partial tear of the ligament.
Grade 3 Sprains. Commonly referred to as a complete tear of the ligament. The ligament
has been split into two pieces, and the knee is unstable.
Partial tears of the anterior cruciate ligament are rare. Most ACL injuries are complete or near
complete tears and normally require surgery.