Published on February 22nd, 2013 | by Papa Doc1
PapaDoc by Gil Leora
Everything You’ve Ever Wanted to Know about ACL Injuries
This is a follow-up on the previous article about posterior cruciate ligament injuries.
There are two cruciate ligaments in the knee. They are both attached to the tibia (shin
bone) and femur (thigh bone) and criss-cross in the knee; they are named from the point at
which they attach to the tibia (anterior cruciate on the front part, posterior cruciate on the back
part). The anterior ligament keeps the tibia from sliding too far forward on the femur. The
posterior ligament keeps the tibia from sliding too far back on the femur. The posterior cruciate
ligament is actually a stronger ligament than the ACL.
Mechanism of Injury
The anterior cruciate ligament can be injured in one of several ways:
⁃ Changing direction rapidly
⁃ Stopping suddenly
⁃ Slowing down while running
⁃ Landing from a jump incorrectly (i.e., the tendency of women athletes to land with
the knee straight instead of flexed).
⁃ Direct contact or collision, such as a football tackle
It is estimated that 70 percent of ACL injuries occur through non-contact mechanisms
while 30 percent result from direct contact with another player or object. Several studies have
shown that female athletes have a higher incidence of ACL injury than male athletes. It has been
proposed that this is due to differences in physical conditioning, muscular strength, and
neuromuscular control. Other suggested causes include differences in pelvis and lower
extremity (leg) alignment, increased looseness in ligaments, and the effects of estrogen on
When you injure your anterior cruciate ligament, you might hear or feel a “popping”, and
you may feel your knee give out from under you. Immediately after the injury, there is usually
significant pain and swelling. If ignored, the swelling and pain may actually resolve on its own.
However, if you attempt to return to sports, your knee will be unstable and painful, and you risk
causing further damage to the cushioning cartilage (meniscus) of your knee. Diagnosis
An initial exam is done by a trainer or team doctor, and pain and swelling are controlled.
Crutches or a knee brace may be needed initially. Then a full examination of the knee should be
done by an orthopedist. Since ACL injuries frequently involve injuries to other knee ligaments
or structures, the findings may not be limited to the ACL only. Since other knee structures are
often injured along with the ACL, further studies such as x-ray and MRI are needed in most
The natural history of an ACL injury without surgical intervention varies from patient to
patient and depends on the patient’s activity level, degree of injury to the ACL, associated
injuries, and instability symptoms.
The prognosis for a partially torn ACL is often favorable with the recovery and
rehabilitation period being usually at least three months. However, some patients with partial
ACL tears may still have instability symptoms. Close clinical follow-up and a complete course of
physical therapy helps identify those patients with unstable knees due to partial ACL tears who
need further treatment, i.e., surgery.
Complete ACL ruptures have a much less favorable outcome. After a complete ACL tear,
most patients are unable to participate in sports; others have instability during even normal
activities, such as walking. This variability is related to the severity of the original knee injury,
as well as the physical demands of the patient. For example, the young athlete involved in agility
sports will most likely require surgery to safely return to sports. The less active individual may
be able to return to a quieter lifestyle without surgery. About half of ACL injuries occur in
combination with damage to the meniscus, articular cartilage or other ligaments; this
combination of injuries often requires surgery. Secondary damage such as arthritis may occur in
patients who have repeated episodes of instability due to ACL injury.
Nonsurgical treatment may be effective for patients who are not good candidates for
surgery or have a sedentary life style. If the overall stability of the knee is relatively intact, your
doctor may recommend simple, nonsurgical options.
Bracing. Your doctor may recommend a brace to protect your knee from
instability. To further protect your knee, you may be given crutches to keep you from putting
weight on your leg.
Physical therapy. As the swelling goes down, a rehabilitation program is started.
Specific exercises will restore function to your knee and strengthen the leg muscles that support
Most ACL tears cannot be sutured (stitched) back together. To surgically repair the ACL
and restore knee stability, the ligament must be reconstructed. Your doctor will replace your
torn ligament with a tissue graft. This graft acts as a scaffolding for a new ligament to grow on.
Grafts can be obtained from several sources. Your own tendons may be used as a source:
commonly a piece of the patellar, hamstring,or quadriceps tendons is used. A cadaver graft can
also be used. There are advantages and disadvantages to all graft sources. You should discuss
graft choices with your own orthopedic surgeon to help determine which is best for you.
Unless ACL reconstruction is treatment for a combined ligament injury, it is usually not
done right away. This delay gives the inflammation a chance to resolve, and allows a return of
motion before surgery. Performing an ACL reconstruction too early greatly increases the risk of
scar forming in the joint which would risk a loss of knee motion.
Because the regrowth takes time, it may be six months or more before an athlete can
return to sports after surgery. Surgery to rebuild an anterior cruciate ligament is done with
arthroscopy, a less invasive method. The benefits of less invasive techniques include less pain
from surgery, less time spent in the hospital, and quicker recovery times.
As you can gather from the causes, much is not truly preventable. However, by
strengthening and increasing the flexibility of the knee support muscles (mainly the hamstrings
and quads), you will reduce the likelihood or maybe the severity of an ACL injury. Below are
some sources for exercises if you do not have a trainer or sports medicine person to help you.
Learning to land from jumps with the knees flexed rather than stiff and extended is also
Please skate safely – your medical personnel will thank you because then they can watch
the bout and cheer more!
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