Anterior Cruciate Ligament (ACL) Injury
What
is it?
Anterior cruciate ligament (ACL) injury is the
most common knee injuring, resulting from a
stretch or tear in the ligament. Ligaments are
strong bands of tissue that connect one bone to
another. The ACL is one of the major ligaments in
the knee, connecting the thigh bone (femur) to the
shin bone (tibia). It helps to keep the knee
stable and protects the femur from sliding or
turning on the tibia.
Who
gets it?
While
anyone can injure an ACL, it is unusual in
childhood. The incidence of ACL injury peaks in
adults during their middle years.
What
causes it?
ACL
injuries most often result from sports where the
foot is planted on the ground while the leg is
being twisted, such as in football, soccer,
basketball and skiing. The ACL may also become
injured when the knee is straightened further than
it normal (hyperextended). It can also occur when
the thigh bone is forcefully pushed across the
shin bone, such as with a sudden stop while
running or a sudden transfer of weight such as in
skiing.
A
chronic ACL injury is often the result of an
injury in which the patient either did not consult
a doctor after initial injury, the diagnosis was
missed, or nonoperate care of an ACL injury was
unsuccessful.
What
are the symptoms?
Often
the patient will hear a popping sound when the ACL
injury occurs and will not be able to continue the
activity. Swelling of the knee within the first
several hours of injury will usually follow.
In the case of a chronic ACL injury, the patient
will sometimes experience increasing instability
of the knee during twisting and pivoting movements
and muscle weakness.
How is
it diagnosed?
A
doctor may suspect an ACL injury after noticing
the knee is loose and swelling is present upon
initial examination. To confirm diagnosis, the
doctor may draw blood from the knee for testing
and order x-rays to be taken to see if there is an
injury to the bones in the knee. An MRI test may
be done to show the condition of the ACL.
The
doctor may also examine the ligament, lateral
ligament and posterior cruciate ligament for
injury, and may make a comparison of the injured
and uninjured knee to make sure that another
injury is not overlooked.
In a
chronic ACL injury, the longer the injury has been
present the more likely it is to have an abnormal
appearance on MRI examination. The doctor should
also determine if there is an associated
instability from other tears.
What
is the Treatment?
Initial
treatment for an ACL injury may including icing
the knee, keeping the knee elevated whenever
possible and administering anti-inflammatory
medications.
Long-term treatment for ACL injuries may vary for
each patient. Activity level, age, job demands,
and general medical condition may be factors in
the decision to recommend reconstruction. If the
knee "gives way" during daily activities, this is
a strong indication for surgery to prevent
injuries from falls.
Since a
torn ACL will not heal by itself, reconstructions
by using ligaments or tendons from another part of
the body (graft) are used. During ACL
reconstruction, holes are drilled in the femur and
tibia, and the torn ACL is removed. The graft is
passed through the drill holes to replace the ACL,
and is anchored in place using screws or staples.
The hope is that stabilized knees will allow
patients to return to pre-injury activity level
and prevent further damage to the knee.
New
surgical equipment has made this operation easier
to perform and more precise, so that more surgeons
are able to perform it. Patients with a chronic
ACL injury and recurrent giving way of the knee
are also candidates for ACL reconstruction.
Self-care tips
With
successful ACL reconstruction, the patient may
expect to return to vigorous sporting activities
and degenerative changes will be prevented.
Current rehabilitation after ACL reconstruction
includes achieving full motion very quickly after
reconstructive surgery. Exercises such as the leg
press, bicycling and stair-climbing machines are
usually recommended during rehabilitation.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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