Dr Delee Talks About Anterior Cruciate
Ligament Injuries Of The Knee
 The
Anterior Cruciate Ligament is the most commonly injured ligament of the
knee. The ACL controls how far the tibia moves anteriorly (forward) in
relation to the femur. ACL injury is usually sports related. This
injury occurs when the knee is forcefully twisted or hyperextended.
Many patients recall hearing a loud "pop" when the ligament tears, and
they feel the knee give way. Rapid swelling may occur.
The ACL may not be the only ligament injured when the knee is
twisted violently. It is not uncommon to have both the Medial
Collateral ligament and the ACL injured. The menisci (cartilage) of the
knee may also be torn. Rarely, the joint surfaces may be damaged.
Symptoms
How does a torn anterior cruciate ligament cause problems?
The symptoms following a tear of the ACL are variable. Usually there is
swelling of the knee within a short time following the injury due to
bleeding into the knee joint from torn blood vessels in the ligament.
The instability caused by the torn ligament leads to a feeling of
insecurity and giving way of the knee, especially when trying to change
direction on the knee.
The pain and swelling from the initial injury will usually resolve
after 2 to 4 weeks, but the instability remains. Symptoms of
instability, and the inability for the patient to trust the knee for
support are indications for surgical treatment. Also important in the
decision about treatment is the growing realization by Orthopaedic
Surgeons that long-term instability may leads to arthritis of the knee.
Diagnosis
The History and Physical Examination are the most important tools in
diagnosing a rupture or deficient ACL. In the acute injury, swelling is
a good indicator. A good rule of thumb is that any tense swelling that
occurs within two hours of the knee injury is blood in the joint; this
is called a Hemarthrosis. If such swelling is marked, draining as much
fluid as possible gives relief and provides useful information. If
blood is found when draining the knee, there is about a 70% chance the
ACL is torn.
An X-ray of the knee to rule out a fracture will also be ordered on the
initial examination. While ligaments and tendons do not show up on
x-rays, bleeding into a joint also occurs when a fracture into the knee
joint is present, or when portions of the joint surface are "chipped
off". An x-ray helps to exclude these possibilities.
In some cases, an MRI is obtained to further evaluate the knee injury.
The MRI (Magnetic Resonance Imaging) uses magnetic waves rather than
x-rays to show the soft tissues of the body. An MRI is able to "slice"
through the area and see the anatomy and injuries very clearly. An MRI
does not require any needles or special dye, and is painless.
In rare cases, Arthroscopy may be used to make a definitive diagnosis
if there is a question about what is causing knee symptoms. Arthroscopy
is a type of an operation where a small fiberoptic TV camera is placed
into the knee joint, allowing the physician to look at the structures
inside the knee joint directly.
Treatment
Initial treatment of an ACL injury includes the use of crutches and
physical therapy until the swelling resolves and motion and strength
improve. The knee joint may be aspirated to remove the blood in the
joint.
When the ACL is torn, the small "proprioceptive" nerve endings in the
ligament are also torn. These nerves function to give the brain
information about where the body is in space. For instance, these
nerves are what make it possible for you to touch your nose with your
eyes closed. Joints rely on these nerves to fine tune the muscle's
actions that allow the joint to function properly. A good Physical
Therapy program will help retrain these nerves as they repair
themselves, and will strengthen certain muscles that take over some of
the functions of the ACL in stabilizing the knee joint.
To help restore the stability of the knee due to loss of the ACL, an
ACL Brace may be suggested. Most of these braces must be fitted by the
therapist or athletic trainer. The brace may allow the patient to
participate in athletics without surgery. Also, wearing a brace for one
year after an ACL reconstruction may be recommended.
If the symptoms of instability of the knee are not controlled by a
brace and rehabilitation program, then surgery may be suggested.
Surgeons now favor reconstruction of the ACL, using a piece of tendon
or ligament to replace the torn ACL. Today, this surgery is completed
via the arthroscope. Incisions are usually still required around the
knee, but the joint itself is not opened. The arthroscope is also used
to perform other work needed on the inside of the knee joint. Most
patients can expect one night in the hospital, although more surgeries
are being done as outpatient, where the patient leaves the hospital the
day of surgery.
In a typical reconstruction, the torn ends of the ACL, are removed. The
Intercondylar Notch is enlarged so that there is no bone rubbing on the
newly installed ACL graft. This process is referred to as a
Notchplasty. Once this is done, holes are drilled in the tibia and the
femur to place the graft. These holes are placed so that the graft runs
between tibia and the femur in the same direction as the original
anterior cruciate ligament. The graft is then pulled into position
using sutures placed through the drill holes. Several types of tissues
are used as grafts. One is the hamstring tendon, another is a portion
of the patellar tendon, and a third is an allograft of tissue from a
cadaver. The decision on which graft to use is individualized.
After surgery, a physical therapist or athletic trainer begins
the rehabilitation program. Patients participate in some type of
rehabilitation for 6 months after surgery to ensure the best results.
Following the initial period, patients are placed on a home program
monitored by the therapist.
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