How does a torn anterior cruciate ligament cause
The symptoms following a tear of the
ACL are not always the same in different people. Usually, there is
swelling of the knee within a short time following the injury. This
is due to bleeding into the knee joint from torn blood vessels in the
damaged 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 knee may feel like it
wants to bend to far backwards.
The pain and swelling from the
initial injury will usually be gone after 2 to 4 weeks, but the
instability remains. The symptom of instability, and the inability for the
patient to trust the knee for support is what requires treatment.
Also important in making decisions about which way the knee should be
treated is the growing realization by orthopedic surgeons that long term
instability leads to early arthritis of the knee. (These two images
illustrate the degenerative arthritis present after longstanding ACL
deficiency, both in the x-ray films and in the artist's rendition based on
the x-rays.) Many orthopedic surgeons feel that by treating the
instability and performing a reconstruction of the ligament, the risk of
developing wear and tear arthritis in the knee can be reduced.
How do we look into this
and physical examination is probably the most important tool in
diagnosing a ruptured or deficient ACL. In the acute injury, the
swelling is a good indicator. A good rule of thumb that orthopedic
surgeons use is that any tense swelling that occurs within two hours of a
knee injury usually represents blood in the joint, or a hemarthrosis.
If the swelling occurs the next day, the fluid is probably from the
inflammatory response. Placing a needle in the swollen joint and
draining as much fluid as possible, gives relief from the swelling and
provides useful information to your doctor. If blood is found when
draining the knee, there is about a 70% chance it came from a torn ACL.
of the knee to rule out a fracture may also be ordered on the initial
examination. Ligaments and tendons do not show up on x-rays, but
bleeding into the joint also occurs when a fracture through the knee joint
is present, or when portions of the joint surface are chipped off.
most accurate test without actually looking into the knee, is the MRI
scan. The MRI (Magnetic Resonance Imaging) machine uses magnetic waves
rather than x-rays, to show the soft tissues of the body. With this
machine, we are able to "slice" through the area we are
interested in and see the
In some cases, arthroscopy may be
used to make the definitive diagnosis - if there is a question about what
is causing your knee problem. Arthroscopy is a type of an operation
where a small fiberoptic TV camera is placed into the knee joint, allowing
the orthopedic surgeon to look at the structures inside the knee joint
directly. The vast majority of ACL tears are diagnosed without
resorting to surgery, and arthroscopy is usually reserved to treat the
problems identified by other means.
How do we treat this problem?
treatment for ACL injury includes crutches and rest until the
swelling resolves. The knee joint may be
Once, the initial pain and swelling
begins to resolve, physical therapy will probably be initiated to
regain as much of the normal range of motion as possible. One
of the problems that tearing the ACL causes, is that small proprioceptive
nerve endings in the ligament are torn as well. These nerves are
there to give the brain information about where the body is in 3D space.
For instance, these nerves are what makes it possible for you to touch
your nose with your eyes closed. The joints rely on these nerves to
fine tune the muscles' 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 will take over
some of the functions of stabilizing the knee joint from the loss of the
To help replace the stability of the knee due to
the loss of the ACL, an ACL brace may be suggested. These
braces are fairly effective at preventing the knee from giving way
during strenuous activity. Most of these braces must be fitted by a
certified orthotist, a physical therapist, or physician. They are NOT
the type you can buy at the drugstore. Most orthopedists will
recommend wearing a brace for at least 1 year after a reconstruction, so
even if you decide to have surgery, a brace is a good investment.
If the symptoms of instability are
not controlled by a brace and rehabilitation program, then surgery
may be suggested. Most surgeons now favor reconstruction of
the ACL using a piece of tendon or ligament to replace the torn ACL.
Today, this surgery is most often done using the arthroscope.
Incisions are usually still required around the knee, but the joint itself
is not opened. The arthroscope is used to perform the work needed on
the inside of the knee joint. Most patients can expect at least one
night in the hospital, although more and more surgeries are being done
outpatient, where you leave the hospital the same day.
In the typical surgical
reconstruction, the torn ends of the ACL must first be removed. Once this has been done, the type of graft that will be used is
determined. One of the most common tendons used for the graft
material is the patellar tendon. This tendon connects the
kneecap (patella) to the lower leg bone (tibia). Another very common
graft that is used is to combine two of the hamstring muscle tendons that
attach to the tibia just below the knee joint - the gacilis tendon
and the semitendinosis tendon. Studies have shown that these
two tendons can be removed without really affecting the strength of the
leg. There are other, much bigger and stronger hamstring
muscles that can take over the function of the two tendons that are
If the patellar tendon is used,
about one third of the patellar tendon is removed, with a plug of bone at
either end. The bone plugs are rounded and smoothed. Holes are
drilled in each bone plug to place sutures that will pull the graft into
place. The next procedure is to prepare the knee to place the
graft. The intracondylar notch is enlarged so that there is no
rubbing on the graft. This process is referred to as a notchplasty.
Once this is done, holes need to be drilled in the tibia and the femur to
place the graft. These holes are placed so that the graft will run
between the tibia and 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. Screws are used to hold the
bone plugs in the drill holes.
Other types of materials are also
used to replace the torn ACL. In some cases, an allograft is
used. An allograft is tissue that comes from someone else.
This tissue is harvested from tissue and organ donors at the time of death
and sent to a tissue bank. There the tissue is checked for
any type of infection, sterilized, and stored in a freezer. When
needed, the tissue is ordered by the physician and used to replace the
torn ACL. The advantage of using allograft is that the surgeon does
not have to disturb or remove any of the normal tissue from your knee to
use as a graft. The operation is also usually takes less time
because the graft does not to be harvested from your knee.
After surgery, a physical
therapist will be contacted to begin your rehabilitation program.
You will probably be involved in some type of rehabilitation for 6
months after surgery to ensure the best result from your anterior
cruciate ligament reconstruction. The first 6 weeks following
surgery expect to see the physical therapist about three times a week.
Following the initial period, you may be placed on a home program and
monitored by the therapist.
your leg muscles, including the quadriceps (the muscles in your front thighs)
and hamstrings (the muscles in your back thighs). Running, biking and stair
climbing are the most effective ways to build these muscles. For best results,
combine with squats and lunges.