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Bursitis
Prepatellar bursitis, also known as housemaid's knee, is a
common cause of swelling and pain on top of the kneecap. The
name "housemaid's knee" comes from the association of this
condition with individuals whose work necessitates kneeling
for extended periods of time. Prepatellar bursitis is common
in professions such as carpet layers and gardeners.
What is a bursa?
A bursa is a thin sack filled with the body's own natural
lubricating fluid. This slippery sack allows different
tissues such as muscle, tendon, and skin slide over bony
surfaces without catching. These bursa are normally very
thin (like a plastic bag with the air sucked out of it), but
they do present a potential space that can become inflamed
and irritated. This is what is known as bursitis.
If the inflammation of bursitis is associated with trauma
and a break in the skin, the bursa can become infected, this
is called infected bursitis
The symptoms of bursitis are directly related to the degree
of inflammation present in the bursa. The inflamed bursa can
cause localized pain and tenderness. If the bursa is so
inflamed that swelling occurs, it can cause local swelling
and stiffness, sometimes associated with local redness and
warmth. The inflammation can make it painful to support body
pressure. Bursitis in the knee can make it painful to lay
with the knees touching each other.
Bursitis is typically identified by localized pain or
swelling, tenderness, and pain with motion of the tissues in
the affected area. X-ray testing can sometime detect
calcifications in the bursa when bursitis has been chronic
or recurrent.
In some cases, a direct blow or a fall onto the knee can
damage the bursa. This usually causes bleeding into the
bursa sac, because the blood vessels in the tissues that
make up the bursa are damaged and torn. In the skin, this
would simply form a bruise, but in a bursa blood may
actually fill the bursa sac. This causes the bursa to swell
up like a rubber balloon filled with water.
The blood in the bursa is thought to cause an inflammatory
reaction. The walls of the bursa may thicken and remain
thickened and tender even after the blood has been absorbed
by the body. This thickening and swelling of the bursa is
referred to as prepatellar bursitis.
Prepatellar bursitis can also occur over a longer period of
time. People who work on their knees, such as carpet layers
and plumbers, can repeatedly injure the bursa. This repeated
injury can lead to irritation and thickening of the bursa
over time. The chronic irritation leads to prepatellar
bursitis in the end.
The prepatellar bursa can also become infected. This may
occur without any warning, or it may be caused by a small
injury and infection of the skin over the bursa that spreads
down into the bursa. In this case, instead of blood or
inflammatory fluid in the bursa, pus fills it. The area
around the bursa becomes hot, red, and very tender.
To remove the prepatellar bursa, an incision is made over
the top of the knee (either straight up and down or across
the knee). Since the bursa is in front of the patella, the
knee joint is never entered. The thickened bursa sac is
removed, and the skin is repaired with stitches. You may
need to stay off your feet for several days to allow the
wound to begin to heal and to prevent bleeding into the area
where the bursa was removed.
Some types of bursae will probably grow back after surgery,
because the skin needs to slide over the kneecap smoothly.
The body will form another bursa as a response to the
movement of the patella against the skin during the healing
phase. If all goes well, the bursa that returns after
surgery will not be thick and painful, but more like a
normal bursa.
After surgery you will need to be on crutches for a few days
and your doctor will advise a rehabilitation program to
follow.
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