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|| An invasion of the knee joint by a
bacteria or other organism
Model and X-ray of a Normal Knee
||Knee infections most commonly are caused
by bacteria. Other types of organisms such as a fungus can also
cause joint infections but these occur much less frequently.
||There are many ways a knee can become
infected. Direct trauma to the knee with a puncture wound into the
joint can lead to a deep infection. Fractures when the bone breaks
through the skin (Compound Fractures) are especially vulnerable to
infection. A sexually transmitted disease (gonorrhea) can also lead
to a knee infection by traveling there via the bloodstream. Knee
surgery is another risk factor for deep infection. Finally, patients
with a compromised immune system or who have an artificial knee are
at higher risk for joint infection. Special precautions are
sometimes needed for these patients during dental procedures to help
||The diagnosis of a knee infection is made
by a history of severe pain in the knee associated with fever,
chills and an inability to move the knee. Usually, it is also not
possible to walk on the leg of the affected knee. On physical exam,
the knee is swollen, warm and sometimes red. X-rays reveal the knee
swelling and may show joint destruction if there is infection deep
into the bone.
An aspiration (sticking a needle into the joint) is the definitive
way of diagnosing a knee infection. Any fluid obtained from the knee
is sent to the lab for analysis immediately. Rarely, a MRI or other
test is needed to aid in making the diagnosis.
||A true knee infection is a surgical
emergency. The knee needs to be drained as soon as possible. This
can initially be done with an aspiration but typically a severe
infection requires surgery. This can take the form of an arthroscopy
(use of small incisions and instruments to evaluate and treat joint
problems) or may require opening of the knee with larger incisions.
Patients with artificial knees or patients in immuno-suppressed
states may require antibiotic treatment prior to dental procedures.