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Patellar Instability
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The patella, or knee
cap, is an important component of the knee joint. It is a bone through
which the tendon of the quadriceps, the largest muscle in the body, inserts
onto the front aspect of the top of the tibia (shin bone). The back side
of the patella is covered by thick articular cartilage and moves against the
end of the femur (thigh bone) which is also covered by thick articular
cartilage. The end of the femur has a small groove in which the patella
tracks. Some people have a very shallow groove and some have a
deeper groove. However, the groove is not enough to maintain the
patella’s position. There are important soft tissue attachments that help control the
patella’s motion. These can be torn by a traumatic event or stretched
over time. Also, some people have soft tissue attachments that are
genetically loose or thin and
insufficient to keep the patella in its track, especially when exerting. |
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With patellar
instability, one can have episodes of the patella coming partially out of the
groove (called patellar subluxation) or completely coming out of the groove (dislocation). These can be
very painful and debilitating. Treatment is aimed at restoring the patella’s
position and trying to maintain it in its track. |
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Depending on the cause
and severity of
the patellar instability, one can control or correct it by either non-operative
or operative means. Non-operative means include muscle strengthening
exercises, as well as the use of certain braces (see also "Braces" in the
"Treatment Modalities" section). Operative correction
involves balancing the soft tissue attachments to the patella by surgical
releases of overly tight structures and/or tightening of overly loose
structures. Also, sometimes the insertion of the quadriceps tendon itself
onto the shin bone needs to be altered surgically. |
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Successful treatment
depends on correct diagnosis and intervention by the physician as well as a
lot of effort in rehabilitation and compliance with exercises and activity
modification by the patient. |
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