الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Historically, four principle anatomic factors have been identified that
increase one’s risk of episodic patella dislocations. These are trochlear
dysplasia, excessive patella height (patella alta), excessive lateral patellar
tilt, and excessive tibial tubercle/trochlear groove (TT-TG) distance. A
treatment algorithm has been proposed to correct these factors that
includes bony realignment (Dejour et al., 1994).
Trochlear anatomy is recognized as being important in patellofemoral
stability. Trochlear anatomy includes not only the depth of the groove, but
also its length. The patella achieves increasing stability in flexion due to
not only the confines of the trochlear walls (depth of the groove), but also
increasing tension in the retinacular structures.
When the trochlear groove is short and shallow, the patella has greater
excursion in early flexion unprotected by the trochlea.
Likewise, patella position in the sagittal plane dictates the flexion arc
at the time of patella engagement.
The combination of an excessively high patella position combined
with trochlear dysplasia offers increasing challenges for the kneecap to
remain on a stable path to the protections of the trochlear groove in early
flexion.
The retinacular restraints have only recently been given importance as
an anatomic factor critical for patellofemoral stability. The retinacular
restraints protect the limits of patellar motion. The medial patellofemoral
ligament (MPFL) has been recognized as the ‘‘essential’’ stabilizer against
lateral patellar displacement (Amis, et al., 2003).