Definition of Patellofemoral syndrome (PFS)
Patellofemoral syndrome (PFS): The commonest
cause of chronic knee pain, PFS characteristically causes
vague discomfort of the inner knee area, aggravated
by activity (running, jumping, climbing or descending
stairs) or by prolonged sitting with knees in a moderately
bent position (the so-called "theater sign" of pain upon
arising from a desk or theater seat). The knee may be
mildly swollen. If chronic symptoms are ignored, the loss
of quadriceps strength may cause the leg to "give out."
PFS is caused by an abnormality in how the kneecap
(patella) slides over the lower end of the thigh bone (the
femur). Normally, the patella (kneecap) is pulled up over
the end of the femur in a straight line by the quadriceps
(thigh) muscle. In PFS, there is patellar "tracking" toward
the lateral (outer) side of the femur. This off-kilter path
permits the underside of the patella to grate along the
femur leading to chronic inflammation and pain. Females are
at greater risk than males for PFS. Knock-kneed and
flat-footed runners and persons with an unusually shaped
patella are predisposed to PFS.
Initial pain management is icing, anti-inflammatory
drugs (Advil/Motrin; Aleve) and avoiding motions which
irritate the kneecap. Treatment and rehabilitation are
designed to create a straighter
pathway for the patella to follow during quadriceps
contraction. Selective strengthening of the inner portion
of the quadriceps muscle helps normalize the tracking of
the patella. Cardiovascular conditioning can be maintained
by stationary bicycling (low resistance but high rpms),
pool running, or swimming (flutter kick). Changes in
training that may have led to the PFS pain should
be reviewed and running shoes examined for proper
biomechanical fit to avoid repeating the painful PFS
cycle. Occasionally bracing with patellar centering
devices is required. Stretching and strengthening the
quadriceps and hamstring muscle groups are essential to an
effective and lasting rehabilitation of PFS. "Quad sets"
are the foundation for such a program and are done by
contracting the thigh muscles while the legs are straight
and holding the contraction for a count of ten. Sets of 10
contractions are done between 15-20 times per day. Under
optimal circumstances, there should be a rapid recovery and
return at full functional level to sports.
PFS has also been called "housemaid's knee",
"secretary's knee" and chondromalacia patella.
Last Editorial Review: 12/16/1998 3:24:00 PMCommon Misspellings: patellofemoral syndrone (pfs)
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