This article is from the Aerobics Fitness FAQ, by email@example.com (Robles) with numerous contributions by others.
Chondromalacia literally refers to the wearing away of the
cartilage on the back surface of the kneecap, which might be
first exhibited as a "clicking" or "grating" sound, and knee
pain under the patella (kneecap).
Chondromalacia refers to the condition, and not a specific
disease state, as a great many possible causes exists for
damage to the cartilage.
Patellofemoral syndrome, likewise, refers to generalized
knee pain, often associated with runners, but not limited to
runners alone. In this context, the cause is usually improper
running mechanics over a period of time, though in many cases
the cause is unknown.
Once chondromalacia has occurred, the process is irreversible,
and attention is paid to achieving the maximal amount of pain-free
activity, and avoiding activities which will cause further damage
to the joint.
Note that patellofemoral pain is of a more general nature,
and may or may not be due to the pathological condition of
It is best to consult a physician or a physical therapist
when any sort of knee pain is encountered.