Chondromalacia patella is the most common cause of chronic knee pain. Chondromalacia patella results from poor alignment of the kneecap (patella) as it slides over the lower end of the thigh bone (femur). Chondromalacia patella is also informally called "housemaid's knee" or "secretary's knee."
What are the symptoms of chondromalacia patella?
The symptoms of chondromalacia patella are generally a 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).
http://www.medterms.com/script/main/art.asp?articlekey=7940 - Secretary's knee: The 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.
Treatment: 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.