Chondromalacia patellae often causes generalized knee pain especially when climbing or descending stairs, playing sports that exert an axial load on the knee, or sitting for a long time (theater sign). Usually the pain occurs without swelling. This disorder probably results from angular or rotational changes in the leg that unbalance elements of the quadriceps and cause patellar misalignment during movement.
Acute pain due to chondromalacia patellae is treated by doing physical therapy to improve the mechanics, applying ice, and taking analgesics. Children with chondromalacia patellae should avoid pain-causing activities (typically, those that involve bending the knee) for several days. Persistent or recurrent pain due to chondromalacia patellae may rarely require arthroscopic smoothing of the patella’s undersurface.