Chondromalacia patellae is softening of the cartilage under the kneecap (also called the patella). Cartilage is the smooth, firm tissue that protects bones where they meet, such as the kneecap and other bones in the knee joint.
Chondromalacia patellae is often caused by a kneecap that is out of line so it doesn't slide smoothly over your knee joint. Running or other activities that involve a lot of knee bending make the bottom of the kneecap scrape on the knee bones. This can damage the cartilage on the bottom of the kneecap.
Doctors treat chondromalacia patellae by having your child:
Sometimes, doctors do surgery to smooth the underside of the kneecap.