Osteochondritis dissecans
Osteochondritis dissecans affects children between the ages of 10 and 15 most commonly and is twice as common in boys as in girls. It normally affects the inner knuckle at the end of the thigh bone and normally causes pain. A fragment of bone and cartilage my separate and cause a loose body. In many cases the condition is self-limiting and requires no active treatment but if the osteochondritic fragment separates the fragment may be reattached by surgery.