Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Legg-Calv-Perthes disease ?
    ### Response:
    Legg-Calv-Perthes disease is a bone disorder that affects the hips. Usually, only one hip is involved, but in about 10 percent of cases, both hips are affected. Legg-Calv-Perthes disease begins in childhood, typically between ages 4 and 8, and affects boys more frequently than girls.
    