Bone age is advanced in
An advanced or delayed bone age does not always indicate disease or "pathologic" growth. Conversely, the bone age may be normal in some conditions of abnormal growth. Children do not mature at exactly the same time. Just as there is wide variation among the normal population in age of losing teeth or experiencing the first menstrual period, the bone age of a healthy child may be a year or two advanced or delayed. Those with an advanced bone age typically hit a growth spu early on but stop growing at an earlier age. Consequently, when a naturally sho child has an advanced bone age, it stunts their growth at an early age leaving them even shoer than they would have been. Because of this, those who are sho with an advanced bone age, need medical attention before their bones fully fuse. An advanced bone age is common when a child has had prolonged elevation of sex steroid levels, as in precocious pubey or congenital adrenal hyperplasia. The bone age is often marginally advanced with premature adrenarche, when a child is overweight from a young age or when a child has lipodystrophy. Those with an advanced bone age typically hit a growth spu early on but stop growing at an earlier age. Bone age may be significantly advanced in genetic overgrowth syndromes, such as Sotos syndrome, Beckwith-Wiedemann syndrome and Marshall-Smith syndrome. Bone maturation is delayed with the variation of normal development termed Constitutional delay of growth and pubey, but delay also accompanies growth failure due to growth hormone deficiency and hypothyroidism. Reference: GHAI Essential pediatrics, 8th edition
Congenital adrenal hyperplasia
Hypothyroidism
Hypopituitarism
Constitutional delay in growth
Musculoskeletal  disorders