<unk> '<unk>  is one of the most common hip disorders in young children, occurring in roughly 5.5 of 100,000 children per year. The lifetime risk of a child developing the<unk>  is about one per 1,200 individuals. Boys are affected about three to five times more often than girls. New cases of<unk> '<unk>  rarely occur after age 14 years (if diagnosed after 14 years of age, then it is usually old<unk>  from early in childhood or avascular necrosis from an alternative cause). White northern Europeans appear to be affected more frequently than other ethnicities, though a paucity of reliable epidemiology exists in the Southern Hemisphere. Children of sufferers of the<unk>  themselves may have a very slightly increased risk, though it is unclear if this is because of a genetic predisposition, or a shared environmental factor. It is most commonly seen in persons aged three to 12 years, with a median of six years of age. The UK incidence rates show an intriguing pattern with low incidence rates in London, and a progressive increase in<unk>  in more northerly areas (maximal in Scotland). Some evidence suggests, at least in developed countries, more socioeconomically deprived communities have a greater risk of<unk>  (a similar trend to<unk> s such as adult heart<unk> , though the reason for this remains unknown. One possible explanation that has been considered is tobacco smoke exposure, though this is significantly confounded by the strong socioeconomic gradient common to both smoking and<unk> '<unk> .
Legg–Calvé–Perthes disease
Langer–Giedion syndrome
Osgood–Schlatter disease
Avascular necrosis
Iliotibial band syndrome
Löfgren syndrome
Patellar subluxation syndrome
Boxer's fracture