It has been known for a long time that systemic steroids can affect bone density. This effect is both dose and durations of therapy related.
Until recently, there has not been a good scientific study of topical steroids and bones. Danish scientists recently Finished (pun intended) a 15-year study of 723,000 adults using topical steroids. They found that long term use of medium or high potency steroids did contribute to the development of osteoporosis and also increased risk for bone fractures.