CHICAGO (Reuters) - Fatter rear ends are causing many drug injections to miss their mark, requiring longer needles to reach buttock muscle, researchers said on Monday. Standard-sized needles failed to reach the buttock muscle in 23 out of 25 women whose rears were examined after what was supposed to be an intramuscular injection of a drug. Two-thirds of the 50 patients in the study did not receive the full dosage of the drug, which instead lodged in the fat tissue of their buttocks, researchers from The Adelaide and Meath Hospital in Dublin said in a presentation to the annual meeting...