Researchers say careless cellphone use can lead to facial cuts, bruises and fractures. A study published Thursday found a spike in U.S. emergency room treatment for these mostly minor injuries. Some cases were caused by phones themselves, including people getting hit by a thrown phone. But researchers say many injuries were caused by distractions like texting while walking. Though most patients in the study weren’t hospitalized, experts say the problem should be taken seriously. The study examined 20 years of emergency room data and found a spike in visits after 2006, around the time when the first smartphones were introduced.