Hoverboards are fun toys, having tried it myself during this holiday season! However, as fun as some activities are, there are certain risks. I believe the injury risk associated with hoverboards is significant because the balance that is required may not be what many people are used to.
Kids and adults who perform balance-related activities such as skateboarding or surfing, have little trouble maneuvering hoverboards, even with little experience on them. However, problems and injuries can arise when kids and especially adults, who are not used to these balance-type activities, try the hoverboards. These injuries include back sprains and contusions or worse, wrist sprains and fractures, and head injuries, among others.
My advice would be to be careful when trying these hoverboards. If you're going to do it, the use of protective equipment is warranted.
For additional information on preventing and treating head injuries or injuries caused by falls, I recommend the following articles: