no idea
Because as you know,it would have depended upon the severity of the injury as to whether a hospital visit was needed. If not,then it would have been amongst the normal bumps and bruises that a toddler collects along the way.
Also the age of the child too because if under one year old,the skull is still soft enough to buffer a bump.
I haven't read about anything having been made of it,which leads me to believe that it wasn't a worry.