There have been a number of changes to the rules of the game in an attempt to reduce the risk of these injuries .
It is possible that these changes have reduced the incidence of nonfatal catastrophic spinal injuries ; however , this has not objectively tested .
There have been a number of changes to the rules of the game in an attempt to reduce the risk of these injuries , and it is possible that these changes have reduced the incidence of nonfatal catastrophic spinal injuries ; however , this has not objectively tested .