What is Clear
There is one thing that is perfectly clear, the number of catastrophic cervical spine injuries that result in paralysis have declined since 1977. That was the was the first year after the NCAA and high school rule change which occured in 1976 (regarding helmet contact and spearing). Although it varies by year, in general there has been over an 80% reduction in these injuries in football.

On the Surface
Things become a bit murkier when you ask, why have these numbers decreased? Well, we all agree that axial loading of the cervical spine is the primary mechanism for these injuries in football. Axial loading occurs as a result of head-down contact. So the simplest explanation is there has been a decrease in the incidence of head down contact and spearing (the mechanism of injury). This in turn reduced the number of axial loading injuries. Although, one research article I did contradicted this concept (I still find it hard to believe that no one has replicated this study for more recent data).

What's the Best Indicator
Axial loading and head down contact are our primary concern. It's important to keep in mind that the primary result of an axial loading injury is fracture or dislocation to the cervical vertebrae. Injury to the spinal cord and paralysis occur secondary to the injury of the vertebrae. So paralysis is actually a secondary result of axial loading.

This means that you can have a fracture/ dislocation of the cervical spine without paralysis. And historically the numbers represent that this is quite frequent. Generally there have been 3-4 times more fractures/ dislocations of the cervical spine that occur without paralysis than with paralysis. So we can say, just about every axial loading injury results in fracture/dislocation of the cervical spine, but not every fracture/ dislocation results in paralysis.

If you're following my train of thought, you will agree that the most accurate indicator of axial loading injuries in football is the number of cervical spine fractures/dislocations that occur ... regardless of paralysis. If we want to determine how succesful we have been reducing axial loading, this is the best indicator.

Here's the Rub
The data on cervical spine fractures/dislocations occuring without paralysis have not been officially collected and reported since 1987 (by the National Football Head and Neck Injury Registry). Primarily because this data is much harder to collect and track reliably. Simply put, it is not as well documented/reported by the football community. This is according to Dr. Torg and Dr. Mueller, who have been responsible for collecting it. It is much easier and more reliable to collect data on athletes who have had cervical spine injuries that have resulted in paralysis. So by default it's this number that has become our indicator of success or failure.

But let's take a look at the numbers we do have from 1976 through 1987. The reduction in these injuries has varied between about 20% and 60%. While still substantial, it's not as successful as the reduction in the athletes that have been paralyzed during that period. Graphs representing this data can be found in this article. Between 1977 and 1987 there was a high of 96 and a low of 32 for fractures/ dislocations.

Currently, for 2005 the National Football Head and Neck Injury Registry has reported 3 injuries that resulted in paralysis. Only one cervical fracture/ dislocation without paralysis is reported. It is also clearly stated that the non paralysis data are not considered reliable. No data is included on previous years for the fractures/ dislocations (but from my memory of previous reports it's been less than 5/ year). From the numbers we have from the 1980's I would expect to see between 9-12 fractures dislocations in 2005 if there were 3 athletes paralyzed. In 2004 there were 12 athletes paralyzed and I would expect to see between 36 and 48 fractures/ dislocations.

So have the numbers of fractures/ dislocations occurring without paralysis really decreased this much from the 1980's? Or are we just not finding out about them? My guess is the latter.

Looking Deeper
In my mind, these are the pressing questions:

How much of the decrease in paralyzed football players is accounted for by improvements in their care after an axial loading injury has already occured? (Improved on the field management and improved surgical techniques/ strategies)

And how much of the decrease in paralyzed football players is accounted for by eliminating head down contact from football and actually preventing cervical fractures/dislocations from occurring in the first place? Without the primary injury, the secondary result of paralysis can not occur.

It seems the answer to these questions lies in finding the accurate number of fracture/ dislocations that occur without paralysis on an annual basis. And I don't know that we will ever have an accurate picture of this.

But keep in mind that the possibility exists that head down contact occurs about as frequently as it did in the 1970's and we haven't been as successful as we think in preventing axial loading injuries of the cervical spine in football. We have been successful in improving the post injury care. Or perhaps a sliding scale between the two.