"RESULTS: There was less neurologic disability in the unimmobilized Malaysian patients"
I once saw a study claiming that ICU patients who received more units of blood had higher mortality rates, and therefor concluded that you should avoid giving blood. However, it stands to reason that if a patient were receiving multiple units, his underlying disease was probably more severe to begin with, hence the higher mortality...
Same here: I don't have access to the full article, but I would imagine that patients who were backboard-stabilized probably had more severe injuries (or at least mechanisms of injuries) than those who weren't. I also have no idea where the two university centers mentioned are in relation to each other, but perhaps patients with more severe injuries are transfered to the New Mexico one? Or perhaps the other one is in a setting with less likelihood of high-speed collisions, etc.
In short, it seems like their study group and control group could, potentially, be very different from one another.