Ah, to collar or not to collar! I hate the bloody things, and as far as I'm aware research has shown that they are of very little benefit except in a few very specific circumstances (e.g. unconscious with high index of suspicion for a spinal injury). As Tom says, applying them can cause more injuries than it helps to treat. The boards inparticular carry a high risk of pressure damage, back pain etc., and often make it more difficult to extricate/treat the patient (thus leading to treatment delays for other injuries, and therefore potential harm). Most people who are involved even in high risk incidents don't infact have a spinal injury (for example, I read some research recently that showed that only ~8% of people thrown at speed from a motorbike have any spinal compromise). There is little evidence to suggest that in those who do have a spinal injury, immobilisation actually prevents deterioration. Almost everything we do in this area of care is based on ritual, shaky opinion and defensive medicine. We'd be best to do away with spinal immobilisation altogether.