I'm just curious to know what an ALS unit would do for this patient that hasn't been done already or couldn't be done by BLS?
Clinical clearance of C-spine? A Psychiatrist, is a specialty of a physician. (if I am not mistaken the med director of Acadian is/was a psychiatrist) Is it possible that the patient was evaluated and needed transefer to cover him/her?
An IV for pain meds? In the length of time taken, PO sedation or medication could have been given.
A heart monitor? A patient has to be medically cleared to be admitted to a psych facility.
Advanced airway? For a talking "trauma" patient with leg pain?
As food for thought, the original traumatologists were orthopods. ~80% of all trauma is ortho in nature. The only recognized life threatening ortho injury is compartment syndrome. Unless a medic is planing on calling for orders to perform an emergent fasciotomy, (aka surgery), there is little a medic can do that BLS cannot. Infact I can't think of anything.
The lactic acidosis would be released after the compartment is opened. Even if there was a slight increase in blood lactate, the bodies natural buffers and the heart and liver metabolizing lactate back to pyruvate, as well as NAD+ to NADH should be more than able to compensate for even moderate lactate levels.
as for the mechanism, vertical compression of the spine would cause a fx at the atlanto-occipital joint. (aka c-1) Which would very likely cause and immediate cord insult.
Bi peds are specifaclly built to reduce such compression forces. If the impact wasn't significant enough to even fx his femoral neck, it is not even reasonable to think there is an occult c-1 fx.
Obviously I wasn't there, but it sounds like the pt was being routinely transferred for another medical clearence so he could be turned around and shipped back to the facility. Dramatic though the story sounds.
Based on the OP desription, i think asking the pt to sit quietly on the cot, put on the seat belts, a splint and some ice (coldpack) would be the treatment of the trip.
In the long term, if nothing is broken but there is a joint insult. he will probably get a plaster or other formed splint, told to keep it on for 2 weeks, heat and ice as required, and told to take some ibuprofin for pain.
If there is a fx, he'll get the same with an ortho follow up for a full cast after he gets out of the psych facility as they usually don't allow full casts in psych or prisons because they can be used as a weapon.