Dear friend, welcome and thanks for entrusting your query here at HCM!
I am Dr. Prasad Akole (Critical Care Expert- http://bit.ly/Dr-Prasad-Akole) and am glad to address to your query here.
Trauma is the commonest logical cause of a vertebra being pushed back on to the next one, being strongly connected to each other.
However, as in your case, if there is a likelihood of disease infiltration (by
myeloma) of the vertebra, it does not remain as strong and can cause retropulsed appearance even without or with slightest trauma.
So, I do agree with the radiology impression. And they are reporting a film. A clinician is the person who examines and knows the patient and gives opinion on its importance.
Please be guided by your treating doctor.
I hope to have answered your query satisfactorily. I would be glad to answer any further queries.
Please ask for any clarifications before closing and rating this answer.
Take care and please keep me informed of your progress at http://bit.ly/Dr-Prasad-Akole
Good Luck! Thank you!!