This question concerns an adult male soldier who is basically human and resides in a setting very similar to modern day earth. Assume medical knowledge is roughly equivalent to present day, but a lot of technology and treatment is beyond this character's reach as he lives in a war zone in a country that regards its working class citizens as disposable. He is injured twice in the course of the war: the second injury leaves him permanently paraplegic. Is it possible for a previous injury to his spine to cause a weakness or instability that might make it more likely that his spinal cord would be severed following a second injury to his back? I have referred to Primary Surgery: volume 2, Trauma and the Red Cross publication "war surgery", and have googled "consequences of untreated sci", "untreated, unstable spinal fracture", "bone fragment sci", "projectile retained in sci". (The last two because I was running out of ideas).
It's currently integral to the plot for him to be injured twice, briefly hospitalised the first time and then permanently disabled the second time. I wanted the second injury to be connected to the first injury but I am beginning to wonder if it's actually possible. Do I just make him unlucky and give him two separate, unconnected injuries, or is what I want possible?