I think that the likelihood of running across traumatic implant failures is nil
1. FRONTAL IMPACT/anterior-posterior force: great deal of very sudden force, or gargantuan crushing. I'd say you have a deader on your hands. Not sure about torso restrain in a MVA, but probably not airbag deployment. Still, a lot of the type of force to snap your neck or deform your rib cage.
2. Lac or GSW: going to be busy with bleeding, and unless it is selective (lateral grazing GSW, or mutiliation with a sharp object) maybe talking pneumo and/or haemothorax.
3. Barometric change, microwave oven, meteorites, tatooing, slam dancing....naw.
4. Immune response against the envelope ("baggie"): big problems for the pt, but the plastic will be immune.
5. Operative accident on implantation or manufacturing defect: maybe your best chance for a leaker, but any reputable surgeon and his scrub nurse will have inspected that implant three or more times, not to mention a leak showing up on the sterile field. As with manufacture, no idea about work done on the cheap in Thailand or some other cut rate scenario.
But again back to OP: in the short period of field tx, use of SNS versus sterile water for initial irrigation is about even. Might want to check neb meds for compatibility with saline before it's used as the diluent, but I never heard of one that was incompatible.