In an adult? No way.
Can you tell us about these patients? Fracture is really not described as a complication of IO. You're making an 18ga puncture into a thick part of a long bone, that should not fracture a healthy tibia or even an unhealthy tibia for that matter.
Not trying to be an *****, but if you brush up on I/O literature, you'll see it's a well-described (albeit rare) documented complication. For example: Katz DS, Wojtowycz AR. Tibial fracture: a complication of intraosseous infusion.
Am J Emerg Med. Mar 1994;12(2):258-9. eMedicine (one of my fav. quick references) lists it as a known complication as well: "Other possible complications include local hematoma, pain, fracture and growth plate injuries (with incorrect placement), and fat microemboli (not clinically significant) and compartment syndrome if extravasation is not recognized upon insertion."
Your experience is very different from mine. Neck landmarks and positioning in super obese is a pain in the rear.
I'm not going to even play like it isn't a pain. But I can pretty much ALWAYS find a clavicle in an obese patient. How medial or lateral you are can be hard to assess, but I can at least get an idea of the general area to make my attempt.
IJs...I only do by ultrasound. Partly because I've never been taught to do it blind (except once or twice a LOOONG time ago) and partly because I honestly believe it to be the standard of care - a PTX or dilated carotid is a completely unacceptable complication IMO when you're able to do IJs under real-time visualization. Granted, in really large & extremely dehydrated patients, my approach as varied between a true IJ and a supraclavicular subclavian approach (both via U/S guidance), the point remains the same. It's nearly fool-proof I find.
Femorals...same spot in almost everyone. Even if you can't find a pulse. In fact, I harp on the lower classmen that when a cardiac arrest comes in and we need a line, they NEED to be able to place & secure a femoral without being able to locate a pulse (ie the femoral artery). The anatomy is fairly reliable across the vast majority of patients. Having said that, you do often need someone to retract the pannus in a larger patient lol.