Hacker News Reader

It may also be for the purpose of simulating to some degree the flexibility of the ribs at each level.

Titanium 4.5g/cubic cm versus human bone at 1.85g/cubic cm.

You could make the titanium parts hollow. That would solve the density problem.

3d printing with metals allows for much more complicated geometries but it's not magic, there are still significant limitations, doubly so when you're talking about implants.

For example, there would have to be perforations for extracting the raw material from inside the hollow interior (probably titanium powder in this case) which means that you now have a hard to post process implant (titanium isn't exactly bioinert) with an exponentially greater surface area for possible autoimmune reactions or infections and an interior that is probably damn near impossible to sterilize (since you'd probably honeycomb the walls).