Hi; Has anyone had anything like this or can offer advice?

My wife just had a 4 level ACDF. After surgery the OS said she should have her bone density looked at. She had it evaluated in May and was told she was fine.
The post op check up a week later showed the plate had shifted due to some of the screws pulling away (OS said due to her bones being soft).

They are now proposing a second surgery; 1 remove the plate and screws, 2. flip her over and go through the back to put in a cage with rods.

Her pain is actually worse than prior to the surgery. She was diagnosed with 2 bone spurs (removed as part of the ACDF) and narrowing of the spine due to compression as well as arthritic joints.

Should the surgeon have order a bone density scan prior to surgery?