I am looking for ideas for strengthening my core while healing from a small fracture of my T4 vertebrae (between the shoulder blades). For 8 weeks I should not do much with my arms while the crack is knitting (result of fall), and apart from isometrics, and general postural excellence, I'm not sure what other exercises would target my abdominals and back without pulling on my thoracic vertebrae.
I can't help you with specifics, but in your situation, I personally would consult a physical therapist. I see a doctor who specializes in rehabilitation medicine, and he will write me a prescription for PT when I have injuries or need to strengthen some specific muscles.
Your doctor should be able to write you a prescription (identifying the problem) for PT.
Usually, I only need one or two visits to learn the exercises, and then I can continue them on my own.