Would it be possible for the jury to look at Jodi's left ring finger to see if there is a cut along the tendon? vs a break?
Looking only at the finger it would be impossible to tell (edit) that information. The most they could tell just by looking is at any scarring she would have there. (end edit)
An x-ray of her finger *might* show evidence of a previous break if it occurred - actually it would only *possibly* show evidence of a previous break that had healed...most times extra bone or calcium deposits would show, or if a bone was broken but not re-set so it healed straight - but it depends on many, many factors. - how badly it was broken, if so, did it heal straight or was it not set so it would heal straight - how much time has elapsed since the break and the new x-ray - dependent on age of the person, how bad the break was, how fast that specific person heals, what shape the person has been in, any vitamin deficiencies, if that person has arthritis, joint disease, and other factors.
A Radiologist would probably be able to tell there was an injury "in the past" they can not tell how long ago it happened with any accuracy.
A bone density test could be done and it would show more than a 'regular x-ray' but still would not be able to tell you when it happened to any accurate degree.
An MRI could, or probably would, show past or current tendon damage. But again, there is no way to accurately tell *when* it happened.
In all cases above, soft tissue damage (ex; bruises) would probably not show up unless the injury was new.
If it was a larger bone than just a finger (and we are most likely talking a tendon and/or joint injury, not just a tiny little finger bone) - say, a femur or rib, clavicle, etc more healing bone growth would show up and there would be a better chance of getting an idea of when it happened... however, even then, they would be unable to pinpoint when it happened, especially without any previous records - to either days, months, years. More like longer spans of years. Example; either from birth to age 20 or age 20 to now.