The 'Vampire Diaries' alum shared this unfortunate news Monday by posting a photo from her hospital bed on Instagram ... where she was hooked up to a monitor while sporting a knee brace AND a neck brace.

Nina appeared to blame an e-bike for her current state ... as her first slide in the upload featured her posing on the vehicle in a little black outfit -- looking as happy as can be.

Unfortunately, the good vibes did not last long ... as she captioned the post ... "how it started vs how it’s going 🤕."

As fans began clamoring for answers about her injury, Nina took to her Instagram Stories, where she confirmed that she'll be ok but has "a long road of recovery ahead."

Nina is known for being particularly athletic and risk-taking, often documenting her sporty adventures with Olympian boyfriend Shaun White on social media.

Of course, Nina is far from the first star to be foiled by an electric bike. Take Simon Cowell, for example -- who suffered a severe back injury after an e-bike accident in 2020 ... and required six hours of surgery, where a metal rod was put in his back.

Simon broke his arm 2 years later after reportedly getting into another e-bike crash.

Comedian Kenny DeForest was hospitalized last December after the electric bike he was riding struck an unoccupied car. He later succumbed to his injuries, dying at age 37.