"In the hospital thanks to @khloekardashian," Jenner, 16, said in a message posted Tuesday. "My mom said, 'Never thought I would take u to the doctor for a trampoline accident at this age.' This means war Khloe."
"This started out calm and ended in a war! Sorry @kyliejenner," Khloe Kardashian, 29, wrote back.
Instagram photos showed Khloe tackling Jenner, but they didn't suggest what Jenner's injuries are.