"She has dislocated her shoulder and it was after she released the javelin so it looks like it is the rear side of it," Australian head coach Craig Hilliard said.
"We know nothing else other than she has gone to hospital to have it put in place. It's unfortunate Kim did everything with her rehabilitation, she had MRI checks before she came away.
"She met all her fitness standards before she left, threw well in Florida but once you have surgery on a shoulder it doesn't matter what sport you are in the propensity for re-injuring is always high.
"She knew the risk but it is horrible for her. Everything had been ticked off ... we wouldn't have been taking risks given what occurred to her last year."
Mickle was always in a race against time to be ready for Rio after having a shoulder reconstruction last year. She hadn't competed in the lead-up to the Games but despite only being 11 months post operation she had been confident the shoulder would stand up.
Mickle threw 57.20m with her opening throw, fouled the next before suffering the injury as she tried to find extra with her third throw to stay in the competition.