The superstar golfer announced she had surgery Thursday to fix a right hand that not only had a small avulsion fracture in it ... but also had bone spurring AND nerve entrapment.

The good news ... Wie says the surgery should fix the pain she's been dealing with FOR MONTHS.

"It’s been disheartening dealing with pain in my hand all year but hopefully I am finally on the path to being and STAYING pain free!" Wie said.

Michelle tried to stick out the season ... saying she even got 3 cortisone injections -- but it just became too much.

Wie says her season's now over ... but rehab and a big 2019 are comin'.

"I cannot wait to start my rehab so that I can come back stronger and healthier than ever."

She also quoted an inspirational lyric from a John Mayer song. It's from this song. Enjoy ...