The 49-year-old actress, best known to many fans for playing Mandy Dingle on the long-running British soap Emmerdale, shared the painful update with followers after what she described as a very bad fall over the weekend.
Riley posted photos from the hospital, including one in a gown with her surgeon and another showing her arm in a sling, as she opened up about the freak accident.
According to Riley, the whole thing happened after she slipped off a breakfast stool. She joked that she was not drunk and shut down any jokes before they could start, blaming the mishap on a slippery stool and a wool cardigan.
Unfortunately, the fall did serious damage to her left thumb.
She revealed that the injury badly affected her ulnar collateral ligament, also known as the UCL, which helps keep the thumb stable. Because of the severity of the damage, she had to undergo surgery.
Even while dealing with the painful recovery, Riley made sure to praise the medical team who treated her, thanking her specialist surgeon and the hospital staff who took care of her.
She said she was now recovering with pain relief after the operation.
Fans and famous friends quickly rushed to send their support online, with many wishing her a speedy recovery and sharing messages of love after the shocking update.
Riley has been a familiar face to soap fans for decades thanks to her role as Mandy Dingle, a character who has made her one of the most recognizable stars on Emmerdale.
Her latest health scare comes not long after she also made headlines for her appearance on I’m A Celebrity… Get Me Out Of Here!, where she talked openly about weight loss and lifestyle changes.