Paris Hilton spent her birthday in hospital with her boyfriend.

The reality TV star celebrated turning 31 on Sunday by hitting the ski slopes of Lake Tahoe, California with partner River Viiperi, but the celebratory occasion soon turned sour as the 21-year-old male model ended up hospitalised after a scary skiing accident.

"Just got out of the hospital with @RiverViiperi. He was doing a high jump while skiing & the ski sliced in to his leg! 19 stitches! Oww! (sic)" she wrote on Twitter.

The blonde beauty played the doting girlfriend as she sat by her boyfriend's hospital bedside, but admitted that she "almost passed out" after seeing the nasty cut on his leg. "Such a scary day on the slopes today. After seeing the gash on @RiverViiperi's leg, I almost passed out. I have never seen a cut that deep in my life. He is so brave, I can't even imagine the pain he went through today. (sic)" she continued.

River was clearly grateful to have Paris by his side, tweeting the Hilton Hotel heiress, "Thank you for being there for me my Love, your the best Girlfriend in the world!! I'm so lucky to have you! #love (sic)"

After the ordeal, Paris salvaged what was left of her birthday as the couple flew home to Los Angeles for a night in: "Can't wait to get home to play with my puppies & watch movies in bed with @RiverViiperi. Chill birthday night."

(FYI - You can also follow VIP Breakdown on Twitter.)