Sources close to the actor tell TMZ... Penn's assistant was taking a shower at Sean's Malibu home when she fell ... and popped out her elbow.
Sean wrapped her up in a towel and took her to a nearby urgent care facility.
Sean and his girlfriend, Shannon Costello were clearly upset over the accident as they waited while the assistant was being treated.
We're told doctors managed to pop the visibly damaged elbow back into place ... and now the assistant is recovering at her home.
The HOLLYWOOD HEATWAVE
If you feel like you are the only one getting hit by the late-summer swelter -- check out these super HOT Hollywood stars ... no seriously they are all hot, gross and sweaty looking.
Keep it cool people.
Teen Heartthrobs of the '90s
THEN & NOW!
The resurfacing of JTT, aka Jonathan Taylor Thomas, last week brought back fond memories of Teen Beat, Tiger Beat and Bop -- but whatever happened to those magazines' other teen heartthrobs
Check out the Now & Then side-by-sides above and let us know which was your childhood crush back in the day!
These celebrities have been broken down and mixed around into tiny squares ... can you piece them back together?
Kim & Kourtney Support Sister
Kendall at Her Runway Debut!
Kim Kardashian must be a very proud sister this week -- as last night, a second younger sibling made her runway debut during a Fashion Week show!
Kylie Jenner, 14, hit the catwalk Monday night for Avril Lavigne's Abbey Dawn show -- and last night Kendall Jenner, 15, followed suit.
Kendall was seen strutting her stuff at the Sherri Hill show held at Trump Tower on Wednesday, modeling three different outfits from the designer as Kim and Kourtney Kardashian watched on from the front row.
Famous Football Fans
THE PIGSKIN PICTURES
'Tis the season for the great gridiron games ... and even famous people are big football fans! Check out which stars are getting in on the action and are into playing a little game of catch with the 'ol pigskin.
"Are you ready for some football?"
Huge DISCOUNT On Bev Hills Mansion
Mark Wahlberg has knocked a cool $2 MILLION off the asking price on his UNBELIEVABLE Beverly Hills mansion ... asking $13.95 mil for one of the coolest pads EVER!!!
The place is UNREAL -- 8,932 square foot home sits on nearly 2 acres ... with a movie theater, 2-STORY GYM (complete with a boxing ring) ... basketball court and putting greens.
Like to sleep? It's got 7 bedrooms.
Like to pee? It has 10.5 bathrooms.
Like to swim? It has a RIDICULOUS pool ... with a grotto!!!
Mark put the place up for sale back in 2008 for $15.9 mil ... but he took it off the market when he couldn't find a buyer.
Now, he's trying his luck again -- probably because he's building a new 33,000 square foot compound in nearby Beverly Park.
Britney Spears' Birthday Boys
Growing Up Fast!
Britney Spears' two adorable sons -- Sean Preston and Jayden James Federline -- both celebrate birthdays this week.
Sean Preston turns six today, while Jayden James celebrated his fifth birthday on Monday. Time sure flies fast -- it seemed like just yesterday that Brit was driving down the freeway with baby Sean Preston on her lap. Click on the "Launch Gallery" button to see photos of the boys through the years:
Britney posted a message to her firstborn on facebook today that read: "Preston Happy Birthday! My little baby is growing up so fast. I love you. Mommy." She posted a similar message to her youngest on Monday: