Bethanie Mattek-Sands broke down repeatedly as she promised to fight back and return to action following her serious knee injury suffered at Wimbledon.

The American's right leg buckled early in the deciding set of her second-round match against Sorana Cirstea on Thursday, causing her to go down in agony as she clutched her knee and scream for help.

Cirstea ran to her aid as the umpire called for paramedics before Mattek-Sands was carried away on a stretcher.

In an emotional video posted on Facebook on Saturday, the 32-year-old confirmed that she would need surgery after dislocating her patella and rupturing her patella tendon, but vowed that she would return to the tour.

"It's obviously been an emotional and painful rollercoaster the last couple of days," said Mattek-Sands, who was reduced to tears a number of times throughout the 10-minute post.

"I know a lot of you guys have seen the replay and for obvious reasons I have not looked at it, I hate watching sports injuries on TV, let alone myself.

"There was a loud pop, my knee felt really tight and I took a look at it, I kind of freaked out and it's probably when you guys heard me all drop an F-bomb! It was one of the most painful injuries and I've had a few. I saw a picture afterwards of [husband] Justin on the court holding my face and telling me not to look at my leg and I said 'F you I already did it's too late but please cover it up I don't want to see it again!'

"I remember Sorana coming over and telling me it's ok and I think that's amazing because we're all competitors on tour and yet so many of the girls on tour are my friends and I think in that moment Sorana was there as my friend, it didn't really matter we were in the middle of a match and it means a lot to me, she's an amazing person.

"I think anyone who knows me knows I'm pretty positive and I smile a lot. But in that moment I couldn't enjoy it, so I want to let everyone know that there are times even I'm upset and down but I want to stay strong and get through these times.

"I want to let you guys know I'm feeling a lot better today. I'll be out for a while but I want to keep you guys updated because all your messages have been really inspiring and have meant a lot to me.

"I can't reply to all of them but the support has been amazing, I'll get through this. There's moments when it helps to hear so many positive things so thankyou and I'll get back out there."