The Avengers director Joss Whedon is recovering after undergoing knee surgery.

The writer/moviemaker was rumoured to be making an appearance at the Comic-Con event in San Diego, California over the weekend (26-27Jul14) to promote his latest Marvel superhero film, but he has suggested he will be missing out after undergoing an operation.

Whedon posted a picture on his account showing himself in hospital, and another of him at home lying in bed with a cast on his leg, alongside the caption, "My Comic-Con is way better than your 'real one'."

He added in a series of messages on Twitter, "San Diego!!! Are you ready to paaaaarrtay (sic)?!?!?!?! Then don't have knee surgery.... Marvel will dazzle with stars galore and mega mondo movie magic Madness!!!! Also, I will be live tweeting my soup. #parsnip."