Sir Mick Jagger's eight-year-old son has been left on crutches after sustaining a leg injury.

The Rolling Stones frontman's boy Deveraux has his left limb in a blue cast and is using mobility aids after being involved in a mystery incident, the rocker's partner Melanie Hamrick has revealed.

Melanie took to her Instagram Story to show a picture of her son's injured leg and admitted it was painful seeing the boy struggle.

She captioned her post: "Nothing feels more true - When they hurt you hurt (crying emoji) He'll be back playing football again in no time though!!"

It is unclear when or how Deveraux was injured, or if he is at home or being treated in hospital.

The 37-year-old former ballerina previously praised her son's dancing abilities, but admitted his moves were more like his famous father's than her own.

She told Britain's HELLO! magazine: "I can't wait to see what he does but I don't want to put pressure on him, as between Mick and I, that's a lot of pressure.

"When I hear him sing in school shows, I say things like, 'Oh my God, his singing voice was amazing. Did everyone hear that?' And then I think, 'Melanie, let him be a kid! Don't be a stage parent.'

"He has more confidence and freedom in his style - like Mick, who is unique when he dances.

"I feel as though Dev's got that feeling of, 'This is how I'm dancing - I'm the best."

And Melanie admitted it can be "really hard" to keep the little boy grounded, though she often takes the youngster to the Manhattan apartment she lived in when she was a dancer in order to give him a reset and an experience of normal life.

She told the Sunday Times Culture magazine: "It's a very nice apartment, but it's not a hotel. He helps me with the laundry, he helps me cook dinner. We take the subway."

But one such trip ended with a "parenting fail" after Melanie and Deveraux volunteered at an animal shelter and were left distraught when they couldn't rehome all the kittens.

She recalled: "Oh my God, that was a parenting fail. We were both on the street crying, and Mick's [on the phone], like, 'Just take the cats!' "

The family travel frequently, with Deveraux enrolled in a school in France, where they have a chateau on the Loire River, or has tutors when they are on the road.

Melanie said: "Mick can't stay put and I'm similar. I'll say, 'I want to stay put.' Then after two weeks, I'm, like, 'Where are we going?' "