Sir Paul McCartney's wife Heather Mills McCARTNEY is preparing to undergo a rare surgical procedure to cure complications with her amputated leg.

The former model, who lost the lower part of her leg after a motorcycle accident in 1993, is due to have 'revision amputation' to re-attach muscle tissue onto her bone.

The operation will leave the animal rights campaigner on crutches for at least two months.

Her spokesperson says, "I can confirm that Lady Mills McCartney is due to have revision amputation and will have to spend several weeks on crutches.

"However, I am not able to give any details on when the operation will take place or what it will involve."