A method of deriving an estimate of the extent of fracture in a vertebra shown in an image of part of A spine is provided. The images of at least two vertebrae are segmented to obtain data representative of the shape and size of each of the vertebrae. An approximation of the shape of a first of the vertebrae is reconstructed by comparing the data obtained for a second of the two vertebrae with a mathematical model of at least the same two vertebrae of an unfractured spine . The unfractured shape of the first vertebra is predicted to enable a comparison of the shape and size of the first vertebra as imaged with the predicted unf ractured shape and size. The difference between the respective images is subsequently computed to obtain a result representative of the extent of fracture in the first vertebra.