We report the case of a 21-year-old man with a unilateral lumbosacral dislocation together with a fracture of L1 resulting in "en bloc" dislocation, which is difficult to classify from an anatomopathological and biomechanical point of view. Unilateral lumbosacral dislocation is likewise an infrequent injury with less than 10 cases previously reported. Its association results in an anterior displacement to the left of the whole lumbar spine. To our knowledge, this displacement "en bloc" of the lumbar spine represents a rotatory dislocation of the same, an injury which we have not seen described until now in the literature.