An energy-absorbing deformable structure to attach a child seat to a mounting portion of a vehicle is provided. The energy-absorbing deformable structure comprises a loop of metal rod including a base end configured to be coupled to the mounting portion of the vehicle, a distal end configured to be coupled to a child safety seat, and a plurality of sinuous deformable portions positioned intermediate to the base end and the distal end, wherein each of the sinuous deformable portions includes an inwardly extending portion that extends inward from a perimeter of the deformable structure to a substantially central interior region of the deformable structure; wherein the sinuous deformable portions of the deformable structure are configured to be deformed when the base end and distal end are pulled in tension, thereby absorbing energy.