Prashanth J Rao1,2,3, Victor M Lu4, Ioannis G Sergides4,5. 1. Neurospine Surgery Research Group, Prince of Wales Private Hospital, Sydney, New South Wales, Australia. 2. Department of Neurosurgery, The University of New South Wales, Sydney, New South Wales, Australia. 3. Department of Neurosurgery, Prince of Wales Hospital, Sydney, New South Wales, Australia. 4. Department of Neurosurgery, The University of Sydney, Sydney, New South Wales, Australia. 5. Department of Neurosurgery, Royal North Shore Hospital, Sydney, New South Wales, Australia.