Answer to the Letter to the Editor of A. Gardner concerning “Loss of apical vertebral derotation in adolescent idiopathic scoliosis: 2-year follow-up using multi-planar reconstruction computed tomography” (by G. Cui, K. Watanabe, Y. Nishiwaki, N. Hosogane, T. Tsuji, K. Ishii, M. Nakamura, Y. Toyama, K. Chiba, M. Matsumoto; Eur Spine J (2012) Jun;21(6):1111–20. doi:10.1007/s00586-012-2633-0)