Answer to the letter to the editor of Gadjradj PS, et al. concerning "prodisc–c versus anterior cervical discectomy and fusion for the surgical treatment of symptomatic cervical disc disease: two-year outcomes of asian prospective randomized controlled multicentre study" by N. Kumar, et al. (Eur Spine J [2022]: doi: 10.1007/s00586-021–07055-0)