Answer to the Letter to the Editor of Y. Xu et al. concerning "Correlations between sedimentation sign, dural sac cross-sectional area, and clinical symptoms of degenerative lumbar spinal stenosis" by Sangbong Ko (Eur Spine J [2018] 27:1623–1628)

[摘要] Question: There was an obvious mistake in the paragraph one in the introduction section. The sentence “CSA<100 cm2 is clinically diagnosed as LSS.” is wrong. Based on the original defnition of CSA by Chiaki Hamanishi, we know that the unit of CSA is mm2 not cm2 . We do believe that it is a clerical error of the author, but we also believe this kind of error should not exist in the scientifc article.