ELN and spinal stenosis: Previous studies have mainly investigated the histologic changes in the ligamentum flavum of spinal stenosis patients and they reported that there was degradation of elastin fibers, with an increase in collagen fibers, fibrosis and calcification within the hypertrophied ligamentum flavum tissues.1-5) However, to the best our knowledge, there has been no study that has investigated the biochemical factors associated with these histologic changes.