Reviewer's comment to "Functional MRI of the spine: different patterns of positions of the forward flexed lumbar spine in healthy subjects" by Alexander König and Hans-Ekkehart Vitzthum.

lumbar spine flexion by means of a new type of magnetic resonance imaging (MRI) system, the authors open new perspectives in functional radiological studies of the spine without exposure to ionising radiation. Although measurement error due to drawing lines along vertebral endplates and positioning in a rather narrow gantry opening might have played an unknown role, the findings, if reproducible, are interesting as they establish significant relationships between lumbar facet joint orientation and patterns of lumbar spine flexion motion. This interesting paper highlights the fact that, besides constituting a welcome alternative to classical functional X-ray studies, MRI is also able to include the muscular apparatus in the picture. In the past, although they have recognised the importance of the muscular apparatus, spine surgeons have had to focus mainly on the osseo-ligamentous system, as the muscular apparatus was not able to be visualised. With MRI allowing studies of muscles, and possibly also functional studies, this might change in the future. REVIEWER’S COMMENT Eur Spine J (2001) 10 :443 DOI 10.1007/s005860000242