The planning of decompressive and reconstructive spine surgery is based on clinical findings and diagnostic imaging. The evaluation of segmental instability, but also of the risk of destabilization following a needed decompression of the spinal canal and/or neural foramina make complex spine surgery a challenge, bearing in mind the risk of failures in case of an inadequate operation. The insufficient correlation between imaging and clinical symptoms originating from the spine and its nerve roots has been frustrating for some decades. This review focuses on the new upright, dynamic-kinetic, i.e., "functional" MRI and its ability to detect load- and motion-dependent disc herniations, stenosis, instabilities, and combinations of these pathologies not seen during recumbent imaging.