Fig. 5.

Functional Upright MRI in a 71-year-old female patient with monosegmental lumbar stenosis at L4/5 and position-dependent neurologic claudication (exacerbation in extension and relief in flexion). Preoperative sagittal scans in extension (a) and flexion (c) were shown with the corresponding postoperative fMRI scans (b, d). The position-dependent “soft” lumbar stenosis in extension is reduced after implantation of the X-Stop. No change is seen in the flexion scans, where the patient is asymptomatic. Radiologic findings corresponded to the satisfactory postoperative outcome with a markedly increased walking distance and relief of symptoms