Concurrent Validity of Flexicurve Instrument Measurements: Sagittal Skin Contour of the Cervical Spine Compared With Lateral Cervical Radiographic Measurements

The flexicurve sagittal skin contour measurement has poor concurrent validity compared with established radiographic measurements of the cervical lordosis. The flexicurve tracings always predicted lordosis, overestimated the lordosis compared with x-ray values, and cannot discriminate between radiographic lordosis, straightened, S curves, and kyphotic alignments of the cervical curve.