A digital videofluoroscopic technique for spine kinematics

The kinematic behaviour of the vertebral segments under the influence of spinal injury and other mechanical problems is difficult to quantify in patients. This paper describes the use of a calibration model and human subjects to investigate the accuracy of a method for determining lumbar intervertebral rotations using images digitized from an image intensifier. The main influences were found to be observer error in marking co-ordinates, scaling of the image presented by the computer's monitor, distortion caused by out-of-plane images and loss of image quality as a result of scattered radiation from the soft tissues. The technique may be valuable in the light of its efficiency and low X-ray exposure to patients.