Method for measuring vertebral kinematics from videofluoroscopy.

Optical distortions and digitizing errors must be minimized to obtain accurate measurements of spine kinematics from videofluoroscopic imaging. This study adapted and evaluated a method for reducing these errors. Image and signal processing techniques were applied to obtain lumbar spine kinematic measures from walking and trunk extension trials. Mean absolute error was conservatively estimated to be 0.69° (sd = 0.43°) for vertebral rotation, independent of angle, and 0.33 mm (sd = 0.25 mm) for linear measurements. Digital filtering was applied to further minimize random errors.