Biomechanical analysis of the lumbar spine.

Physiological mobility of the lumbar spine, as a very important feature of this spinal segment biomechanics, has been defined, i.e., physiological instability has been proven on a sample of 35 fresh cadaveric human lumbar spine specimens which were tested in experimental conditions of both centric and eccentric static loads. The presence of physiological instability or physiological mobility of the lumbar spine in the form of so called relative oblique or tangential shifts was already been numerically quantified. The lumbar spine is continuously deformed through the action of static centric and eccentric loads ranging from 0-1000 N(ewton). Using a very sensitive method for detecting the lumbar spine deformities, based on measuring the angle of deflection of the laser beam on the screen, angular shifts of the spinal vertebrae can be defined within the sensitivity range of 0 degree to 1 degree (degree) with a standard error of +/-0.1 degree.