The effect of posture on diffusion into lumbar intervertebral discs

The diffusion of small solutes into the intervertebral discs of cadaveric lumbar motion segments was measured using a radioactive tracer technique. The motion segments were wedged and loaded to simulate erect posture and flexed sitting postures. The results show that erect posture favours diffusion into the anterior half of the disc compared to the posterior half. Flexed posture, by deforming the annulus fibrosus, reverses this imbalance.