Extension of an In Vitro Spine Test Rig to Track Load‐dependent Biomechanics of the Lumbar Spine under Physiological Conditions

Abstract Low back pain is a major cause of chronic health problems and is often related to loading history. A test rig was developed at the Institute of General Mechanics, RWTH Aachen University to investigate the influence of duration and intensity of spinal loading using in vitro experiments on spinal cadavers. In this work, several extensions of this spine test rig are presented: (1) a hydraulic cylinder with a force measuring unit was added to apply axial compression; (2) a new follower load principle system was developed to achieve uniform compression of the naturally curved spine; (3) the specimen is immersed in phosphate‐buffered saline with protease inhibitors during the testing period to allow osmotic interactions on the one hand and the investigation of the influence of different loading and rest cycles on the other hand; (4) a fiber‐optic pressure measurement system was added to successfully measure the intradiscal pressure during the test series. The first results obtained using these test rig extensions and the new pressure measurement system show their functionality. The new test rig enables the investigation of a wide range of load scenarios and further measurement parameters.