Development and validation of a new transducer for intradiscal pressure measurement

Potentially damaging tensile stresses in the annulus fibrosus are directly related to the hydrostatic pressure in the centre of an intervertebral disc: the design and development of a miniature strain gauge pressure transducer is described for measuring such pressures. Static calibration tests in bulk liquid demonstrated that measurements made with the transducer were of sufficient accuracy and stability for in vitro and in vivo investigations of spinal mechanics, and a study of the dynamic behaviour of the transducer demonstrated that it had a frequency response suitable for in vitro and in vivo investigations. Tests within loaded cadaveric discs showed that the transducer could be used to make repeatable measurements which were free from significant artefacts, when the disc was subjected to forces of up to 4000 N and when deformed in full flexion/extension.