In vivo measurement of the pressure signal in the intervertebral disc of an anesthetized sheep.

The purpose of the present study was to measure the intradiscal pressure signal of an anesthetized sheep under spontaneous breathing. An ultra-miniature fiber optic high-pressure sensor was implanted into the nucleus pulposus of the fifth lumbar intervertebral using a dorsolateral transforaminal approach. Results suggested the periodicity of the intradiscal pressure signal was similar to the mean respiratory rate of the animal. The average resting intradiscal pressure was also calculated and compared to available data.