Among various spinal soft tissues, facet joint capsules (FJC) have been the focus of several research studies due to their important roles in physical activities and spine pathology. The human spine provides substantial load-bearing capability and range of motion due to important properties of its tissues and structures.

This method enables the investigation of the correlation between tissue load, deformation and neural responses of mechanoreceptors in spine facet joint capsules, and can be adapted to investigate tissue loading and neural response of other soft tissues. Neural responses of all mechanosensitive units showed statistically significant correlations (all P<<0.05) with both capsular load ( r 2=0.744вђ.109) and local strain ( r 2=0.868вђ.088). Mechanosensitive afferents in goat capsules had tensile strain thresholds of 0.119вђ.080. Preliminary data showed that 18 of 23В afferents (78.3%) were found to be mechanosensitive to tensile stretch, and five were not responsive, even under tensile load as high as 27.5В N. It was tested by loading goat C5вЂ“C6 FJC in vivo with simultaneous nerve root recordings and 3D strain tracking of the capsules. The method incorporated a custom-fabricated testing frame for facet joint loading, a stereoimaging system, and a template-matching technique to obtain single afferent response. A new methodology was developed to investigate biomechanical and neurophysiological properties of spine facet joint capsules in vivo. Space limitation in the cervical spine makes such a study difficult, as the facet joint must be loaded while simultaneously monitoring nerve discharge from nerve roots immediately adjacent to the loaded tissue.

There has been no previous quantitative study of the relationship between capsular strain and sensory nerve activation in spine FJC in vivo. Facet joint capsules (FJC) may experience large mechanical deformation under spine motion.

Spine2d frame by frame per limb