Annulus Fissures Are Mechanically and Chemically Conducive to the Ingrowth of Nerves and Blood Vessels

作者：Stefanakis Manos; Al Abbasi Maan; Harding Ian; Pollintine Phillip; Dolan Patricia; Tarlton John; Adams Michael A^*

来源：Spine, 2012, 37(22): 1883-1891.

DOI：10.1097/BRS.0b013e318263ba59

• intervertebral disc
• nerve ingrowth
• fissure
• proteoglycans
• pressure

Study Design. Mechanical and biochemical analyses of cadaveric and surgically removed discs. %26lt;br%26gt;Objective. To test the hypothesis that fissures in the annulus of degenerated human discs are mechanically and chemically conducive to the ingrowth of nerves and blood vessels. %26lt;br%26gt;Summary of Background Data. Discogenic back pain is closely associated with fissures in the annulus fibrosus, and with the ingrowth of nerves and blood vessels. %26lt;br%26gt;Methods. Three complementary studies were performed. First, 15 cadaveric discs that contained a major annulus fissure were subjected to 1 kN compression, while a miniature pressure transducer was pulled through the disc to obtain distributions of matrix compressive stress perpendicular to the fissure axis. Second, Safranin O staining was used to evaluate focal loss of proteoglycans from within annulus fissures in 25 surgically removed disc samples. Third, in 21 cadaveric discs, proteoglycans (sulfated glycosaminoglycans [sGAGs]) and water concentration were measured biochemically in disrupted regions of annulus containing 1 or more fissures, and in adjacent intact regions. %26lt;br%26gt;Results. Reductions in compressive stress within annulus fissures averaged 36% to 46%, and could have been greater at the fissure axis. Stress reductions were greater in degenerated discs, and were inversely related to nucleus pressure (R-2 = 47%; P = 0.005). Safranin O stain intensity indicated that proteoglycan concentration was typically reduced by 40% at a distance of 600 mu m from the fissure axis, and the width of the proteoglycan-depleted zone increased with age (P %26lt; 0.006; R-2 = 0.29) and with general proteoglycan loss (P %26lt; 0.001; R-2 = 0.32). Disrupted regions of annulus contained 36% to 54% less proteoglycans than adjacent intact regions from the same discs, although water content was reduced only slightly. %26lt;br%26gt;Conclusion. Annulus fissures provide a low-pressure microenvironment that allows focal proteoglycan loss, leaving a matrix that is conducive to nerve and blood vessel ingrowth.

• 出版日期2012-10-15