Endplate calcification and cervical intervertebral disc degeneration: the role of endplate marrow contact channel occlusion.

BACKGROUND The aim of this study was to determine the fundamental relationships between cervical intervertebral disc (IVD) degeneration, endplate calcification, and the patency of endplate marrow contact channels (MCC). MATERIALS AND METHODS Sixty cervical IVDs were excised from 30 human cadavers. After sectioning the specimens underwent micro computed tomography (microCT) - from all images the number, calibre, diameter and distribution of endplate openings were measured using ImageJ. Next, the specimens were scored for macroscopic degeneration (Thompson's classification), and subsequently underwent histological analysis for both IVD and endplate degeneration (Boos's classification) and calcification. RESULTS The study group comprised 30 female and 30 male IVDs (mean age ± SD: 51.4 ± 19.5). Specimen's age, macroscopic and microscopic degeneration correlated negatively with the number of MCCs (r = -0.33-(-0.95); p < 0.0001), apart from the MCCs > 300 μm in diameter (r = 0.66-0.79; p < 0.0001). The negative relationship was strongest for the MCCs 10-50 μm in diameter. CONCLUSIONS There is a strong negative correlation between the number of endplate MCCs, and both macroscopic and microscopic cervical IVD and endplate degeneration. This could further support the thesis that endplate calcification, through the occlusion of MCCs, leads to a fall in nutrient transport to the IVD, and subsequently causes its degeneration.