The course of macroscopic degeneration in the human lumbar intervertebral disc

Study Design. Assessment of age-related macroscopic changes in human lumbar intervertebral discs (IVD) and vertebral bodies. Objectives. To determine the sequence of macroscopic changes during aging/degeneration. Summary of Background Data. Descriptive studies on macroscopic alterations of the IVD during aging/degeneration are readily available, but quantitative analyses are sparse. Methods. A total of 248 mid-parasagittal sections of lumbar IVD and vertebral bodies from 41 routine autopsies (range, 7 months to 88 years) were semiquantitatively assessed for macroscopic parameters and correlated with age. Results. Nuclear fibrous transformation, anular disorganization, endplate, and vertebral body alterations progress predominantly in the first two and in the fifth to seventh decades. In the third and fourth decade, little progression occurs. Nuclear clefts and anular tears appear later, mostly starting in the second decade, with clefts preceding tear formation. Radial and concentric tears develop similarly over time, whereas rim lesions mostly develop after the sixth decade. Significant differences are observed between upper and lower lumbar spine. Conclusion. Our data show that fibrous nuclear transformation during aging/degeneration precedes cleft formation. The temporal sequence suggests a strong correlation of cleft and tears formation starting with clefts in the second decade. Our results support the hypothesis that disc degeneration starts in the nucleus. Extensive macroscopic alterations already apparent in the second life decade present a challenge to any tissue engineering and repair attempt.