Effect of age and lordotic angle on the level of lumbar disc herniation

Abstract

It has been previously suggested in the literature that with aging, degenerative changes as well as disc herniation start at the lower lumbar segments, with higher disc involvement observed in an ascending fashion in older age groups. We conducted a study to investigate this correlation between age and level of disc herniation, and to associate it with the magnitude of the Lumbar Lordotic Angle (LLA), as measured by Cobb's method. We followed retrospectively lumbosacral spine MRI's of 1419 patients with symptomatic disc herniation. Pearson's correlation was used in order to investigate the relationship between LLA, age, and level of disc herniation. Student's t-test was applied to assess gender differences. Young patients were found to have higher LLA (R = 0.44, P < 0.0001) and lower levels of disc herniation (R = 0.302, P < 0.0001), whereas older patients had higher level herniation in lower LLA group (mean LLA 28.6° and 25.4°) and lower level herniation in high LLA group (mean LLA 33.2°). We concluded that Lumbar lordotic Cobb's angle and age can be predictors of the level of lumbar disc herniation. This did not differ among men and women (R = 0.341, P < 0.0001).

Figure 1

Measurement of lumbar lordotic angle α. Using Cobb's method, tangent lines are drawn along the superior end pated of L1 and S1. Perpendiculars to each of the lines are added to form α.

Figure 2

Lumbar disc herniation and lumbar disc degeneration versus age. The numbers in the figure correspond to different mean ages (±SEM) with respect to disc herniation and degeneration levels. The level of lumbar disc herniation and degeneration increased with age.

Figure 3

Level of lumbar disc herniation versus age and lumbar lordotic Cobb's angle. (a) The numbers in the figure correspond to different mean ages (±SEM) with respect to disc herniation levels. There is a significant increase in age as the lumbar disc herniation moves in the cranial direction. (b) The numbers in the figure correspond to the measured mean angles (±SEM) at different lumbar levels. The angle tends to decrease according to the lumbar disc herniation level in the cranial direction.

Figure 4

Lumbar lordotic Cobb's angle and decades of life. The numbers in the figure correspond to the mean angles (±SEM) at different decade of life. It shows a decrease in the magnitude of LLA with age.

Figure 5

Number of disc degeneration and age. The numbers in the figure correspond to different mean ages (±SEM) with respect to the number of degenerated discs. There is a significant increase in that number with aging.