Background:

Adjacent segmental degeneration (ASD) is one of the common complications following posterior lumbar interbody fusion (PLIF). Both whole body vibration (WBV) and osteoporosis are important factors associated with the biomechanics of the lumbar spine. However, up to now, no literature has been published to investigate the effect of osteoporosis on ASD following PLIF under WBV.

Methods:

In the current study, based on one normal model, one PLIF model and one PLIF with osteoporosis model of L1-S1 segment were developed. A 5 Hz, 40N sinusoidal vertical load was imposed on the superior surface of L1 of each model to simulate WBV, and dynamic responses and maximal values of intradiscal pressure, shear stress on annulus fibrosus, total deformation, and disc bulge were evaluated in L1-L2, L2-L3, L3-L4, and L5-S1 segments.

Results:

At L1-L2, L2-L3, and L3-L4 levels, the differences of dynamic responses and maximal values in intradiscal pressure, shear stress, total deformation, and disc bulge between the PLIF and PLIF with osteoporosis models were slight. However, at L5-S1 level the dynamic response curves and maximal values of intradiscal pressure, shear stress, and disc bulge in PLIF with osteoporosis model were significantly lower than those in PLIF model.

Conclusions:

Osteoporosis can mitigate the development of ASD in the lower adjacent segment, but has no obvious influence on the upper adjacent segments during WBV.