Regeneration, Reconstruction & Restoration (Triple R)

Abstract

Introduction: Occupational whole body vibration (WBV) plays a major role in determining dynamic responses of the lumbar spine. WBV has been shown to cause low-back problems and degenerative disc diseases. Fusion surgery such as trans-formal lumbar inter-body fusion (TLIF) have been widely utilized to treat such disorders.

Materials and Methods: In this study, finite element method (FEM) was used to investigate dynamic responses of the lumbar spine due to WBV with the frequency in the range of regular physiologic activities after TLIF. A FE model of the L1-L5 lumbar spine was modeled and cyclic loading with the frequency of 1 Hz and 5 Hz were exerted to the model. Then, the disc bulge and stress distribution on the annual ground substance and vertebral bodies were measured.

Results: It was observed that the maximum disc bulge (MDB) and maximum von-Mises stress (MMS) occurred in proportion to the loading frequency; overall, in the 5 Hz model, MDB and MMS were detected to happen 5 times more frequently as compared to the 1 Hz model. However, the magnitude of MDB and MMS were not generally affected by the loading frequency.

Conclusions: It can be concluded that different frequency of WBV, although in the physiologic range, can alter dynamic responses of the lumbar spine and, thus, their fatigue behavior. In the results can be of assistance to broaden the understanding regarding the dynamic responses of the lumbar spine during WBV after TLIF.