Table 2.

The von-Mises stress on the structures of the L4–5 spine in the flexion mode when the disc height was reduced to 75% and 50% compared to normal (100%).

Component		The 50% anterior disc model, MPa (a)	The 75% anterior disc model, MPa (b)	The 100% anterior disc model, MPa (c)	Rate of change [(a-c)/c ∗ 100] (%)	The 50% posterior disc model, MPa (d)	The 75% posterior disc model, MPa (e)	The 100% posterior disc model, MPa (f)	Rate of change [(d-f)/f ∗ 100] (%)
Cortical bone	L4	1.6156	1.4583	1.3132	23.03∗	1.0364	1.1683	1.3132	−21.08
	L5	1.2441	1.1806	1.1147	11.61∗	1.0202	1.0689	1.1147	−8.48
Cancellous bone	L4	0.0983	0.0935	0.0870	13.01∗	0.0785	0.0835	0.0870	−9.82
	L5	0.0846	0.0878	0.0886	−4.48	0.0888	0.0888	0.0886	0.32∗
Posterior bone	L4	0.5045	0.5271	0.5514	−8.50	0.4352	0.5064	0.5514	−21.07
	L5	0.6889	0.6768	0.6636	3.80∗	0.6376	0.6526	0.6636	−3.91
Endplate (upper)	L4–5	1.5277	1.3928	1.2242	24.79∗	0.8875	1.0533	1.2242	−27.50
Endplate (lower)	L4–5	0.9118	0.8047	0.7028	29.75∗	0.5642	0.6352	0.7028	−19.72
Disc (outer)	L4–5	0.1805	0.1714	0.1598	12.97∗	0.1434	0.1517	0.1598	−10.25
Disc (inner)	L4–5	0.0388	0.0370	0.0338	14.79∗	0.0283	0.0309	0.0338	−16.09

^∗ indicates that a larger load than normal was received when the disc height was reduced by 50%.