Table 2.

Comparison of maximum stress values of four groups of models ($\overline{\mathrm{x}}\pm \mathrm{s}$, mPA, P < 0.01)

Working condition	Conservative treatment group	Open surgical treatment group	PKP group	PVP group
Vertical load	11.97 ± 4.29	11.61 ± 3.26	10.87 ± 1.98	10.67 ± 5.17
Anteflexion	42.24 ± 7.92	41.87 ± 9.03	35.10 ± 6.09	37.27 ± 2.92
Extension	42.72 ± 6.28	41.64 ± 7.35	39.79 ± 8.03	38.07 ± 5.58
Left flexion	54.49 ± 8.01	42.72 ± 3.65	36.24 ± 3.97	37.31 ± 4.12
Right flexion	52.63 ± 6.77	41.70 ± 7.02	35.03 ± 2.55	38.20 ± 2.84
Left rotation	16.17 ± 5.11	13.22 ± 1.60	13.24 ± 2.04	13.18 ± 2.13
Right rotation	14.42 ± 2.15	11.74 ± 1.04	11.55 ± 0.99	11.72 ± 1.79