Figure 4: Range of motion at L4-L5 in intact and fixation models under six operation conditions. The ROM was smaller in all internal fixation groups than in the intact group. Furthermore, the ROM was smaller in the ELIF + UPS group than in the TLIF + UPS group, under all operating conditions, especially left lateral flexion and right rotation. The ROM was smaller in the TLIF + BPS group than in the ELIF + UPS group. Similarly, in the ELIF + UPS + TLFS group, the ROMs were much smaller than those in the ELIF + UPS group. When compared with the TLIF + BPS group, the ROM in the ELIF + UPS + TLFS group shows no obvious difference in the range of experimental loading. AF: anterior flexion; PE: posterior extension; LF: left lateral flexion; RF: right lateral flexion; LR: left rotation; RR: right rotation.