Fig. 5.

Average ROM at UIV (T8–T9) as a percentage of total ROM. After instrumenting a two-level fusion from T9 to T11, ROM at T8–T9 increased significantly, as expected, for all but lateral bending (*p < 0.05). After instrumenting the UIV with bilateral hooks, hybrid hook–screw, and bilateral screws, there was a significant decrease in the percent of motion carried at the segment (^# p < 0.01). Hooks allowed significantly more motion at the UIV when compared with hybrid in flexion, and both hybrid and hooks in left bending and torsion (^† p < 0.05). Abbreviations: ROM, range of motion; UIV, upper-instrumented vertebrae.