Fig. 5

Three representative cases illustrate the interrelations among translation, ROM, and COR (Y) at the operated level. a–c Superimpose the flexion and extension radiographs with the alignment of the inferior vertebrae. The vertical distance between the yellow solid and broken lines represents the translation. The angle between the black solid and broken lines defined as the ROM. a Female of 49-year-old patient with C5–C6 as the operated level and 88 months of follow-up. Translation: 0.4 mm; ROM: 6.21°; COR (Y): 102.86%. b Male of 36-year-old patient with C5–C6 as the operated level and 89 months of follow-up. Translation: 1.1 mm; ROM: 10.05°; COR (Y): 90.63%. c Female of 51-year-old patient with C5–C6 as the operated level and 93 months of follow-up. Translation: 1.6 mm; ROM: 12.34°; COR (Y): 62.23%