Table 8.

Results of the assessment of adjacent-segment degeneration according to the classification of Kellgren [19]

	Second cephalad level	First cephalad level	First caudal levela	Second caudal levelb
Injury	0.19 ± 0.63 (0–3)	0.65 ± 0.98 (0–3)	0.67 ± 1.1 (0–4)	1.15 ± 1.4 (0–4)
Follow-up	0.23 ± 0.65 (0–4)	1.46 ± 1.42 (0–4)	1.22 ± 1.31 (0–4)	1.17 ± 1.75 (0–4)
Progression	0.04 ± 0.2 (0–1)	0.81 ± 0.85 (0–3)	0.61 ± 0.72 (0–2)	0.27 ± 0.65 (0–2)

^a7.7 and 11.5% of fusions did not have a cervical first adjacent-caudal level and could not be assessed on injury or follow-up radiographs, respectively

^b15.4 and 53.8% of fusions did not have second adjacent-caudal levels and could not be assessed on injury or follow-up radiographs, respectively