Table A1.

Neck motion as described in the medical records.

Case number	Neck motion	Information from the medical records	Follow up time (months)
1	Minor limitation in range of motion	Painless, full range of motion except for neck extension.	57
2	Full range of motion	Range of motion of cervical spine almost 100%.	31
3	Full range of motion	Range of motion of cervical spine almost 100%. Some stiffness of the neck.	48
4	Not reported	Not reported due to progression of systemic disease.	NA
5	Minor limitation in range of motion	Limited range of motion, in particular for neck extension and rotations.	42
6	Full range of motion	Full rotations possible in the neck.	6
7	Minor limitation in range of motion	Limited range of motion due to general neck stiffness.	11
8	Minor limitation in range of motion	Limited range of motion in rotations and extensions of the neck.	47
9	Early removal	Early removal due to rapid progression of disease.	NA
10	Full range of motion	No complaints in neck movement.	8
11	Minor limitation in range of motion	Limited range of motion in neck extension.	31
12	Major limitation in range of motion	Limited range of motion due to pain during movement. (this patient received spondylodesis surgery)	27
13	Early removal	Early removal due to rapid progression of disease.	NA
14	Full range of motion	Full range of motion of the neck.	78
15	Early removal	Patient died 43 days after halo fixation due to perforated diverticulitis.	NA
16	Minor limitation in range of motion	Range of motion somewhat limited in rotations.	115
17	Minor limitation in range of motion	Hesitant to move beyond current limited range of motion.	17
18	Minor limitation in range of motion	Limited mobility of the neck during daily activies, for example navigating traffic.	20
19	Full range of motion	Range of motion of cervical spine almost 100%.	8
20	Early removal	Early removal due to rapid progression of disease.	NA