PMC9873479_01
Trauma computed tomography (CT) and magnetic resonance imaging (MRI) showing increase in condyle-C1 interval (CCI), basion-dens interval (BDI), and retroclival hematoma in cases 1 and 2.
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Supplementary Fig. S2 (online only); then, one continues dissection deep toward the C1 arch and the posterior tubercle of atlas to remove the origin of rectus capitis posterior minor muscle approximately 1 cm laterally from midline. Supplementary Fig. S2 , (online only). 
Postop computed tomography (CT) showing screws and plate. Rotation at the 11-month follow-up. Perioperative image with (1) semispinalis capitis muscle, (2) rectus capitis posterior major and obliquus capitis inferior muscle, and (3) semispinalis cervicis muscle.
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Supplementary Fig. S3 (online only). 
PMC9873479_02
Yellow (1): basion-dens interval (BDI). Purple (2): condyle-C1 interval (CCI). Green (3): basion-axis interval (BAI) (PAL = posterior axial line). Blue (4): powers ratio (BP/OA).
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PMC9873479_02_10-1055-s-0043-1760830-i22aug0058-1.jpg
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Supplementary Fig. S1 (online only). 
Trauma computed tomography (CT) and magnetic resonance imaging (MRI) showing increase in condyle-C1 interval (CCI), basion-dens interval (BDI), and retroclival hematoma in cases 1 and 2.
10-1055-s-0043-1760830-i22aug0058-2.jpg
PMC9873479_02_10-1055-s-0043-1760830-i22aug0058-2.jpg
FI22aug0058-2
Supplementary Fig. S2 (online only); then, one continues dissection deep toward the C1 arch and the posterior tubercle of atlas to remove the origin of rectus capitis posterior minor muscle approximately 1 cm laterally from midline. Supplementary Fig. S2 , (online only). 
Postop computed tomography (CT) showing screws and plate. Rotation at the 11-month follow-up. Perioperative image with (1) semispinalis capitis muscle, (2) rectus capitis posterior major and obliquus capitis inferior muscle, and (3) semispinalis cervicis muscle.
10-1055-s-0043-1760830-i22aug0058-3.jpg
PMC9873479_02_10-1055-s-0043-1760830-i22aug0058-3.jpg
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Supplementary Fig. S3 (online only). 
Case 2: Postop computed tomography (CT) and magnetic resonance imaging (MRI) at the 8-year follow-up in rotation dexter (dx) and sinister (sn).
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An MRI of C1-C2 showed that the alar ligaments and tectorial membrane were normal and rotation MRI of the CCJ showed 30 degrees of motion in C1-C2 segment (9 degrees dexter, 21 degrees sinister), shown in Fig. 4 .  Supplementary Fig. S4 (online only) by the blue rubber bands. Supplementary Fig. S4 (online only).