. 2018 Feb 20;30(2):271–276. doi: 10.1589/jpts.30.271

Table 2. Initial, 2-month, 6-month, and 2.5 year follow-up assessment results for radiographic parameters.

Variable	Normal	Initial	2nd exam	6-month	2.5-year
	values^{41, 42)}	exam		f/up	f/up
		7-21-04	9-27-04	1-15-05	3-12-07
ARA C2–C7*	−34–42°	−25°	−31°	31°	−30°
TzH**	0–15 mm	59 mm	39.5 mm	46 mm	46 mm
APL***	−24–29°	3°	−6°	−4°	−4°
RRA C2–C3⁺	−7–9°	−2°	−3°	−4°	−4°
RRA C3–C4⁺	−6–8°	−3°	−4°	−7°	−6°
RRA C4–C5⁺	‘−6–8°	−8°	−12°	−9°	−9°
RRA C5–C6⁺	‘−6–8°	0°⁺⁺	0°⁺⁺	0°⁺⁺	0°⁺⁺
RRA C6–C7⁺	‘−6–8°	−12°	−12°	−11°	‘−11°

*ARA: Absolute rotation angle between posterior vertebral body tangents on C2 and C7. Negative values indicate spinal extension.

**TzH: Forward head translation distance: Horizontal distance of C2 posterior-superior body corner to posterior-inferior body corner of C7.

***APL: Atlas plane line: Angle between estimated cross-section of C1 to horizontal (negative indicates backward rotation compared to horizontal).

+ RRA: Relative rotation angle (segmental angle between posterior tangents). Negative values indicate spinal extension.

++ The C5–C6 segment is the one that is fused in this patient and no movement is possible.