Table 1.

Characteristics of various classes of cervical maturation degree

Stages		CS1	CS2	CS3	CS4	CS5	CS6
Inferior border concavity*	Vertebra
	C2	Absent	Present	Present	Present	Present	Present
	C3	Absent	Absent	Present	Present	Present	Present
	C4	Absent	Absent	Absent	Present	Present	Present
Body form†	C3	Trapezoid	Trapezoid	Trapezoid orHorizontal-rhomboid	Horizontal-rhomboid	Square‡ orHorizontal-rhomboid	Vertical-rhomboidor Square‡
	C4	Trapezoid	Trapezoid	Trapezoid orHorizontal-rhomboid	Horizontal-rhomboid	Square‡ orHorizontal-rhomboid	Vertical-rhomboidor Square‡

CS, cervical stage.

*Inferior border concavity is assessed by measuring the distance between the central point of the concavity and the line drawn from the outer endpoint of the inferior border, which is tangent to the most inferior point of the inferior border. A concavity characterizes a concave inferior border in the middle of the inferior vertebral border that is at least 7% of the length of the line connecting the two endpoints of the inferior border with an error range of 0.2% (based on the measurements conducted on the radiographic samples presented by McNamara et al.³).

^†In stages CS3, CS5, and CS6, the morphology of at least one of the vertebrae, either C3 or C4, must be characteristic (the bolded body form).

^‡A square morphology is characterized by equal length and width with an error range of 10%. The vertebra’s length is assessed by measuring the distance between the middle point of the superior border and the middle point of the line connecting the two end points of the inferior border. The width of the vertebra is assessed by measuring the distance between the middle points of the lateral borders.