Cobb's Angle

This is nomenclature used by a physician to describe a method of which to measure the degree angle of the spinal curve. The Cobb’s method is the accepted standard technique for measuring the scolotic curve worldwide. The technique consists of four lines constructing a geometric figure. To construct the superior aspect of the diagram, a line is drawn along the superior edge of the vertebra, (the end plate of the vertebra); this line is extended into the margin of the X-ray (Line “A”). A second line is drawn downward perpendicular to the superior line, forming a right angle (Line “B”). Next step is to construct a line along the inferior vertebra, (the end plate of the vertebra); this line is extended into the margin of the X-ray (Line “C”). A second line is drawn upward perpendicular to the inferior line (Line “D”). The angle that is formed by the two meeting perpendicular lines is the Cobb’s angle.
Identifying the superior and inferior vertebra is somewhat difficult. First one must identify the vertebra located at the apex of the curve. This vertebra is the most lateral displaced and rotated with the lest amount of tilted end plate from a line that’s projected from the center of the head to the center of the pelvis. The end vertebras are the most superior and inferior vertebras that are least displace from the centerline and have the maximum end plate tilt. Your physician identifies these area and calculate the degrees of cures. Each physician may develop his or her own computation. A plus or minus of 5 degrees is the common appetence of curve calculation error.