Scoliosis Measurement with Cobb's Method

                     The Cobb Angle is Angle used as a standard measurement to determine and track the progression of scoliosis. it is a very Generalised and common method used by Physiotherapists now a day. Scoliosis of the vertebral column can be assessed with the Cobb's angle.

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                       Cobb's Angle suggests that the angle of curvature can be measured by drawing lines parallel to the upper border of the upper Displaced vertebral body and the lower border of the lowest Displaced vertebra of the structural curve, then erecting perpendiculars from these lines to cross each other, the angle between these perpendiculars being the ‘angle of curvature’.

                              In Above Images, Figures A and B are showing measuring Procedure for Scoliosis with the help of cobb's Angle. Figure B is showing implement of Cobb's Angle On X-Ray View. Sometimes  Hyperkyphosis (it is a kyphotic angle) of greater than 40° commonly measured by the Cobb method.

Measurement of Spinal Curvature for Scoliosis With the Cobb method

1. an anteroposterior view of X-ray is used.
2. A line is drawn parallel to the superior cortical plate of the proximal end vertebra and to the inferior cortical plate of the distal end vertebra. 
3. A perpendicular line is erected to each of these lines, and the angle of intersection of the perpendicular lines is the angle of spinal curvature resulting from scoliosis.
 Such techniques have led the Scoliosis Research Society to classify all forms of scoliosis according to the degree of curvature:

  1. group 1, 0° to 20°; 
  2. group 2, 21° to 30°; 
  3. group 3, 31° to 50°;
  4. group 4, 51° to 75°; 
  5. group 5, 76° to 100°;
  6. group 6, 101°to 125°; 
  7. group 7, 126° or greater.

                           Other noninvasive methods of measuring the curve have been adviced. However, the examiner should use the same method each time for consistency and reliability. The rotation of the vertebrae may also be estimated from an anteroposterior view.  
                            This estimation is best done by the pedicle method, in which the examiner determines the relation of the pedicles to the lateral margins of the vertebral bodies. If rotation is evident, the pedicles appear to move laterally toward the concavity of the curve. The vertebra is in a neutral position when the pedicles appear to be at equal distance from the lateral margin of the peripheral bodies on the film.

According to Cobb's Angle Severity

Not scoliosis
Mild scoliosis
10 - 30°
Moderate scoliosis
30 - 45°
Severe scoliosis

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