The Cobb's and Ferguson's methods are widely used in order to measure scoliotic angle using the X-ray photograph. Since the scoliotic angle is detected on the bases of the positions of only two and three spines, the measured value includes various kinds of errors. Thus, the present study was designed to examine accuracy and reliability of the Cobb's and Ferguson's methods. The scoliotic angle corresponding to the Cobb's and Ferguson's method were computed using the least square approximating curve that was obtained on the basis of the positions of spines from thoracic to lumbar vertebrae.
As a result, it was found that the scoliotic angle by means of the clinical Cobb's method was closely correlated to that by the least square method with positive correlation coefficient of 0.98. On the other hands, the Ferguson's method showed less relation to the least square method. Thus, it was confirmed that the Cobb's method was more reliable for diagonsis of the scoliosis.