Alternative approach to evaluating lumbar lordosis on direct roentgenograms: projection area per length squared

Several methods have been described to evaluate the degree of lumbar lordosis. However, suggested methods have used non-standardized terminology and landmarks to measure the degree of lumbar lordosis. In the present study a practical method for evaluating the degree of lumbar lordosis is described and, for this purpose, 24 lateral roentgenograms were obtained retrospectively from the archive of Department of Physical Medicine and Rehabilitation, Ondokuz Mayis University, Samsun, Turkey. The length between the superior and inferior angles of the first and fifth lumbar vertebral bodies, and the area behind the lumbar vertebral bodies, were estimated using the point counting and planimetry methods. A new unit, the projection area per length squared (PAL) was described on lateral roentgenograms. The planimetric approach was used as the gold standard in the present study. The point-counting method was also used to estimate the PAL and it was repeated three times to determine the variability of the technique. To evaluate the estimates' accuracy, the results of point-counting were compared with those of the planimetry methods. The PAL changed by between 3.93 and 13.59% for the examined subjects. A high correlation was also noted between the results of the point-counting and planimetry methods (r = 0.997). It is concluded that the PAL approach could provide accurate and reproducible data for evaluating the degree of lumbar lordosis and low back pain.