ABSTRACT

Sagittal plane inclinations of the lumbar vertebrae are changeable due to the position of the patients du-ring surgery when compared with preoperative x-rays. In this study, sagittal inclination and lordosis of lumbar area in prone position is searched. Radiographs are taken at right lateral decubitis (LD) and prone decubi-tis (PD) position from 30 volunteers (mean age 29 ye-ars old) without low back complaint. The position of the patient during the radiographs is similar to the pro-ne position during surgery with semi-rigid pillows. Sa-gittalplane inclination (SPI) of each vertebra were me-asured manually on both LD and PD position radiographs. Values were analysed statistically by paired t test. SPI of the L1 vertebra at LD and PD position we-re measured +19.8 degree and +14.3 degree as mean values respectively (p<0.001). SPI of the L2 vertebra were measured as +16.0 degree as mean value at LD position and +13.1 degree mean value at PD position (p=0.017). Values of lumbar lordosis were measured as 38.7 degree mean value at LD position and 28.4 degree mean value at PD position (p<0.001). There are no statistically significant diffe-rences between groups of patients L3, L4 and L5 le-vel. Lumbar vertebrae have greaterrange of motion at sagittal plane. According to our results upper lumbar vertebrae have more prominent movement when the patient’s position is changed to PD from LD and with the decreasing of lumbar lordosis. During the applica-tion of transpedicular screw fixation for posterior inst-rumentation especially in the upper lumbar vertebrae level, it should be remembered that preoperative ro-entgenograms may not reflect the current orientation of vertebrae in sagittal plan.