[Manufacture and usage of a new rotatometer of spine]

The purposes of this research are to study the changes of some projective points of vertebrae on roentgenogram during consecutive axial rotation and to design and manufacture a new rotatometer of spine for clinical and research work. Using 2 anatomic specimens of normal spines, aged 10 and 17 years. We took anteroposterior roentgenograms for each vertebra during consecutive axial rotation from 0 th 90 degrees. Some projective points on the roentgenograms were selected. Changes of the projective points were measured. The data were analysed with the stepwise regression, linear fitting in a microcomputer. The rotatometer was designed and manufactured upon the linear regressional equation. The results showed that there was an excellent correlation between actual rotation of vertebra and changes of the projective points on anteroposterior roentgenograms. The distances between the center of vertebral pedicle and lateral edge on convex side of vertebra and rotation angle Q were the reliable references which express the actual axial rotation of vertebra. We thought that rotation angle Q was the mark which had advantages of definition, directness, precision and extended measurable range. The 3 sets of graduations were used to measure the segments of T3-6, T7-12 and L1-4 neuromuscular scoliosis, some congenital scoliosis and axial rotation of spine without certain causes in adolescents. Quantitative measurement of scoliotic rotation is very important for determinating and selecting schemes of operations on scoliosis. It is also helpful to predict prognosis of scoliosis and evaluate the results of corrective operations on spinal deformity.