SIGNIFICANT ROENTGENOGRAPHIC PARAMETERS FOR EVALUATING THE FLEXIBILITY OF ACUTE THORACOLUMBAR BURST FRACTURES - AN IN-VITRO STUDY

Plain lateral radiographs in a neutral position were studied in ten ac ute thoracolumbar burst fractures produced by high speed impact on thr ee vertebrae human cadaveric spine segments. Six linear geometric para meters were measured on each film. The ratio of each value in the neut ral injured to the intact condition was correlated linearly with the m otion parameters obtained from post-traumatic three-dimensional flexib ility data (neutral zone NZ; range of motion ROM). Anterior unit heigh t (vertebra + adjacent discs) had the highest correlation with the neu tral zone and flexibility in all directions, especially flexion-extens ion (NZ, R-2 = 0.93; flexion ROM, R-2 = 0.86, extension ROM, R-2 = 0.7 9) lateral bending (NZ, R-2 = 0.83; ROM, R-2 = 0.90) and right axial r otation (NZ, R-2 = 0.53; ROM, R-2 = 0.86). The deformation ratio (aver age height to depth) correlated most with the neutral zone in left axi al rotation (R-2 = 0.91) and right lateral bending (R-2 = 0.92). Due t o the high correlations obtained these parameters should be evaluated in clinical situations To assess their effectiveness in predicting the instability of burst fractures. Ultimately, prospective clinical stud ies are required to verify their clinical utility.