Measurement of Vertebral Compression and Kyphosis in the Thoracolumbar and Lumbar Fractures

ABSTRACT

STUDY DESIGN: A retrospective radiologic study. OBJECTIVES: We wanted to compare the compression ratio and kyphosis of thoracolumbar and lumbar fractures according to the radiologic measuring methods and we wanted to analyze their relationship with the stability of fracture. SUMMARY OF THE LITERATURE REVIEW There are several methods for measuring the compression ratio and kyphotic angle in thoracolumbar fractures, but no definitive measurements and no different values according to the stability have been established. MATERIALS AND METHODS: From July 2002 to August 2008, the plain films, CT, MRI and medical records of thoracolumbar and lumbar fracture were reviewed. The compression ratio and kyphotic angle were calculated by several different formulas with using the lateral view of the plain X-ray film, the sagittal reconstruction image of CT and the sagittal image of MRI and the results were compared. Each subject was classified according to both McAfee's classification and the TLISS classification. RESULTS: Two hundred forty eight vertebral bodies of 205 thoracolumbar fracture patients were analyzed. The compression ratio according to formula 1, which was calculated as 1-anterior vertebral height/posterior vertebral height, was significantly correlated with Cobb's angle and the local kyphotic angle. There was no significant difference between the Cobb's angle calculated using the lateral X-ray and that using the sagittal view of CT; however, it was significantly less using the sagittal MRI view. The unstable fractures according to McAfee's classification showed a significantly higher compression ratio and kyphotic angle compared to those of the stable fractures. CONCLUSIONS: The compression ratio formula 1 was most significantly correlated with the kyphotic deformity. The unstable fractures showed a mean compression ratio higher than 30%, a mean Cobb's angle of 15degrees and local kyphotic angle of 18degrees. The sagittally reconstructed CT was a useful measuring method for the evaluation of kyphotic deformity, and it was more accurate than that of the plain film.