To evaluate the efficacy of X-ray plain film and computed tomography in detecting posterior ligamentous complex injury

English Keywords:Posterior ligamentous complex  Vertebral fracture  Superior and inferior endplate angle  Inter-spinous distance  Logistic models  X-ray

English Abstract:

  【Abstract】 Objectives: To evaluate the efficacy of X-ray plain film and computed tomography in detecting posterior ligamentous complex(PLC) complete rupture through the combination of different parameters by using magnetic resonance imaging(MRI) as a reference. Methods: This was a retrospective review of patients with thoracic or lumbar vertebral fracture treated in the spine surgery department during January 2012 to July 2016. The inclusion criteria included: (1)thoracic or lumbar vertebral fracture; (2)definite history of trauma; (3)performed X-ray plain film, computed tomography and magnetic resonance examination in 5 days after injury. The exclusion criteria included: (1)pathological fracture; (2)old vertebral fracture; (3)combined with spinous process fracture; (4)chance fracture; (5)combined with vertebra dislocation or rotation distinctly; (6)two or more vertebral fractures; (7)congenital or degenerative scoliosis. These patients were divided into two groups according to the appearance of PLC in MRI. Then, parameters with significant difference in two groups were found out and ROC curve was applied to evaluate the diagnostic capacity of different combined parameters. Parallel test and serial test were performed on the combined parameters with supreme diagnostic capacity. Results: 120 out of 600 patients with thoracic or lumbar vertebral fractures were included in this study. There were 78 males and 42 females with an average age of 43.4±16.2 years(range 16-67 years). The cause of injury included traffic accident injury in 62 cases, falling injury in 40 cases and crush injury in 18 cases. The lesion site included thoracic vertebral fracture in 30 cases, lumbar vertebral fracture in 26 cases and thoracolumbar vertebral fracture in 64 cases, among whom 29 cases were with L1 injury as the most frequent segments. There was significant difference in the superior and inferior endplate angle(SIEA) and loss of vertebral body height(LOVBH) on plain and inter-spinous distance difference(ISDF) on CT. The area under ROC curve of SIEA+ISDF was 0.844 and Youden index was 0.675, which showed the highest diagnostic capacity of two-parameter combinations. No significant difference of AUC was found between two-parameter combinations and three-parameter combinations. The sensitivity, specificity, Youden index of the combination of SIEA>20° or ISDF>2mm were 95.3%, 62.8%, 0.581, respectively. Conclusions: The combination of SIEA>20° on plain or ISDF>2mm on CT might be acted as a screening measure in detecting posterior ligamentous complex complete rupture.