The Vertebral Tropism Unit, A New Research Model Studying Zygoapophysial Joint Tropism in the Spine, Literature Review

Abstract

AIM: To study the effect of Zygoapophysial Joint Tropism in the vertebrae after changing the point of reference by looking into a new research model, the Vertebral Tropism Unit (VTU) and delineate it’s uniqueness. METHODS: 44 papers in the current literature were studied. The endpoint of the research was correlated to the results. The correlation between tropism and fractures, demographics pertaining to age, spinal level, and morbidity were studied in order to study the validity of the VTU model. For the purpose of this study, the sagittal orientation of the Zygoapophysial joints (ZAJ) of 398 vertebrae in 75 patients was measured on MRI scans. RESULTS: 509 ZAJ pairs studied. In 199 Thoracic ZAJ pairs, 121 presented with a fracture, 41% demonstrating tropism; while 78 had no fracture, 42% demonstrating tropism. In 310 Lumbar ZAJ pairs, there were 196 with a fracture, 76% demonstrating tropism; there were 114 with no fracture, 43% demonstrating tropism. CONCLUSION: Our study suggests that if the centre point of reference in the study of tropism is changed to the vertebral body instead of the Intervertebral Disc (IVD), then a correlation between the emergence of pathological fractures in the spine and tropism is evident.