Prediction of posterior ligamentous complex injury in thoracolumbar fractures using non-MRI imaging techniques

Purpose We aimed to formulate a radiological index based on plain radiographs and computer tomography (CT) to reliably detect posterior ligamentous complex (PLC) injury without need for MRI. Methods Sixty out of 148 consecutive thoracolumbar fractures with doubtful PLC were assessed with MRI, CT and radiographs. PLC injury was assessed with the following radiological parameters: superior-inferior end plate angle (SIEA), vertebral body height (BH), local kyphosis (LK), inter-spinous distance (ISD) and inter-pedicular distance (IPD) and correlated with MRI findings of PLC injury. Statistical analysis was performed to identify the predictive values for the parameters to identify PLC damage. Results MRI identified PLC injury in 25/60 cases. The ISD and LK were found to be significant predictors of PLC injury. On radiographs the mean LK with PLC damage was 25.86 degrees compared to 21.02 degrees with an intact PLC (p = 0.006). The ISD difference was 6.70 mm in cases with PLC damage compared to 2.86 mm with an intact PLC (p = 0.011). In CT images, the mean LK with PLC damage was 22.96 degrees compared to 18.44 degrees with an intact PLC (p = 0.019). The ISD difference was 3.10 mm with PLC damage compared to 1.62 mm without PLC damage (p = 0.005). Conclusions On plain radiographs the presence of LK greater than 20 degrees(CI 64-95) and ISD difference greater than 2 mm (CI 70-97) can predict PLC injury. These guidelines may be utilised in the emergency room especially when the associated cost, availability and time delay in performing MRI are a concern.