Advance in the study of distal junctional problem after thoracolumbar surgery

Distal junctional problem (DJP) is one of the severe complications after spinal correction, fixation and fusion. As the number of patients receiving spinal surgery increased recently, the incidence of DJP also increased dramatically. Compared with proximal junctional problem, the incidence of DJP is low. However, the clinical symptoms are severe, and the rate of surgical revision is high in patients with distal junctional problems. DJP include distal junctional kyphosis (DJK) and distal junctional failure(DJF). The definition of DJK is confusing, however, and the most commonly used was that the distal junction Angle at the last follow-up was greater than 10° and increased by 10° compared with that before surgery. There are 6 DJF modes: progressive loss of lumbar lordosis,acute wedging in the disc below the instrumentation, fracture of LIV, osteoporotic fracture below the long rigid fixation, failure of the instrumentation at LIV, spinal stenosis and or segmental instability underneath the instrumentation. Possible risk factors for DJP include weight, age, type of spinal deformity, osteoporosis, choice of LIV, hip disease, deformity location, surgical approach, surgical procedure, fusion segments, fixation devices, LIV at L5, fixed to S1 with no iliac screws, poor restoration of spinal alignment, et al. Currently, there are some controversies in DJP, mainly including the incidence, risk factors whether needs to and how to revise. The review intends to conduct a simple literature review of the current DJP diagnostic criteria, incidence, risk factors, and other research progress, in order to improve the understanding of the distal junction problem.