The Choice Of Caudal Extent In Long Fusions Arthrodesis Stopping At L5 For Adult Scoliosis: A Systematic Review

Long fusions arthrodesis surgery for adult scoliosis has shown good clinical results as an important surgical procedure.However,the controversies with reference to the potential caudal extents of the fusion still exist.There were several choices for caudal extents: L5,S1,Iliac screws or S2 alar-iliac(S2AI)screws.The focus of the controversy is the complications and severity of them from different caudal extents.There are some obvious advantages for caudal extent to L5 versus S1: decreasing operative time and bleeding,preserving the motion of lumbosacral region,lower incidence of pseudarthrosis and screw-related complications.However,there are also some complications occurred,such as secondary disc accelerated degeneration,secondary sagittal imbalance,and loss of lumbar lordosis.These complications are often not independent,whereas they are communicated with each other and they are risk factors for each other.Fusion to S1 reduces the above complications,but due to stress concentration and other reasons,the incidence of the pseudarthrosis and screw-related complications increase.Pseudarthrosis and screw-related complications often occur together and promote mutually.To solve a series of complications associated with the fusion of S1,surgeons have begun to explore the method of fusion to ilium or pelvis,which is represented by iliac screws or S2 AI screws.The complications of iliac screws are screw prominence,wound dehiscence,and postoperative pain,which limited its application.S2 AI screws hold the similar biomechanical strength with iliac screws,however the incidence of complications is significantly lower.The period of S2 AI screws practice is still short and the long-term clinical outcomes and complications are still to be further observed.