cancellous bone screw 

Cancellous screw is divided into two types,full thread and half thread, usually partial thread and generally self-tapping screw.  Cancellous bone is at the bony end,and cannulated screws are generally used at the bony end.The bone density of cancellous bone is lower than that of cortical bone,but it is elastic.The scaffolding structure of cancellous bone helps maintain skeletal morphology,resists stress,and constitutes the majority of axial bones such as the skull,ribs,and spine. Characteristics and Advantages Larger outer diameter,deeper threads,wider thread spacing,for epiphysis use.The anterior part of the trauma screw is provided with a cancellous bone thread,which is characterized by a posterior end thread on the screw inside the tail screw cap that rotates in the same direction as the anterior cancellous bone thread.Its advantages are to enhance the compression effect of the screw,fill the residual gap of the front thread,and prevent long-term withdra…