Wu X, et al. - Authors estimated 33 individuals to classify the risk factors for low extraction torque of pedicle screw which might cause loosening and also to investigate the prevalence of pedicle screw loosening according to extraction torque during screw removal surgery and to assess the sensitivity and specificity of both X-ray and CT scan to diagnose screw loosening. They estimated fixation stability through X-ray and CT scan 2 years after primary surgery. They observed 33% of the loosening rate. They also calculated a sensitivity of 24% and a specificity of 98% with X-ray and 22% and 96% of sensitivity and specificity in CT scan respectively. They suggested the surgeons be more careful while evaluating screw loosening merely according to radiological examination because screws in fractured vertebrae or non-fusion surgery were ordinarily observed vulnerable to loosening.