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Fig. 3 | Journal of Orthopaedic Surgery and Research

Fig. 3

From: Pedicle screw loosening: the value of radiological imagings and the identification of risk factors assessed by extraction torque during screw removal surgery

Fig. 3

Analyzing risk factors for low extraction torque of pedicle screw. a No significant difference was found between polyaxial and monoaxial screws. p = 0.673, Mann-Whitney Test. b There were significant differences of screw extraction torque among different fixation segments. Screws inserted in the lumbosacral junction (L4, L5, and S1) showed the highest torque. L lumbar vertebrae, S sacrum, T thoracic vertebrae. *p < 0.001, Kruskal-Wallis test. c Screw placed in fractured vertebrae showed significantly lower extraction torque than those in non-fractured vertebrae. *p = 0.009, Mann-Whitney Test. d There was no significant difference regarding extraction torque between screws placed in the end segments and those in the mid segments. p = 0.437, Mann-Whitney Test. e Extraction torques of pedicle screw after fusion surgery (n = 142) were significantly higher than those in non-fusion surgery. *p = 0.001, Mann-Whitney Test. f No significant difference of extraction torque was found among different screw diameter. p = 0.988, Mann-Whitney Test. g No significant difference of extraction torque was found among different screw length. p = 0.746, Kruskal-Wallis test

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