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BACKGROUND:Klinefelter nails and external fixation were commonly used treatment methods for Bennett fracture, but study about biomechanics of two methods was little. OBJECTIVE:To establish three-dimensional finite element models of Bennett fracture by Klinefelter nails and external fixation, and analyze its biomechanics. METHODS:Three-dimensional models of Bennett fracture were established by smal external fixation and Kirschner nail treatment. The Bennett fracture models established by smal external fixation treatment were considered as model A. Bennett fracture models established by Kirschner nail treatment were considered as model B. 120 N load was applied to the first metacarpal X-axis direction. The X-direction displacement and total displacement of model A and model B, and the fracture fragments stress of model A and model B were observed. RESULTS AND CONCLUSION:(1) In the X direction, the absolute values of maximum displacement and minimum displacement of model A at proximal fragment and distal fragment were less than model B;the maximum relative displacement, minimum relative displacement and average relative displacement of model A were less than model B. The differences of the average displacement of the proximal fracture fragment and the distal fragment, and the relative mean displacement in two models were statistical y significant (P<0.05). (2) In total displacement, absolute values of the maximum displacement and minimum displacement of model A at proximal fragment were less than model B;absolute values of the maximum displacement and minimum displacement of model A at distal fragment were less than model B;the maximum relative displacement, minimum relative displacement and average relative displacement of model A were less than model B. The differences of the average displacement of the proximal fracture fragment and the distal fragment, and the relative mean displacement in two models were statistical y significant (P<0.05). (3) The maximum stress value, a minimum stress value and the average stress values of fracture fragments of model A were significantly smal er than model B. The difference of the mean stress value in two models was statistical y significant (P<0.05). (4) These findings showed that the X-direction displacement and the total displacement were smal er, and the fracture fragments stress was uniform in smal external fixation and Kirschner nail treatment for Bennett fracture, indicating that smal external fixation for Bennett fracture has more advantages compared with Klinefelter nail.