Abstract:

BACKGROUND: Compared with the metal screws, absorbable screws have more obvious advantages, such as does not have to conduct internal fixation removal, non-metallic components, no influence on the magnetic resonance imaging of patients after implantation, relatively simple operations, namely drilling-tapping-screws fixation, more in line with the principles of minimally invasive in orthopedics.
OBJECTIVE: To investigate the biomechanical characteristics of absorbable screw fixation in repair of simple lateral malleolus fractures by means of finite element technology.
METHODS: The three-dimensional model of simple lateral malleolus fractures and absorbable screw model were established, and then fixed according to standard orthopedic surgical techniques. The reference load when the load bearing of fibulotalar joint reaching the peak value in a normal adult gait cycle was loaded. The stress distribution and displacement of fibula and absorbable screws were analyzed.
RESULTS AND CONCLUSION: There were totally 38 542 units, 8 790 nodes in the single screw fixation model. When the articular facet of lateral malleolus loading 300 N, the maximum stress of screws was 89.35 MPa, the maximum displacement was 0.5 mm, the maximum displacement of the distal fracture was 0.5 mm. When the articular facet of lateral malleolus loading 450 N, the maximum stress of screws was 152.58 MPa, the maximum displacement was 0.59 mm, the maximum displacement of the distal fracture was 0.77 mm. There were totally 43 115 units, 9 496 nodes in the double screws fixation model. When the articular facet of lateral malleolus loading 300 N, the maximum stress of screws was 38 MPa, the maximum displacement was 0.44 mm, the maximum displacement of the distal fracture was 0.44 mm. When the articular facet of lateral malleolus loading 450 N, the maximum stress of screws was 66.68 MPa, the maximum displacement was 0.48 mm, the maximum displacement of the distal fracture was 0.49 mm. The experiment verified the biomechanical feasibility of absorbable screw fixation in repair of simple lateral malleolus fractures. For simple involving only the lower lateral fibular fracture, absorbable screw fixation is entirely feasible, and usually requires at least two screws to maintain the stability of the articular surface of the reset.