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Abstract

BACKGROUND:

Studies on tibial plateau fractures had gradually focused on “360° stereochemical structure” from medial and lateral “double track structure” nowadays. Scholars pay great attention on the stability and reposition of posterior plateau and functional recovery after reduction. The choice of fixation material of posterior plateau was controversial.

OBJECTIVE:

To discuss the biomechanical characteristics of posterolateral fracture of tibial plateau using three types of internal fixation.

METHODS:

Using three-dimensional finite element analysis, we simulated 1/2 and 1/4 posterolateral tibial plateau fractures. Three types of internal fixation were used: two anterior 6.5 mm lag screws, lateral 4.5 mm

METHODS:

L-shape plate, and posterior 3.5 mm T-shape plate. 500 N was loaded at the center of the tibial plateau vertically, and biomechanical status of three types of fixation was compared.

RESULTS AND CONCLUSION:

In 1/2 fracture model, anterior lag screw group and posterior plate group gained least displacement in all directions, as lateral plate group gained more. In 1/4 model, the advantage in displacement of anterior lag screw group was more apparent, the second was posterior plate group, and the last was lateral plate group. In 1/2 fracture model, the maximum stress of anterior lag screw was 36.523 MPa, which of lateral plate group was 153.372 MPa and posterior plate group was 115.922 MPa. The maximum stress left in the separate bone of lag screw group was 4.309 MPa, which of lateral plate group was 4.37 MPa and posterior plate group was 3.124 MPa. In 1/4 fracture model, the maximum stress of anterior lag screw was 36.803 MPa, which of lateral plate group was 153.336 MPa and posterior plate group was 104.234 MPa. The maximum stress left in the separate bone of lag screw group was 1.195 MPa, which of lateral plate group was 0.827 MPa and posterior plate group was 1.196 MPa. Results indicated that anterior lag screw could bear more stress and gained least displacement after loading, and the fixation was more stable. Posterior plate can give more stabilization when the separate bone was bigger (1/2), similar to anterior lag screw. When the separate bone was smaller (1/4), posterior plate model was less stable than anterior lag screw. Lateral plate model, with poor stabilization, was the worst choice in three types of fixation.

Subject headings:

tibial fractures; finite element analysis; internal fixators; stress, mechanical

Funding:

the Shanghai Pudong District Science and Technology Development Innovation Project, No. PKJ2011-Y9; the Academic Leaders of Health System Project of Shanghai Pudong District, No. PWRd2012-16

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