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. 2022 Sep 15:2022:1268774.
doi: 10.1155/2022/1268774. eCollection 2022.

Effect of Calcar Screw in Locking Compression Plate System for Osteoporotic Proximal Humerus Fracture: A Finite Element Analysis Study

Jung-Soo Lee  1   2   3 , Jong Hoon Kim  2   3 , Kwang Gi Kim  1   2   3 , Yong-Cheol Yoon  4
Affiliations

Effect of Calcar Screw in Locking Compression Plate System for Osteoporotic Proximal Humerus Fracture: A Finite Element Analysis Study

Jung-Soo Lee et al. Biomed Res Int. .

Abstract

This study proposes a finite element analysis (FEA) model for complex fractures at the osteoporotic proximal humerus and investigates the relevance of using a calcar screw in surgical treatments using this model. Two types of three-dimensional (3D) fracture models of patients with osteoporotic humerus were constructed reflecting the mechanical properties of the osteoporotic humerus, such as the Young's modulus and Poisson's ratio, and two load conditions mimicking the clinical environment were applied for simulation. Using the 3D models and the conditions, the FEA software calculated the concentration and distribution of stresses developing in the humerus, locking compression plate (LCP), and screws. Then, we evaluated and predicted the fixed state of a LCP system depending on whether the maximum stress value exceeded tensile strength. When axial force was applied, insertion of the calcar screw led to significant reduction of stress applied on screws in the fracture model having a medial gap by approximately 61%, from 913.20 MPa to 351.84 MPa. Based on the results, it was clearly confirmed that using of calcar screws improved the stability of a three-part fractures and simultaneously reinforced medial support.

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Conflict of interest statement

The authors declare that they have no conflicts of interest.

Figures

Figure 1
Figure 1
(a) Overall preprocessing, (b) description of locking compression plate system and proximal humerus, (c) details of four finite element models, and (d) illustration of two types of applied loads.
Figure 2
Figure 2
Comparison of maximum stresses with respect to four different fracture models grouped by the individual finite element models. The red dotted lines represent ultimate tensile strength (UTS) of locking compression plate (LCP) and screw: (a) result of finite element analysis under 500 N of axial force and (b) result of finite element analysis under 500 N/20° of shear force.
Figure 3
Figure 3
Stress maps of model C under axial force conditions: (a) maximum shear stresses on locking screw–cortical bone interface at cortical head and shaft, (b) maximum von-Mises stresses on the locking compression plate, and (c) maximum von-Mises stresses on locking screw.
Figure 4
Figure 4
Stress maps of model C under shear force conditions: (a) maximum shear stresses on locking screw–cortical bone interface at cortical head and shaft, (b) maximum von-Mises stresses on the locking compression plate, and (c) maximum von-Mises stresses on locking screw.
See this image and copyright information in PMC

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