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14th Triennial Congress of the International Federation of Societies for Surgery of the Hand (IFSSH), 11th Triennial Congress of the International Federation of Societies for Hand Therapy (IFSHT)

17.06. - 21.06.2019, Berlin

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Stress behavior in CMC thumb in Bennet’s fracture: Finite element analysis

Meeting Abstract

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  • presenting/speaker Carlos Torres - Hospital de San José, Eciplast, Bogotá, Colombia
  • Mauricio Toro - Techfit, Sampedro Inc., Bogotá, Colombia
  • Carlos Morales - Hospital de San José, Eciplast, Bogotá, Colombia

International Federation of Societies for Surgery of the Hand. International Federation of Societies for Hand Therapy. 14th Triennial Congress of the International Federation of Societies for Surgery of the Hand (IFSSH), 11th Triennial Congress of the International Federation of Societies for Hand Therapy (IFSHT), 11th Triennial Congress of the International Federation of Societies for Hand Therapy (IFSHT). Berlin, 17.-21.06.2019. Düsseldorf: German Medical Science GMS Publishing House; 2020. DocIFSSH19-784

doi: 10.3205/19ifssh1058, urn:nbn:de:0183-19ifssh10589

Published: February 6, 2020

© 2020 Torres et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.

Outline

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Objectives/Interrogation: Evaluate the effort that occurs in a normal CMC thumb during grip and index-thumb pinch in comparison with a joint with a Bennett’s fracture.

Methods: A 3D reconstruction using the Mimics® software was performed on images obtained by CT of a healthy right hand. A solid model was generated using design software to perform the finite element analysis. Subsequently, we proceeded to simulate a Bennett's fracture by performing an axial cut corresponding to 1/6 of the articular surface of the first metacarpal and removing the resulting fragmentThe software used for the simulation by finite elements was Ansys®. The solid models were assigned cortical bone and cartilage properties as appropriate: a Young's modulus of 18 GPa and a Poisson's coefficient of 0.2 for bone (Gíslason, Stansfield, & Nash, 2010), and a Young's modulus. of 10MPa and a Poisson's coefficient of 0.45 for cartilage (Carrigan, Whiteside, Pichora, & Small, 2003). Both between the cartilage with the trapezius, and between the cartilage and the metacarpal, a rigid fixation contact was established.

The next step was to generate the mesh which was refined in the contact surfaces with 0.4 mm elements to improve the analysis in those points. Subsequently, an axial compression force was applied on the distal articular surface of the metacarpal as illustrated in Figure 3, with a value of 66.1 N simulating the force that is exerted on the metacarpophalangeal joint when grip force is made. To simulate the role of the ligaments that stabilize the joint when making a clamp, the movement of it was limited only on the axial axis of the metacarpal.

Results and Conclusions: The simulated model does not show a significant difference between the efforts that occur in the joint when it is healthy or when it presents a Bennett type fracture, which seems to indicate that in this type of fractures the joint is not subjected to greater stresses than those who would be subjected in a normal situation.

It could support the advantages of the P.O.L.A.R technique (presented in other abstract).