Biomechanical study of different internal fixations in Pauwels type III femoral neck fracture - A finite elements analysis

Anderson Freitas; Joubert Vieira Toledo Júnior; Adeni Ferreira Dos Santos; Rubén Jeri Aquino; Vitor Negreiro Leão; Weverton Péricles de Alcântara

doi:10.1016/j.jcot.2020.06.006

Biomechanical study of different internal fixations in Pauwels type III femoral neck fracture - A finite elements analysis

J Clin Orthop Trauma. 2020 Jun 9:14:145-150. doi: 10.1016/j.jcot.2020.06.006. eCollection 2021 Mar.

Authors

Anderson Freitas^{1

2}, Joubert Vieira Toledo Júnior¹, Adeni Ferreira Dos Santos¹, Rubén Jeri Aquino¹, Vitor Negreiro Leão¹, Weverton Péricles de Alcântara¹

Affiliations

¹ Hospital Regional do Gama, Brasília, Distrito Federal, Brazil.
² Instituto de Pesquisa e Ensino do Hospital Ortopédico e Medicina Especializada (IPE - H O M E), Brasília, Distrito Federal, Brazil.

Abstract

Objective: To evaluate biomechanical behavior of different internal fixation methods for the treatment of Pauwels Type III femoral neck fractures.

Methods: Three internal fixators were developed to treat Pauwels Type III femoral neck fracture using finite elements: dynamic hip screw (DHS); DHS combined with anti-rotation screw; three cannulated screws in an inverted triangular configuration (ASNIS). Under the same conditions, vertical fracture displacement, and maximum and minimum principal, and Von Mises stresses were evaluated.

Results: The vertical displacements evaluated were: 5.43 mm, 5.33 mm and 6.22 mm, rotational displacements values were 1.1 mm, 0.4 mm and 1.3 mm; maximum principle stress values obtained for the upper region of the femoral neck were 3.26 hPa, 2.77 hPa, and 4.5 hPa, minimum principal stress values obtained for the inferior region of the femoral neck were -1.97 hPa, -1.8 hPa and t -3.15 hPa; Von Mises peak stress values were 340.0 MPa, 315.5 MPa and 326.1 Mpa, for DHS, DHS with anti-rotation device, and ASNIS, respectively. Conclusion: The DHS combined with anti-rotation screw yielded better results in terms of rotational and vertical displacements, traction and compression distributions on fractures, and Von Mises stress, demonstrating mechanical superiority for Pauwels Type III fracture.

Keywords: Biomechanics; Femoral neck fracture; Finite element analysis; Internal fixation.