Biomechanical study of two alternative methods for the treatment of vertical femoral neck fractures - A finite element analysis

Yutong Xia; Wendong Zhang; Hai Hu; Lianqi Yan; Shi Zhan; Jingcheng Wang

doi:10.1016/j.cmpb.2021.106409

Biomechanical study of two alternative methods for the treatment of vertical femoral neck fractures - A finite element analysis

Comput Methods Programs Biomed. 2021 Nov:211:106409. doi: 10.1016/j.cmpb.2021.106409. Epub 2021 Sep 9.

Authors

Yutong Xia¹, Wendong Zhang², Hai Hu³, Lianqi Yan⁴, Shi Zhan⁵, Jingcheng Wang⁶

Affiliations

¹ Dalian Medical University, Dalian 116044, Liaoning Province, China.
² Department of Orthopedics, Subei People's Hospital of Jiangsu Province, Yangzhou 225001, Jiangsu Province, China.
³ Orthopedic Biomechanical Laboratory of Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
⁴ Department of Orthopedics, Subei People's Hospital of Jiangsu Province, Yangzhou 225001, Jiangsu Province, China. Electronic address: yanlianqi@126.com.
⁵ Orthopedic Biomechanical Laboratory of Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China. Electronic address: zhanshi4890966@yeah.net.
⁶ Dalian Medical University, Dalian 116044, Liaoning Province, China; Department of Orthopedics, Subei People's Hospital of Jiangsu Province, Yangzhou 225001, Jiangsu Province, China. Electronic address: jingchengwang001@163.com.

PMID: 34560605
DOI: 10.1016/j.cmpb.2021.106409

Abstract

Background: No consensus has been reached for the treatment of vertical femoral neck fractures (vFNFs). Recently, two alternative methods were invented to treat vFNFs, one of which is a new plate with a sliding groove, which was designed as a substitution of the medial buttress locking plate to combine with cannulated compression screws (CCS) for reducing the breakage possibility of the proximal locking screw during the bone healing. Another one is the femoral neck system (FNS), which was believed with biomechanical superiority. This study aims to compare the biomechanics of these two new implants with three previous methods via finite element analysis (FEA) to validate whether they are suitable for the treatment of vFNFs.

Methods: Five 70-degree Pauwels type III transcervical FNFs (vFNFs, AO/OTA 31B2.3^r) models were built and fixed by CCS augmented with the newly designed sliding groove buttress plate (CCS+BS) and FNS. For comparison, models fixed by three parallel cannulated compression screws (CCS), biplane double-supported screw fixation (BDSF), CCS augmented with a medial buttress locking plate (CCS+BL) were also built. A 2100N load was applied along with the mechanical axis. Parameters of the maximal stress as well as the maximal displacement of the implants and bone, the maximal relative displacement of interfragments, and the stiffness, were analyzed to compare the biomechanical characteristics of the five models.

Results: CCS+BS and CCS+BL showed stronger fixation strength with improved stiffness (1012.05N/mm, 1092.04N/mm), reduced maximal displacement of the implants (1.976mm, 1.838mm) and bone (2.075mm, 1.923mm), when compared with CCS (925.11N/mm, 2.158mm and 2.270mm) and BDSF (842.36N/mm, 2.299mm and 2.493mm). While FNS showed the weakest stiffness (593.22N/mm) and largest maximal displacement of the implants (3.234mm) and bone (3.540mm) among the five models.

Conclusions: CCS+BS has a better biomechanical performance than CCS and BDSF, which offers a new choice to deal with vFNFs. The construction stability of FNS is weaker than CCS, BDSF, and CCS+BL, indicating that this method may not as stable as reported in the previous study.

Keywords: Biomechanics; Femoral neck system; Medial buttress sliding plate; Vertical femoral neck fractures.

MeSH terms

Biomechanical Phenomena
Bone Plates
Bone Screws
Femoral Neck Fractures* / surgery
Finite Element Analysis
Fracture Fixation, Internal
Humans