A novel interlocking intramedullary nail for type AO 32-A3 femoral shaft fractures: a finite element analysis
10.3760/cma.j.cn115530-20241231-00517
- VernacularTitle:新型交锁髓内钉固定AO分型32-A3型股骨干骨折的有限元分析
- Author:
Peisheng CHEN
1
;
Chaohui LIN
1
;
Fengfei LIN
1
;
Bin CHEN
1
;
Dongze LIN
1
;
Ke ZHENG
1
Author Information
1. 福州市第二总医院骨科，福建医科大学临床医学部，福建省创伤骨科急救与康复临床医学研究中心，福州 350007
- Publication Type:Journal Article
- Keywords:
Femoral fractures;
Fracture fixation, intramedullary;
Bone nails;
Finite element analysis;
Biomechanics
- From:
Chinese Journal of Orthopaedic Trauma
2025;27(3):228-233
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To compare the biomechanical stability of a novel interlocking intramedullary nail (nIMN) with that of a traditional interlocking intramedullary nail (tIMN) in the treatment of type AO 32-A3 femoral shaft fractures using a finite element analysis.Methods:A healthy adult male volunteer, aged 30 years old and weighing 70 kg, was selected for collection of his CT scan data of the femur. A three-dimensional finite element model of the femur was established using software Mimics 17.0 and Geomagic Studio. After femoral shaft fractures of AO/OTA types 32-A3a, 32-A3b, and 32-A3c were simulated, nIMN and tIMN were assembled respectively. After boundary conditions and material properties of the models were set based on reference literature, 4 load states were simulated: vertical standing, slow walking, fast walking, and descending stairs. The displacements and stress distribution at the femoral fracture ends under the same conditions were compared between nIMN and tIMN schemes of fixation. The stabilities of each fracture model at different fixation schemes and load states were analyzed.Results:In the 4 load states simulated, the displacements of the fracture ends averaged 0.129 mm, and the maximum stresses 111.00 MPa. The smallest displacement and maximum stress (0.014 mm and 29.48 MPa) were found in the vertical standing in the femoral shaft fracture of type 32-A3c fixed with nIMN. The largest displacement and maximum stress (0.325 mm and 242.98 MPa) were found in descending stairs in the femoral shaft fracture of type 32-A3a fixed with tIMN. In femoral shaft fractures of types 32-A3a, 32-A3b, and 32-A3c, regardless of tIMN or nIMN fixation, the displacement and maximum stress increased with the load, with the femoral shaft fracture of type 32-A3a being particularly evident. nIMN fixation resulted in lower displacements and maximum stresses in AO/OTA types 32-A3a, 32-A3b, and 32-A3c than tIMN fixation. Taking descending stairs as an example, the overall maximum stress occurred on the proximal part of the femur and the surrounding area of Adams'arc, with the maximum stress fluctuating between 86.62 and 242.98 MPa. The maximum stress at the fracture end fluctuated between 0.44 and 56.49 MPa. The stress mainly concentrated on the medial part, and decreased from type 32-A3a to type 32-A3b to type 32-A3c.Conclusion:In type AO 32-A3 femoral shaft fractures, nIMN leads to a smaller fracture end displacement and a lower maximum stress than tIMN, indicating better rotational stability.
