Finite element analysis of locking plate and two types of intramedullary nails for treating mid-shaft clavicle fractures.
BACKGROUND
Both plate and intramedullary nail fixations, including straight and anatomic nails, have been clinically adopted for the treatment of displaced mid-shaft clavicle fractures. However, the biomechanical performances of these fixations and implants have not been well evaluated. This study aims to compare the construct stability, stress distribution and fracture micro-motion of three fixations based on finite element (FE) method.


METHODS
The FE model of clavicle was reconstructed from CT images of a male volunteer. A mid-shaft fracture gap was created in the intact clavicle. Three fixation styles were simulated including locking plate (LP), anatomic intramedullary nail (CRx), and straight intramedullary nail (RCP). Two loading scenarios (axial compression and inferior bending) were applied at the distal end of the clavicle to simulate arm abduction, while the sternal end was fixed.


RESULTS
Under both conditions, the LP was the stiffest, followed by the CRx, and the RCP was the weakest. LP also displayed a more evenly stress distribution for both implant and bone. RCP had a higher stress compared with CRx in both conditions. Moreover, all implants sustained higher stress level under the loading condition of bending than compression.


CONCLUSIONS
The plate fixation significantly stabilizes the fracture gap, reduces the implant stress, and serves as the recommended fixation for the mid-shaft clavicle fracture. The CRx is an alternative device to treat clavicle shaft fracture, but the shoulder excessive activities should be avoided after operation.
Tongji Hospital, Tongji University School of Medicine, Shanghai, China; Pudong New Area People's Hospital, Shanghai 201299, China; Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China.
Ming
M
Ni
Yangzhi Rehabilitation Hospital, Tongji University School of Medicine, Shanghai, China.
Wenxin
W
Niu
Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China.
Duo Wai-Chi
DW
Wong
CEAS-Biomedical Engineering (BME), University of Cincinnati, 2901 Woodside Dr., Cincinnati, OH 45221, USA; CEAS-School of Aerospace Systems, University of Cincinnati, 2851 Woodside Dr., Cincinnati, OH 45221, USA.
Wei
W
Zeng
Tongji Hospital, Tongji University School of Medicine, Shanghai, China. Electronic address: meijiong@163.com.
Jiong
J
Mei
Interdisciplinary Division of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China.
Ming
M
Zhang
D001696:Biomechanical Phenomena; D001860:Bone Plates; D002968:Clavicle / Q000601:surgery*; D020342:Finite Element Analysis; D005594:Fracture Fixation, Intramedullary / Q000295:instrumentation*; D050723:Fractures, Bone / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015203:Reproducibility of Results; D013314:Stress, Mechanical
Biomechanics; Clavicle fracture; Finite element; Internal fixation; Intramedullary nailing; Plate