Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis

Abstract Background Good clinical outcomes for locking plates as an external fixator to treat tibial fractures have been reported. However, external locking plate fixation is still generally rarely performed. This study aimed to compare the stability of an external locking plate fixator with that of a conventional external fixator for extraarticular proximal tibial fractures using finite element analysis. Methods Three models were constructed: (1) external locking plate fixation of proximal tibial fracture with lateral proximal tibial locking plate and 5-mm screws (ELP), (2) conventional external fixation of proximal tibial fracture with an 11-mm rod and 5-mm Schanz screws (EF-11), and (3) conventional external fixation of a proximal tibial fracture with a 7-mm rod and 5-mm Schanz screws (EF-7). The stress distribution, displacement at the fracture gap, and stiffness of the three finite element models at 30-, 40-, 50-, and 60-mm plate–rod offsets from the lateral surface of the lateral condyle of the tibia were determined. Results The conventional external fixator showed higher stiffness than the external locking plate fixator. In all models, the stiffness decreased as the distance of the plate–rod from the bone surface increased. The maximum stiffness was 121.06 N/mm in the EF-11 model with 30-mm tibia–rod offset. In the EF-7 model group, the maximum stiffness was 40.00 N/mm in the model with 30-mm tibia–rod offset. In the ELP model group, the maximum stiffness was 35.79 N/mm in the model with 30-mm tibia–plate offset. Conclusions Finite element analysis indicated that external locking plate fixation is more flexible than conventional external fixation and can influence secondary bone healing. External locking plate fixation requires the placement of the plate as close as possible to the skin, which allows for a low-profile design because the increased distance from the plate to the bone can be too flexible for bone healing. Further experimental mechanical model tests are necessary to validate these finite element models, and further biological analysis is necessary to evaluate the effect of external locking plate fixation on fracture healing.

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Biomechanical effect of anterior talofibular ligament injury in Weber B lateral malleolus fractures after lateral plate fixation: A finite element analysis

Foot and Ankle Surgery ◽

10.1016/j.fas.2019.11.004 ◽

2020 ◽

Vol 26 (8) ◽

pp. 871-875

Author(s):

Lin Zhou ◽

Jiaming Lin ◽

Bata Wang ◽

Weidong Gan ◽

Anfei Huang ◽

...

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Plate Fixation ◽

Lateral Malleolus ◽

Ligament Injury ◽

Anterior Talofibular Ligament ◽

Lateral Plate ◽

Element Analysis ◽

Biomechanical Effect

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Biomechanical Analysis of Blade Plate Versus Locking Plate Fixation for a Proximal Humerus Fracture: Comparison Using Cadaveric and Synthetic Humeri

Journal of Orthopaedic Trauma ◽

10.1097/01.bot.0000244997.52751.58 ◽

2006 ◽

Vol 20 (8) ◽

pp. 547-554 ◽

Cited By ~ 118

Author(s):

Paul C Siffri ◽

Richard D Peindl ◽

Edward R Coley ◽

James Norton ◽

Patrick M Connor ◽

...

Keyword(s):

Proximal Humerus Fracture ◽

Locking Plate ◽

Proximal Humerus ◽

Plate Fixation ◽

Biomechanical Analysis ◽

Humerus Fracture ◽

Plate Versus ◽

Locking Plate Fixation ◽

Blade Plate

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Finite Element Analysis of Different Locking-Plate Fixation Methods for the Treatment of Ulna Head Fracture

10.21203/rs.3.rs-99417/v1 ◽

2020 ◽

Author(s):

Yue Zhang ◽

Qin Shao ◽

Chensong Yang ◽

Changqing Ai ◽

Di Zhou ◽

...

Keyword(s):

Finite Element Analysis ◽

Locking Plate ◽

Plate Fixation ◽

Dorsal Side ◽

Locking Plate Fixation ◽

Element Analysis ◽

Side Plate ◽

Ulnar Side ◽

Ulnar Head ◽

Fixation System

Abstract Background: Ulnar head fractures are increasingly higher with the growing proportion of the elderly in the population. Failure to achieve stable anatomic reduction of ulna head fracture may lead to the DRUJ dysfunction and nonunion of distal radius. Due to the lack of the postoperative reporting outcomes and the biomechanical studies, it has not been well established about the optimal management of the comminuted distal ulna head fracture. This study aimed to explain the advantages and disadvantages of the ulnar-side locking plate fixation, compared with the dorsal-side one, and its screws arrangement in the treatment of the ulnar head fracture by using finite element analysis. Methods: FE models of the ulnar head fracture and the models of ulnar-side locking plate and dorsal-side plate with two or three distal screws was constructed. In order to simulate forces acting on the ulnar and the osteosynthesis material during daily-life activity in subjects who underwent reconstructive surgery, we applied three loading conditions to each model, viz. axial compression 20N, 50N, and torsion moments 1Nm. Under these conditions, values of the von Mises Stress (VMS) distribution of the implant, peak VMS, and model displacement were investigated. Results: Both the stress values and model displacement of ulnar-side plate were lower than those of dorsal-side plate. When adding a screw in the middle hole of the ulnar head, the values of model displacement and the peak stress in fixation system are lower, but it may evidently concentrate the stress on the middle screw. Conclusions: In conclusion, our study indicated that plating locking plate on ulnar side had lower stress distribution on the plate and better stability than on dorsal side in ulnar head fracture fixation. Adding the additional screw on the ulnar head could reduce the displacement of the fixation system and increase the stability of the fixation system. This study requires clinical confirmation as to its practicality in the treatment of ulnar head fracture.

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ESTIMATION OF THE OPTIMAL FIBULAR GRAFT ANGLE FOR PROXIMAL HUMERUS FRACTURES USING FINITE ELEMENT ANALYSIS

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519420400291 ◽

2020 ◽

Vol 20 (10) ◽

pp. 2040029

Author(s):

JIN WOONG YI ◽

JONG UN KIM ◽

HYUN JAE CHA ◽

JINBOK YI ◽

KI SIK TAE

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Proximal Humerus Fracture ◽

Proximal Humerus ◽

Varus Deformity ◽

Humerus Fracture ◽

Fibular Graft ◽

Element Analysis ◽

Insertion Angle ◽

Graft Angle

Proximal humerus fracture is a common injury and is usually treated using an internal fixation. However, clinical studies have reported that such treatments are associated with problems such as varus deformity and screw penetration. Therefore, to solve these problems, a surgical method using fibular allografts (FAs) is recently reported. Thus, this study is aimed to confirm the effective insertion angle ([Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) of the FA. We applied axial and shear loads to finite element models used in our study. Finite element simulations using these models were repeated five times for each fibular insertion angle. We evaluated the construct stiffness, stress distribution on the plate and fibula, and fracture micromotion. Results showed that the method using the FA caused less stress on the plate and provided higher structural stability than the method without using the FA. In particular, the axis perpendicular condition yielded significantly greater construct stiffness and caused less von Mises stresses than the other conditions. In conclusion, the finite element analysis results showed that the FA inserted horizontally was effective in the treatment of proximal humerus fracture with an unstable medial support.

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