Finite element analysis comparison between superior clavicle locking plate with and without screw holes above fracture zone in midshaft clavicular fracture

Abstract

BackgroundMidshaft clavicular fractures are common fractures and generally treated conservatively. Among the surgical options, plate fixation is the most popular and has been biomechanically and clinically proven in numerous studies. However, implant failures caused by plate deformations or breakage still occur in up to 16.7% of cases, and recent studies showed that screw holes above fracture zone (SHFZ) might be the at-risk location. Using finite element analysis, this study aimed to test the biomechanical property of the superior clavicle locking plate (SCLP) with and without SHFZ in comminuted midshaft clavicular fracture.MethodsFinite element models of comminuted midshaft clavicular fracture fixed with standard 8-hole titanium SCLP with screw holes (SHFZ plate) and without screw holes above fracture zone (No-SHFZ plate) were built. Both groups were tested under three different loading models (100-N cantilever bending, 100-N axial compression, and 1-Nm torsion). The average peak stress on medial clavicle, fracture zone, and lateral clavicle, and the peak stress on each screw hole (or the same position in the No-SHFZ plate) were measured and compared.ResultsThe highest average peak stress on the fracture zone was higher than those on medial and lateral clavicles under all loading conditions in both plates. However, the No-SHFZ plate significantly reduced the average peak stress value on the fracture zone, compared to the SHFZ plate (45.0% reduction in cantilever bending, 52.2% reduction in axial compression, and 54.9% reduction in axial torsion). The peak stress value on the maximal stress point in the SHFZ and No-SHFZ plates with cantilever bending, axial compression, and torsion loads were 1257.10 MPa vs. 647.21 MPa, 186.42 MPa vs. 131.63 MPa, and 111.86 MPa vs. 82.41 MPa, respectively.ConclusionThe weakest link of the SCLP construct in comminuted midshaft clavicular fracture fixation is the SHFZ, especially in the cantilever bending load. Additionally, the biomechanical property of the SCLP without SHFZ model (No-SHFZ plate) is superior to the standard SCLP model (SHFZ plate), with a significantly lower peak stress on the SHFZ location in all loading conditions. We recommend a new SCLP design with SHFZ to prevent implant failure and improve surgical outcomes.

Numerical simulation and biomechanical analysis of locking screw caps on clavicle locking plates

“…Therefore, some finite element studies recommend different types of plates, such as anterior plates, spiral plates, and superior plates with no screw holes above the fracture area. [ 17 , 18 , 20 , 21 ]…”

“…4). [15][16][17]19] The distribution of stress in the plate was measured using simulation. The stresses on 7 points representing the 7 locking holes of the superior LCP, that is, the medial (M) M1, M2, and M3; FZ; lateral (L) L1, L2, and L3 and ultimate stress of both models for all 3 forces were analyzed as the Von Mises stress (Fig.…”

“…Therefore, to prevent breakage, a new design consisting of superior LCPs with no screw holes on top of the FZ was proposed. [ 17 ] Nevertheless, it is virtually impossible to omit the screw holes on the fracture site during the mass production of metal plates.…”

Biomechanical Analysis of Personalised 3D-Printed Clavicle Plates of Different Materials to Treat Midshaft Clavicle Fractures

“…Finally, the properties of all types of materials were assumed to be homogeneous, isotropic, and linearly elastic. This assumption was made regarding previous studies [7,9,18,26,30] , which discussed the FE analysis of plate fixation to treat midshaft clavicle fractures. Although this assumption was slightly different from the actual conditions, we believe the conclusion of this study should be the same.…”

“…It was found by previous studies that 6.9%-16.7% of plate fixation cases required revision surgery [9] , and inadequate plate fixation and nonunion caused by plate stress shielding were the main factors resulting in the failure of bone plate fixation [10][11] . Plates in clinical use were manufactured following fixed models that are not completely suitable for the clavicle shape of every patient, which might induce loosening of the plate fixation and difficulty in bone healing [12] .…”