Finite element analysis of a new plate for Pauwels type III femoral neck fractures

Abstract

Background: A new plate for the treatment of Pauwels type III femoral neck fractures was developed, and its biomechanical stability was analyzed by the finite element method. Method: Using 3-matic and UG-NX software, we constructed models of Pauwels type III femoral neck fractures with angles of 50 , 60 , and 70 . Moreover, a new femoral neck plate (NFNP) fixation model and a Pauwels screw fixation model were developed. Under axial loads of 1400 N and 2100 N, von Mises stress (VMS) distribution on the screws, peak VMS, displacement between fracture fragments, and model principal strains in cancellous bone were recorded. Result: The peak VMS of internal fixation in the two models was mostly located near the fracture line, and the screw closest to the femoral calcar experienced maximum stress. With a Pauwels angle of 50 , 60 , and 70 , the peak VMS values of the new plates were lower than in the Pauwels screw. The displacement of fracture fragments in the NFNP was smaller than in the Pauwels screw, and peak VMS values of cancellous bone in the NFNP were lower than in the Pauwels screw. Conclusion: The newly developed plate provided excellent biomechanical stability for Pauwels type III femoral neck fractures.

Biomechanical study of different internal fixations in Pauwels type III femoral neck fracture - A finite elements analysis

“…The main explanations relate to the lack of pressure perpendicular to the fracture line and presence of pressure at the parallel level, exerting a pulling force on the screw and predisposing the generation of a slip between the ends, allowing recurrent complications, such as the non-union of the fracture and varus deformity of the hip. 23 These findings are reinforced by previous studies, where the use of three cannulated screws in an inverted triangular configuration did not generate the necessary mechanical stability to treat femoral neck fractures, showing a significantly lower capacity to withstand maximum loads than an L-shaped fixation set with three screws. 15 Compared to the classical configuration of DHS and ASNIS, the DHS with anti-rotation screw, in the present study, was also superior in terms of the biomechanical variables evaluated.…”

Finite element analysis of a new internal fixation implant for Pauwels type III femoral neck fractures

“…In a clinical study, Ye et al 36 also explored three cannulated screws augmented with a medial buttress plate for the treatment of Pauwels type III femoral neck fractures, and their results showed that this surgical method improved the fracture healing rate. In a recent study by Wang et al 37 , a new femoral neck plate with four screws (a 7.3-mm partially threaded cancellous compression screw, two 7.3-mm half-screw locking compression screws, and a 5-mm locking screw) was designed by an orthopedic surgeon and a design engineer, and they found that the new plate is superior to the Pauwels screw with regard to biomechanical stability in Pauwels type III femoral neck fracture models with three different fracture angles. Despite the many advantages of those studies, proximal femoral locking plates or a medial buttress plate with cannulated screws require a large surgical incision, which undoubtedly damages the surrounding tissue and impairs the blood supply of the femoral head.…”

Biomechanical study of a new cannulated screw for Pauwels type III femoral neck fractures

“…We further tested and validated the two groups using biomechanical experiments with the fourthgeneration composite femur model, and the results showed that the femur deformation and fracture line displacement were signi cantly lower in the NCS group than in the CCS group, while the vertical stiffness was signi cantly higher than in the CCS group, which also con rmed that the xation effect of the NCS group was signi cantly better than that of the CCS group, both in the fatigue test (vertical load 0-1000 N) and in the static test (vertical load 1400 N, equivalent to 2 times the body weight). It may be related to the caudal nut of the new screw design, which is xed to the femoral cortex to provide angular stability and support the forces transmitted from the femoral head rather than compression, which can provide shear resistance and effectively prevent femoral neck shortening [25]. Also the upper 2 half-threaded screws still have a partial sliding pressure effect [26,27].…”