Modified F configuration in the treatment of Pauwels type III femoral neck fracture: a finite element analysis

Abstract

Background The optimal treatment of Pauwels type III femoral neck fracture (FNF) in young patients remains a worldwide challenge in orthopedic surgery. Methods Finite element models of four internal fixations were developed to treat Pauwels type III FNF: a: the traditional inverted triangular parallel cannulated screw (PCS) model, b: the F-technique cannulated screw model, c: the modified F-technique cannulated screw model using a fully threaded screw instead of a partially threaded distally, d: the dynamic hip screw coupled with derotational screw (DHS + DS) model. Under the same conditions, finite element analyses were carried out to compare the displacement and von Mises stress distribution of four internal fixations and femurs, the maximum crack distances of the fracture surfaces, Z axis displacements of four models as well as the stress distribution in the subtrochanteric region. Results The modified F-technique configuration resulted in a more stable fixation as compared to the other three configurations, with respect to the maximum displacement and stress peaks of femur and internal fixations, the maximum crack distances of the fracture surfaces, Z axis displacements of four configurations as well as the stress distribution in the subtrochanteric region. Conclusions Our results suggested that modified F-technique configuration show a better performance in resisting shearing and rotational forces in treating Pauwels type III FNF compared to those using traditional inverted triangular PCS, the F-technique configuration or DHS + DS, providing a new choice for the treatment of FNFs.

Finite Element Analysis of Six Internal Fixations in the Treatment of Pauwels Type III Femoral Neck Fracture

“…The rationale for this phenomenon might be attributed to the augmented cross‐sectional area and the structurally robust triangular arrangement of multiple screws, which possess the capability to distribute stress from the upper part of the femoral head to the calcar, making it more conducive for weight bearing 15,28 . Nevertheless, similar to our investigation, previous finite element analyses had suggested that CCS exhibited inadequate mechanical stability in withstanding high shear and inversion forces at fracture sites, potentially leading to varus deformity, nonunion, femoral neck shortening and femoral head necrosis after surgery 17,29 . Likewise, Liporace et al 4 .…”

“…15,28 Nevertheless, similar to our investigation, previous finite element analyses had suggested that CCS exhibited inadequate mechanical stability in withstanding high shear and inversion forces at fracture sites, potentially leading to varus deformity, nonunion, femoral neck shortening and femoral head necrosis after surgery. 17,29 Likewise, Liporace et al 4 showed that the overall rate of postoperative complications was 32% in the fixation of Pauwels type III fractures using an "inverted triangle" CCS, with a non-union rate of 19% and an incidence of femoral head necrosis rate of 14%. Consequently, based on our findings, we did not advocate for the use of CCS in the fixation of Pauwels type III fractures.…”

The novel magnesium–titanium hybrid cannulated screws for the treatment of vertical femoral neck fractures: Biomechanical evaluation

“…[ 45 ]. Nevertheless, the estimated load (2–3 times body weight or 2100 ​N) used for the load input in the FEA method in the previous computational studies [ 2 , 5 , 20 , 46 ], which was lower than the result calculated by the musculoskeletal multibody dynamics model based on the subject's experimental data. Therefore, considering the higher hip joint force employed as the load input in the FEA method in the present study, the maximum stresses/displacements in the hybrid/conventional cannulated screw system were higher than those in the previous computational studies [ 2 , 5 , 12 ].…”

Non-sliding Fixation Shows Improved Clinical Outcomes for Displaced Femoral Neck Fractures as Compared to Sliding Fixation

“…FCS aims to increase the stability of internal fixation while retaining the minimally invasive advantages of TCS. Lin et al ( 19 ) reported that in finite element analysis, a modified F-technique configuration (similar to our FCS technique) showed a better performance in resisting shearing and rotational forces in treating Pauwels type III femoral neck fracture compared to those using traditional inverted triangular TCS. However, few studies have compared the clinical results of FCS with TCS.…”