Finite element analysis of femoral neck system in the treatment of Pauwels type III femoral neck fracture

Abstract

The optimal treatment strategy for femoral neck fractures remained controversial, especially the Pauwels type III femoral neck fracture of young patients was a challenge. Femoral neck system (FNS) was a newly developed internal fixation for treating femoral neck fracture and this study aimed to compare the biomechanical advantages and disadvantages between FNS and 3 cannulated configuration screws (CCS) with or without an additional medial buttress plate (MBP).In this study, Pauwels type III femoral neck fracture model with an angle of 70° was constructed and 3 different fixation models, FNS, CCS + MBP, CCS alone, were developed. A vertical force of 2100N was applied on the femoral head, then the maximum von Mises stress of whole model, distal femur, femoral head, and internal fixation was recorded, as well as the stress distribution of whole model, proximal fracture section, and internal fixation of the 3 models. Moreover, the maximum displacement of the whole model, distal femur, femoral head, internal fixation, and the relative displacement of the proximal and distal portion was also compared.The maximum von Mises stress value was 318.302 MPa in FNS, 485.226 MPa in CCS + 1/3 plate, and 425.889 MPa in CCS. The FNS showed lowest maximum von Mises stress values in distal part, femoral head, and internal implant. All fixation configurations were observed stress concentrated at the posteroinferior area of cross-section of femoral head and at the fracture section area of implant; however, FNS had more uniform stress distribution. For displacement, the maximum displacement value was 8.5446 mm in FNS, 8.2863 mm in CCS + 1/3 plate, and 8.3590 mm in CCS. However, FNS had higher maximum displacement in femoral head and internal implant, but lower maximum displacement in the distal part of fracture model. The FNS represented a significantly higher relative displacement between the femoral head and distal femur when compared with the other 2 fixation configurations.The newly developed FNS could achieve the dual effect of angular stability and sliding compression for the treatment of Pauwels type III femoral neck fractures, which provided superior biomechanical stability than CCS alone and CCS with additional MBP.

Femoral neck system interferes less with the gluteus medius muscle than cannulated compression screws in patients with Pauwels' type III femoral neck fracture: a retrospective study of 103 cases

“…This system assumes a critical role, orchestrating a reduction in micromotion at the fracture locale -a factor that is not only pivotal due to its immediate impact on fracture healing but also owing to its secondary repercussions concerning pain management and, concomitantly, recovery trajectories. [26][27][28][29] The pro cient capacity of the FNS system to con ne this micromotion inherently mitigates pain, conventionally precipitated by the instability of fractured termini. This pain palliation and fracture stabilization not merely catalyze the healing trajectory directly, but also, indirectly prop up recovery by facilitating earlier ambulation.…”

Comparison of the clinical efficacy of three cannulated screws with parallel distribution and inverted triangular distribution in the treatment of femoral neck fractures in the elderly

“…Since Dr Smith-Petersen, an American physician, invented trifin screws for treating femoral neck fractures in 1931, femoral neck internal fixation surgical devices have been rapidly developed over the decades, and various internal fixation devices such as cannulated screws, DHS, proximal femoral locking plate, percutaneous compression plate, medial buttress plate, and FNS have been invented are used in clinical practice to this day. Among them, the novel FNS has obvious biomechanical advantages and can support the fracture in multi-axial direction, with excellent anti-rotation and anti-shortening properties, with significant clinical efficacy (15)(16)(17)(18)(19). However, in China, limited by unbalanced economic development, cannulated screw internal fixation is still the most important surgical method, especially in the vast Central and Western regions and primary hospitals.…”

“…At present, to the best of the authors' knowledge there is no clinical report on the treatment of femoral neck fractures in the elderly with three cannulated screws with parallel distribution in China. In biomechanical studies, the biomechanical stability of various femoral neck fixation devices varied due to their own structure and indications (17,18,30,31). At present, the mainstream view is that FNS exhibits good stability (17,18).…”

“…In biomechanical studies, the biomechanical stability of various femoral neck fixation devices varied due to their own structure and indications (17,18,30,31). At present, the mainstream view is that FNS exhibits good stability (17,18). However, there is a lack of biomechanical stability studies on three cannulated screws with parallel distribution and inverted triangular distribution, thus requiring further elucidation in future studies.…”

Proximal femoral bionic nail—a novel internal fixation system for the treatment of femoral neck fractures: a finite element analysis

“…Furthermore, an attempt has also been made to increase the anti-compression force by adding additional screws and medial femoral support plates based on CSs and DHSs ( Mir and Collinge, 2015 ; Zhuang et al, 2019 ; Li et al, 2023 ). However, these improvements increase tissue damage and overlook the design for anti-tension force, resulting in stress distribution, plate fractures, and limiting clinical application ( Teng et al, 2022 ; Huang et al, 2023 ; Nan et al, 2023 ). Therefore, our team was the first to propose the concept of triangular-supported fixation (TSF) and design the proximal femoral bionic nail (PFBN) based on the triangular structure and mechanics characters of the proximal femur ( Ding et al, 2022b ; Xu et al, 2022 ).…”