A finite element analysis of a low-profile femoral neck system of screws in sleeves in a vertical femoral neck fracture model.

BMC Musculoskelet Disord

Department of Trauma Orthopaedics, Shanghai East Hospital, Tongji University School of Medicine, 150 Jimo Road, Shanghai, 200120, China.

Published: June 2024

AI Article Synopsis

  • The study investigates the biomechanical performance of three femoral neck systems (1-hole, 2-hole, and low-profile) to address issues with existing systems, such as compatibility, pain, and fracture risk.
  • Finite element analysis was conducted to compare their performance in terms of stress, stiffness, displacement, and post-implant removal effects on the femur.
  • Results indicate that the low-profile FNS showed better rotational resistance and similar biomechanical stability compared to the traditional systems, particularly under neutral hip joint conditions.

Article Abstract

Background: Femoral neck system (FNS) has exhibited some drawbacks, such as non-fit of the plate with the lateral femoral cortex, postoperative pain, and the potential risk of subtrochanteric fractures. We have developed a low-profile FNS system that addresses some compatibility issues in FNS. In this study, we conducted finite element analysis on the 1-hole FNS (1 H-FNS), 2-holes FNS (2 H-FNS), and low-profile FNS (LP-FNS) and compared their biomechanical performance.

Methods: After the mesh convergence analysis, we established three groups of 1 H-FNS, 2 H-FNS, and LP-FNS. The interfragmentary gap, sliding distance, shear stress, and compressive stress and the bone-implant interface compression stress, stiffness, and displacement were determined under the neutral, flexion, or extension conditions of the hip joint, respectively. The stress and displacement of the femur after the implant removal were also investigated.

Results: (1) There were no obvious differences among the three FNS groups in terms of the IFM distance. However, the LP-FNS group showed less rotational angle compared with conventional FNS (neutral: 1 H-FNS, -61.64%; 2 H-FNS, -45.40%). Also, the maximum bone-implant interface compression stress was obviously decreased under the neutral, flexion, or extension conditions of the hip joint (1 H-FNS: -6.47%, -20.59%, or -4.49%; 2 H-FNS: -3.11%, 16.70%, or -7.03%; respectively). (2) After the implant removal, there was no notable difference in the maximum displacement between the three groups, but the maximum von Mises stress displayed a notable difference between LP-FNS and 1 H-FNS groups (-15.27%) except for the difference between LP-FNS and 2 H-FNS groups (-4.57%).

Conclusions: The LP-FNS may not only provide the same biomechanical stabilities as the 1 H-FNS and 2 H-FNS, but also have more advantages in rotational resistance especially under the neutral condition of the hip joint, in the bone-implant interface compression stress, and after the implant removal. In addition, the 1 H-FNS and 2 H-FNS have similar biomechanical stabilities except for the maximum von Mises stress after the implant removal. The femur after the LP-FNS removal not only is subjected to relatively little stress but also minimizes stress concentration areas.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11155040PMC
http://dx.doi.org/10.1186/s12891-024-07550-7DOI Listing

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