Chinese Journal of Tissue Engineering Research ›› 2025, Vol. 29 ›› Issue (27): 5757-5764.doi: 10.12307/2025.816

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Comparison of biomechanical characteristics of superior and inferior pubic ramus fractures fixed with different internal fixation methods

Rao Xin1, 2, 3, Jiang Daixiang1, 2, 3, Lu Hui3, Luo Yangxing3, Li Meng4, Liu Dingxi4, Wu Qimei5, Liu Rong1, 2, 3, 5   

  1. 1Department of Orthopedics, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China; 2School of Medicine, Wuhan University of Science and Technology, Wuhan 430065, Hubei Province, China; 3Institute of Medical Innovation and Transformation, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China; 4School of Mechanical Engineering, Wuhan University of Science and Technology, Wuhan 430080, Hubei Province, China; 5Wuhan Liu Sanwu Traditional Chinese Medicine Orthopedic Hospital, Wuhan 430200, Hubei Province, China
  • Received:2024-04-22 Accepted:2024-07-10 Online:2025-09-28 Published:2025-03-04
  • Contact: Liu Rong, MD, Professor, Chief physician, Master’s supervisor, Department of Orthopedics, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China; School of Medicine, Wuhan University of Science and Technology, Wuhan 430065, Hubei Province, China; Institute of Medical Innovation and Transformation, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China; Wuhan Liu Sanwu Traditional Chinese Medicine Orthopedic Hospital, Wuhan 430200, Hubei Province, China Co-corresponding author: Wu Qimei, MS, Chief physician, Wuhan Liu Sanwu Traditional Chinese Medicine Orthopedic Hospital, Wuhan 430200, Hubei Province, China
  • About author:Rao Xin, Master candidate, Department of Orthopedics, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China; School of Medicine, Wuhan University of Science and Technology, Wuhan 430065, Hubei Province, China; Institute of Medical Innovation and Transformation, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China Jiang Daixiang, Master candidate, Department of Orthopedics, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China; School of Medicine, Wuhan University of Science and Technology, Wuhan 430065, Hubei Province, China; Institute of Medical Innovation and Transformation, Puren Hospital Affiliated to Wuhan University of Science and Technology, Wuhan 430081, Hubei Province, China Rao Xin and Jiang Daixiang contributed equally to this article.
  • Supported by:
    2023 Joint Fund for Occupational Hazard Identification and Control in Hubei Key Laboratory, No. JF2023-K01 (to LR)

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Abstract: BACKGROUND: Percutaneous retrograde screws and minimally invasive percutaneous plates are extensively used in the treatment of unilateral pubic ramus fractures. However, the above internal fixations have the disadvantages of mistakenly penetrating the hip joint and damaging the medial pelvic trophoblastic artery. A new type of retrograde superior pubic ramus intramedullary nail offers advantages, such as fewer radiographic exposures and shorter surgery times, but the validation of the biomechanical properties of the three endoprostheses is lacking.
OBJECTIVE: To compare the biomechanical differences post-treatment of upper and lower pubic ramus fractures using percutaneous retrograde screws, minimally invasive percutaneous plates, and retrograde superior pubic ramus intramedullary nail under various conditions through finite element analysis.
METHODS: Pelvic CT data were collected from one volunteer and imported into Mimics 20, Geomagic Wrap 2021, and SolidWorks 2019 to create geometric models of three types of internal fixation for treating unilateral pubic ramus fractures: hollow screw group, plate group, and intramedullary nail group. Each model was imported into Ansys 2022 software, where it was set up in vertical, book-opening, and shear conditions for preprocessing and calculation to compare and analyze the mechanical stability of the implants.
RESULTS AND CONCLUSION: (1) In vertical conditions, the biomechanical stability of the hollow screw treatment for unilateral pubic fractures was superior to that of the steel plate and intramedullary nail, with the smallest peak stress in the implant, which was four times lower compared to the other two groups. (2) In book-opening conditions, the steel plate treatment for unilateral pubic fractures showed better biomechanical stability, particularly in reducing stress at the fracture ends of the upper pubic branch, with stress values five times higher in the other two groups. (3) In shear conditions, the intramedullary nail treatment for unilateral pubic fractures exhibited good biomechanical stability, maintaining the best pelvic displacement, with a 25% greater displacement observed in the other two groups. (4) These findings reveal the biomechanical differences of different implants: the peak stress of implants is the smallest under vertical working conditions with percutaneous retrograde screws. Minimally invasive percutaneous plates reduce the stress at the broken end of superior pubic branch under open-book working condition. Retrograde superior pubic ramus intramedullary nail of superior pubic branch maintains pelvic displacement under shear working condition. The surgeon can combine the biomechanical differences of the implants with the actual situation of pubic injury in clinical practice to make the best implant treatment.

Key words: fracture of upper and lower rami of pubis, percutaneous reverse hollow screw, minimally invasive percutaneous plate, retrograde intramedullary nail in superior rami of pubis, finite element analysis, biomechanics

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