Objectives This study aims to compare the mechanical features of the existing proximal femoral nail antirotation (PFNA) system and the new PFNA system that we designed using three-dimensional (3D) finite element analysis. Materials and methods This experimental study was conducted between 2019 and 2020. We constructed two femur models with Arbeitsgemeinschaft für Osteosynthesefragen (AO) type A1 fractures using 3D computed tomography scans. The new and standard PFNA designs were inserted into the femur models and subsequently transferred to the program. We investigated the distribution of stress on the tip of the lag screw, the calcar region, lag screw-nail junction, and the additional screw inserted through the greater trochanter (only present in the new PFNA design) using 3D finite element analysis. Results When the von Mises stress distributions in our models were examined, the maximum stress at the lag screw-nail junction was 18 mpa in the new design PFNA, while it was 20 mpa in the classic PFNA model. The maximum stress at the junction of the additional screw that had greater trochanter inlet with the nail was found as 42.5 mpa. The maximum stress on the calcar region was found to be 10 mpa at the new design PFNA, while it was 13 mpa with 30% increase in the classic PFNA. The stress on the tip of the lag screw was found to be 49 mpa in the classic PFNA design, while in the new design PFNA it was found as 28 mpa with a decrease of more than 40%. Conclusion As per our findings, the new PFNA design leads to reduced stress on the lag screw-nail junction, the calcar region, and the tip of the lag screw.
Objectives This study aims to investigate the effects of the angles created by the Kirschner wires (K-wires), which are applied in the percutaneous fixation of supracondylar humerus fractures with cross K-wire, with the fracture line on fracture stabilization. Patients and methods The study was conducted on distal humerus fracture models. Medial and lateral K-wires were placed in the fracture models. The angle between the fracture line and the K-wire inserted from medial was represented by alpha (α), while the angle between the fracture line and the K-wires inserted from lateral was represented by beta (β). A combination of various angles (30°, 45°, and 60°) was used in each model, where no two models had the same combination of α and β, resulting in nine different wire configurations. The simulation program was used to simulate the effects of forces, which were applied on rotation, flexion and extension directions, on these models. We measured and compared the stress on the wires and the displacement of fractures under different force configurations. Results When the force was applied in the counterclockwise direction, the stresses were 58 megaPascal (MPa) on medial K-wire, 24 MPa on lower lateral K-wire, and 45 MPa on upper lateral K-wire in (45°, 45°) wire configuration. When the force was applied in the clockwise direction, the stresses were 57 MPa on medial K-wire, 23 MPa on lower lateral K-wire, and 45 MPa on upper lateral K-wire in (45°, 45°) wire configuration. In all models, the increased α and β angles were translated into the decreased stress on K-wires at the fracture level and decreased displacement under rotational deforming forces. Despite having generally lower fracture displacement, the increased α and β angles led to variable changes in the stress on K-wires against flexion and extension forces. Conclusion In supracondylar humerus fractures, increasing the insertion angle of both medial and lateral K-wires augments stabilization and reduces displacement, particularly against rotational deforming forces.
Pelvis injuries account for approximately 3% of all skeletal injuries. [1] In unstable fractures, morbidity and mortality rates are particularly high, requiring surgery to provide stability and prevent potential morbidities and mortality. [2] In posterior pelvis fractures and dislocations, surgery can be performed with an open or percutaneous approach; however, the latter has become the preferred mode of treatment in recent years. [3,4] ÖZ Amaç: Bu çalışmada, iliyosakral vida sabitlemede vida giriş noktası ve vida yöneliminin belirlenmesinde pelvik haritalamanın uygulanabilir olup olmadığı araştırıldı. Hastalar ve yöntemler: Sakroiliyak eklem yaralanması ve sakrum kırığı nedeniyle iliyosakral vida sabitleme uygulanan 16 hastanın (10 erkek, 6 kadın; ort. yaş 35 yıl; dağılım, 20-57 yıl) klinik dosyaları ve görüntüleri retrospektif olarak incelendi. Hastaların ameliyat öncesi tomografi görüntüleri kullanılarak pelvik haritalama yapıldı ve uygun vida giriş noktası ve yönelimi belirlendi. Tüm hastaların ameliyat sonrası bilgisayarlı tomografi taramaları alındı ve bunlar vida pozisyonunun doğruluğunu değerlendirmek için kullanıldı. Bulgular: Ameliyat sırasında herhangi bir komplikasyon gelişmedi. Vidaların giriş noktaları ve yönelimleri ameliyat öncesi ve sonrasında tüm hastalar için uyumluydu. Sonuç: Pelvisin haritalanması, iliyosakral vidalamanın ameliyat öncesi planlamasında kullanılabilecek bir yöntemdir.Anahtar sözcükler: İliyosakral vida sabitleme, haritalama yöntemi, pelvik kırığı, perkütanöz sabitleme, sakroiliyak eklem. ABSTRACTObjectives: This study aims to investigate if pelvic mapping is applicable in iliosacral screw fixation to determine screw entry point and screw trajectory. Patients and methods: Clinical files and images of 16 patients (10 males, 6 females; mean age 35 years; range, 20 to 57 years) who underwent iliosacral screw fixation due to sacroiliac joint injury and sacrum fracture were retrospectively reviewed. Pelvic mapping was performed using preoperative tomography images of the patients and appropriate screw entry point and trajectory were determined. Postoperative computed tomography scans of all patients were obtained and these were used to evaluate the accuracy of the screw position. Results: No intraoperative complications occurred. The entry points and trajectory of the screws were compatible for all patients pre-and postoperatively. Conclusion: Mapping of the pelvis is a method that can be used for preoperative planning of iliosacral screwing.
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