26dkou162 10.3205/26dkou162 urn:nbn:de:0183-26dkou1625 Meeting Abstract Bori Bori Edoardo E

ECAM Brussels Engineering School – Health Department, Brussels, Belgien

author Maaref Maaref Bechir B

ECAM Brussels Engineering School – Health Department, Brussels, Belgien

author Ciatti Ciatti Corrado C

Orthopaedics and traumatology department, Guglielmo da Saliceto Hospital, AUSL Piacenza, Piacenza, Italien University of Parma, Parma, Italien

author German Medical Science GMS Publishing House

Düsseldorf

610 20261020 engl This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). M0659 162 Deutsche Gesellschaft für Orthopädie und Unfallchirurgie Deutsche Gesellschaft für Orthopädie und Orthopädische Chirurgie Deutsche Gesellschaft für Unfallchirurgie Berufsverband für Orthopädie und Unfallchirurgie Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2026) Abstracts | Schultertrauma Berlin 20261020 20261023 DKOU26_Abs_2208 TextObjectives and questions: This study aims to compare the mechanical stability and load-sharing behavior of two common internal fixation devices (locking plates and intramedullary nails) for the treatment of proximal humeral shaft fractures in both healthy and osteoporotic bone conditions across multiple physiological loading scenarios.Material and methods: The analysis was conducted using the Finite Element Method (FEM) on ABAQUS software. A 3D humerus model was developed from CT-scan data, distinguishing between cortical and cancellous bone properties; a simple proximal, extraarticular, unifocal, 2-part surgical neck fracture was then introduced on the model and the two different fixation approaches were simulated. Materials were modeled as linear elastic and isotropic: Titanium alloy ( E=110 GPa) for implants, healthy cortical bone (E=15.3 GPa), and cancellous bone (E=2 GPa). Osteoporosis was simulated by reducing cortical stiffness by 32% and cancellous stiffness by 66%. Three loading cases (from literature) were simulated: (1) axial bending, (2) torsion, and (3) inclined compression-bending. A “Tie” interaction was utilized for screw-bone interfaces to ensure numerical stability.Results: Quantitative analysis of fracture plane stability demonstrated that intramedullary nails provided superior angular stability in most scenarios, particularly in torsion where the nail significantly reduced rotational variance compared to the plate. In Case 1 (axial bending), the nail reduced rotation difference by approximately 30.8% compared to healthy bone. However, qualitative stress analysis revealed a more pronounced “stress shielding” effect with the nail, which shifted load paths internally and significantly reduced cortical bone solicitation. In contrast, locking plates allowed for a more physiological stress distribution in healthy cortical bone, which is potentially beneficial for secondary fracture healing. All models confirmed that osteoporosis drastically increases implant stress and bone deformation, highlighting the critical role of bone density in fixation success.Discussion and conclusions: Case-specificity in the choice of implant returned to be fundamental: intramedullary nails appear to be mechanically more effective for osteoporotic bone due to their superior resistance to rotation and fracture collapse under compromised bone support, while locking plates remain a valid alternative for active patients with adequate bone density, as they better preserve physiological cortical loading. 0 0 0 0