25dkou591 10.3205/25dkou591 urn:nbn:de:0183-25dkou5912 Meeting Abstract Bori Bori Edoardo E

ECAM Brussels Engineering School – Health Department, Brussels, Belgien Université Libre de Bruxelles – BEAMS Department, Brussels, Belgien

author Maaref Maaref Bechir B

ECAM Brussels Engineering School – Health Department, Brussels, Belgien

author Priest Priest Nicolas N

ECAM Brussels Engineering School – Health Department, Brussels, Belgien

author Levander Levander Allan A

ECAM Brussels Engineering School – Health Department, Brussels, Belgien

author Thienpont Thienpont Benjamin 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 20251031 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). M0634 591 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 2025) Abstracts | AG Evidenzbasierte Medizin | Becken- und Hüftchirurgie – konservativ & minimal-invasiv Berlin 20251028 20251031 AB94-4293 TextObjectives and questions: Proximal femoral fractures are common in elderly and osteoporotic patients. The gamma nail system is widely used for fixation , but the necessity of the distal locking screw in stable fractures remains debated : it ensures stability, but it can lead to increased stress concentration. This study aims to biomechanically evaluate the impact of distal screw omission in two-parts fractures, at different follow-up situations.Material and methods: The analysis was conducted using the Finite Element Method (FEM). Geometries of a healthy femur were obtained from CT scans of a Sawbone, and a model of a gamma nail was designed, based on the commercially available one used by the surgeons. Five models were analyzed: a healthy femur (as reference) and four implanted configurations, with or without the distal screw, at two follow-up stages – immediate post-op (with a simulated two-part fracture) and complete bone healing. Material properties for bone and implant were sourced from the literature. A 2400 N load, simulating walking, was applied along the mechanical axis. Bone stresses and micromotions were assessed in three regions of interest: (1) fracture site, (2) metaphysis, and (3) femoral shaft, and compared to the healthy model.Results: Omitting the distal screw reduced stress concentrations in the distal femur, especially in fracture cases. However, it increased peak stresses in the proximal femur, indicating potential higher micromotion at the fracture site. Distal locking enhanced stability but caused greater stress near the locking hole.Discussion and conclusions: The findings suggest that omitting the distal screw in two-part fractures may reduce stress-related complications in the femoral shaft and simplify surgery. This biomechanical advantage, aligning with previous clinical results , is fracture-pattern dependent: screw-free fixation may be valid for stable fractures with good alignment, reducing the risk of fractures near the screw hole, but distal locking remains beneficial for less stable cases to ensure mechanical integrity.Figure 1 Table 1 Valverde JA Alonso MG Porro JG Rueda D Larrauri PM Soler JJ Use of the gamma nail in the treatment of fractures of the proximal femur. 1998 2003 J Orthop Trauma S51-6 Valverde JA, Alonso MG, Porro JG, Rueda D, Larrauri PM, Soler JJ. Use of the gamma nail in the treatment of fractures of the proximal femur. 1998. J Orthop Trauma. 2003 Sep;17(8 Suppl):S51-6. DOI: 10.1097/00005131-200309001-00010 https://doi.org/10.1097/00005131-200309001-00010 Quattrini F Ortolani A Ciatti C Puma Pagliarello C Martucci A Gurrieri L Stallone S Melucci G Domenico T Maniscalco P Static vs dinamic short nail in pertrochanteric fractures: experience of two center in Northern Italy 2021 Acta Biomed e2021021 Quattrini F, Ortolani A, Ciatti C, Puma Pagliarello C, Martucci A, Gurrieri L, Stallone S, Melucci G, Domenico T, Maniscalco P. Static vs dinamic short nail in pertrochanteric fractures: experience of two center in Northern Italy. Acta Biomed. 2021 Jul 26;92(S3):e2021021. DOI: 10.23750/abm.v92iS3.11745 https://doi.org/10.23750/abm.v92iS3.11745 11

Table 1: Average Von Mises Stress [MPa] from the 3 ROIs in the different configurations.

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1 1 Figure 1: Section of the femur model, in the configuration involving the presence of the fracture and a gamma nail implant with distal screw.

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