26dkou572 10.3205/26dkou572 urn:nbn:de:0183-26dkou5720 Meeting Abstract Menger Menger Maximilian M

BG Klinik Tübingen, Klinik für Unfall- und Wiederherstellungschirurgie, Tübingen, Deutschland

author Nakisli Nakisli Oguzhan O

Klinisch-Experimentelle Chirurgie, Universität des Saarlandes, Tübingen, Deutschland

author Herath Herath Steven S

BG Klinik Tübingen, Klinik für Unfall- und Wiederherstellungschirurgie, Tübingen, Deutschland

author Braun Braun Benedikt B

BG Klinik Tübingen, Klinik für Unfall- und Wiederherstellungschirurgie, Tübingen, Deutschland

author Menger Menger Michael M

Klinisch-Experimentelle Chirurgie, Universität des Saarlandes, Homburg, Deutschland

author Laschke Laschke Matthias M

Klinisch-Experimentelle Chirurgie, Universität des Saarlandes, Homburg, Deutschland

author Histing Histing Tina T

BG Klinik Tübingen, Klinik für Unfall- und Wiederherstellungschirurgie, Tübingen, Deutschland

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 572 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) Poster experimentell | Stütz- und Bindegewebe Berlin 20261020 20261023 DKOU26_Abs_2148 TextObjectives and questions: Non-unions remain among the most serious complications in trauma surgery. The expression profile of pro-angiogenic and pro-osteogenic growth factors at the fracture site plays a central role in bone healing. Adequate vascularization is crucial for supplying the callus tissue with nutrients, oxygen and stem cells.Moreover, the expression of vascular endothelial growth factor (VEGF) receptors may influence angiogenesis at the fracture site and, consequently, the healing process. However, the exact expression profiles of angiogenic and osteogenic growth factors as well as VEGF receptors between unions and non-unions remain unknown.Material and methods: Growth factor and VEGF receptor expression were investigated during physiological fracture healing and in non-unions of the femora in 2–4 months-old CD1 mice. For physiological fracture healing, an intramedullary screw was used as a model for a closed, stable fracture (union group). To generate non-unions, a 1.8 mm segmental defect was created and stabilized with an intramedullary pin. For additional rotational stability, the defect was further stabilized with a ventro-dorsal clip (non-union group). Femora were harvested after 7, 10, and 14 days, as well as 10 weeks post-surgery. The callus tissue was investigated by X-ray, µCT, biomechanical testing, histology and Western blot analyses. Data are given as Mean ± SEM.Results: Biomechanical, histological, and radiological analyses demonstrated reliable fracture healing in the union group, whereas in the non-union group, no bony bridging of the fracture gap was observed in any of the animals up to 10 weeks after surgery. Western blot analysis revealed a significantly higher expression of the VEGF2 receptor in non-unions when compared to unions 14 days after surgery (1.7 ± 0.5 vs. 14.9 ± 6.8 [pixel intensity*104]). Moreover, the ratio of VEGF2 receptor/VEGF (0.04 ± 0.01 vs. 0.69 ± 0.35) was significantly higher, whereas the ratio of VEGF1/VEGF2 receptor (29.97 ± 10.30 vs. 1.87 ± 0.75) was significanlty lower. Interestingly, the overall expression of the blood vessel marker CD31 did not differ between the two groups.Additional analyses demonstrated a significantly reduced expression of bone morphogenetic protein (BMP)2 in non-unions 7 days after surgery.Discussion and conclusions: These novel data demonstrate significantly altered expression profiles of VEGF receptor as well as pro-angiogenic and pro-osteogenic growth factors in unions and non-unions. The increased expression of the VEGF2 receptor along with elevated VEGFR2/VEGFR1 and VEGFR2/VEGF ratios indicate an overshooting pro-angiogenic signaling, which may result in uncoordinated vascularization and a dysfunctional vascular network, ultimately hampering bone regeneration. In addition, the reduced expression of the pro-osteogenic markers BMP2 and CYR61 at an early healing time point may contribute to non-union formation. By specifically targeting these dysregulations, novel therapeutics may overcome bone healing failure. 0 0 0 0