26dkou369 10.3205/26dkou369 urn:nbn:de:0183-26dkou3697 Meeting Abstract Gatto Gatto Giulio G

Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Department of Trauma Surgery and Orthopedics, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Deutschland

author Kirschweng Kirschweng Coletta C

Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Department of Trauma Surgery and Orthopedics, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Deutschland

author Signor Signor Matteo M

Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Department of Trauma Surgery and Orthopedics, University Hospital Frankfurt, Goethe University, Frankfurt am Main, Deutschland

author Zaucke Zaucke Frank F

Dr. Rolf M. Schwiete Research Unit for Osteoarthritis, Department of Trauma Surgery and Orthopedics, University Hospital Frankfurt, Goethe University, Frankfurt am Main, 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 369 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) Grundlagenforschung | Tribologie & Gelenke Berlin 20261020 20261023 DKOU26_Abs_2171 TextObjectives and questions: In knee joints, aging is associated with progressive degradation of the extracellular matrix (ECM). Collagen II is a major component of cartilage ECM, determining its mechanical properties and undergoing age-related molecular modifications. However, other collagen types (e.g., collagen III, IX, and X) also contribute to cartilage development and function. In addition, collagen I is the main component of subchondral bone (SB), located beneath articular cartilage and subjected to sclerosis or osteoporosis during aging. The aim of the present study was to investigate age-related changes in the expression of specific collagen types and the fibril organization during aging and joint compartments.Material and methods: 50 WT C57BL/6J mice (3-, 6-, 12-, 18- and 24-months-old, 5 males and 5 females per timepoint) were sacrificed and dissected. Paraffin-embedded knee sections were stained with Picrosirius red (PSR) and collagens I, II, III, IX and X were detected by immunohistochemistry (IHC). Staining was analyzed in menisci, different articular cartilage compartments and SB. The surface percentage of thick and thin collagen fibers was determined in PSR-stained sections, while immunostained sections were evaluated quantitatively to characterize age-related changes.Results: The amount of thick collagen fibers decreased during aging in articular cartilage and SB (p<0,001 between 3 and 18 months of age), displaying a significant re-increase at 24 months (p<0,05, compared with 3 months old). Thick fibers were more abundant in medial compared to lateral and femoral compared to tibial cartilage compartments (max. p<0,05). Thin fibers displayed an increase between 3 and 6 months old mice in SB (p<0,05) and were more expressed in femoral compared to tibial cartilage (p<0,05). Collagen II and III IHC revealed an age-dependent decrease in articular cartilage and different expression between femoral and tibial compartments similar to the ones observed in PSR-stained thick fibers (same significances). Collagen III IHC displayed differences between lateral and medial menisci (p<0,05). A stronger expression of collagen IX and X was visually found in 24 months old mice compared to other time points. No sex-specific differences were detected.Discussion and conclusions: A clear age-dependent change in both collagen fiber surface and expression was observed in mouse knee joints. The re-increase in thick fibers between 18 and 24 months may result from collagen molecular modifications or from reactivation of collagen synthesis and secretion by chondrocytes at later life stages. Intra-articular compartmental variations may reflect developmental differences and/or an altered mechanical loading. Differences between PSR- and IHC-derived results suggest a differential susceptibility of specific collagen types to aging-related processes. Overall, our findings reveal age-related molecular dynamics and intra-articular differences which, if confirmed in humans, could substantially advance our understanding of aging-associated osteoarthritis. 0 0 0 0