26dkou030 10.3205/26dkou030 urn:nbn:de:0183-26dkou0305 Meeting Abstract Roshardt Roshardt Jose J

Department for Orthopaedic Surgery and Traumatology, Inselspital, University Hospital Bern, Bern, Schweiz

author Meier Meier Malin M

University Institute of Diagnostic, Interventional and Paediatric Radiology, Inselspital, University of Bern, Bern, Schweiz

author Ruckli Ruckli Adrian A

Department for Orthopaedic Surgery and Traumatology, Inselspital, University Hospital Bern, Bern, Schweiz

author Hirt Hirt Julien J

Department of Orthopaedic Surgery and Traumatology, Fribourg Cantonal Hospital, University of Fribourg, Fribourg, Schweiz

author Alonso Domenech Alonso Domenech Elisabeth E

Department for Orthopaedic Surgery and Traumatology, Inselspital, University Hospital Bern, Bern, Schweiz

author Gerber Gerber Nicolas N

Department for Orthopaedic Surgery and Traumatology, Inselspital, University Hospital Bern, Bern, Schweiz

author Tannast Tannast Moritz M

Department for Orthopaedic Surgery and Traumatology, Inselspital, University Hospital Bern, Bern, Schweiz

author Schmaranzer Schmaranzer Florian F

Radiology Department, Balgrist University Hospital, Zürich, Schweiz

author Steppacher Steppacher Simon Damian SD

Department for Orthopaedic Surgery and Traumatology, Inselspital, University Hospital Bern, Bern, Schweiz

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 030 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 | Dysplastisches Becken Berlin 20261020 20261023 DKOU26_Abs_2451 TextObjectives and questions: Borderline dysplasia (BDDH) shows variable morphology and remains a treatment challenge. Surgical decision-making relies on instability markers such as femoral head decentration (FHD); however, the three-dimensional (3D) morphology of borderline hips remains undefined. This study aimed to determine whether BDDH hips with and without FHD differ in lunate surface morphology, labral morphology, and cartilage quality assessed by artificial intelligence (AI)-based MR segmentation.Material and methods: A total of 307 consecutive hips undergoing MR arthrography between 2019 and 2025 were included in the current study. Based on lateral center-edge angle (LCEA), hips were classified as normal (25–33°, control), BDDH (20–25°), or dysplasia (DDH) (<20°, pathological reference). The primary comparison was within the BDDH cohort (n = 77), subdivided into hips with and without FHD (n = 27 and n = 50). Radiographic evaluation included 17 parameters assessing coverage (LCEA, acetabular index, extrusion index, and femoral head coverage), instability signs (e.g., upsloping sourcil, Shenton line), femoral torsion, acetabular version, and all three retroversion signs. 3D analysis was performed using an in-house validated AI-based algorithm for automatic segmentation of hip cartilage and labrum, including volumetric delayed gadolinium-enhanced MRI (dGEMRIC) for assessing cartilage quality. Cartilage thickness, surface area, volume, labral volume, surface and cross-sectional area, and dGEMRIC were measured at each clock-face position in absolute and relative terms (area/volume relative to femoral head), yielding 170 variables. Group comparisons were performed using one-way ANOVA and independent t tests and Fisher’s exact tests.Results: Demographics did not differ between BDDH hips with and without FHD, including age (31 ± 10 vs 31 ± 10 years; p = 0.975) and sex (63% vs 52% female; p = 0.471). BDDH hips with FHD showed increased femoral torsion (34.1 ± 10.6° vs 25.7 ± 15.0°, p = 0.013) and a higher prevalence of a positive Shenton line (11% vs 0%, p = 0.040); no other radiographic parameters differed significantly. Morphological 3D parameters did not differ between BDDH hips with and without FHD (all p ≥ 0.144). However, BDDH hips with FHD demonstrated lower dGEMRIC values than hips without FHD (p < 0.001–0.045), particularly in postero-inferior and superior peripheral regions corresponding to the direction of decentration. Across DDH, BDDH, and normal hips, most 3D parameters differed significantly; relative cartilage area was lowest in dysplastic hips and highest in normal hips (p < 0.001).Discussion and conclusions: BDDH hips with and without FHD showed identical 3D cartilage and labral morphology. FHD was associated with increased femoral torsion and lower dGEMRIC values due to contrast distribution between cartilage layers (decentration). These findings indicate that decentration in BDDH relates primarily to femoral torsion rather than acetabular morphology and may support consideration of derotational femoral osteotomy. 0 0 0 0