26dkou001 10.3205/26dkou001 urn:nbn:de:0183-26dkou0018 Meeting Abstract Sequenzielle Pseudolaxitäts-Phänotypen bei varischer Gonarthrose: Robotische Identifikation von frühem anteromedialem Verschleiß, Pseudokontraktur und echter Bandinstabilität mittels REAL-Klassifikation Maslaris Maslaris Alexander A

Universitätsmedizin Greifswald, Klinik für Orthopädie, Unfallchirurgie und Rehabilitative Medizin, Aristotle University of Thessaloniki, Academic Orthopaedic Department, Campus PGH, Thessaloniki, Griechenland

author Wassilew Wassilew Georgi G

Universitätsmedizin Greifswald, Klinik für Orthopädie, Unfallchirurgie und Rehabilitative Medizin, Greifswald, Deutschland

author Kenanidis Kenanidis Eustathios E

Aristotle University of Thessaloniki, Academic Orthopaedic Department, Campus PGH, Thessaloniki, Griechenland

author Mylonakis Mylonakis Nikolaos N

Aristotle University of Thessaloniki, Academic Orthopaedic Department, Campus PGH, Thessaloniki, Griechenland

author Tsiridis Tsiridis Eleftherios E

Aristotle University of Thessaloniki, Academic Orthopaedic Department, Campus PGH, Thessaloniki, Griechenland

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 001 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 | Alignment, Anatomie und Implantatpositionierung Berlin 20261020 20261023 DKOU26_Abs_932 TextObjectives and questions: Varus knee osteoarthritis (OA) progresses from anteromedial to posteromedial wear and is frequently accompanied by apparent ligament imbalances and flexion contractures. Distinguishing true ligament pathologies from bone- & osteophyte-driven pseudolaxities remains challenging. Using a real-time robotic protocol for articular laxities evaluation (REAL-Classification) during total knee arthroplasty (TKA) after systematic osteophyte removal, aim was primarily given to define a sequential pseudolaxity-model (SEQ) for varus OA and to analyse possible behaviours of gap-laxities, contractures, and substance losses. Secondarily, a SEQ-based management is unfolded pointing different approach-tendencies.Material and methods: In 254 varus robotic-assisted functionally aligned TKAs, the REAL laxity-phenotypes with gap-opening side were defined. Bone resections in mm and joint line orientations in extension and flexion were retrieved from the robotic database. Mid-flexion laxity ranges was assessed in degrees of axis-deviation. Preoperative ROM-data were also defined. Knees were classified into five sequential phenotypes: Seq0 [lateral-opening, extension-deficit(ED)≤5°], Seq1 (medial-opening, ED≤5°), Seq2 (medial-opening, ED>5°), Seq3 (lateral opening, ED>5° with low lateral laxity (LL) bellow the top tertile <7.07mm), and Seq4 (lateral opening, >5° with high LL>7.07mm). Preoperative ROM, midflexion laxity range at 45°, gap imbalances, REAL distributions, and robotic management parameters were analysed.Results: Seq0 represented an early anteromedial OA stage with no contracture and minimal cartilage loss (extension deficit 0.5 ± 3.0°), preserved ROM (126 ± 9°), small lateral opening (−1.7 ± 1.1 mm in extension), and predominantly low REAL-grades (REAL 1A-1B: 75%). Seq1 represented a posteromedial OA with more cartilage but no contractures. Seq2 represented a progressed varus OA with progressed cartilage-/ bone-losses and fixed-flexion deformities. Despite increasing contractures from Seq1 to Seq2, REAL severity did not decrease, indicating osteophyte-related pseudo-contractures rather than true ligament tightening. However, in the more progressed Seq3 phenotype a fixed-flexion varus OA with possible MCL contracture illustrated an increasing lateral opening but with suppressed REAL-imbalances. In Seq4 through an progressing lateral elongation, a sequent increase in lateral REA-imbalances could be illustrated.Discussion and conclusions: Varus knee OA demonstrates a reproducible sequence of pseudolaxity phenotypes. Early apparent contracture is predominantly osteophyte-driven, whereas true ligament imbalance emerges later. REAL classification provides a real-time, alignment-independent framework to distinguish pseudolaxity from true ligament pathology and to guide personalized robotic TKA strategies. 0 0 0 0