26dkou006 10.3205/26dkou006 urn:nbn:de:0183-26dkou0061 Meeting Abstract Restricted Torsional Adjustment in der individualisierten Knieendoprothetik: Indikation und rationale Anwendung Maslaris Maslaris Alexander A

University of Oxford, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, UK, Universitätsmedizin Greifswald, Klinik für Orthopädie, Unfallchirurgie, und Rehabilitative Medizin, Greifswald, Deutschland

author Talbot Talbot Simon S

Department of Orthopaedic Surgery, Western Health, Melbourne, Australien

author Wassilew Wassilew Georgi G

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

author Hofer Hofer Andre A

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

author Schietsch Schietsch Ulrich U

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 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 006 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_911 TextObjectives and questions: The treatment of extensor mechanism malalignment (EMM) in total knee arthroplasty (TKA) remains relatively unpredictable, with controversial treatment strategies and variable outcomes. The presence of pre-existing torsional abnormalities (TAs) is decisive and may significantly influence the results of different individualized TKA approaches. The concept ofRestricted Torsional Adjustment (RTA)is introduced, and its clinical & biomechanical implications are analyzed and compared with current literature.Material and methods: The present project comprises four sections: (1) A case series demonstrating the use of RTA in patients with EMM caused by TAs. (2) A CT-based analysis of 256 native lower limbs examining the relationships between femoral torsion (FT), tibial torsion (TT), posterior condylar angle (PCA), tibiofemoral rotation (TFR), tibial tubercle–trochlear groove distance (TTTG), patellar tilt (PT), & patellar lateral shift (PLS). (3) A retrospective analysis of 70 CAS-assisted TKAs using a tibia-first FA strategy. Patellar tracking was assessed at 1 week and 1 year postoperatively. Patients with pre-existing patellar tilt ≥5° were compared with those with tilt <5°. (4) A literature review evaluating the impact of different surgical approaches & implant designs on patellar tracking, bony torsion, index of cumulative torsion (ICT), quadriceps tendon angle (QTA), and TFR. Finally, an evidence-based approach is proposed.Results: (1) The RTA technique restored patellar maltracking and improved TAs, TFR, and ICT. (2) Correlation analysis of CT-derived parameters is presented. (3) While mobile-bearing implants initially improved patellar tracking, recurrence of patellar tilt was observed at 1 year, particularly in patients with pre-existing tilt >5°. (4) Single-radius implants demonstrate biomechanical advantages in patellar tracking due to the longer lever arm of the extensor mechanism. Medial ball-in-socket designs support medial pivoting and enhance extensor mechanism function while providing medial stability. Constrained posterior-stabilized (PS+) implants retain corrected TFR and represent a reliable option in EMM associated with TAs. Kinematic alignment (KA), especially when performed through a subvastus approach, offers several advantages for patellofemoral joint function. However, KA in the presence of pre-existing EMM due to TAs (bony or soft tissue-related) may be associated with inferior PROMs & functional outcomes.Discussion and conclusions: In the absence of TAs, KA represent an optimal treatment strategy for patellar tracking. In more severe cases of EMM with coexisting TAs, RTA combined with fixed-bearing PS+ implants provides a reliable treatment option to improve extensor mechanism function. RTA defines the boundaries of safe external femoral rotation and higher degree of constraint (PS+ designs) retains rotational correction. Patients with EMM may benefit from preoperative torsional CT assessment to identify underlying bony or soft tissue TAs and to define individualized RTA boundaries. 0 0 0 0