Evidence map›Paper›PMID 41801503›Full record

ArticleEuropean journal of orthopaedic surgery & traumatology : orthopedie traumatologie2026

Influence of the screw-home mechanism on TT-TG distance: a 3D kinematic simulation study.

Maximilian Jörgens, Julian Fürmetz, Markus Bormann, Wolfgang Böcker, Boris Michael Holzapfel, Sebastian Siebenlist, Julius Watrinet

Abstract read
In one paragraph

Article in European journal of orthopaedic surgery & traumatology : orthopedie traumatologie, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
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1 · What the graph read from it

What it found

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2 · The registry

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3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

7 authors.

Maximilian JörgensDepartment of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), University Hospital, LMU, Munich, Germany. maximilian.joergens@med.uni-muenchen.de.
Julian FürmetzDepartment of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), University Hospital, LMU, Munich, Germany.
Markus BormannDepartment of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), University Hospital, LMU, Munich, Germany.
Wolfgang BöckerDepartment of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), University Hospital, LMU, Munich, Germany.
Boris Michael HolzapfelDepartment of Orthopaedics and Trauma Surgery, Musculoskeletal University Center Munich (MUM), University Hospital, LMU, Munich, Germany.
Sebastian SiebenlistDepartment of Orthopaedic Sports Medicine, Technical University of Munich, Munich, Germany.
Julius WatrinetDepartment of Trauma Surgery, BG Trauma Center Murnau, Murnau am Staffelsee, Germany.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundThe axial distance between the tibial tuberosity and the trochlear groove (TT-TG) is a significant parameter in the preoperative analysis of patellofemoral instability. Discrepancies in TT-TG measurements between imaging modalities are largely attributed to differences in knee flexion and the associated tibial rotation (screw-home mechanism). However, the quantitative impact of the screw-home mechanism and its inter-individual variability on TT-TG measurement remains incompletely characterized. The aim of this study was to measure and evaluate the influence of the screw-home mechanism during knee flexion on the TT-TG distance.

methods56 computed tomography (CT) scans were obtained and segmented into surface models. Anatomic landmarks were defined to determine the TT-TG. Kinematic simulations of knee flexion (0–30° in 10° increments) were performed. Concurrently, various combined screw-home mechanisms were performed in 5° increments (0–20°) for each model. Data analysis involved the paired samples Friedman test with post-hoc Wilcoxon signed-rank tests (p < 0.05).

resultsFlexion and internal tibial rotation led to significant changes in TT-TG values (p < 0.001). Post-hoc analyses showed that all pairwise comparisons within a degree of flexion were statistically significant at different rotation angles. Knee flexion resulted in minimal changes in TT-TG distance, whereas the additional screw-home mechanism caused significant deviations depending on the degree of flexion and rotation, ranging from -1.5 mm (± 0.3) to − 11.0 mm (± 1.1). Once the rotation was complete, further flexion increased the TT-TG distance.

conclusionThe TT-TG distance is significantly influenced by the screw-home mechanism. Standardizing the TT-TG assessment at 30° of flexion minimizes rotational variability, potentially improving diagnostic consistency. However, in vivo validation is required before clinical implementation.

Indexed as

Joint InstabilityKnee JointPatellofemoral JointTibiaBiomechanical PhenomenaBone ScrewsComputer SimulationHumansImaging, Three-DimensionalRange of Motion, ArticularRotationTomography, X-Ray Computed3D simulationKnee kinematicsScrew-home mechanismTT-TG

Identifiers

PMID41801503
PMCPMC12971818

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.