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Erschienen in: Knee Surgery, Sports Traumatology, Arthroscopy 8/2017

19.10.2015 | Knee

Effects of upright weight bearing and the knee flexion angle on patellofemoral indices using magnetic resonance imaging in patients with patellofemoral instability

verfasst von: Christoph Becher, Benjamin Fleischer, Marten Rase, Thees Schumacher, Max Ettinger, Sven Ostermeier, Tomas Smith

Erschienen in: Knee Surgery, Sports Traumatology, Arthroscopy | Ausgabe 8/2017

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Abstract

Purpose

This study analysed the effects of upright weight bearing and the knee flexion angle on patellofemoral indices, determined using magnetic resonance imaging (MRI), in patients with patellofemoral instability (PI).

Methods

Healthy volunteers (control group, n = 9) and PI patients (PI group, n = 16) were scanned in an open-configuration MRI scanner during upright weight bearing and supine non-weight bearing positions at full extension (0° flexion) and at 15°, 30°, and 45° flexion. Patellofemoral indices included the Insall–Salvati Index, Caton–Deschamp Index, and Patellotrochlear Index (PTI) to determine patellar height and the patellar tilt angle (PTA), bisect offset (BO), and the tibial tubercle–trochlear groove (TT–TG) distance to assess patellar rotation and translation with respect to the femur and alignment of the extensor mechanism.

Results

A significant interaction effect of weight bearing by flexion angle was observed for the PTI, PTA, and BO for subjects with PI. At full extension, post hoc pairwise comparisons revealed a significant effect of weight bearing on the indices, with increased patellar height and increased PTA and BO in the PI group. Except for the BO, no such changes were seen in the control group. Independent of weight bearing, flexing the knee caused the PTA, BO, and TT–TG distance to be significantly reduced.

Conclusions

Upright weight bearing and the knee flexion angle affected patellofemoral MRI indices in PI patients, with significantly increased values at full extension. The observations of this study provide a caution to be considered by professionals when treating PI patients. These patients should be evaluated clinically and radiographically at full extension and various flexion angles in context with quadriceps engagement.

Level of evidence

Explorative case–control study, Level III.
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Metadaten
Titel
Effects of upright weight bearing and the knee flexion angle on patellofemoral indices using magnetic resonance imaging in patients with patellofemoral instability
verfasst von
Christoph Becher
Benjamin Fleischer
Marten Rase
Thees Schumacher
Max Ettinger
Sven Ostermeier
Tomas Smith
Publikationsdatum
19.10.2015
Verlag
Springer Berlin Heidelberg
Erschienen in
Knee Surgery, Sports Traumatology, Arthroscopy / Ausgabe 8/2017
Print ISSN: 0942-2056
Elektronische ISSN: 1433-7347
DOI
https://doi.org/10.1007/s00167-015-3829-8

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