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The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study

PURPOSE: The purpose of the study was to investigate the theoretical isometric point based of the curve of the femoral groove and relating it to the origin of the MPFL femoral tunnel on lateral radiograph by comparing a patellar instability cohort with a control cohort. METHODS: From a Patellar Inst...

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Autores principales: Campos, Tulio, Soogumbur, Akash, McNamara, Iain R., Donell, Simon T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Springer Berlin Heidelberg 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105162/
https://www.ncbi.nlm.nih.gov/pubmed/29204862
http://dx.doi.org/10.1007/s00167-017-4740-2
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author Campos, Tulio
Soogumbur, Akash
McNamara, Iain R.
Donell, Simon T.
author_facet Campos, Tulio
Soogumbur, Akash
McNamara, Iain R.
Donell, Simon T.
author_sort Campos, Tulio
collection PubMed
description PURPOSE: The purpose of the study was to investigate the theoretical isometric point based of the curve of the femoral groove and relating it to the origin of the MPFL femoral tunnel on lateral radiograph by comparing a patellar instability cohort with a control cohort. METHODS: From a Patellar Instability database the radiographs of 40 consecutive patients were analysed to define Schöttle’s point, and the arc of the circle of the trochlear groove. A comparison population of 20 radiographs from comparable patients with tibiofemoral joint disorders was used as a control. The distance from Schöttle’s point to the most anterior part of the groove (extension) was also compared to the distance to the distal end of the roof of the notch (flexion). RESULTS: The trochlea was circular in the controls but not the Patellofemoral Instability cohort where trochlear dysplasia is usually present. The difference between the extension and flexion length was a mean of − 2.0 ± 0.5 mm in the controls and + 6.0 ± 0.5 mm in the patellofemoral cohort. In neither cohort did the centre of the circle correspond to Schöttle’s point. The extension distance correlated with the boss height. CONCLUSIONS: The dysplastic trochlea is not circular and the centre of the best matched circle was different to the control trochleae which were circular. The circle centres did not correlate with Schöttle’s point for either cohort, and was more proximal in the Patellofemoral Instability cohort. CLINICAL RELEVANCE: For the MPFL to have equal tension throughout flexion within the groove, the length should not change. In normal knees the MPFL does not behave isometrically. The change in length, as measured from Schöttle’s point to the trochlea, was greater for patellofemoral instability patients explaining why an isolated MPFL reconstruction in the presence of severe trochlear dysplasia risks poor outcomes. Level of evidence III.
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spelling pubmed-61051622018-08-30 The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study Campos, Tulio Soogumbur, Akash McNamara, Iain R. Donell, Simon T. Knee Surg Sports Traumatol Arthrosc Knee PURPOSE: The purpose of the study was to investigate the theoretical isometric point based of the curve of the femoral groove and relating it to the origin of the MPFL femoral tunnel on lateral radiograph by comparing a patellar instability cohort with a control cohort. METHODS: From a Patellar Instability database the radiographs of 40 consecutive patients were analysed to define Schöttle’s point, and the arc of the circle of the trochlear groove. A comparison population of 20 radiographs from comparable patients with tibiofemoral joint disorders was used as a control. The distance from Schöttle’s point to the most anterior part of the groove (extension) was also compared to the distance to the distal end of the roof of the notch (flexion). RESULTS: The trochlea was circular in the controls but not the Patellofemoral Instability cohort where trochlear dysplasia is usually present. The difference between the extension and flexion length was a mean of − 2.0 ± 0.5 mm in the controls and + 6.0 ± 0.5 mm in the patellofemoral cohort. In neither cohort did the centre of the circle correspond to Schöttle’s point. The extension distance correlated with the boss height. CONCLUSIONS: The dysplastic trochlea is not circular and the centre of the best matched circle was different to the control trochleae which were circular. The circle centres did not correlate with Schöttle’s point for either cohort, and was more proximal in the Patellofemoral Instability cohort. CLINICAL RELEVANCE: For the MPFL to have equal tension throughout flexion within the groove, the length should not change. In normal knees the MPFL does not behave isometrically. The change in length, as measured from Schöttle’s point to the trochlea, was greater for patellofemoral instability patients explaining why an isolated MPFL reconstruction in the presence of severe trochlear dysplasia risks poor outcomes. Level of evidence III. Springer Berlin Heidelberg 2017-12-04 2018 /pmc/articles/PMC6105162/ /pubmed/29204862 http://dx.doi.org/10.1007/s00167-017-4740-2 Text en © The Author(s) 2017 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
spellingShingle Knee
Campos, Tulio
Soogumbur, Akash
McNamara, Iain R.
Donell, Simon T.
The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
title The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
title_full The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
title_fullStr The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
title_full_unstemmed The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
title_short The trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
title_sort trochlear isometric point is different in patients with recurrent patellar instability compared to controls: a radiographical study
topic Knee
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105162/
https://www.ncbi.nlm.nih.gov/pubmed/29204862
http://dx.doi.org/10.1007/s00167-017-4740-2
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