Reliability of patellotrochlear index in patellar height assessment on MRI—correction for variation due to change in knee flexion

Ahmad, Mehtab; Janardhan, S; Amerasekera, Steve; Ashraf, T; Choudhary, Surabhi

doi:10.1007/s00256-018-3040-3

Cited by 19 publications

(15 citation statements)

References 21 publications

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“…In humans, a proximally positioned patella (patella alta) is associated with patellar instability, due to which the patella exceeds the femoral trochlea proximally and loses support from the trochlear ridge [11,[14][15][16]. Based on these human studies, veterinary researchers have investigated the association between the PLL/PL and patellar luxation [2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Examination of the proximodistal patellar position in small dogs in relation to anatomical features of the distal femur and medial patellar luxation

et al. 2021

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Objective To determine the influence of anatomical features of the distal femur on the proximodistal patellar position and compare the proximodistal patellar position between dogs with and without medial patellar luxation (MPL). Study design Retrospective case series (n = 71). Methods Mediolateral-view radiographs of clinical cases of dogs weighing less than 15 kg were obtained. The stifle joint angle, patellar ligament length, patellar length, size of the femoral condyle, trochlear length, and trochlear angle were measured and included in multiple linear regression analyses to ascertain their effects on the proximodistal patellar position. Radiographs were divided into MPL and control groups. The effects of MPL on the proximodistal patellar position and morphological factors were also examined. Results The final model for the proximodistal patellar position revealed that the patella became distal as the ratio of the patellar ligament length to patellar length decreased, the trochlear angle relative to the femur increased, the trochlear length relative to the patellar length increased, or the trochlear length relative to the femoral condyle width decreased. The proximodistal patellar position in the MPL group was not significantly different from that in the control group despite the trend towards a distally positioned patella (p = 0.073). The MPL group showed a significantly shorter trochlea (p<0.001) and greater trochlear angle relative to the femur (p = 0.029) than the control group. Conclusion The proximodistal patellar position depends on multiple factors, and its determination based on PLL/PL alone may not be appropriate. Dogs with MPL did not have a proximally positioned patella compared with dogs without MPL. Although hindlimbs with MPL had a shorter trochlea than those without patellar luxation, this difference did not appear to be sufficient to displace the patellar position proximally in small dogs, possibly compensated by increased trochlear angle relative to the femur.

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Section: Introductionmentioning

confidence: 99%

Examination of the proximodistal patellar position in small dogs in relation to anatomical features of the distal femur and medial patellar luxation

et al. 2021

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“…Recently, Ahmad et al reported PTI values for 64 symptomatic patients, but they had only three healthy volunteers. 20 Thus, this current study represents an important addition to the literature providing a reference level of 36.8% for patella height as defined by PTI in a normal knee. It also suggests that PTI measurement has a good interclass correlation and excellent intraclass correlation.…”

Section: Discussionmentioning

confidence: 88%

Patellotrochlea Index in Normal Healthy Knees

et al. 2020

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Patella alta is a common and significant abnormality responsible for many patellofemoral joint-related conditions. Many methods of patella height measurements are described; however, patellotrochear index (PTI) is the most logical method as it measures the direct relation between patella and trochlea. The aim of this study is to investigate PTI in normal healthy asymptomatic volunteers to understand the patellofemoral relation in normal knees. Twenty-five healthy volunteers underwent magnetic resonance imaging (MRI) scans of both knees. Two observers independently measured PTI on two different occasions at 6-week interval. Statistical analysis was performed to identify intra- and interobserver correlation between two observers and the mean value of PTI. Agreement analysis was performed according to Bland and Altman. Comparisons of means were made using paired t-tests. The mean age of 25 healthy volunteers was 21.28 years (19–23) with a male:female ratio of 14:11. The overall mean PTI value of all observations was 36.8% and pooled standard deviation (SD) 11.5%. Intraclass correlation (ICC) testing showed “good” interobserver ICC between two observers for PTI for both first (0.80) and second (0.84) set of measurements. There was “excellent” intraobserver correlation for two sets of measurements of PTI made by each first (0.96) and second (0.91) observer. Intraobserver repeatability for PTI was ± 0.07 and ± 0.1, respectively, for the first and second observer. Interobserver repeatability for PTI was ± 0.159 and ± 0.133, respectively, for the first and second set of measurements. Analysis of individual measurements of patella and trochlear articular cartilage revealed that the largest repeatability values were for trochlea measurements. The study reports that the average PTI in asymptomatic healthy knee utilizing current clinical MRI scanning conditions is 36.8%. This provides surgeons with a gold standard normal PTI value, which can serve as a target value in clinical diagnosis as well as surgical correction of patella height. There is good to excellent intra- and interobserver correlation with limited variability in assessing patella height using PTI on MRI scan.

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“…B. patellotrochleärer Index) hat. Formeln zur Adaptation werden vorgeschlagen, können jedoch nur limitiert eine Aussage über die tatsächlich vorliegende Dynamik treffen [2].…”

Section: Funktionsabhängige äNderungen Der Statischen Parameterunclassified

Funktionelle Diagnostik der patellofemoralen Instabilität

Bartsch

Egloff

2023

Arthroskopie

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Zusammenfassung Hintergrund Die Routinediagnostik der patellofemoralen Instabilität evaluiert überwiegend statische Faktoren. Obwohl es sich bei der Instabilität um ein dynamisches Geschehen handelt, wird statisches Malalignement und nicht Maltracking als Surrogat für die patellofemorale Instabilität erfasst. Mehrere statische Parameter wie TT-TG-Abstand (Distanz zwischen Tuberositas tibiae und Trochlearinne) oder Patellahöhe ändern sich mit der Beinposition, und durch die Kontraktion des M. quadriceps femoris kann sich die Position der Patella um über ein Viertel ihrer Breite mediolateral verschieben. Funktionelle Diagnostik, die das Patellatracking erfasst, beschreibt eine patellofemorale Instabilität daher differenzierter als eine alleinige statische Diagnostik. Ergebnisse Um als funktionelle Diagnostik eingesetzt zu werden, muss die Patellabewegung in verschiedenen Kniewinkeln, mit unterschiedlich hoher Anspannung des Quadrizeps, unter externer Stressbelastung und unter Belastung im Stehen durchgeführt werden können. Als neue Methoden zur funktionellen Diagnostik haben sich Ultraschall, dynamische Magnetresonanztomographie (MRT) und muskuloskeletale Modellierung in unterschiedlichen Anwendungsbereichen hervorgetan, die ein großes Potenzial zeigen, diese diagnostische Lücke zu schließen. Die Sonographie kann in der Sprechstunde einfach durchgeführt und wiederholt werden, die dynamische MRT kann eine hochauflösende Aussage über Translation und Rotation inkl. Knorpelevaluation bieten, und die muskuloskeletale Modellierung kann Gelenkbelastungskräfte während der physiologischen Ambulation bestimmen. Diskussion Funktionelle Diagnostik der patellofemoralen Instabilität eröffnet neue Perspektiven und erlaubt eine tiefgreifende Analyse der patellofemoralen Biomechanik. Referenzwerte und spezifische Bewegungen für den Einsatz in Diagnose, Behandlung und Nachsorge müssen jedoch noch spezifiziert werden.

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Reliability of patellotrochlear index in patellar height assessment on MRI—correction for variation due to change in knee flexion

Cited by 19 publications

References 21 publications

Examination of the proximodistal patellar position in small dogs in relation to anatomical features of the distal femur and medial patellar luxation

Examination of the proximodistal patellar position in small dogs in relation to anatomical features of the distal femur and medial patellar luxation

Patellotrochlea Index in Normal Healthy Knees

Funktionelle Diagnostik der patellofemoralen Instabilität

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