Assessment of Patellar Height Measurement Methods From Digital Radiography

Gracitelli, Guilherme Conforto; Pierami, Rafael; Tonelli, Thomaz Antônio; Falótico, Guilherme Guadagnini; Silva, Flávio Duarte; Nakama, Gilberto Yoshinobu; Franciozi, Carlos Eduardo da Silveira; Queiroz, Antônio Altenor Bessa de; Filho, Mário Carneiro

doi:10.1016/s2255-4971(15)30088-4

Cited by 17 publications

(19 citation statements)

References 26 publications

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“…The reason why the authors chose the C-D as the benchmark over the IS method are the following: C-D is a simple, reproducible method validated in asymptomatic patients and reported sensitivity and specificity are similar to other CRRs. 9 Experience is proven to increase reliability of patellar height measurements, 13 and C-D is the mskR's preferred method to determine patellar height. In this study, C-D was measured by the same trained mskR and proved to have excellent intrarater reliability.…”

Section: Discussionmentioning

confidence: 99%

Is the Clinician's Eye a Valid and Reproducible Tool for Diagnosing Patella Alta on a Lateral Knee Radiography?

et al. 2020

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Introduction: Validity and reproducibility of the clinician's eye (CE) to diagnose patella alta (PA) on a lateral knee radiography (radiograph) is unknown. Methods: Cross-sectional study of 46 lateral knee x-rays. Three blind observers used CE, Insall-Salvati (IS), modified Insall-Salvati (mIS), and Caton-Deschamps (C-D) to determine patellar height. Sensitivity and specificity of each observer was compared with the musculoskeletal radiologist's C-D measurements. Intraobserver and interobserver agreement were assessed with intraclass correlation coefficient and Fleiss κ, respectively. Time needed to estimate patellar height for every method was recorded in seconds. Statistical differences between observers were calculated with a generalized estimating equation. Analysis of variance and post hoc Bonferroni test compared duration of each method ( P < 0.05). Data were analyzed using Stata 15 (StataCorp). Results: CE, IS, mIS, and C-D's sensitivity and specificity values are as follows: 77%, 92%; 94%, 52%; 67%, 58%; and 53%, 89%, respectively. Intraclass correlation coefficient and Fleiss κ of CE, IS, mIS, and C-D values are as follows: 0.66 and 0.43, 0.88 and 0.68, 0.54 and 0.09, and 0.68 and 0.59, respectively. CE was the second most sensitive and most specific method for diagnosis of PA, with moderate intraobserver and interobserver agreement. IS was the most sensitive method with good intraobserver and interobserver agreement. CE was significantly faster ( P < 0.05) than all other conventional radiographic ratios. Conclusion: CE's sensitivity increases with observer's experience and is highly specific. If normal patellar height is diagnosed, no other ratios are necessary, even in the less experienced clinician. Intraobserver and interobserver reproducibilities were moderate and only inferior to the IS ratio. In case patellar height is uncertain with the CE, the IS ratio is the most sensitive and reproducible method to confirm the diagnosis of PA.

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Section: Discussionmentioning

confidence: 99%

Is the Clinician's Eye a Valid and Reproducible Tool for Diagnosing Patella Alta on a Lateral Knee Radiography?

et al. 2020

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“…Similar to our results, both Nizić et al (ICC ¼ 0.93-0.95) and Gracitelli et al (ICC ¼ 0.603-0.809) found IS to have the best interobserver reliability among the four measurement tools on XR. 28,29 However, there is a mixture of reported data on the patellar height ratio with the next best ICC on XR. 19,[29][30][31][32] BP on MRI had the worst interobserver reliability in our study.…”

Section: Discussionmentioning

confidence: 99%

“…28,29 However, there is a mixture of reported data on the patellar height ratio with the next best ICC on XR. 19,[29][30][31][32] BP on MRI had the worst interobserver reliability in our study. Lee et al found similar results with BP on CT and MRI.…”

Section: Discussionmentioning

confidence: 99%

“…The resulting MRI image creates a difficulty when drawing the straight line on the tibial plateau; this, in turn, contributes toward the lower ICC with this method. 29 One limitation of this study is the control of image production since we could not control the image quality, how the images were obtained, and the patient positioning during imaging. The patient positioning has previously been discussed, but otherwise we feel that the images used in the study were of good quality and represent the type of images typically seen in the clinical setting, and the results are therefore applicable to a clinical setting.…”

Section: Discussionmentioning

confidence: 99%

“…Although it is possible that our ICCs could have been higher since interobserver reliability has been shown to be positively influenced by the observer's level of experience, the fact that there was a difference in the observers' experience may help to better illustrate which measurement techniques are more consistent between observers in general. 13,29 Patellar height ratios IS, mIS, CD, and BP can be effectively used to assess patella alta on both MRI and XR; however, MRI was higher than XR by roughly a factor of 0.1 across all four measurement ratios in patients with primary patellar instability. Skeletally immature patients may have higher patellar height measurements than skeletally mature patients, but sex did not have an effect on patellar height measurements.…”

Section: Discussionmentioning

confidence: 99%

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Patellar Height Measurements on Radiograph and Magnetic Resonance Imaging in Patellar Instability and Control Patients

2017

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Insall-Salvati (IS) ratio, modified IS ratio (mIS), Caton-Deschamps (CD) index, and Blackburne-Peel (BP) index are patellar height measurements commonly made on lateral radiographs (XRs) in patients with patellofemoral instability. More recently, magnetic resonance imaging (MRI) has been used as an additional imaging modality to measure patellar height. However, different imaging modalities have not been previously compared for all of these measurements. First, to compare the patellar height measurements of IS, mIS, CD, and BP on XR and MRI in first-time lateral patellar dislocation (LPD) patients and a control population and, second, to evaluate for the effect of sex and skeletal maturity. All first-time LPD patients with both MRI and XR of the knee within 6 weeks of injury from 2008 to 2012 were included in the LPD group ( = 112). Patients without patellofemoral instability who underwent both MRI and XR of the knee served as controls ( = 129). Two independent observers measured patellar height. Mean values were compared among the radiographic modalities, sex, and skeletal maturity status. Interobserver reliability was assessed using intraclass correlation coefficients (ICCs). Patellar height in the LPD group measured greater on MRI than on XR for all four patellar height ratios (IS: 0.11; mIS: 0.07; CD: 0.18; BP: 0.08). In controls, MRI also demonstrated higher readings than XR on two indices (CD: 0.17; BP: 0.16). Skeletally immature patients measured higher than skeletally mature patients in the majority of the measurements by 0.12 to 0.20 on MRI and XR; the majority of the measurements showed no sex differences. ICC was excellent for IS on both MRI (ICC = 0.830) and XR (ICC = 0.849) and for CD on XR (ICC = 0.786). Patellar height measured greater on MRI than XR by approximately 0.10 across four patellar height measurement indices. Skeletally immature patients measured higher than skeletally mature on both MRI and XR, but sex did not have an effect. This is a retrospective cohort study and its level of evidence is 3.

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Patellar height measurements: Insall–Salvati ratio is most reliable method

Verhulst

Sambeeck

Olthuis

et al. 2019

Knee Surg Sports Traumatol Arthrosc

120

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Purpose Patella alta is a risk factor for patellofemoral pain and instability. Several measurement methods and imaging modalities are in use to measure patellar height. The first aim of this study was to determine the intra-and interrater reliability of different patellar height measurement methods on conventional radiography (CR), CT and MRI. The second aim was to examine the applicability of patellar height measurement methods originally designed for CR on CT and MRI. Methods Forty-eight patients who were treated for patellar instability were included. All patients had undergone a pre-operative conventional radiograph, CT scan and MRI. Five methods for measuring patellar height were performed on radiographs, CT and MRI by four observers. For each measurement, the intra-and interrater reliability was determined by calculating the intra-class correlation coefficient (ICC). A Bland-Altman analysis was performed for measurements with an ICC ≥ 0.70. ResultsThe Insall-Salvati (IS) ratio was the only measurement that showed good intra-and inter-observer reliability on CR, CT and MRI. The intra-and inter-observer reliability of the patellotrochlear index (PTI) for MRI was good to excellent for all observers. The IS ratio showed a moderate to good reliability for comparison of all three imaging modalities with the best agreement between radiography and MRI. The other patellar height measurements showed only poor to moderate inter-method agreement. Conclusion In this study, the Insall-Salvati ratio shows better intra-and inter-observer reliability than the Blackburne-Peel ratio, the Caton-Deschamps ratio and the modified Insall-Salvati ratio on all imaging modalities. Radiography and CT seem to have better reliability than MRI. The patellotrochlear index, however, shows good inter-and intra-observer reliability on MRI. Only for the IS method was there acceptable agreement between CR and MRI. This means that the established Insall-Salvati normal values could be used for MRI as well. This study shows that the most reliable method to measure patella height is the Insall-Salvati ratio measured on conventional radiographs or the patellotrochlear index on MRI. Level of evidence Level II diagnostic.

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Assessment of Patellar Height Measurement Methods From Digital Radiography

Cited by 17 publications

References 26 publications

Is the Clinician's Eye a Valid and Reproducible Tool for Diagnosing Patella Alta on a Lateral Knee Radiography?

Is the Clinician's Eye a Valid and Reproducible Tool for Diagnosing Patella Alta on a Lateral Knee Radiography?

Patellar Height Measurements on Radiograph and Magnetic Resonance Imaging in Patellar Instability and Control Patients

Patellar height measurements: Insall–Salvati ratio is most reliable method

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