Diagnostic Accuracy of MRI Evaluation of Patellar Position According to the Physeal Line in Pediatric Patients

Abstract

Aim: Abnormal positioning of the patella, of which the superior position is defined as patella alta (PA), whereas the inferior position is defined as patella baja (PB). Most of the measurements of patellar position evaluations are time-consuming. In this study, we aimed to examine the diagnostic accuracy of visual evaluation of the patellar position according to the physeal line and to determine the inter- and intraobserver agreement of this evaluation in MRI examinations. Material and Methods: Knee MRI examinations performed between 2019-2021 with different knee symptoms and prediagnoses were retrospectively analyzed in this study. As a reference test, Insall-Salvati Ratio was calculated by the following formula: Tendon length/patellar length. Two visual evaluation methods were used; physis line to the patella (PLP) and physis line to patellar joint cartilage (PLC). Results: Three hundred and sixty consecutive children aged 60-215 months were included in the study. There was excellent an agreement of both intra- and interobserver on PLP and PLC for two observers (κ > 0.800, for all). When we evaluated intra- and interobserver agreements according to groups, almost perfect agreements were detected (κ > 0.750, for all). Diagnostic accuracy for both two observers on the visual evaluation of PLP was almost perfect (Sensitivity 95.5%, specificity 87.2% for observer 1, and Sensitivity 94.7%, specificity 87.2% for observer 2), and on the PLC evaluation was also good (Sensitivity 89.3%, specificity 82.9% for observer 1, and Sensitivity 88.1%, specificity 85.5% for observer 2). Conclusion: Even though direct radiography is used in the diagnosis of PA and PB, it has been shown that MRI can also be used in pediatric patients in daily practice. Instead of the time-consuming measurements used in MRI, it may be kept in mind to use these methods in our study for practical and accurate diagnosis.