PURPOSE OF THE STUDY Radiographs are preferred for understanding the deformity and containment in Legg-Calvé-Perthes disease (LCPD), as well as for treatment planning, but plain radiographs provide only static information and are inadequate for dynamic assessment of the joint. Magnetic resonance imaging (MRI) has been shown to be superior to other diagnostic modalities. The aim of this study was to determine the importance of hip MRI in LCPD treatment decision-making processes between pediatric orthopedic surgeons and orthopedic surgery residents. MATERIAL AND METHODS Eight orthopedic surgery residents and eight pediatric orthopedic surgeons were invited to retrospectively evaluate hip radiography images and MRI sections of 34 patients with LCPD. The treatment choices were divided into two groups as conservative and surgical. Gwet's AC1 analysis was used to establish the relative level of intra-observer agreements. The correlation between the professional experience and the agreement parameters was also evaluated using the Pearson correlation coefficient. ANOVA was used to compare multiple groups. p ≤ 0.05 was statistically significant. RESULTS For both groups most preferred treatment method was conservative approaches based on plain radiography and MRI. The resident group showed a significant shift from conservative treatment to surgical treatment choices after MRI evaluation. The difference between the frequencies of each treatment choice for pediatric orthopedic surgeons was not statistically significant among different imaging modalities, but a comparison of the changes in surgical treatment revealed a significant difference between the imaging modalities, with a trend towards more complicated treatment choices. DISCUSSION Conservative methods were the most preferred treatment choice in the study, as it is common. It was observed that treatment choices changed when patients were evaluated together with MRI. Compared to plain radiographs, MRI provides sufficient and particular information for evaluating the structures of the hip joint components. CONCLUSIONS We found that consideration of MRI data in LCPD patients changed treatment recommendations substantially towards more complicated surgical procedures. We consider this to be an 'MRI effect' where using a more complex imaging modality leads surgeons to more complicated treatment modalities in LCPD. Key words: imagnetic resonance imaging, reliability, MRI effect, Perthes disease, children.

Izmir Tınaztepe University Department of Orthopaedics and Traumatology Izmir Turkey

Ortopediatri Pediatric Orthopedic Academy Istanbul Turkey

Tepecik Training and Research Hospital Department of Orthopaedics and Traumatology Izmir Turkey

Van Training and Research Hospital Department of Orthopaedics and Traumatology Van Turkey

Vliv vyšetření MR na klinické rozhodování u Perthesovy choroby: čím komplexnější zobrazení, tím komplikovanější operace