Critical Shoulder Angle Assessment in Radiographies and Magnetic Resonance Imaging (MRI): Measurement of Intra and Inter-Observer Agreement

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José Carlos Souza Vilela, MD, PHD Anna Luiza Amancio Vidal Mabelly Andrade Correa Luciene Mota de Andrade Paulo Henrique Sampaio Ribeiro Bruno Biller Teixeira Fernandes de Araúj Tadeu Fonseca Barbosa Thalles Leandro Abreu Machado


Objective: to evaluate the critical shoulder angle by comparing the results of measurements performed by radiography and magnetic resonance imaging, considering the intra and interobserver perspectives.

Methods: we evaluated radiographic and magnetic resonance images of 74 shoulders (71 patients) submitted to these exams between 2017 and 2020, regardless of the acquired pathology. We ran a statistical analysis comparing the mean values of the data obtained by the student's t-test, and the analysis of intra and interobserver agreement used the Interclass Correlation Coefficient (ICC), with bidirectional mixed models and a confidence interval of 95%.

Results: the patients had a mean age of 51.7 years, with a predominance of men (51.9%) and the most affected shoulder was the right-sided one (57.9%). There were no significant differences between the measurements made by radiography and those by magnetic resonance, both by intra and interobserver views, and the ICC showed a satisfactory level of agreement in relation to these aspects. Conclusion: there was an excellent degree of agreement between the examiners, in all the situations compared (intra and interobserver, radiography and MRI), considering the two periods of analysis.

Keywords: Critical Shoulder Angle, X-ray, Magnetic Resonance Imaging

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SOUZA VILELA, José Carlos et al. Critical Shoulder Angle Assessment in Radiographies and Magnetic Resonance Imaging (MRI): Measurement of Intra and Inter-Observer Agreement. Medical Research Archives, [S.l.], v. 10, n. 4, apr. 2022. ISSN 2375-1924. Available at: <>. Date accessed: 28 nov. 2023. doi:
Research Articles


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