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J Child Orthop. 2019 Apr 1;13(2):226-235. doi: 10.1302/1863-2548.13.180140.

Inter-rater reliability of the radiographic assessment of simple bone cysts.

Author information

Department of Surgery, The Hospital for Sick Children, Toronto, Ontario, Canada.
Department of Medical Imaging, University of Saskatchewan and Saskatoon Health Region, Saskatoon, Saskatchewan, Canada.
Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada.
Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada.



To develop and evaluate the reliability of an explicit set of parameters and criteria for simple bone cysts (SBCs) and evaluate the reliability of single versus serial chronological reading methods.


Radiographic criteria were developed based on the literature and expert consensus. A single anteroposterior/lateral radiograph from 32 subjects with SBC were evaluated by three radiologists. A second reading was then conducted using revised criteria including a visual schematic. In the third reading the same images were assessed but radiologists had access to images from two additional time points. Inter-rater reliability was assessed after each reading using kappa (κ) and percentage agreement for categorical and binary parameters and intra-class correlation coefficient (ICC) for continuous parameters.


Parameters that were revised with more explicit definitions including the visual schematic demonstrated consistent or improved inter-rater reliability with the exception of continuous cortical rim present and cyst location in the metaphysis and mid-diaphysis. Cortical rim displayed only slight reliability throughout (κ= -0.008 to 0.16). All other categorical parameters had a percentage agreement above 0.8 or a moderate (κ= 0.41 to 0.60), substantial (κ = 0.61 to 0.80) or almost perfect inter-rater reliability (κ = 0.81 to 1.0) in at least one reading. All continuous parameters demonstrated excellent inter-rater reliability (ICC > 0.75) in at least one reading with the exception of scalloping (ICC = 0.37 to 0.70). Inter-rater reliability values did not indicate an obviously superior method of assessment between single and serial chronological readings.


Explicit criteria for SBC parameters used in their assessment demonstrated improved and substantial inter-rater reliability. Inter-rater reliability did not differ between single and serial chronological readings.

Level of Evidence:

Not Applicable.


bone cyst; inter-rater reliability; radiography; simple bone cyst; unicameral bone cyst

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