Reporting On Acromion Morphology: Classifications Demonstrate Significant Correlation

Objectives Various classifications of acromion morphology exist in the literature. Only a few studies have compared these classifications and their results vary substantially. The primary purpose of this study was to determine a correlation between different classifications of acromial morphology on a large cohort. The secondary purpose was to establish if there is a difference between age, sides and gender.Methods A retrospective analysis of 1853 subjects' shoulder CTs has been performed. A total of 350 CT scans of polytraumatised patients have been selected out of the initial cohort, after exclusion of fractures and technically insufficient scans. Acromial slope, type, lateral acromion angle (LAA) and acromion index were measured and gender, age and side differences were analysed. Correlations between the different classifications were analysed using the Pearson correlation coefficient.Results The average patient age of this cohort was 48 (range 16-90). There were 232 men and 118 women. There was a significant correlation between all classifications. Excellent correlations have been shown for left-right comparison of all measurements. Gender showed no correlation to any of the measurements. Age was correlated to LAA and acromial type.Conclusion There is a significant correlation between all investigated acromion classifications, demonstrated with the CT. This may aid the clinician in choosing a classification to use when reporting on a patient, depending on the pathology even when plain X-rays are obtained. Age is correlated to LAA and acromial type. There is a strong bilateral correlation within each patient. Gender is not correlated to the acromial shape in any classification.Level of evidence Level III diagnostic study.