Acromion morphology and its relationship with sub acromial Impingement

Abstract

Background And Objectives: Shoulder pain due to Impingement syndrome is a common clinical entity. The cause of which are generally supported by typical changes in Acromion morphology on standard radiographs. We Evaluated 5 commonly used radiographic parameters of acromial morphology and assessed the association between different radiographic characteristics on the one hand and sub-acromial impingement on the other. Methods: Measurement of acromial type (Bigliani), acromial Slope (AS), acromial tilt(AT), Lateral acromial angle (LAA), and acromion index (AI) were done on standard radiographs of 100 patients with sub acromial impingement and 100 controls without sub-acromial pathology. Results: The acromial type III according to Bigliani was associated with Impingement, A statistically significant difference between controls and impingement patients was found for AS. AT of controls was significantly smaller than that of impingement patients. LAA of controls was not significantly different from that of impingement patients. AI of controls was significantly lower than of impingement patients. A good correlation was found between acromial type and AS. Interpretation And Conclusions: A low lateral acromial angle and a large lateral extension of the acromion are associated with a higher prevalence of Impingement. Type II Acromion is most common type whereas Type III is a risk factor for Impingement. Higher degrees of Acromion slope and lower degrees Tilt are found in Impingement syndrome. Keywords: Acromion, Impingement, Bigliani