Background: Due to its many variations, the scapula is among the most frequently examined bones. Especially the acromion can be of different shapes and sizes. Measurement of the morphometric structures in the shoulder joint make it easier to explain the cause of the various shoulder problems. The objective of this study is putting emphasis on the importance of acromion types, os acromiale presence and acromial morphometric measurements in the etiology and diagnosis of shoulder pain.

Materials and methods: A retrospective study, based on 100 patients of both genders presented with the complaints of shoulder pain and underwent magnetic resonance imaging, was conducted. Within this scope, types of acromion, slope of acromion, length of acromion, length of coracoid process, the distance between acromion and coracoid process, lateral acromial angle (LAA), critical shoulder angle (CSA), acromial index (AI) and acromiohumeral distance were measured. The data was analyzed considering the gender and acromion types and the presence of os acromiale is investigated.

Results: The most common acromion was type-II (curved) (% 62) frequency rate while the rate of type-I (flat) and type-III (hooked) acromions were 21% and 17%, respectively. The length of acromion and coracoid process were found to be significantly longer in males, while no significant difference between genders in terms of the distance between acromion and coracoid process were observed. Furthermore, while negative correlation between LAA and AI as well as LAA and CSA were observed; positive correlation between AI and CSA was found. In addition, there was negative correlation between slope of acromion and acromiohumeral distance. Besides, acromiohumeral distance was significantly higher in males. Regarding the presence of os acromiale, it was observed in 3 women out of 59 and 2 men out of 41, which indicated no significant difference between genders.

Conclusions: It is evaluated that the morphometric measurement is of importance in contributing clinically in distinguishing the problems that may occur according to gender and acromion types.