Anatomical basics and variations of the scapula in Turkish adults

OBJECTIVE: To analyze the anatomical basis of the scapula, acromion, os acromiale, coracoid process, coraco-acromial arch, and glenoid cavity in Turkish adults.

METHODS: We performed the study at the Faculty of Medicine, Akdeniz University, Turkey between January 2004 and December 2005. A total of 90 dry bones of the scapula from human cadavers were randomly selected. The length, width, and anterior thickness of the acromion and the acromial facet of the acromioclavicular joint were measured with an electronic caliber and was examined visually. For the radiological evaluation, the posterior anterior and the lateral shoulder radiographs of 90 consecutive adult patients with normal findings were used. These films were evaluated and grouped according to the acromial arch morphology.

RESULTS: The distribution of the acromial morphologic types according to slope was type I (flat) 10%, type II (curved) 73%, type III (hooked) 17%. Type I was seen in 11%, type II 66%, type III 23% of the specimens. The morphological shape of the tip of the acromion was 31% cobra shaped, 13% square shaped, and 56% intermediate type. The scapulas, coracoid process and the coraco acromial arch were measured. In 72% of the specimen, the glenoid notch of the scapulas were absent and oval shaped, whereas in 28% the notch was well expressed and the glenoid cavity was pear shaped. The mean vertical length of the glenoid cavity was 36.3 ± 3 mm, and the mean transverse length was 24.6 ± 2.5 mm. Os acromiale is a rare anatomical condition. Its incidence has been documented in radiographic and anatomical studies to be between 1-15%. The presence of os acromiale was 1% in shoulder radiographs (os pre-acromiale), and in dry bones (os meta-acromiale)

CONCLUSION: We reported the exact morphological measurements of the bone structures of the scapula in Turkish adult population. Our results present an instructive figures of anatomical preparations and radiological cases that can be used to make a more precise radiological and a differential diagnoses.