THE CORRELATION BETWEEN ACROMION TYPES, SUBACROMIAL SPACE DIMENSIONS AND ACROMIAL UNDERSURFACE DEGENERATIVE CHANGES: AN ANATOMICAL STUDY AMONG EGYPTIANS
Hanan Dawood Yassa and Maha Khalid Abd El Wahed*
Departments of Anatomy and Embryology, Faculty of Medicine, Bani Suif and *Fayoum University
Introduction: The correlation between acromion types according to Bigliani et al. (1986) classification and the dimensions of subacromial space is a matter of debate especially with accompanying degenerative changes on the inferior surface of acromion.
Materials and Methods: 132 scapulae were selected from the Anatomy and Embryology Department of Faculties of Medicine of Cairo, Fayoum and Bani Suif Universities, Egypt. Acromions were sorted into three types by visual inspection and by measuring the acromion inclination angle. Subacromial space surface area (SASA) and its relative ratio to the total surface area of the scapula (SASA/TSA) were measured. The inferior surface of acromion was examined for the presence or absence of degenerative signs as osteophytes or facies articularis acromialis. Scapulae in each acromial type were divided into two groups: normal scapulae with smooth inferior surface of acromion and degenerative scapulae with osteophytes or facies articularis acromialis on the inferior surface of acromion. Then, the measured parameters were compared between the different types of acromion as well as between normal and degenerative scapulae.
Results: The incidence of acromion types was 31.8% type-I, 51.5% type-II and 16.7% type-III. No significant difference in the subacromial space surface area between the three types of acromion. The degenerative signs were more common in acromion type III. The ratio of SASA/TSA was significantly decreased in acromion type III. Moreover, there was a significant decrease in subacromial space surface area and the SASA/TSA ratio in degenerative scapulae with acromion type III.
Conclusion: In the collected Egyptian scapulae, type-II (curved) acromion is the commonest type and the degenerative signs on the inferior surface of acromion are more prevalent in type-III (hooked) acromion. There is a significant decrease in the subacromial space surface area to the total surface area of the scapulae in type III (hooked) acromion and particularly with those having underlying degenerative signs.