Acromial Morphology and Subacromial Architecture: A Preliminary Osteological Study

Background Acromial morphology may influence the bony configuration of the subacromial region, but osteological evidence quantifying this relationship remains limited. This preliminary study evaluated the association between acromial morphology and subacromial area and described related scapular morphometric parameters in dry human specimens. Materials and methods A descriptive cross-sectional osteological study was conducted on 40 dry adult human scapulae, comprising 20 right and 20 left specimens, from the departmental osteology museum. Acromia were classified as Bigliani Type I (flat), Type II (curved), or Type III (hooked). Subacromial area, coracoacromial tilt angle, posterior acromial tilt angle, acromion-supraglenoid distance (DA), and coracoacromial distance were assessed using a digital Vernier caliper and ImageJ (National Institutes of Health, Bethesda, MD, USA). Osteophytes were recorded descriptively. Group differences were evaluated using one-way ANOVA; right-left differences were analyzed using a paired t-test. Results Type I acromion was identified in 18 (45.0%) specimens, Type II in 12 (30.0%), and Type III in 10 (25.0%). Osteophytes were present in 24 (60.0%) specimens. The subacromial area showed a progressive reduction from Type I to Type III on both sides; Type III had the smallest mean area (right, 433.50 ± 86.01 mm²; left, 429.86 ± 88.43 mm²). Coracoacromial and posterior acromial tilt also decreased across acromial types, whereas DA did not show a statistically significant difference among types. Because of small subgroup sizes, these inferential findings should be considered exploratory. Conclusions Hooked acromial morphology was associated with a smaller osteological subacromial area and lower angular measurements in this specimen series. These findings describe structural variation of the coracoacromial arch but do not establish clinical shoulder impingement or rotator cuff disease. Larger cadaveric and imaging studies with demographic, reliability, and clinical correlation are warranted.