Quantitative morphology of the scapula: normal variation of the superomedial scapular angle, and superior and inferior pole thickness.

This study examined the normal variation of the superomedial scapular angle and the thickness of the superior and inferior scapular borders. Scapulae of 53 cadaver shoulders were dissected free from all soft tissue. A line was drawn from the most superior to the most inferior point on each scapula, and the scapulae were cut along this line to obtain cross sections. The supero-medial scapular angle (alpha) was measured with a goniometer from the cross section as a ABC: through the inferior tip (A), base of the spine (B), and superior tip (C). Superior and inferior pole thickness was measured with a digital caliper from the thickest portions on the cross section of the poles. Average superomedial angle was 139 degrees +/- 6 degrees (range: 125 degrees - 156 degrees). Average thickness for the superior and inferior poles was 3.9 +/- 0.9 mm (range: 2.1 - 8.3 mm) and 7.5 +/- 1.5 mm (range: 4 - 11 mm), respectively. The thickness of both superior and inferior poles was significantly different between male and female specimens (P < .05), with male scapulae having the higher values.