The Legend of the Luschka Tubercle and Its Association With Snapping Scapulae: Osseous Morphology of Snapping Scapulae on CT Images.

Abstract

The purpose of this article is to determine the osseous morphology of snapping scapulae on CT images. Retrospectively, 2D and 3D CT images of the scapulae of 35 patients with snapping scapula were compared with 35 age-matched control group subjects. Two observers analyzed the following parameters: presence of the Luschka tubercle; abnormalities of the bones and periscapular soft tissues; shape, thickness, and length of the superior angle of the scapula; craniocaudal length of the scapula; minimum distance between the scapula and rib cage; depth of the subscapular fossa; and the superomedial angle. In patients with snapping scapulae, observer 1 did not find any Luschka tubercles, whereas observer 2 detected one; in the control group both observers found two Luschka tubercles (p > 0.49). One scapular osteochondroma was found in the group with snapping scapulae. No further abnormalities of the rib cage or periscapular soft tissues were found in that group. The superior angle of the scapula was significantly thicker in the snapping scapula group compared with the control group (4.8 ± 1.3 mm vs 4.0 ± 1.0 mm, p < 0.012). The subscapular fossa was significantly deeper in patients with snapping scapula than in control group subjects (25.7 ± 5.2 mm vs 21.8 ± 5.0 mm, p < 0.005). The remaining parameters did not differ significantly between the groups. The Luschka tubercle was rarely observed and not associated with a snapping scapula. However, the superior angle of the scapula was significantly thicker and the subscapular fossa was significantly deeper in patients with snapping scapula than in control group subjects.