Snapping scapula syndrome (SSS) was originally described by Boinet. Thickening of the superior scapula angle from post-traumatic changes, Luschka tubercle, osteochondroma, or subscapular elastofibroma may be factors for painful snapping scapula. However, in many cases, the origin of SSS remains unclear.
Variations of the scapula costal surface, such as inward bending of the medial scapula border reported in 2% to 6% of the scapulae, have been described as contributing to SSS. In addition, multiple clinical studies have reported pain relief after resection of the superior medial border of the scapula. Currently, there are no evidence- based guidelines regarding the amount of scapular resection needed. Warth suggested the removal of a 2-cm (superior-to-inferior) by 3-cm (medial-to-lateral) triangular section of bone. Mozes defined incongruity of the thoracoscapular articulation as either a superomedial scapula angle of less than 142 , inward bending of the medial scapula border, or the presence of a rhinoceros horn–like deformity inferiorly. They found deformities in all snapping scapulae by 3-dimensional (3D) computed tomography (CT). These variations in scapula bony morphology may play a role in the development of SSS.
The purpose of this study was to determine whether there was an association between SSS and the scapular configuration on the axial images of magnetic resonance imaging (MRI) scans. We hypothesized that an angulation of the costal surface of the upper third of the medial scapula toward the thorax may lead to painful impingement and that such a bony morphology would be associated with SSS.