Bony structures related to snapping scapula: correlation to gender, side and age

This study aimed at summarizing the non-pathologic bony structures which are involved in the pathogenesis of snapping scapula and evaluate their incidence, morphology and correlation to gender, side and age.

The angulation in the sagittal plane between the supraspinatus and infraspinatus portion of the medial border was measured in 140 dried scapulae. In 264 dried scapulae the medial scapular border morphology was classified into three types and the presence of the Luschka's tubercle and the teres major tubercle or process was recorded. Correlation to gender, side and age was examined using SPSS.

The mean angulation between the supraspinatus and infraspinatus portion of the medial border was 154.6° ± 8.8°. Τhe medial scapular border was straight in 99 (37.5 %), convex in 135 (51.1 %) and concave in 30 bones (11.4 %). The Luschka's tubercle was present in eight bones (3 %), while teres major tubercle was found in 114 scapulae (43.2 %). A teres major process was present in 18 bones (6.8 %). The process was curved towards the chest wall in nine bones (3.4 %), while in the other nine scapulae (3.4 %) it had no curvature.

The non-pathologic bony structures which predispose to snapping scapula are not rare and include the concave medial scapular border, the Luschka's tubercle and the teres major process curved towards the chest wall. Orthopaedic surgeons should bear in mind these non-pathologic bony structures in order not to be overlooked during the diagnostic procedure of a snapping scapula since they usually require surgical treatment.