Classification of the superior angle of the scapula and its correlation with the suprascapular notch: a study on 303 scapulas.

PURPOSE: The aims of this study had been to classify the superior angle of the scapula based on morphological features, and to investigate its correlation with the suprascapular notch.

METHODS: 303 samples of Chinese dried scapular specimens were collected from the Department of anatomy, Southwest Medical University. According to the anatomical morphological characteristics of the superior angle of the scapula, the morphological classification was performed to explore its correlation with the suprascapular notch (SSN).

RESULTS: The superior angle of the scapula was classified into three types (Hilly shape, Mountain Peak shape and Chimney shape). There were 143 cases of Hilly shape (47.20%), 144 cases of Mountain shape (47.52%), and 16 cases of Chimney shape (5.28%). The angle of Hilly shape (93.36° ± 7.76°) was significantly larger than the Mountain Peak shape (86.60° ± 6.61°) and the Chimney shape (86.22° ± 7.20°), and the difference was statistically significant (P < 0.05). The type I-III of Rengachary's classification to SSN was low risk of suprascapular nerve entrapment, while the type IV-VI was high risk of suprascapular nerve entrapment. Compared with the Mountain Peak shape and the Chimney shape, the Hilly shape corresponds to more types I-III of suprascapular notch but to fewer types IV-VI (P < 0.05).

CONCLUSIONS: The superior angle of the scapula was divided into three types: Hilly shape (47.20%), Mountain Peak shape (47.52%) and Chimney shape (5.28%). The Mountain Peak shape might be more likely to result in inability of the levator muscle with acute or chronic overload mechanisms, and the risk of suprascapular nerve entrapment in Mountain peak shape was higher than that of Hilly shape. And, it might have a potential effect on neck pain.