Variable morphology of the suprascapular notch: an investigation and quantitative measurements in Chinese population

Abstract

Although several morphological variations and classification of the suprascapular notch (SSN) were reported in western populations, little attention has been paid to this anatomic issue in the Chinese population. In this research of SSN morphology in Chinese people, 295 specimens of intact dry Chinese adult scapulas were investigated and measured thoroughly and systematically. Morphological features of SSN variations were observed by visual inspection, and correlation parameters of variability and classification were measured in digital images with image processing software and bones with a vernier caliper, respectively. The incidence of different subtypes of SSN classification and comparative analysis of correlation parameters were calculated. It was interesting that a new variable morphology of SSN with a double suprascapular foramen had been found. We found the most prevalent groups were Type II (an incisura that was longer in its transverse diameter) and Type III (an incisura that was longer in its vertical diameter) which accounted for 58.16 and 28.23%, respectively. The circumference and area of Type II and Type III was larger than those of Type IV. The thickness of 1 mm below the lowest point of the SSN ranges from 0.55 to 3.00 mm. Eight cases with a narrow groove on the lowest point of SSN and four cases with bony canals formed by the ossified superior transverse scapular ligament were found. Further, the distance between the SSN and bony landmarks were varied. For AD (the distance between the lowest point of the SSN and the supraglenoid tubercle), Type I was largest, followed by the Type II, Type III, and Type IV. For AE (the distance between the lowest point of the SSN and the base of the spinoglenoid notch), Type IV was the shortest and there was no statistical difference between other types. This study reveals that SSN variations are common in Chinese population. This anatomic information is important in the management of entrapment neuropathy or interventional procedure of the SSN.