Variation in morphology of suprascapular notch as a factor of suprascapular nerve entrapment

PURPOSE: The shape and size of the suprascapular notch (SSN) is one of the most important risk factors in suprascapular nerve entrapment. The aim of the study was to perform a morphological study of SSN variations. METHODS: A total of 616 computer tomography scans of scapulae were retrospectively analysed in 308 patients. The examination focused on the suprascapular region. The type of suprascapular notch was determined by using a classification based on three geometrical measurements: maximal depth (MD), superior (STD) and middle (MTD) transverse diameters. RESULTS: In the scans, five types of SSN were noted. In type I (24.18 %) maximal depth was greater than superior transverse diameter. Type II (1.95 %) has equal MD, STD and MTD. In type III (56.16 %) the superior transverse diameter was greater than the maximal depth. Scapulae with bony foramen were classified as type IV (4.72 %). In type V a discrete notch (12.99 %) was found. Additionally, types I and III were divided into three subtypes: A, B and C. The frequency of type I and IV was lower in females than in males, but type III was more common in females than males. Distribution of other types of SSN in both groups was similar. CONCLUSION: Knowledge of the anatomical variations of the suprascapular notch described in this study should be helpful in endoscopic and open procedures of the suprascapular region and also may increase the safety of operative decompression of the suprascapular nerve.