The incidence of ganglion cysts and other variations in anatomy along the course of the suprascapular nerve

When the diagnosis of suprascapular nerve entrapment syndrome is being cons idered, variations in anatomy are possible etiologic factors. Seventy-nine shoulders from 41 cadavers were examined for anatomic variations and for ga nglion cyst formation in the suprascapular notch, superior transverse scapu lar ligament, and inferior transverse scapular ligament. The morphologic ev aluation of the suprascapular notch revealed a "U" shape in 77% and a "V" s hape in 23%, with 89% of cadavers having the same notch shape bilaterally. In 23% of shoulders a variation of the superior transverse scapular ligamen t was demonstrated such as partial and complete ossification and multiple b ands including the first report of a trifid superior transverse scapular li gament. An inferior transverse scapular ligament was observed in only 14% o f shoulders. One ganglion cyst was identified, for an incidence of 1%. The mass was located in the supraspinatus Fossa adjacent to the superior transv erse scapular ligament and appeared to compress and alter the course of the suprascapular nerve. When operative treatment is elected for suprascapular nerve entrapment syndrome and an open surgical approach is undertaken, the location and source of disease and morphologic and anatomic variants must be recognized to ensure adequate access and complete decompression of the t he suprascapular nerve. The classical description of the superior transvers e scapular ligament as a completely nonossified single band should be expec ted, on average, in approximately three fourths of the cases. Partial or co mplete ossification and anomalous bands of the superior transverse scapular ligament or a ganglion cyst along the course of the suprascapular nerve ma y be encountered. Although a superior transverse scapular ligament should b e anticipated in all shoulders, an inferior transverse scapular ligament wi ll be a much less Frequent finding. The role and significance of suprascapu lar notch morphologic characteristics warrant further investigation.