MYXOID AND GLOBULAR DEGENERATION OF NERVES IN THE SHOULDER JOINT

Characteristic degeneration of the nerves in shoulder joints was recog nized in 26 of 35 capsules (74.3%) from 20 cadavers. No left or right or gender differences were found, Histologic features of the nerves we re (1) thickening of the perineurium, (2) myxoid degeneration in the e ndoneurium, and (3) hyaline globular structures with a whorled, oligoc ellular appearance regarded as Renaut bodies. The results of histochem ical and electron microscopic studies showed prominent degenerated col lagen fibers in the globular areas, These features resembled those fou nd in the fusiform swelling in the axillary nerve branch to the teres minor muscle, believed to be caused by chronic nerve compression, Sixt y percent of the degenerated nerves occurred in the anteroinferior and posteroinferior portions of the capsule, an area that is considered t o be innervated by the axillary nerve, No correlation between age and severity of these degenerative nerve changes was noted, Compression of the axillary nerve and inferior joint capsule caused by repetitive sh oulder movement such as forward flexion, abduction, and external rotat ion of the humerus might result in this form of nerve degeneration fou nd histologically over a lifetime without necessarily causing clinical symptoms.