The os supratrochleare dorsale: a normal variant that may cause symptoms.

Four patients with an os supratrochleare dorsale are presented; three had symptoms that necessitated surgical removal. One patient showed the abnormality in both elbows; three were men and one was a woman. The os supratrochleare dorsale is most likely an accessory bone; however; the location is such that it often becomes traumatized by the olecranon. Posttraumatic pathologic changes with secondary chondrometaplasia of the bone itself occurs as a consequence. Symptomatic patients show posttraumatic changes of the bone, while those without symptoms show a normal trabecular pattern. This condition seems to bear no relation to the supratrochlear septum or to bones in the coronoid fossa.