Ulnar nerve palsy combined with hypoplasia of the trochlea is rare. We have experienced three such cases with ganglion, which seemed to play a part of role causing the palsy.
In the first and the second case, neulolysis and extripation of the ganglion were carried out, and in the third case anterior deep transposition was made simultaneously with moderate recovery except for the second case.
As etiological factors of the palsy, joint laxity due to hypoplasia of the trochlea, abnormal running of the ulnar nerve, abnormal movement of the ulnar nerve at the elbow motion and compression by the ganglion were considered.
