Atypical Fracture of the Proximal Shaft of the Ulna Associated with Prolonged Bisphosphonate Therapy.

Atypical fractures have been reported as a complication of long-standing bisphosphonate therapy and occur commonly in the subtrochanteric region or shaft of the femur showing typical radiographic features. We encountered a case of atypical fracture of the proximal one-third of the shaft of the ulna. Radiographic findings of this case differed from previously reported cases of ulnar fracture in terms of showing a transverse fracture line with cortical thickening and an oblique fracture line with anterior cortical spike. On the other hand, these findings were similar to radiographic features of atypical femoral fractures. The present case was managed surgically and union of fracture was achieved after 6 months. As there are possibilities of occurrence of atypical fractures in sites other than the femur, the physicians should cautiously examine the patients' history and radiographic findings.