Inevitable nonunion after ulnar shortening osteotomy in patients with ulnar impaction syndrome and breast cancer under bisphosphonate treatment.

Background: Nonunion after ulnar shortening osteotomy (USO) was observed at a high rate in patients undergoing long-term bisphosphonate (BP) maintenance treatment after breast cancer surgery. Here, we report the unique features of these nonunions.

Methods: In total, 485 patients who had undergone USO between March 2008 and September 2017 were screened for inclusion based on the following criteria: (1) definitive nonunion after USO; (2) prior history of or ongoing BP therapy after the diagnosis of breast cancer; and (3) no evidence of metastasis in the ulna treated with USO, as determined based on the radiological evaluation.

Results: Five patients with histories of breast cancer and subsequent BP treatment were identified; all (100%) of these patients showed definitive nonunion after USO. The mean age was 56.2 years, and all ulnae were on the contralateral side to that of the original breast cancer. Intravenous Ibandronate and Zolendronate were administrated to one and four patients, respectively. The mean period of administration was 67.8 months. Three patients exhibited suspicious lesions impending atypical fracture on their femurs, and the other two patients were treated by intramedullary nailing after the occurrence of atypical fractures. Radiological evaluation revealed no evidence of a metastatic lesion, including in the musculoskeletal system, in any patient. Osteosynthesis was performed with cancellous iliac bone graft and mean of 4.3 months after osteosynthesis, union in all cases was achieved.

Conclusions: Problems associated with BP treatment are well known. Even in cases in which the agent is essential for preventing bony metastasis of breast cancer, the normal bony physiology, including bone turnover and healing, is likely to be compromised. In addition to atypical fractures of the femur and ulna, procedures such as USO are likely to be affected by BP. Furthermore, not only a primary iliac bone graft but also other method (oblique osteotomy) should be needed to avoid nonunion during plating in USO.

Level Of Evidence: IV, Retrospective case series.