Multiple Stress Fractures in a Young Cancer Patient on Long-Term Zoledronic Acid: A Case Report and Review of Literature.

Bisphosphonates are commonly used in the treatment of osteoporosis and metastatic cancer patients with bone complications. Stress fractures are a well-known complication of long-term bisphosphonate treatment. Cancer patients receive much higher cumulative doses of bisphosphonates than osteoporotic patients and are subject to a higher risk of bisphosphonate-associated stress fractures. While there is an increasing number of reports of bisphosphonate-associated atypical femoral fractures (AFFs) and non-femoral stress fractures in osteoporotic patients, reports of such fractures in cancer patients are much rarer, especially non-femoral stress fractures. We present the first case report of an atypical subtrochanteric femur fracture following a sequential bilateral Jones fracture in a young non-osteoporotic patient with metastatic breast cancer after 12 years of zoledronic therapy. She sustained a left Jones fracture after seven years of zoledronic acid therapy and a right Jones fracture after 11 years of zoledronic acid therapy. She continued receiving regular zoledronic acid after these stress fractures and sustained a right subtrochanteric fracture after 12 years of zoledronic acid therapy. Both Jones fractures were treated conservatively, while the right subtrochanteric fracture was surgically fixed. Zoledronic acid was stopped after she sustained the AFF. This study highlights the need to look out for stress fractures beyond the commonly reported AFFs and atypical ulnar fractures when administering zoledronic acid to cancer patients.