Bisphosphonate associated osteonecrosis(ON) involving the Jaw, a retrospective study
Bisphosphonates are commonly used agents in the management of osteoporosis and primary or metastatic bone tumours. There have been reports of osteonecrosis (ON) involving the maxilla and mandible associated with bisphosphonate therapy. This is a debilitating condition with no specific treatment protocol. Objective: This is a retrospective study to assess the occurrence of ON in patients treated with bisphosphonates. Method: Patients treated by the Haematology / Oncology or Geriatric Services with Bisphosphonates for at least six months were examined clinically and radiographically to identify the presence of osteonecrosis involving the jaws. The occurrence of ON in this population was estimated and recommendations for management suggested. Results: The study population included 70 patients (60 female, 10 male). Mean age was 62 (28-92) years with a mean duration of treatment of 37 (6-108) months. Bisphosphonates were used as follows Intravenous agents : Zolendronate n = 15 , Pamidronate n = 10; Oral agents: Alendronate, n = 21, Residronate, n = 17. The indications for treatment were: Haematology (AML, n=1; Multiple Myeloma, n=10); Oncology (Breast cancer, n= 12; Prostate cancer, n= 1; cancer of the spine n = 1); Osteoporosis (n=45). Five patients had ON (7.1%), two treated with Zolendronate (Prostate and Breast Cancer), three with Pamidronate (Multiple Myeloma). ON involved the maxilla (n =1), mandible (n=3), maxilla and mandible (n=1). The development of ON was spontaneous in two patients on Zolendronate, and following tooth extraction in four other patients. Mean induction time was 42(11-93) months, and mean duration of therapy was 48 (16-96) months. No patients on oral bisphosphonates developed ON. Conclusion: Based on the findings of this study, occurrence of ON is rare, occurring in patients on intravenous bisphosphonates. The occurrences were spontaneous or following tooth extraction. No patient on the oral bisphosphonate had ON.