Endocrine Abstracts

Background: Osteonecrosis of the jaw (ONJ) and atypical femoral fracture (AFF) are rare potential adverse effects of bisphosphonates and RANK-L inhibitor, occurring in 1 and 2 per 100,000 person-years, respectively. The pathogenic mechanisms of both conditions are known to be independent of each other. Here, we report both conditions sequentially occurring in the same patient.

Clinical case: An 81-year old, obese, diabetic, female was admitted due to hypertensive urgency and persistent jaw pain after tooth extraction. The patient has postmenopausal osteoporosis for fourteen years and was on intermittent unsupervised treatment with alendronate, denosumab and ibandronate. She had suffered sequential fracture of both femurs during the eighth and eleventh year of treatment. Both fractures were transverse, non-comminuted, at the proximal femoral shaft, which occurred after a minor trauma, and were managed with open reduction and internal fixation.

Upon presentation, the patient was noted with tenderness intraorally of tooth number 35 periapical region, no pus, no mandibular swelling. There was peripheral leukocytosis, elevated erythrocyte sedimentation rate, C-reactive protein. Panoramic with periapical view radiograph showed presence of bony sclerosis which represent a sequestrum compatible to chronic osteomyelitis in the molar area of the left hemi-mandible. Antibiotic infusion and excision and debridement of left posterior mandible were done. Necrotic bone with histopathologic finding of acute and chronic osteomyelitis with bacterial colonies was removed consistent with a diagnosis of osteonecrosis of the jaw. The patient was discharged on the fourth post-operative day and was placed on drug holiday.

Conclusion: ONJ and AFF can occur both in the same patient during prolonged treatment with bisphosphonates and RANK-L inhibitor and may suggest a common pathogenic mechanism. This case further emphasized that to avoid these grave consequences, bisphosphonates should be given in a limited period—five years, as recommended by experts.