Osteonecrosis of Torus Palatinus after 2 Years of Monthly Oral Risedronate - Would More Frequent Reassessment Prevent Rare Event?

Presentation Number: SUN 308
Date of Presentation: April 2nd, 2017

Carolyn Shan-Yeu Tien*1, Juen Bin Lai2, Qiu Xia Chelsia Sim2 and Zhen-Wei Matthew Tan3
1Singapore General Hospital, 2National Dental Centre, 3Singapore General Hospital, Singapore, Singapore

Abstract

Background:

Osteoporosis is a prevalent problem in post-menopausal women with risk of fractures and associated morbidity and mortality. Treatment of osteoporosis with bisphosphonates is an effective strategy to reduce fracture risk; however rare occurrences of antiresorptive therapy related osteonecrosis of jaw (ARONJ) have been reported which is the presence of exposed bone in the maxillofacial area, lasting for 8 weeks with no history of radiation therapy or metastatic disease to the jaws and with existing or prior exposure to antiresorptive therapy. Risk of ARONJ increases with higher total drug accumulation and hence periodic assessment has to be made to weigh the risks versus benefits of continuing bisphosphonates.

We report a case of a postmenopausal Chinese woman who developed osteonecrosis of the torus palatinus after 2 years of oral bisphosphonates for osteoporosis.

Case report:

Our patient was a 63 year old Chinese woman with Parkinson’s disease and was diagnosed with osteoporosis (lowest T-score -3.1 over lumbar spine BMD) without prior fractures in April 2014 and was started on oral risedronate 150 mg monthly with a protocol to reassess BMD 3 yearly.

She was referred to the oral maxillofacial surgeon (OMS) in May 2016 when she had developed a spontaneous non-healing ulcer and exposed bone over her torus palatinus which lasted for more than 2 month. OMS referred her to us for the endocrine assessment of her bone health in view of possible ARONJ.

BMD was performed and lowest T-score was -2.4 over the lumbar spine. Serum calcium, phosphate and creatinine were normal. 25-hydroxyvitamin D was 23.5 mcg/L. Serum C terminal telopeptide (CTX) was 0.32 mcg/L (reference 0.06 to 1.10 mcg/L).

There was a shared clinical decision with patient and OMS to stop risedronate and to proceed with torus surgery on July 2016. Cholecalciferol 1000 IU om was started for the vitamin D insufficiency.

Post operatively, she recovered well with no healing issues. Histology sent from intraoperative bone specimen was consistent with the diagnosis of osteonecrosis.

CTX was rechecked in September 2016 and it remained stable at 0.30 mcg/L (more than 3 months off bisphosphonates).

Discussion:

Compared to other published case reports of osteonecrosis of torus palatinus which reports use of more than 5 years of oral bisphosphonates or oncologic doses of intravenous bisphosphonates, our patient had a relatively low exposure of bisphosphonates prior to developing ARONJ. In the absence of prior fractures, and with the repeat BMD (at 2 years) in the osteopenia range, it would challenge the need to continue oral bisphosphonates, so perhaps more frequent BMD assessment could be considered rather than 3 yearly to reassess the need to continue bisphosphonates. The other clinical consideration would be prophylactic torus resection prior to starting antiresorptive therapy which is to be a shared clinical decision with patient and dental.

 

Nothing to Disclose: CSYT, JBL, QXCS, ZWMT