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An unusual case of bone regeneration of a necrotic mandible with pathologic fracture in an elderly hemodialysis patient with medication-related osteonecrosis of the jaw: a case report and review of the literature.

ABSTRACT:

Background

Bisphosphonates are frequently used for osteoporosis. Medication-related osteonecrosis of the jaw, a complication of bone-modifying agents, including bisphosphonates or angiogenic inhibitors, can be challenging to treat in elderly patients with numerous preexisting conditions. Achieving good treatment outcomes is especially difficult in patients with pathological fractures accompanied with extraoral fistulae.

Case presentation

We report an unusual case of prominent bone regeneration following palliative surgical treatment in a 72-year-old Japanese female patient undergoing hemodialysis. She previously had severe osteoporosis due to renal osteodystrophy and was receiving antiresorptive intravenous bisphosphonate. Computed tomography revealed a discontinuous left lower mandibular margin with a pathologic fracture and extensive, morphologically irregular sequestrum formation (80 × 35 × 20 mm). The patient was diagnosed with stage III medication-related osteonecrosis of the jaw and pathologic mandibular fracture. Immediately before the surgery, the anticoagulant used for dialysis was changed from heparin to nafamostat mesylate to reduce the risk of intraoperative bleeding. Sequestrectomy was performed under general anesthesia. Postoperative infection was not observed, the intraoral and submandibular fistula disappeared, and, surprisingly, prominent spontaneous bone regeneration was observed postoperatively at 6 months. Despite the severe systemic condition of the patient, the conservative surgical approach with sequestrectomy has yielded desirable results for more than 6 years since the surgery.

Conclusions

This rare report of spontaneous bone regeneration in a patient of advanced age and poor general condition is the oldest case of mandibular regeneration ever reported.

SUBMITTER: Yoshizawa K

PROVIDER: S-EPMC8697441 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Medication-related osteonecrosis of the jaw (MRONJ) is a potentially severe adverse event affecting patients with cancer and patients with osteoporosis who have been treated with powerful antiresorptives (pARs) or angiogenesis inhibitors (AgIs). pARs, including nitrogen-containing bisphosphonates (N-BPs; e.g., zoledronic acid, alendronate) and anti-RANKL antibodies (e.g., denosumab), are used to manage bone metastases in patients with cancer or to prevent fragility fractures in patients with osteoporosis. Though significant advances have been made in understanding MRONJ, its pathophysiology is still not fully elucidated. Multiple species have been used in preclinical MRONJ research, including the rat, mouse, rice rat, rabbit, dog, sheep, and pig. Animal research has contributed immensely to advancing the MRONJ field, particularly, but not limited to, in developing models and investigating risk factors that were first observed in humans. MRONJ models have been developed using clinically relevant doses of systemic risk factors, like N-BPs, anti-RANKL antibodies, or AgIs. Specific local oral risk factors first noted in humans, including tooth extraction and inflammatory dental disease (e.g., periodontitis, periapical infection, etc.), were then added. Research in rodents, particularly the rat, and, to some extent, the mouse, across multiple laboratories, has contributed to establishing multiple relevant and complementary preclinical models. Models in larger species produced accurate clinical and histopathologic outcomes suggesting a potential role for confirming specific crucial findings from rodent research. We view the current state of animal models for MRONJ as good. The rodent models are now reliable enough to produce large numbers of MRONJ cases that could be applied in experiments testing treatment modalities. The course of MRONJ, including stage 0 MRONJ, is characterized well enough that basic studies of the molecular or enzyme-level findings in different MRONJ stages are possible. This review provides a current overview of the existing models of MRONJ, their more significant features and findings, and important instances of their application in preclinical research.