MON-825 - Beyond the Jaw: Suspected Romosozumab-Associated Osteonecrosis of Hip

Introduction:
Romosozumab is sclerostin inhibitor, resulting in dual effects on bone metabolism-stimulation of bone formation and inhibition of bone resorption. It is approved for treatment of postmenopausal osteoporosis at high fracture risk. Clinical trials have demonstrated significant improvements in bone mineral density and fracture reduction, but concerns remain about atypical skeletal complications .We describe a case of bilateral hip osteonecrosis in a patient receiving Romosozumab for osteoporosis. Osteonecrosis of the jaw is a recognized adverse skeletal effect of this drug, with existing case reports limited to jaw involvement. No reports of osteonecrosis at other skeletal sites have been described, highlighting the uniqueness of this case.

Case description:
A 59-year-old female patient with history of Multiple Sclerosis and prior chronic steroid exposure was followed in Endocrinology clinic for osteoporosis management. DEXA scan performed in April 2024 demonstrated osteopenia/osteoporosis with a lumbar T score of -1.4 and left hip neck T-score of -1.7. She also had a prior T10 compression fracture. Given increased fracture risk, romosozumab was initiated in January 2025. After approximately 2-3 months of therapy she developed progressive bilateral hip pain particularly involving the right posterior lateral hip and buttock with referred pain to the groin. MRI of the hip showed bilateral avascular necrosis of the hips, without surrounding subchondral edema. She was evaluated by orthopedic and spine surgery services. Conservative management was advised, given absence of collapse or advanced joint degeneration.
Discussion/

Conclusion:
Romosozumab may contribute to osteonecrosis by potentially causing altered bone remodeling, reduced vascularization or pre-existing risk factors like this patient's history of steroid exposure may have increased susceptibility. Given the temporal relationship between romosozumab initiation and the onset of symptoms along with supporting imaging a causal association is possible though not definitive. Clinicians should consider this possibility in patients presenting with hip pain during romosozumab therapy, particularly those with prior risk factors. Additional pharmacovigilance data and real-world studies are needed to clarify whether this association is causal.

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