Bone Abstracts

Background: Denosumab, a RANKL inhibitor given six-monthly, is an established osteoporosis treatment. Delays in administration can trigger rebound bone resorption, rapid bone loss and increase in fracture risk.

Methods: We report two cases illustrating the real-world consequences of delayed denosumab treatment.

Results: Case 1 A 63-year-old female was commenced on denosumab in 2021 for bone protection after struggling to wean off prednisolone for polymyalgia rheumatica since 2017. She was subsequently diagnosed with axial spondyloarthritis and possible ulcerative colitis in 2023. Her symptoms improved on adalimumab, enabling prednisolone withdrawal in 2024. Denosumab was continued following a low-trauma humerus fracture in February 2023 and DXA in November 2023 showing T scores of -3.0 (lumbar spine), -1.9 (femoral neck) and -1.7 (total hip). In January 2026, she presented to Rheumatology with a five-week history of severe back and pelvic pain. Denosumab had been due August 2025 but was Case Reports until January 2026, 11 months after the previous dose. MRI demonstrated multiple acute-to-subacute vertebral fractures at T8, T10 and L2L5. Pain control has proved difficult despite escalation of analgesia, with ongoing impact on mobility and function. Case 2 A 72-year-old woman with osteoporosis and prior fragility fractures of the wrist, ribs and clavicle had received denosumab since 2017 following bisphosphonate intolerance. After relocating in late 2024, she attended the Emergency Department in August 2025 with severe back pain; CT showed acute vertebral fractures at T6-T8. She required two further admissions for uncontrolled back pain and developed progressive kyphosis. Rheumatology review in October 2025 noted no denosumab had been given since December 2024. DXA showed T-scores of -3.2 (lumbar spine), -2.2 (femoral neck) and -2.6 (total hip). She was urgently restarted on denosumab and referred for specialist physiotherapy input.

Conclusion: These cases demonstrate the severe, avoidable consequences of delayed denosumab administration, including multiple vertebral fractures, uncontrolled pain and impaired mobility. Contributory factors included administrative delay, relocation and limited awareness among patients and non-specialist clinicians of the risks associated with missed doses. Robust prescribing and recall systems for denosumab are essential, and patients must be counselled on the importance of six-monthly administration.