Missed Bilateral Atraumatic Sacral Ala Insufficiency Fractures With Normal Dual-Energy X-ray Absorptiometry (DEXA) Scan and Radiofrequency Echographic Multi-spectrometry (REMS)-Confirmed Osteoporosis.

Sacral insufficiency fractures (SIFs) are often missed in elderly patients, resulting in increased morbidity and mortality. Osteoporosis diagnosis can minimise missing SIFs and other fragility fractures. Dual-energy X-ray absorptiometry (DEXA) remains the gold standard for osteoporosis diagnosis; however, it has its limitations, including reduced accuracy in patients with degenerative spinal changes and prosthetic implants. This case report explores how we can utilise radiofrequency echographic multi-spectrometry (REMS) as an alternative diagnostic tool for osteoporosis. A 75-year-old woman with a history of bilateral (B/L) total hip replacements and chronic back pain presented with increasing low back and hip pain. Initial imaging included pelvic X-rays, which did not show any fractures, and the patient was discharged with analgesics. Patient symptoms persisted, leading to an MRI, which showed B/L sacral ala insufficiency fractures. Subsequently, a DEXA scan was done, which showed a T-score of -0.9, indicating normal bone mineral density (BMD). Given the suspicion of osteoporosis clinically, REMS was done, which showed significant fragility of the bones, a fragility score of 76/100, hence confirming osteoporosis. The patient was initially discharged with oral painkillers and free to mobilise as tolerated. After an MRI confirmed B/L SIF, conservative treatment with analgesics and bed rest with venous thromboembolism prophylaxis (VTEP) was advised temporarily. This was followed by B/L sacroplasty after four months, which resulted in significant pain relief and increased mobilisation. This case showcases the challenges faced in diagnosing fragility fractures in the elderly, diagnostic limitations of DEXA and the potential new role of REMS in the diagnosis of osteoporosis. REMS, being radiation-free, portable and sensitive, may play a role as an alternative or a complementary modality in the diagnosis of osteoporosis and fragility fractures, leading to an improvement of outcomes in vulnerable populations.