The Development of Metabolic Bone Failure as the Principal Manifestation of Undiagnosed Primary Hyperparathyroidism: A Rare Instance of Bilateral Femoral Neck Fractures.

Introduction: Primary hyperparathyroidism, though commonly diagnosed through hypercalcemic symptoms, can rarely present as advanced skeletal pathology due to delayed recognition. Metabolic bone disease, including osteitis fibrosa cystica and fragility fractures, represents a late and uncommon manifestation in the modern diagnostic era. Case Report: We report a rare case of a 26-year-old male who presented with bilateral femoral neck fractures following 4.5 years of progressive hip pain. He had a history of parathyroid adenoma excision 2 years prior and was diagnosed with "hungry bone syndrome" postoperatively. Imaging revealed classic skeletal changes of severe metabolic bone disease, including osteolysis, spinal deformities, and multiple cystic lesions. He underwent staged bilateral total hip arthroplasty with good functional recovery over 1 year. Conclusion: This case underscores the importance of considering primary hyperparathyroidism in young patients presenting with unexplained skeletal complaints. Early recognition and management are essential to prevent irreversible bone damage and avoid debilitating complications such as bilateral femoral neck fractures.