A Rare Case of Sternal Insufficiency Fracture Unveiled by POCUS: A Silent Break in the Osteoporotic Chest
Dr Himanshu Gul Mirani, Consultant in Emergency Medicine, Midland Metropolitan University Hospital, United Kingdom
Case Presentation:
An 84-year-old female with significant past medical history of hypertrophic cardiomyopathy and severe osteoporosis (currently on teriparatide therapy) with multiple previous vertebral fractures initially presented to the Emergency Department following a forward fall in her garden. Initial examination revealed facial bruising and bilateral anterior chest wall tenderness. A comprehensive CT chest-abdomen-pelvis performed at this time demonstrated no acute traumatic findings, with only previously documented spinal insufficiency fractures noted.
Three days post-initial assessment, the patient re-presented with new-onset sternal tenderness and visible sternal swelling. Crucially, she reported no intervening trauma between presentations. Physical examination confirmed a palpable sternal deformity with significant point tenderness that had not been present during her first attendance.
Sternal fracture picked up on POCUS; later confirmed on CT.
Management and Outcome:
The absence of sternal fracture on initial high-resolution CT imaging despite clear clinical findings of chest wall trauma created a significant diagnostic challenge. The patient's osteoporotic background suggested potential for insufficiency fractures, yet the temporal progression of injury without additional trauma was atypical. The mild troponin elevation (97 and 111 ng/L) initially raised concern for potential cardiac contusion or ischaemic event but could represent a false lead given the patient's underlying hypertrophic cardiomyopathy.
Point-of-care ultrasound (POCUS) proved pivotal, demonstrating:
1. Clear cortical disruption with buckling at the sternal body, representing a new finding compared to the CT performed 72 hours earlier
2. Normal left ventricular contractility with expected hypertrophy and absence of pericardial effusion
Subsequent sternal radiography confirmed a buckled fracture configuration, strongly suggestive of an insufficiency mechanism rather than direct traumatic fracture. Definitive CT imaging revealed a comminuted, displaced fracture of the sternal body with moderate retrosternal haematoma formation.
ECG demonstrated sinus rhythm with left axis deviation and voltage criteria consistent with the patient's known left ventricular hypertrophy, without acute ischaemic changes.
The final diagnosis of sternal insufficiency fracture was established based on the delayed presentation, imaging evolution, and known severe osteoporosis. The patient received conservative management with analgesia and thoracic surgical review, followed by referral back to the community osteoporosis service for initiation of bisphosphonate therapy.
Key Learnings and Points:
This case offers several important lessons for acute care and geriatric medicine:
• Rarity and Diagnostic Delay: Sternal insufficiency fractures are extremely rare, comprising just 0.1–0.5% of all insufficiency fractures (Richardson et al., 2022). Unlike traumatic sternal fractures, which represent 3–8% of thoracic trauma cases, insufficiency fractures arise from minimal physiological stress in osteoporotic bone, sometimes without any discernible trauma.
• Delayed Radiological Evolution: Davies and Collins (2023) report that up to 4% of osteoporotic fractures may evolve after initial trauma with delayed radiological evidence. This case exemplifies the "CT-negative, later-positive" fracture pattern, which should prompt emergency physicians to maintain diagnostic vigilance in high-risk patients, even after a negative initial scan.
• Biomechanics of Fragility: In healthy bone, the sternum typically requires over 2,500 Newtons to fracture (Khoriati et al., 2024). In severe osteoporosis, this threshold may be reduced by up to 85%, making fractures possible through muscle contraction or mild impact—as likely occurred here.
• Utility of POCUS: Point-of-care ultrasound was pivotal. Literature reports 91–97% sensitivity for detecting sternal fractures, compared to 78% for plain radiographs (Thomas and Ahmed, 2023). POCUS offered real-time, radiation-free confirmation of a diagnosis missed on CT.
• Conservative Management and Monitoring: Most insufficiency fractures can be managed non-operatively. However, complications such as retrosternal haematoma require close follow-up. This case underscores the broader implications of osteoporosis, as NICE guidelines (2024) emphasize a one-year mortality rate of up to 20% for non-hip, non-vertebral fragility fractures in older adults.