Opportunistic CT screening demonstrates increased risk for peri-articular fractures in osteoporotic patients.

Background: Underdiagnosis or undertreatment of osteoporosis consequently impacts individual morbidity and mortality, as well as on healthcare systems and communities as a whole. Dual-energy x-ray absorptiometry (DXA) is the gold standard method for identifying osteoporosis, however, opportunistic CT screening is capable of precisely estimating bone mineral density (BMD) in abdominopelvic imaging with no additional cost, radiation exposure or inconvenience to patients. This study uses opportunistic CT screening to determine the prevalence of osteoporosis and anatomic distribution patterns in patients presenting with lower extremity fractures at our institution.

Hypothesis: Trauma patients with low bone mineral density (BMD) are more likely to present with peri-articular versus shaft fractures.

Patients and methods: We conducted a retrospective review of 721 patients presenting as trauma activations to the emergency department (ED) of a Level 1 Trauma Center with lower extremity fractures. Patients were excluded if under the age of 18 or lacking a CT scan upon arrival in the ED. Hounsfield Units (HU) were measured at the L1 vertebral level on CT scans to determine bone mineral density. Values of ≤100 HU were consistent with osteoporosis, whereas 101-150 HU were consistent with osteopenia.

Results: The final cohort included 416 patients, with mean age of 49 ± 21 years. Average bone density was 203.9 ± 73.4 HU. 15.9% of patients were diagnosed as osteopenic and 9.9% as osteoporotic. 64.2% of fractures were peri-articular, 25.7% were shaft, and 10.1% were a combination. Peri-articular fractures were significantly more likely to have lower average BMD than shaft fractures (189 ± 74.7 HU vs. 230.6 ± 66.1 HU, p < 0.001).

Discussion: Our study demonstrates a significant relationship between low bone mineral density and lower extremity fracture pattern, however, likely influenced by other factors such as sex. Opportunistic CT screening for osteoporosis in trauma settings provides ample opportunity for early detection of low BMD and implementation of highly effective lifestyle modification and pharmacotherapy intervention. Reduction in the overall incidence of peri-articular fracture with widespread adoption of opportunistic CT screening may lessen the morbidity, mortality, and total cost currently afflicting patients, healthcare systems, and communities.

Level of evidence: III, therapeutic.