Bone microarchitecture, density, and strength assessment in automotive trauma patients using HR-pQCT: a pilot study

Automotive trauma patients enrolled in the Crash Injury Research and Engineering Network (CIREN) typically undergo computed tomography (CT) imaging as part of emergency care. HR-pQCT is a noninvasive imaging technique that enables assessment of bone microarchitecture at the peripheral sites. CT and HR-pQCT can be used to estimate volumetric bone mineral density (vBMD) and strength via finite element analysis (FEA). However, HR-pQCT's superior resolution (approximately 10 times higher than conventional clinical CT scanners) captures in vivo trabecular and cortical microarchitecture, enabling high fidelity FEA. This study examines HR-pQCT-derived bone microarchitecture and strength measurements in relation to fracture patterns, bone-related comorbidities, and CT-derived vBMD in CIREN trauma patients, while providing foundational evidence to support HR-pQCT use following motor vehicle crashes (MVC) and pedestrian crashes.

Nine automotive trauma patients (ages 17-76; 78% female) enrolled at Atrium Health Wake Forest Baptist Medical Center from the National Highway Safety Administration's CIREN study participated in the HR-pQCT pilot study. HR-pQCT scans were acquired within 1-12 months following the patient's MVC (n = 7) or pedestrian crash (n = 2). Scans were acquired at four sites: 1) distal tibia, 2) diaphyseal tibia, 3) distal radius, and 4) diaphyseal radius. HR-pQCT normative percentiles were determined using Indiana University's calculator. Descriptive statistics were used to present HR-pQCT musculoskeletal outcomes based on bone-related comorbidities, BMI, and fracture incidence. Pearson correlations were performed between HR-pQCT-derived distal tibia and radius total vBMD and CT-derived total vBMD at the spine and femoral compartments.

At the distal tibia, participants without tibia and fibula fractures tended to show greater mean cortical thickness (1.63 ± 0.38 versus 1.15 ± 0.05 mm), cortical area (146.24 ± 46.07 versus 103.70 ± 1.70 mm²), cortical vBMD (943.83 ± 79.18 versus 861.05 ± 26.52 mg HA/cm³), and bone strength (10.25 ± 3.72 versus 7.00 ± 0.70 kN). Additionally, HR-pQCT-derived distal tibia total vBMD demonstrated a strong positive correlation with CT-derived femoral head total vBMD (r = 0.766; p = 0.045). Normative percentiles showed that participants with bone-related comorbidities had lower bone microarchitectural and strength percentiles than the group without comorbidities.

This study demonstrates the viability of HR-pQCT for characterizing bone microarchitecture, strength, and density in automotive trauma patients and identifying differences that might relate to fracture and bone-related comorbidities. These preliminary findings support incorporating HR-pQCT imaging into automotive crash research due to its ability to provide detailed cortical and trabecular microarchitectural measurements that are not available from clinical CT.