Region-specific evaluation of Hounsfield units on elbow computed tomography as a predictor of osteoporosis in patients at risk.

BACKGROUND

Assessment of osteoporosis is crucial for favorable outcomes after trauma surgery, but a formal dual energy X-ray absorptiometry (DXA) scan may not be available preoperatively. The aim of the present study was to assess standardized measurements of Hounsfield units (HU) on computed tomography (CT) images of the elbow as a predictor for the presence of osteoporosis.

METHODS

Patients who underwent both a CT scan of the elbow and a DXA measurement within a period of two years were included. Standardized HU measurements with a diameter of 3 mm each were carried out in defined regions of interest (ROIs) on the humerus, ulna, and radius. The lowest T-value of the respective DXA measurement was correlated with the mean value of the HU of the corresponding ROI. Subsequently, the discriminatory capacity of the HU for osteoporosis determination was evaluated by calculating the area under the ROC curve (AUC).

RESULTS

Forty patients (72.6 ± 12.2 years; 83% female) met the inclusion criteria with an average of 1.1 ± 3.8 months between DXA measurement and elbow CT scan. Significant correlations were identified between DXA measurements and HU measurements at all individual ROIs: humeral lateral column (r = 0.43, P = .015), humeral medial column (r = 0.54, P = .002), humeral capitulum (r = 0.64, P < .001), humeral lateral trochlea (=0.52, P = .003), humeral medial trochlea (r = 0.66, P < .001), olecranon (r = 0.49, P = .004), trochlear notch (r = 0.57, P = .001), coronoid process (r = 0.49, P = .003), radial head (r = 0.46, P = .006), radial neck (r = 0.38, P = .021), radial tuberosity (r = 0.51, P = .001). The highest discriminatory power for the presence of osteoporosis was detected at the trochlear notch (AUC: 0.88) followed by the area of the humeral capitulum (AUC: 0.86).

CONCLUSIONS

CT-based assessment of the elbow joint indicates a promising method for estimating bone quality in at-risk patients. Regional HU measurements may serve as a preliminary reference for osteoporosis and could support treatment planning and implant selection in acute trauma care.