Opportunistic assessment of bone quality using CT-derived hounsfield units in postmenopausal women with femoral trochanteric fractures.

BACKGROUND: CT-derived Hounsfield unit (HU) measurements may provide an opportunistic assessment of bone density when dual-energy X-ray absorptiometry (DXA) is difficult to obtain during acute treatment of femoral trochanteric fractures. We compared three femoral-head regions of interest (ROIs) and explored their ability to identify markedly low total hip bone mineral density (BMD).

METHODS: This single-center retrospective study included 87 women aged ≥ 65 years with AO/OTA type 31A1 (excluding A1.1) or 31A2 femoral trochanteric fractures treated with intramedullary nailing. Admission CT HU values were measured in three femoral-head ROIs on coronal and axial images and compared with contralateral hip DXA T-scores measured approximately 1 week after surgery. Pearson correlations and receiver operating characteristic (ROC) analyses were performed. The prespecified total hip T-score thresholds were ≤ -2.5 and ≤ -3.3; the latter was used as an operational definition of markedly low BMD in this study.

RESULTS: Coronal whole-femoral-head HU values (ROI 1) showed a moderate correlation with total hip T-scores (r = 0.569). For the ≤ -2.5 threshold, 74 women met the criterion and only 13 did not; the ROI 1 coronal AUC was 0.841. For the ≤ -3.3 threshold, 51 women met the criterion and 36 did not. A coronal ROI 1 threshold of < 158.7 HU had an AUC of 0.765 (95% CI, 0.660-0.870), sensitivity of 84.3% (43/51), and specificity of 66.7% (24/36) for identifying a total hip T-score ≤ -3.3.

CONCLUSION: Whole-femoral-head HU values were moderately associated with DXA-derived T-scores in this cohort. Admission CT may help flag patients with markedly low BMD, but the threshold showed limited specificity and requires external validation. Its effect on surgical decisions or clinical outcomes was not assessed.