Comparison of HU histogram analysis and BMD for proximal femoral fragility fracture assessment: a retrospective single-center case-control study

Abstract

Objectives: To evaluate the feasibility of HU histogram analysis (HUHA) to assess proximal femoral fragility fractures with respect to BMD.

Methods: This retrospective study included 137 patients with femoral fragility fractures who underwent hip CT and 137 control patients without fractures who underwent abdominal CT between January 2018 and February 2019. HUHA was calculated with the 3D volume of interest from the femoral head to the lesser trochanter. HUHA_fat (percentage of negative HU values) and HUHA_bone (percentage of HU values ≥ 125 HU) were assumed to be fat and bone components, respectively. Statistical significance was assessed using the area under the receiver operating characteristic curve (AUC), Spearman correlation (ρ), and odds ratio.

Results: HUHA_fat was strongly positively correlated (ρ = 0.56) and BMD was moderately negatively correlated with fragility fractures (ρ = - 0.37). AUC of HUHA_fat (0.82, 95% CI [0.77, 0.87]) significantly differed from that of BMD (0.69, 95% CI [0.63, 0.75]) (p < .001). The cutoff value was 15.8% for HUHA_fat (sensitivity: 90.4%; specificity: 67.7%) and 0.709 g/cm² for BMD (sensitivity: 87.5%; specificity: 51.5%), with higher HUHA_fat and lower BMD values indicating fragility fractures. The odds ratio of HUHA_fat was 19.5 (95% CI [9.9, 38.2], p < .001), which was higher than that of BMD, 7.4 (95% CI [4.0, 13.6], p < .001).

Conclusion: HUHA_fat revealed better performance than BMD and demonstrated feasibility in assessing proximal femoral fragility fractures.

Key points: • HUHA_fat showed a strong positive correlation (Spearman ρ = 0.56, p < .001), and BMD showed a moderate negative correlation (Spearman ρ = - 0.37, p < .001) with proximal femoral fragility fractures. • HUHA_fat (AUC = 0.82) performed significantly better than BMD in assessing proximal femoral fragility fractures (AUC = 0.69) (p < .001). • The odds ratio of HUHA_fat for proximal femoral fragility fractures was higher than that of BMD (19.5 and 7.4, respectively; p < .001).

Keywords: Bone Density; Femur; Fractures, Bone; Osteoporosis; Tomography, X-ray computed.