Intra-Individual Differences of the Femoral Cortical Thickness Index in Elderly Patients with a Proximal Femoral Fracture

<b>Background/Objectives:</b> Osteoporosis is prevalent in the elderly and increases fracture risk. Bone density is commonly assessed using dual-energy X-ray absorptiometry (DEXA). The femoral cortical thickness index (CTI) also provides indirect information for osteoporosis. It remains unclear whether there are intra-individual differences and if a correlation to fracture risk of the CTI in fractured femora results due to fracture related malrotation during X-rays. The aim of this study was to investigate the individual bilateral CTI in patients with proximal femoral fractures. <b>Methods</b>: A retrospective analysis of 200 surgically treated patients (100 trochanteric, 100 femoral neck fractures) was performed. Measurements included the bilateral CTI at 10 and 15 cm below the lesser trochanter. Analysis of the correlation of those examinations, in comparison to the contralateral CTI at 15 cm, and correlation of the CTI with the body mass index (BMI) and age was performed. <b>Results</b>: Results showed significant differences (<i>p</i> < 0.001) in bilateral CTIs for both fracture types at 15 cm with a strong inter-rater reliability (ICC > 0.9). There was no significant correlation between age and CTI, as well as BMI and CTI in both cohorts (<i>p</i> > 0.1). Sex-specific subgroup analyses revealed that females exhibited significant differences in CTI between fractured and non-fractured sides (<i>p</i> < 0.001). <b>Conclusions</b>: In conclusion, CTI, and the modified CTI at 15 cm below the lesser trochanter in fractured proximal femora, is lower compared to the non-fractured side. The femoral CTI could help in daily clinical routines and circumstances, where more detailed risk prediction tools are lacking.