2017 ISAKOS Biennial Congress IFOSMA ePoster #5005

 

Cortical Bone Thickness And Cortical Index Of Distal Femur As New Indicators For Predicting Osteoporosis And Instruction To Peri-Knee Fractures

Qifang He, PhD, Shanghai CHINA
CongFeng Luo, MD, PhD, Shanghai CHINA

Shanghai Sixth People’s Hospital, Shanghai, Shanghai, China

FDA Status Not Applicable

Summary

Cortical bone thickness and cortical index of distal femur coule be used as new indicators for predicting osteoporosis and instruction to peri-knee fractures

Abstract

Background

Osteoporotic fractures around the knee is increasing. The current gold standard to diagnose the bone quality, dual x-ray absorptiometry (DXA), is rarely scanned in fracture management. Our aim therefore was to determine the correlation between two new raised indicators and bone quality.

Methods

Both indicators are based on the cortical thickness of the distal femur diaphysis measured on anteroposterior (AP) radiographs, the average cortical bone thickness of the distal femur(CBTavg) and distal femoral cortex index(DFCI). 361 adult patients’ (61.8 ± 12.31 years) DXA scans and knee AP view were retrospectively analyzed. The gold standard for bone quality, BMD and T-score, were obtained from DXA results. In knee AP view, we defined two indicators, CBTavg and DFCI, in a simple fashion. The correlation between BMD, age, CBTavg and DFCI were evaluated. Thresholds of CBTavg and DFCI to predict state of osteoporosis or osteopenia were calculated by Receiver operating characteristic (ROC) analysis. The CBTavg had a moderate and significant correlation with BMD of hip (r = 0.664 vs r=-.410, p<0.01) and lumbar spine (r=0.410, p<0.01), and also well correlated with T-score (r=0.654, p<0.01) (Fig 2). DFCI also had a moderate but lower correlation with BMD of hip (r=0.457, p<0.01) and T-score (r=0.464, p<0.01), but weakly correlated with lumbar spine (r=0.235, p<0.01).

Results

DFCI had better intra-class correlation coefficients (ICCs) than CBTavg, which indicated it has a better stability during measurement. CBTavg showed better correlation with BMD of hip than DFCI(r=0.664 vs r=0.457, p<0.01) and better predicting function for osteoporosis and osteopenia seeing from area under curve (AUC) in ROC curves(0.82 vs 0.74, z=2.432, p=0.015, 798 vs 0.721, z=4.929, p<0.0001, Delong’s test). ), and also better for predicting osteopenia than DFCL (0.798 vs 0.721, z=4.929, p<0.0001). The criterion value for the CBTavg to identify osteoporosis was 4.4mm (sensitivity of 100 and specificity of 60.53), and was 4.5 for osteopenia (sensitivity of 78.03 and specificity of 66.81). Same analysis for DFCL decided the criterion value of osteoporosis to be 1.10 (sensitivity of 0.88 and specificity of 0.80), and 1.08 for osteopenia (sensitivity of 51.52 and specificity of 80.35).

Conclusions

Both indicators in knee AP view, CBTavg and DFCI, has moderate and positive correlation with BMD and T-score. They are capable to predict osteoporosis and possibly helpful to predict the bone quality of peri-knee fractures. Furthermore, CBTavg method is more accurate and representative, while DFCI is more stable and accessible.