Image-based　finite　element　modelling　has　been　commonly　used　to　determine　the　biomechanical　behaviours　of　human　femora,　particularly　for　the　diagnosis　of　femoral　head　necrosis.　One　of　the　fundamental　aspects　of　biomechanical　modelling　is　the　relationship　between　bone　density,　which　is　obtained　from　images,　and　elastic　modulus.　While　there　exist　some　empirical　equations　relating　density　with　elastic　modulus,　the　characterization　of　this　relationship　remains　incomplete,　especially　for　necrotic　femoral　heads.　The　objective　of　this　study　was　to　determine　the　relationship　between　density　and　elastic　modulus　by　combining　ultrasonic　scanning　and　computed　tomography　(CT).　Bone　specimens　were　surgically　removed　from　the　femora　of　eight　persons　(seven　females　and　one　male　in　the　age　range　of　55-68　years　old)　and　underwent　both　ultrasonic　and　CT　scanning.　The　images　were　processed　with　MATLAB　scripts,　and　a　bilinear　interpolation　algorithm　was　used　to　determine　the　relationship　between　the　CT-measured　densities　and　ultrasound-measured　elastic　moduli.　The　results　showed　different　density-elastic　modulus　relations　between　the　hardening　strap　of　the　necrotic　region　and　non-hardening　strap　areas　of　the　necrotic　region.　The　uniqueness　of　this　study　is　the　characterization　of　mechanical　properties　(in　the　present　study,　the　density-modulus　relationship)　from　clinical　images,　which　would　be　valuable　in　computational　biomechanics　used　for　the　diagnosis　and　treatment　evaluation　of　femoral　head　necrosis.　(C)　2019　Published　by　Elsevier　Ltd　on　behalf　of　IPEM.