Euler(strut.cavity), a new histomorphometric parameter of connectivity reflects bone strength and speed of sound in trabecular bone from human os calcis.

The amount of bone and the trabecular microarchitecture are two determinants of bone strength which can be quantified by bone histomorphometry. Among the parameters of bone microarchitecture, the Euler number developed in our laboratory (E( strut.cavity )) and trabecular bone pattern factor (TBPf) evaluate the connectivity and complexity independently of the bone quantity, and the speed of sound (SOS) measured by quantitative ultrasound (QUS) corroborates E( strut.