Comparative left-right mechanical testing of cancellous bone from normal femoral heads

In order to assess the potential influence of various physical or chemical treatments on bone grafts, and in particular, on femoral heads to be used as bone grafts, the mechanical symmetry of the femoral head was investigated. Pairs of proximal human femora were harvested and transversally sliced using a coordinate system to orient correctly the head. After being embedded and polished, bone slices were loaded to failure between two steel columns (6 mm of diameter) in a sequential and symmetrical manner for both heads. From ten pairs, 592 mechanical assays on the cancellous bone of femoral heads were performed. There was a high variation in the mechanical properties of the specimens from the different donors. However, no statistical difference could be observed within each pair when side-to-side symmetry was tested for the different mechanical characteristics. Ultimate stress at failure and stiffness were also highly correlated for each mirror location of each pair. Provided that an accurate and reproducible method of slicing femoral head can be achieved, an excellent mechanical symmetry is observed using a static compressive test. Such a method could be used to determine the mechanical influence of any treatment applied to bone.