Dynamic testing of bone grafts.

The influence of cycling loading force on the substrate made of frozen bone grafts was investigated. Three layers of bone grafts were compacted in a spherical model of hip joint acetabulum and then subjected to a sinusoidal loading force. For each layer a series of N = 30 loading cycles were performed. The least impacted grafts were located in the upper part of the acetabulum, close to its opening, whereas the bed is the most compacted part. Compacting is a non-linear process which quickly loses its dynamics during subsequent cycles. Most of the compacting was observed during the first cycles and the deformation of bone grafts has clearly plastic character. Bone grafts initially compacted by orthopedist undergo further compacting when exposed to a cyclic load.