Pressure during compaction of morsellised bone gives an increase in stiffness: an in vitro study.

Morsellised bone impaction is used in joint prosthesis revision surgery to repair structural damage to the periarticular bone stock. The initial stiffness of the impacted bone is crucial for the survival of the revised hip joint. Impaction of morsellised bone in a femoral canal can cause fractures that may induce implant loosening in both femur and acetabulum. Alternative techniques to increase stiffness can therefore be of major interest. In this study we analyse whether applying a constant pressure during impaction can increase the stiffness of the morsellised bone. We constructed bone pellets by impaction with and without applying a constant pressure. The constrained stiffness and coefficient of secondary strain were determined by unidirectional load testing after construction of the pellets. A significant increase in constrained stiffness (P < 0.001) from 3.9 to 5.5 MPa and a decrease in the coefficient of secondary strain (P < 0.001) from 1.1 to 0.5 were found.