Larger bone graft size and washing of bone grafts prior to impaction enhances the initial stability of cemented cups - Experiments using a synthetic acetabular model

Background Bone defects after failed total hip arthroplasty can be reconstructed with impacted morselized bone grafts and a cemented cup. On the acetabular side, the effects on initial cup stability of washing bone grafts prior to impaction and bone graft size remain unclear. Related to these variables, cement penetration and inter-particle shear resistance have been suggested to be critical factors to ensure initial cup stability. Methods Using a synthetic acetabular model, we studied the effects of (1) washing bone grafts prior to impaction, and (2) bone graft size on the initial stability of cemented cups. In addition, cement penetration was measured using CT scans. Results Reconstructions with large, washed bone grafts provided the highest stability during mechanical compression and in a lever-out situation. Washing of the bone grafts had a positive effect on initial cup stability, but the size of the bone grafts appeared to be more important. Cement penetration was affected by bone graft size but not by washing. Interpretation From a mechanical standpoint, large bone grafts that have been washed prior to impaction may be preferable in order to obtain optimal cup stability using the bone impaction grafting technique.