The Initial Stability of Femoral Impaction Grafting

Abstract

Aseptic loosening is the major cause of failure in primary total hip replacements. Loss of bone stock occurs in both cementless and cemented implants. Impaction of morsellised allograft represents a major advance in the restoration of bone loss at revision hip surgery. This study was designed to test the early stability of the femoral impaction construct. Polished double tapered stems were inserted into neomedullary canals within impacted allograft in fibreglass femora. Subsidence was measured during cyclical loading. Four methods of impaction grafting were tested: allograft alone; allograft and heparinised blood; allograft/cement/heparinised blood; allograft/cement/clotted blood. Uncemented impaction grafting failed at low loads and few cycles. The cemented technique supported higher loads. Heparinised blood reduced the strength of the composite. Initial stability was achieved with allograft, cement and clotted blood. There is need for caution in the early post-operative period due to the wide variation in initial stability of the allograft composite. The reliability of this technique has been increased by the use of specialised instruments. Experimental studies and clinical experience suggest that this approach to revision surgery is technique dependent.