The John Charnley Award: The Efficacy of BMP-2 to Induce Bone Ingrowth in a Total Hip Replacement Model

The purpose of this canine total hip arthroplasty (THA) study was fourfold: (1) to quantify the efficacy of rhBMP-2 in a carrier (αBSM) versus αBSM alone, and versus untreated controls to induce bone formation across a defect between a porous acetabular component and host bone; (2) to quantify whether rhBMP-2/αBSM improves bone growth into the porous surface beneath that defect; (3) to quantify the efficacy of rhBMP-2/αBSM in inducing bone ingrowth into the porous layer at points of intimate bone-implant contact; and (4) to determine whether rhBMP-2/αBSM placed in the lateral uncovered aspect of the porous acetabular component promotes de novo bone formation. Fifteen dogs were sacrificed 12 weeks after uncemented THA. Five dogs received rhBMP-2/αBSM, five dogs received αBSM, and five dogs were controls. In contrast to the controls in which no bone filled the defect, the rhBMP-2/αBSM induced defect filling and full bone formation in the underlying porous coating. The αBSM produced an intermediary response. However, no increase in new bone formation occurred at sites of intimate bone porous surface contact. Recombinant bone morphogenetic protein-2/αBSM promoted defect filling and bone ingrowth into the porous coating beneath the defect region, both of potential value in future total joint replacement surgery.