Influence of intraoperative femoral fractures and cerclage wiring on bone ingrowth into canine porous-coated femoral components.

Intraoperative femoral fractures occur more frequently with cementless than with cemented components. In this study, the influence of controlled femoral fractures fixed with cerclage wires on rotational stability and bone ingrowth into porous-coated canine femoral components was evaluated. These data were compared with results of previous studies on unrecognized femoral fractures (not stabilized) and on the intact canine femur. Micromotion analysis revealed a significant increase in rotational instability in fractures not stabilized with cerclage wires (P < .05) compared with the intact femur. Experimentally created femoral fractures had a significantly deleterious effect on bone ingrowth even after cerclage wiring. This appears to be caused by a lack of bone ingrowth deep to the fracture and an increase in femoral component micromotion. In clinical practice, femoral fractures occurring during cementless total hip arthroplasty are a serious problem, and use of a cemented prosthesis is recommended if rotational stability of the stem cannot be ensured.