Biomet Cement and Cementing Systems

Bone bed preparation

Preservation of cancellous bone

To achieve adequate cement interdigation and a viable interlock, preservation of cancellous bone stock is of great importance.

To preserve cancellous bone careful bone preparation is essential. The cancellous structure can be regarded as a system of springs; the superficial layer of the cancellous bone in contact with the surface of the cement will move as one with the cement surface when load is applied; the deflection of the cancellous structure will take place inside the bulk of cancellous bone. In this way we can explain the paradox of the transmission of load from a hard to a soft substance without relative motion taking place between the surfaces in contact.

Numerous in vitro experiments have showed a strong correlation between improved cement penetrations and increased shear strength of the cement-bone interface. The interface strength is not only affected by the degree of cement penetration but also by the quality of the supporting cancellous framework.⁴

To achieve a good cement fixation and penetration into the cancellous bone a vital step is the bone bed preparation. In acetabulum preparation the reaming should only partly remove the subcondral bone. A 2 to 3 mm cement mantle is recommended.