An in-vitro investigation of the CPS-Plus femoral stem: influence of the proximal centraliser on cement pressurisation during stem insertion.

The CPS-Plus stem is designed for use with a proximal and distal stem centraliser. This in-vitro study examined the cement pressurisation achieved during insertion of the CPS-Plus femoral stem into a model femur. Cement pressures were measured at proximal, mid and distal stem levels. Pressures were recorded during insertion of the CPS-Plus stem with both proximal and distal centralisers and compared with those achieved when only a distal centraliser was used with digital occlusion of the proximal femur. The CPS-Plus with a proximal centraliser generated significantly greater cement pressures than the CPS-Plus without a proximal centraliser at proximal and mid-stem regions. The use of a proximal stem centraliser may improve the cement-bone interdigitation and shear strength at the cement-bone interface, particularly in the region of the proximal femur.