The femoral cement mantle in three total hip replacements.

We measured the size and volume of the femoral broaches and stems supplied with three commercial total hip replacement (THR) systems (JRI Furlong, Biomet Stanmore, and Howmedica Exeter). Using an in vitro method, we created cement mantles that could be directly measured. The broaches supplied with the Biomet Stanmore and the Howmedica Exeter systems allowed the creation of significantly thicker cement mantles than the JRI broaches and stems (Stanmore mean thickness = 1.7 mm, defects at 3% of measurement sites; Exeter mean thickness = 2.0 mm, no defects; JRI mantles mean thickness = 0.9 mm, cement defects at 29% of measurement sites). We conclude that, in vivo, the broaches supplied with the Stanmore and Exeter systems are significantly larger than the corresponding stems, and will excavate a cavity large enough to accommodate the appropriate femoral stem surrounded by an intact cement mantle.