Torsional resistance and wear of a modular sleeve-stem hip system.

The torsional resistance and wear debris generation of the modular sleeve and stem S-ROM total hip system was evaluated. The results indicate that slippage of the sleeve-stem interface may occur under physiological loading conditions. Slippage is more likely to occur if the junction is contaminated by blood or tissue, or if the stem is disengaged and reimplanted into the sleeve. Significant wear debris was generated during cyclic fatigue loading. The wear debris was of the size (less than 10 mum) readily ingested by macrophages. Particles of these dimensions have been associated with osteolysis, implant loosening and pain. Based upon the findings of this study the implantation of this type system must be carefully considered.