Minimal backside surface changes observed in retrieved acetabular liners

Modular polyethylene liners offer versatility in total hip arthroplasty, but the locking mechanism may allow micromotion and backside wear. We evaluated the backside surface of 56 retrieved acetabular liners (mean 5.54 years in vivo, range 0.003-13.1 years) to determine whether damage correlated with liner age in vivo, patient factors associated with higher activity, and polyethylene quality. Half of the liners exhibited minimal damage, half exhibited no damage and none exhibited severe damage. Backside damage significantly correlated only to liner age in vivo. Ten of the 28 liners revised for osteolysis exhibited no backside damage, but the osteolytic cysts were peripheral and did not originate from screw holes. The results suggest that modular polyethylene liners in a porous titanium-coated shell with screw holes can be designed such that clinically significant backside wear is minimal.