Wear Rates of Larger-Diameter Cross-Linked Polyethylene at 5 to 13 Years: Does Liner Thickness or Component Position Matter?

BACKGROUND

Cross-linked polyethylene (XLPE) has demonstrated significantly reduced wear and osteolysis into the second decade for total hip arthroplasty. There is a relative paucity of data with ≥36-mm bearings. Issues include potential effects of reduced liner thickness and component position on wear, osteolysis, and mechanical failure of the bearing.

METHODS

Radiographs of 48 primary total hip arthroplasties with ≥36-mm modular XLPE bearings were analyzed at a minimum 5 years postoperative on serial radiographs using a validated, edge-detection-based algorithm. Subgroups were examined to assess the effect of bearing diameter, liner thickness, acetabular abduction angle, and acetabular anteversion on XLPE wear.

RESULTS

There was no significant difference in volumetric wear when subgroups were stratified by component factors: liner thickness (<6.5 mm vs ≥6.5 mm) 40.69 mm/y vs 24.47 mm/y, respectively (P = .315); acetabular component abduction angle (<45° vs ≥45°): 38.68 mm/y vs 27.8 mm/y, respectively (P = .522); acetabular anteversion (<20° vs ≥20°): 41.32 mm/y vs 31.79 mm/y, respectively (P = .521). There were no dislocations, mechanical failures, or revisions. There were 7 hips with volumetric wear rates ≥80 mm/y; 1 had possible osteolysis.

CONCLUSION

Larger-diameter XLPE wear was not measurably affected by liner thickness, acetabular abduction angle, or acetabular anteversion. However, there is a trend for increasing volumetric wear with increasing bearing size. Wear outliers do occur, and continued follow-up of larger-diameter XLPE bearings is warranted.