Correlations between polyethylene wear direction and other influencing factors in total hip arthroplasty

Objective To explore the correlations between polyethylene wear direction and implanted parameters of prosthesis in total hip arthroplasty (THA) by computer-assisted measurement techniques. Methods Retrospective analyses were performed for 58 uncemented THAs from April 1997 to March 2006. The sagittal displacement of femoral head to axis of acetabulum opening plane was examined to determine the direction and degree of linear polyethylene wear. Radiographs were assessed for femoral offset, acetabular abduction, acetabular anteversion and conventional polyethylene wear. The linear polyethylene wear directions were compared between different parameter groups. Results The average linear wear rate was 0.17±0.08 mm/year and the angle between linear wear direction and axis of acetabulum 34.2°(±29.3°). Linear wear direction and acetabular abduction were positively relevant(r=0.480, P=0.000). Linear wear direction was negatively correlated with postoperative Harris scores(r=-0.314, P=0.016). Compared with the acetabular abduction of 0.05). Conclusion Reasonable acetabular abduction and femoral offset may decrease linear wear rates, maintain hipstability and improve long-term putcomes. Key words: Arthroplasty, replacement, hip; Polyethylene; Radiometry; Acetabulum