Relationship between polyethylene wear and decrease of femoral offset after total hip arthroplasty / 中华骨科杂志

ABSTRACT

Objective To investigate relationship between polyethylene wear and decrease of femoral offset after total hip arthroplasty (THA).Methods Ninety patients who had undergone unilateral THA were recruited in this study.Coreldraw 12.0 software was used to measure change of femoral offset on the basis of immediate anteroposterior radiographies of bilateral hip after THA.In the light of the decreasing value of femoral offset (F),all patients were equally into 5 groupsF＜2 mm,2≤F≤4 mm,4＜F≤6 mm,6＜F≤8 mm and 8＜F≤ 10 mm.At final follow up,some parameters about polyethylene wear were measured by using Coreldraw 12.0 software on the basis of anteroposterior radiographies of bilateral hip.Results The linear wear volume was 0.72±0.13 mm in group F＜2 mm,0.78±0.11 mm in group 2≤F≤4 mm,0.87±0.09mm in group 4＜F≤6 mm,0.99±0.09 mm in group 6＜F≤8 mm,and 1.17±0.15 mm in group 8＜F≤10 mm.The linear wear rate was 0.132±0.025 mm/yr in group F＜2 mm,0.139±0.019 mm/yr in group 2≤F≤4 mm,0.159±0.029 mm/yr in group 4＜F≤6 mm,0.183±0.032 mm/yr in group 6＜F≤8 mm,and 0.213±0.023 mm/yrin group 8＜F≤ 10 mm.The linear wear angle was 5.0°±3.5° in group F＜2 mm,3.2°±3.8. in group 2≤F≤4mm,-4.3°±4.9° in group 4＜F≤6 mm,-8.7°±4.1° in group 6＜F≤8 mm,and -13.0°±4.7° in group 8＜F≤ 10mm.For three parameters above,there were significant differences between groups,except between group F＜2 mm and group 2≤F≤4 mm.Conclusion The femoral offset should be restored to its anatomic status in THA to avoide superior lateral displacement of center of the femoral head,which could result in uneven stress distribution and increase polyethylene wear.