The Journal of Arthroplasty, Volume 27, Issue 2, 238 - 245.e1

Interface Micromotion of Uncemented Femoral Components from Postmortem Retrieved Total Hip Replacements

Mann, Kenneth A. et al.

Axial torsional loads representative of gait and stair climbing conditions were applied to transverse sections of 8 uncemented postmortem retrievals and a high-resolution imaging system with digital image correlation was used to measure local micromotion along the bone-implant interface. For 7 components that were radiographically stable, there was limited micromotion for gait loading (1.42 ± 1.33 μm) that increased significantly (P = .0032) for stair climb loading (7.32 ± 9.96 μm). A radiographically loose component had motions on the order of 2.3 mm with gait loading. There was a strong inverse relationship between the amount of bone-implant contact (contact fraction) (P = .001) and micromotion. The uncemented components had greater contact fraction (41.8% ± 14.4% vs 11.5% ± 10.2%, P = .0033) and less median micromotion (0.81 ± 0.79 μm vs 28.8 ± 51.1 μm) compared to a previously reported study of cemented retrievals.

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