Retroacetabular Stress-shielding in THA
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We conducted a randomized clinical trial to compare periacetabular bone density changes after total hip arthroplasty using press-fit components with soft and hard liner materials. Bone density changes were assessed using quantitative computed tomography-assisted osteodensitometry. Twenty press-fit cups with alumina ceramic liners and 20 press-fit cups with highly cross-linked polyethylene liners were included; the nonoperated contralateral side was used as the control. Computed tomography scans were performed postoperatively and 1 year after the index operation. At the 1-year followup, we found no differences of periacetabular bone density changes between the alumina and polyethylene liner cohorts. However, we observed marked periacetabular cancellous bone density loss (up to −34%) in both cohorts. In contrast, we observed only moderate cortical bone density changes. The decrease of periacetabular cancellous bone density with retention of cortical bone density after THA suggests stress transfer to the cortical bone.
KeywordsBone Density Cancellous Bone Acetabular Component Bone Remodel Process Cortical Bone Density
We thank Mr. Garnet Tregonning, Dr. Lyndon Bradley, Dr. Godwyn Choy, Dr. Keryn Reilly, and Dr. Melissa Rossaak for their assistance during the clinical followups. We express our gratitude to Cameron Walker, PhD, for statistical analysis of this study. We also thank Dr. Lutz Mueller and Dr. Rainer Schmidt for advice in implementing quantitative computed tomography research at the University of Auckland.
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