Cementless acetabular components are commonly used in primary and revision total hip arthroplasty, and most designs have been successful despite differences in the porous coating structure. Components with 2D titanium fiber mesh coating (FM) have demonstrated high survivorships up to 97% at 20 years1. 3D tantalum porous coatings (TPC) have been introduced in an attempt to improve osseointegration and therefore implant fixation. Animal models showed good results with this new material one year after implantation2, and clinical and radiographic studies have demonstrated satisfactory outcomes3. However, few retrieval studies exist evaluating in vivo bone ingrowth into TPC components in humans. We compared bone ingrowth between well-fixed FM and TPC retrieved acetabular shells using backscatter scanning electron microscopy (BSEM). 16 retrieved, well-fixed, porous coated acetabulum components, 8 FM matched to 8 TPC by gender, BMI and age, all revised for reasons other than loosening and infection, were identified from our retrieval archive (Fig. 1). The mean time in-situ was 42 months for TPC and 172 for FM components. Components were cleaned, dehydrated, and embedded in PMMA. They were then sectioned, polished, and examined using BSEM. Cross-sectional slices were analyzed for percent bone ingrowth and percent depth of bone ingrowth (Fig. 2). Analysis was done using manual segmentation and grayscale thresholding to calculate areas of bone, metal, and void space. Percent bone ingrowth was determined by assessing the area of bone compared to the void space that had potential for bone ingrowth.Introduction
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