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Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_1 | Pages 91 - 91
1 Feb 2020
Baral E Purcel R Wright T Westrich G
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Introduction

Long term data on the survivorship of cemented total knee arthroplasty (TKA) has demonstrated excellent outcomes; however, with younger, more active patients, surgeons have a renewed interest in improved biologic fixation obtained from highly porous, cementless implants. Early designs of cementless total knees systems were fraught with high rates of failure for aseptic loosening, particularly on the tibial component. Prior studies have assessed the bone ingrowth extent for tibial tray designs reporting near 30% extent of bone ingrowth (1,2). While these analyses were performed on implants that demonstrated unacceptably high rates of clinical failure, a paucity of data exists on the extent on bone ingrowth in contemporary implant designs with newer methods for manufacturing the porous surfaces. We sought to evaluate the extent of attached bone on retrieved cementless tibial trays to determine if patient demographics, device factors, or radiographic results correlate to the extent of bone ingrowth in these contemporary designs.

Methods

Using our IRB approved retrieval database, 17 porous tibial trays were identified and separated into groups based on manufacturer: Zimmer Natural Knee (1), Zimmer NexGen (10), Stryker Triathlon (4) and Biomet Vanguard Regenerex (2). Differences in manufacturing methods for porous material designs were recorded. Patient demographics and reason for revision are described in Table 1. Radiographs were used to measure tibiofemoral alignment and the tibial mechanical axis alignment. Components were assessed using visual light microscopy and Photoshop to map bone ingrowth extent across the porous surface. ImageJ was used to threshold and calculate values for bone, scratched metal, and available surface for bone ingrowth (Fig. 1). Percent extent was determined as the bone ingrowth compared to the surface area excluding any scratched regions from explantation. Statistics were performed among tray designs as well as between the lateral and medial pegs, if designs had pegs available for bony ingrowth.


The Bone & Joint Journal
Vol. 101-B, Issue 4 | Pages 386 - 389
1 Apr 2019
Hampton C Weitzler L Baral E Wright TM Bostrom MPG

Aims

The aim of this study was to evaluate fretting and corrosion in retrieved oxidized zirconium (OxZr; OXINIUM, Smith & Nephew, Memphis, Tennessee) femoral heads and compare the results with those from a matched cohort of cobalt-chromium (CoCr) femoral heads.

Patients and Methods

A total of 28 OxZr femoral heads were retrieved during revision total hip arthroplasty (THA) and matched to 28 retrieved CoCr heads according to patient demographics. The mean age at index was 56 years (46 to 83) in the OxZr group and 70 years (46 to 92) in the CoCr group. Fretting and corrosion scores of the female taper of the heads were measured according to the modified Goldberg scoring method.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_3 | Pages 29 - 29
1 Feb 2017
Baral E Trivellas M Ricciardi B Esposito C Wright T Padgett D
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Introduction

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).

Methods

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.