Surface Properties of Retrieved Cementless Femoral Hip Endoprostheses Produced from a Ti6Al7Nb Alloy

Klemen Avsec,Igor Belič,Boštjan Kocjančič,Barbara Šetina Batič,Matevž Gorenšek,Matjaž Godec,Drago Dolinar,Monika Jenko,Marjetka Conradi,Alenka Vesel,Črtomir Donik,Janez Kovač,Aleksandra Kocijan

doi:10.3390/coatings9120868

Abstract

We have investigated new and retrieved cementless hip endoprostheses that prematurely failed due to (i) aseptic loosening, (ii) infection and (iii) latent infection. The aim was to better understand the physico-chemical phenomena on the surfaces and sub-surfaces of the Ti6Al7Nb alloy implant. The results of our studies should enable us to distinguish the causes of premature failure, optimize the surface modification, achieve optimal osseointegration and extend the useful lifetime of the implants. The surface properties of the Ti6Al7Nb alloys of the hip-stem endoprostheses (30 retrieved and 2 new) were determined by contact-angle measurements and the average surface roughness. The surface chemistry and microstructure were analysed by scanning electron microscopy (SEM) for morphology, energy-dispersive X-ray spectroscopy (EDS) for the chemistry, and electron back-scatter diffraction (EBSD) for the phase analysis; Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) for the surface chemistry; and electrochemical measurements for the corrosion. The improved wettability of the grit-blasted surface of the Ti6Al7Nb stems after autoclaving was measured, as was the super wettability after oxygen-plasma sterilization. The secondary-electron images showed that the morphology and microstructure of the new and retrieved stems (prematurely failed due to aseptic loosening, infection and latent infection) differ slightly, while the EDS analysis revealed corundum contamination of the grit-blasted surface. We found corundum-contaminated Ti6Al7Nb stem surfaces and sub-surfaces for all the investigated new and retrieved implants. These residues are a potential problem, i.e., third-body wear particles, and probably induce the osteolysis and aseptic loosening.

Highlights

Total hip-joint arthroplasty (THA) is the most successful surgical method for relieving pain, correcting deformities and treating degenerative joint disease and trauma
The surface chemistry and microstructure were analysed by scanning electron microscopy (SEM) for morphology, energy-dispersive X-ray spectroscopy (EDS) for the chemistry, and electron back-scatter diffraction (EBSD) for the phase analysis; Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) for the surface chemistry; and electrochemical measurements for the corrosion
We found that the surfaces ofthat the retrieved and new stems ofand

Summary

Introduction

Total hip-joint arthroplasty (THA) is the most successful surgical method for relieving pain, correcting deformities and treating degenerative joint disease and trauma. The number of patients who need a total joint arthroplasty, and possible revision, is increasing due to an aging population. Kurtz et al reported that the predictions for the primary revision of hip and knee arthroplasty in the USA in the 10 years is of 1 million total joint arthroplasties (TJAs) per year and 2.5 million THA per year worldwide [1]. The process of an ageing population continues, life expectancy is increasing, so besides premature failures, many patients are outliving their implants, which is a second concern. Both factors lead to the prediction of a large increase in implant failure in the near future and an enormous increase in health costs. On the market there are approximately 60 different types of single-stem cementless prostheses and knowledge of the behaviour of the individual prosthesis in certain clinical conditions is very important [2]

Methods

Results

Conclusion