A comparison of bone remodelling around hydroxyapatite-coated, porous-coated and grit-blasted hip replacements retrieved at post-mortem

Abstract

W e investigated the implant-bone interface around one design of femoral stem, proximally coated with either a plasma-sprayed porous coating (plain porous) or a hydroxyapatite porous coating (porous HA), or which had been grit-blasted (Interlok). Of 165 patients implanted with a Bimetric hip hemiarthroplasty (Biomet, Bridgend, UK) specimens were retrieved from 58 at post-mortem.We estimated ingrowth and attachment of bone to the surface of the implant in 21 of these, eight plain porous, seven porous HA and six Interlok, using image analysis and light morphometric techniques. The amount of HA coating was also quantified.There was significantly more ingrowth (p = 0.012) and attachment of bone (p < 0.05) to the porous HA surface (mean bone ingrowth 29.093 ± 2.019%; mean bone attachment 37.287 ± 2.489%) than to the plain porous surface (mean bone ingrowth 21.762 ± 2.068%; mean bone attachment 18.9411 ± 1.971%). There was no significant difference in attachment between the plain porous and Interlok surfaces. Bone grew more evenly over the surface of the HA coating whereas on the porous surface, bone ingrowth and attachment occurred more on the distal and medial parts of the coated surface. No significant differences in the volume of HA were found with the passage of time.This study shows that HA coating increases the amount of ingrowth and attachment of bone and leads to a more even distribution of bone over the surface of the implant. This may have implications in reducing stress shielding and limiting osteolysis induced by wear particles. The use of hydroxyapatite (HA) coating has been advocated in order to increase the attachment of bone to metal implants. Many animal as well as clinical studies have demonstrated the osseoconductive properties of HA and the results at six to eight years are excellent.1,2 Bone apposition appears to be well advanced as early as three weeks, 3 and some studies have shown it to be greater than 90% at 96 weeks. 4 Although there is concern that HA resorbs with time and that the release of HA debris may have adverse effects, 5 the clinical results reported so far for HA-coated components suggest that at present this is not a significant problem. Several reports of the outcome after the insertion of porous-coated uncemented implants have shown good results.6-8 Most studies found some degree of bone ingrowth into the pores 9-12 with the mean extent reported to be in the range of 5% 9,12 to 39.2% 13 of the available pore volume. An HA coating has been advocated in order to reduce the effects of debonding and to encourage bone ingrowth and attachment to a porous surface. Several studies have examined the use of an HA surface coating on porous-coated implants. Some have reported that there is no clinical advantage 14 while others have demonstrated a significant increase in bone ingrowth. 15,16 We have investigated bone ingrowth and attachment to an HA-coated porous titanium surface, a plain porous titanium surface and a roughened titanium (Interlok) surface finish in one femoral design from s...

Comparison of different hip prosthesis shapes considering micro-level bone remodeling and stress-shielding criteria using three-dimensional design space topology optimization

“…While the Alloclassic and Mayo feature gritblasted rather than porous-coated surfaces, several long-term studies of these devices have shown the identical trend of proximal bone loss and distal bone densification. Studies have also compared these two uncemented fixation techniques (when controlled for hydroxyapatite coating) and have shown no significant clinical or radiographic differences (Coathup et al, 2001;Won et al, 2004). Quantitatively, the bone mineral content had the highest levels of resorption in the proximal region and densification in mid and distal zones.…”

Improving the osteointegration and bone–implant interface by incorporation of bioactive particles in sol–gel coatings of stainless steel implants

“…The analysis of in vivo formation of new tissue at the interfaces of bioactive implants has been reported using histological methods and the interfacial mechanical properties, such as stiffness, have also been studied [22,23]. Recently other techniques that focus at the micro-and nano-structural level analysis of the newly formed tissue, such as nanoindentation, small-angle and wide-angle X-ray scattering, Raman microscopy and elemental analysis are being used in the analysis of biological materials [24,25].…”

Die Ausbildung von Knochengewebe an der Oberfläche von hydroxylapatitbeschichteten Prothesenschäften: eine radiologische Analyse

“…Es können diese Veränderungen aber nicht nur als Erhöhung der Stabilität der Implantate durch den raschen ossären Einheilungsprozess gedeutet werden, sondern auch auf einen raschen Verschluss des Markraums schließen lassen. Der aus den artikulierenden Oberflächen erfolgenden Partikelfreisetzung wird somit eine deutliche Barriere gegenüber dem Markraum des Femurs entgegengesetzt [14,20,29]. Schon Abb.…”

“…Dabei kann offensichtlich die Zahl der RL verringert werden [11][12][13][14][15] oder sogar ein zur zementfreien Verankerung weniger geeignetes Implantat in seinem ossären Einbau verbessert werden [16]. Tierexperimentelle Arbeiten [17][18][19] sowie auch pathologisch-histologische Untersuchungen an Humanpräparaten [20][21][22][23] zeigten das gute Anwachsverhalten des Knochens und die bessere ossäre Verankerung im Vergleich zu unbeschichteten Implantaten. Hinsichtlich der radiologischen Darstellung der Einheilung beschichteter Schäfte gibt es allerdings nur wenig Information [24][25][26].…”