Introduction. Implant contamination prior to cement application has the potential to affect the cement-implant bond. the consequences of implant contamination were investigated in vitro using static shear loading with bone cement and titanium dowels of differing surface roughness both with, and without contamination by substances that are likely to be present during surgery. Namely; saline, fat, blood and oil, as a negative control. Methods. Fifty Titanium alloy (Ti-6Al-4V) dowels were prepared with two surface finishes comparable to existing stems. The roughness (Ra and Rq) of the dowel surface was measured before and after the pushout test. Four contaminants (Phosphate Buffered Saline (PBS), ovine marrow, ovine blood, olive oil) were prepared and heated to 37°C. Each contaminant was smeared on the dowel surface completely and uniformly approximately 4 minutes prior to implantation. Samples were separated into ten groups (n=5 per group) based on surface roughness and contaminant. Titanium alloy dowels was placed in the center of Polyvinyl chloride (PVC) tubes with bone cement, and equilibrated at 37°C in PBS for 7 days prior to mechanical testing. The push out test was performed at 1 mm per minute. The dowel surface and cement mantel were analyzed using a
One out of nine Canadian males would suffer prostate cancer (PC) during his lifetime. Life expectancy of males with PC has increased with modern therapy and 90% live >10 years. However, 20% of PC-affected males would develop incurable metastatic diseases. Bone metastases (BM) are present in ~80% of metastatic PC patients, and are the most severe complication of PC, generating severe pain, fractures, spinal cord compression, and death. Interestingly, PC-BMs are mostly osteoblastic. However, the structure of this newly formed bone and how it relates to pain and fracture are unknown. Due to androgen antagonist treatment, different PC phenotypes develop with differential dependency on androgen receptor (AR) signaling: androgen-dependent (AR+), double negative (AR-) and neuroendocrine. How these phenotypes are related to changes in bone structure has not been studied. Here we show a state-of-the-art structural characterization of PCBM and how PC phenotypes are associated to abnormal bone formation in PCBM. Cadaveric samples (n=14) obtained from metastases of PC in thoracic or lumbar vertebrae (mean age 74yo) were used to analyze bone structure. We used micro-computed tomography (mCT) to analyze the three-dimensional structure of the bone samples. After imaging, the samples were sectioned and one 3mm thick section was embedded in epoxy-resin, ground and polished.
INTRODUCTION. Due to increasing interest into taper corrosion observed primarily in hip arthroplasty devices with modular tapers, efforts towards characterizing the corrosion byproducts are prevalent in the literature [1–4]. As a result of this motivation, several studies postulate cellular induced corrosion due to the presence of remarkable features in the regions near taper junction regions and articulating surfaces [3–5]. Observations made on explanted devices from a retrieval database as well as laboratory tests have led to the alternative proposal of electrocautery-electrosurgery damage as the cause of these features. These surgical instruments are commonly used for hemostasis or different degrees of tissue dissection. METHODS.
Introduction. We conducted independent wear analysis of retrieved metal on metal (MoM) hip components from around the world. All patients with resurfaced hips who developed adverse reactions to metal debris (ARMD) were found to have increased wear of the bearing surfaces. This was untrue in patients with large diameter (?36mm) MoM total hip replacements. This led us to search for other factors leading to ARMD. Methods. MoM THR explants retrieved from 78 patients suffering ARMD underwent full volumetric wear analysis of bearing surface and taper-junctions using coordinate measuring machine.
Introduction. Dislocation of an uncemented total hip replacement (THR) can cause damage to the femoral hear, when it passes through the rim of metal acetabular shell. This can lead to metal transfer on the surface of the head or chipping of bulk head material. Although dislocation is one of most common complications in total hip arthroplasty (THA), little is known if causes any further damage to the articulating surface of ceramic heads in long term observations. Aim of the study. To evaluate, if dislocations of THR with ceramic on polyethylene bearing causes structural damage to the articulating surface of the femoral head in a follow-up of minium 10 years. Materials and methods. MATERIAL. This study included four groups of third generation (CeramTec Biolox forte) ceramic femoral heads with a diameter of 28 mm:. 8 heads dislocated in the first year(managed nonsurgically) where implants functioned for at least 10 years. 9 heads removed within 12 months after implantation because of recurrent dislocations. 11 heads retrieved after a minimum of 10 years from hips where no dislocation occurred. 8 unused heads. METHODS. Surface topography of retrieved heads was evaluated using
Introduction. Protective hard coatings are appealing for several technological applications and even for orthopaedic implants and prosthetic devices. For what concerns the application to prosthetic components, coating of the surface of the metallic part with low-friction and low-wear materials has been proposed [1, 2]; at the same time, concerning use of ceramic materials in joint arthroplasty, zirconia-toughned-alumina (ZTA) ceramic material has shown high strength, fracture toughness, elasticity, hardness, and wear resistance [3, 4]. The purpose of this study was to directly deposit ZTA coatings by using a novel sputter-based electron deposition technique, namely Pulsed Plasma Deposition (PPD) [5]. Preliminary characterization of realized coatings from the point of view of morphology, wettability, adhesion and friction coefficients was performed. Materials and methods. PPD technique was used to deposit ZTA coatings; this technique is able to maintain the stoichiometry of the starting target. In this study we started from a cylindrical ZTA target (30 mm diameter × 5 mm thickness, 75% alumina / 25% zirconia) and followed the procedure described by Bianchi et al [5]. Characterization of morphology, micro-structure and chemistry of deposited coatings was performed by
Introduction. Total joint arthroplasty is frequently necessary when a traumatic or degenerative disease leads to develop osteoarthritis (OA). Nowadays, the main reason for long term prosthesis failure is due to osteolysys and aseptic loosening of the implant itself, that are related to UHMWPE wear debris [1–3]. Different solutions to overcome this issue have been proposed, including different couplings like metal-on-metal and ceramic-on-ceramic. Our hypothesis was that a hard ceramic thin film realized on the plastic component (i.e. UHMWPE) could improve the friction and wear performance in a prosthetic coupling. The purpose of the presented study was therefore to characterize from the point of view of structure and mechanical performance of this ceramic-coated plastic component. The thin films were specifically realized by means of the novel Pulsed Plasma Deposition (PPD) technique [4]. Materials and methods. PPD technique was used to deposit Yttria-stabilized zirconia (YSZ at 3%) films on medical-grade UHMWPE substrates [4]. The morphology and micro-structure were characterized by
Revision of fractured ceramic-on-ceramic total hip replacements with a cobalt-chromium (CoCr) alloy-on-polyethylene articulation can facilitate metallosis and require further expensive revision surgery [1–3]. In the present study, a fifty-two year old male patient suffered from fatal cardiomyopathy after undergoing revision total hip arthroplasty. The patient had received a polyethylene-ceramic acetabular liner and a ceramic femoral head as his primary total hip replacement. The polyethylene-ceramic sandwich acetabular liner fractured in vivo after 58 months and the patient underwent his first revision surgery where he received a Vitamin E stabilized acetabular Polyethylene (PE) liner and a CoCr alloy femoral head with documented synovectomy at that time. After 15 months, the patient was admitted to hospital in cardiogenic shock, with retrieval of the bearing components. Before the second revision surgery, peak serum cobalt levels measured 6,521 μg/L, 78-times greater than serum cobalt levels of 83μg/L associated with cobalt poisoning [4]. Serum titanium levels found in the patient measured 17.5 μg/L) normal, healthy range 0–1.4 μg/L). The retrieved CoCr alloy femoral head had lost a total of 28.3g (24% or an estimated amount of 102 × 10. −9. wear particles (∼2 μm diameter) [1]) within 16 months of in vivo service. Despite initiating a cobalt chelating therapy, the patients' cardiac left ventricular ejection fraction remained reduced at 6%. This was followed by multi-organ failure, and ultimately the patient passed away shortly after being taken off life support. Embedded ceramic particles were found on the backside and articular surfaces of the Vitamin E-stabilized PE acetabular liner. Evidence of fretting wear on the titanium (Ti) alloy acetabular shell was present, possibly explaining the increased serum Ti levels.
In metal-on-metal (MoM) total hip arthroplasty, the taper interface is where the femoral head (female taper surface) attaches to the trunnion (male taper) of the femoral stem. Corrosion is well reported in metal-on-polyethylene hips but little is known about taper corrosion in MoM devices. The aim of this study was to quantify corrosion in modern-generation stemmed MoM hip systems and gain insight into the nature of the underlying corrosive attack. Taper corrosion was quantified in 161 failed MoM components (head components n=128; femoral stem n=33) from nine hip types with the use of a qualitative subjective scoring system. An unanticipated finding on preliminary inspection of the hips was a region on the female taper surface that contained ridges that directly corresponded with the ridged microthread on the trunnion. The ridges were not present on unimplanted (control) female taper surfaces and therefore a novel four-scale subjective scoring system was devised to quantify the prevalence and severity of this ‘imprinting’ phenomenon. Evidence of corrosion was observed in 81% (131/161) of components, with at least moderate corrosion observed in 58% (94/161). Corrosion was greater on the female taper surface than on the male taper (p=0.034) and the two scores were associated (r=0.784, p=0.001). Imprinting affected all manufacturers and was observed in 64% (82/128) of head components. The corrosion and imprinting scores were strongly correlated (r=0.694, p=0.001). Corrosion was largely confined to the area of the female taper interface where imprinting had occurred i.e. the region that had been in contact with the trunnion microthread.
Introduction. Titanium nitride (TiN) coatings are used in total hip arthroplasty to reduce friction of bearing couples or to decrease the allergic potential of orthopaedic alloys. Little is known about performance of currently manufactured implants, since only few retrieval studies were performed, furthermore they included a small number of implants manufactured over 15 years ago. Aim of study. To examine wear and degradation of retrieved TiN coated femoral heads articulating with ultra-high molecular weight polyethylene (UHMWPE). Methods. We included eight femoral heads with a made od TiAl6V4 alloy and coated with TiN using Physical Vapour Deposition (PVD). All heads (28 and 32 mm) were retrieved after at least 12 months of use (range 12–56). The reason for revision was aseptic loosening in 6 cases, septic loosening in one case and recurrent dislocations (five episodes) in one uncemented prosthesis. One unused head was included as reference sample. All implants were evaluated with light
Introduction. Detailed analysis of retrieved total hip replacements (THRs) is valuable for assessing implant and material successes and failures. Reduction of bearing wear and corrosion and fretting of the head-neck trunnion is essential to implant durability and patient health. This research quantifies and characterizes taper and bearing surface damage on retrieved oxidized zirconium THRs. Methods. Initially, 11 retrieved oxidized zirconium femoral heads were examined along with their associated femoral stems. Relevant patient and retrieval data was collected from clinical charts and radiographs. Taper corrosion (Figure 1) and fretting damage (Figure 2) scoring was performed following the Dyrkacz [1] method. A coordinate measuring machine was used to obtain a detailed surface map of the male and female taper surfaces. Taper surface maps were best-fit with an idealized cone followed by volume subtraction to quantify the amount of material removed as a result of fretting and corrosion processes.
Introduction. Protective hard coatings are appealing for several technological applications like solar cells, organic electronics, fuel cells, cutting tools and even for orthopaedic implants and prosthetic devices. At present for what concerns the application to prosthetic components, the coating of the surface of the metallic part with low-friction and low-wear materials has been proposed [1]. Concerning the use of ceramic materials in joint arthroplasty, zirconia-toughned-alumina (ZTA) reported high strength, fracture toughness, elasticity, hardness, and wear resistance [2]. The main goal of this study was to directly deposit ZTA coating by using a novel sputter-based electron deposition technique, namely Pulsed Plasma Deposition (PPD) [3]. The realized coatings have been preliminary characterized from the point of view of morphology, wettability, adhesion and friction coefficients. Materials and methods. ZTA coatings were deposited by PPD technique, which is able to maintain the stoichiometry of the starting target. In this case we started from a cylindrical ZTA target (30 mm diameter × 5 mm thickness, 75% alumina / 25% zirconia). The morphology, micro-structure and chemistry of deposited coatings were characterized by
Infected mega-endoprostheses are difficult to treat with systemic antibiotics due to encapsulation of the implant by fibrous tissue, formation of biofilms and antibiotic resistant bacteria. Modifying the implant surface by incorporating a bactericidal agent may reduce infection. Infection rates are typically in the range of 8% to 30%. This study describes a novel process method of “stitching-in” ionic silver into the implant surface, in vitro testing and its early clinical usage. A novel process has been developed to “stitch in” ionic silver into the upper surface of titanium alloy (Ti6Al4V). The process produces a modification by anodisation of the titanium alloy in dilute phosphoric acid, followed by absorption of silver from an aqueous solution. The engineered surface modification is therefore integral with the substrate and loaded with silver by an ion exchange reaction. Using this technique the maximum inventory of silver for typical a mega-prosthesis is 6mg and this is greater than 300 times lower than the No Observable Adverse Affects Level (NOAEL).
Introduction. Cementless arthroplasty has been widely used for younger patients with osteoarthritis and other joint pathology. Cementless arthroplasty will be required to porous surface which is to similar to the trabecular bone for bone ingrowth. Titanium Plasma Spray (TPS) has been worldwide used for the porous coating method on arthroplasty. However, TPS coating is limited that would not to establish optimal porosity for bone ingrowth due to arbitary position of melted powder by plasma gas on substrate. Therefore, it is reported coating detached from its substrate (i.e. arthroplasty) is induced implant loosening. Thus, a novel Laser-aided Direct Metal Tooling (DMT) based on Additive Manufacturing (AM) was developed to overcome these limitations. In this study, we were done to assess stereological analysis, static tensile, shear, abrasion test, and physical analysis for evaluation of the efficacy of DMT which was newly-developed coating technology. Then, mechanical characteristics of DMT coating were compared to commercial TPS coating's. Materials and Methods. First, porosity of the DMT coating was evaluated using Microphotography and
Introduction. The osteogenic capability of any biomaterial is governed by a number of critical surface properties such as surface energy, surface potential, and topography. Prior work suggested that the Si-Y-O-N phase(s) present in the form of a thin (<150 nm), interrupted film at the surface of an annealed silicon nitride bioceramic may be responsible for an observed upregulation of osteoblastic activity due to passive surface properties and dissolution of chemical species. In this study high- resolution analytical electron microscopy was utilized to identify the Si-Y-O-N phase present on the annealed silicon nitride surface, and dissolution studies were employed to elucidate mechanisms of the material's favorable cell interactions. Materials and Methods. Si. 3. N. 4. discs (12.7 mm diameter × 1 mm thick) containing Y. 2. O. 3. and Al. 2. O. 3. sintering aids were processed using conventional techniques and subsequently subjected to annealing in a nitrogen atmosphere. Pre-cultured SaOS-2 osteosarcoma cells at a concentration of 5 × 10. 5. cells/ml were seeded onto sterile polished nitrogen-annealed Si. 3. N. 4. discs in an osteogenic medium consisting of DMEM supplemented with about 50 µg/mL ascorbic acid, 10 mM β-glycerol phosphate, 100 mM hydrocortisone, and 10% fetal bovine calf serum. The samples were incubated for up to 7 days at 37°C with two medium replenishments. Transmission electron microscopy (TEM) images were acquired from focused ion beam (FIB)-prepared samples using a Hitachi HF-3300 TEM (300 kV).
