Aim. To evaluate bacterial adhesion and biofilm formation to metallic cerclage wire versus polymer cerclage system (SuperCable®). Methods. Experimental in vitro study to evaluate quantitative bacterial adherence to different cerclage wire materials. Two types of cerclage wires were compared: a metallic versus a polymer based wire (SuperCable®). A two-centimeter cerclage wire piece of each material was included in 2 mL of tryptic soy broth (TSB) culture media, inoculated with 10 microliters of a 0.5 McFarland of a Staphylococcus epidermidis strain and cultivated at 37°C during 2h for adhesion and 48h for biofilm formation. After this time, the cerclages were washed using a 1% phosphate buffered saline (PBS) and sonicated in new culture medium. After sonication, dilutions of each culture were spread in TSB agar and incubated 37°C during 24h. The number of colonies were counted and the cfu/cm2 was calculated. Results. There were no differences in the number of colonies counted at 2 hours. At 48 hours, the polymer cerclage system showed a clinically and statistically reduction of 95.2% in the biofilm formation of S. epidermidis. The highest bacterial counts were observed in metallic cerclages after 48h. Conclusion. In in vitro conditions, the polymer cerclage system may offer decreased biofilm formation compared with metallic cerclage wires. However, there are many other factors in in vivo conditions that could play a role in bacterial adhesion to cerclage wires. Further research is needed in order to recommend the use of polymer cerclage systems for septic revision surgery

Ultra-high molecular weight polyethylene (UHMWPE) is the sole polymeric material currently used for weight-bearing surfaces in total joint arthroplasty. However, the wear phenomenon of UHMWPE components in knee and hip prostheses after total joint arthroplasty is one of the major restriction factors on the longevity of these implants. In order to minimize the wear of UHMWPE and to improve the longevity of artificial joints, it is necessary to clarify the factors influencing the wear mechanism of UHMWPE. In the microscopic surface observation of the virgin knee prosthesis with anatomical design, various grades of microscopic surface scratches and defects caused by machining and surface finishing processes during manufacture of the component were observed on the surface of the metallic femoral component [Fig. 1] (C. Cho et al, 2009), although the overall surface were finished at smoother level. It is thought that certain levels of the microscopic surface asperities caused by these surface damages in the metallic femoral component might contribute to increasing and/or accelerating wear of the UHMWPE tibial insert. Therefore, it is necessary to clarify quantitatively the influence of the microscopic surface asperities of the metallic components in virgin artificial joints on the wear of UHMWPE components. The primary purpose of this study was to investigate the influence of the microscopic surface asperities of the virgin metallic femoral component on the wear of the UHMWPE tibial insert in the virgin knee prosthesis. In this study, the authors focused on the three-dimensional shape of the microscopic surface asperities as a factor influencing the wear mechanism of the UHMWPE tibial insert. The 3D microscopic surface profile measurement of the virgin metallic femoral component using a laser microscope and reproduction of the femoral component surface using 3D CAD software were performed [Fig. 2] in order to produce idealized 3D finite element models of the microscopic surface asperity of the femoral component based on actual measurement data. Elasto-plastic finite element contact analyses between idealized microscopic surface asperities and UHMWPE were also performed in order to investigate the influence of the three-dimensional shape of the microscopic surface asperities of the virgin metallic femoral component on the wear of the UHMWPE tibial insert. The analytical findings of this study suggest that the aspect ratio and shape ratio [Fig. 3] of the microscopic surface asperity of the virgin metallic femoral component have an important influence on increasing and/or accelerating wear of the UHMWPE tibial insert

Introduction. The release of metallic debris can promote many adverse tissue reactions, as metallosis, necrosis, pseudotumors and osteolysis . 1–3. This debris is mainly generated by the fretting-corrosion mechanism due to the geometric difference in the head-stem interface . 4. Retrieval and in silico analysis showed the roughness of the stem-head interface appears to play an important role in the volume of material lost and THA failure . 5–7. The technical standard ISO 7206-2 recommends the measurement of average roughness (Ra) and max height of the profile (Rz) to control the quality of the surface finish of articulating surfaces on THA implants. However, despite the importance of the trunnion roughness, there is no specific requirement for this variable on the referred technical standard. The present study carried out a surface finish analysis of the trunnion of hip stems from five distinct manufacturers. Methods. Four stems (n = 4) from five (5) distinct manufacturers (A, B, C, D, and E) were used to evaluate the roughness of the trunnion. All the stems are similar to the classical Exeter stem design, with a 12/14 taper and a polished body surface. The roughness of trunnions was evaluated according to ISO 4287 and ISO 13565-2. The total assessment length was 4.8 mm with 0.8 mm cut-off. The first and last 8.33% of assessment length were not considered. The measurements of all samples were made in a rugosimeter with 2 µm feeler ITP (Völklingen, Germany), the velocity of 0.5 mm.s. -1. , and a force of 1.5 mN. The calibration was made at 20 ºC and relative humidity at 50%. The Kruskal Wallis with post hoc Nemenyi test was used to evaluate the difference of Ra among the manufacturers. The confidence level was set at 5%. Results and Discussion. The analysis of surface finish revealed different roughness among the manufactures (p < 0.005), with Ra between 0.061 µm to 3.184 µm and Rz varying of 0.41 µm to 12.69 µm. The manufacturers A and E had a Ra (2.587±0.050 µm and 3.146±0.031µm) of the trunnion similar to founded by Panagiotidou et al (2013). Within such range, the trunnion has shown a high presence of pit . 8. The manufacturer C, on the other hand, had the best surface finish of the trunnion (Ra = 0.069±0.010 µm and Rz = 0.505 ± 0.076 µm). This more smooth surface might increase the taper strength, reduce the shear stress and the susceptibility to the fretting-corrosion damage . 4,8. . Conclusion. The results were worrying because there is great variability of roughness among the manufacturers with the occurrence of trunnions with roughness too high. Nevertheless, the ISO technical standard does not recommend any procedure or minimum parameters acceptable for the surface finish of the trunnion. The revision of ISO 7206-2 would guarantee better control of trunnion roughness to reduce the amount of metallic debris and increase the safety of THA implants. Additional research is needed to determine a target value for this variable. For any figures or tables, please contact authors directly

Two fixation devices for rotator cuff repair were compared in a sheep model. Surgical transection of the supra-spinatus tendon insertion was repaired using metallic OBL suture anchors or Suretac II anchors. Twelve weeks postoperatively the repair site was assessed using histology, polarized light microscopy and biomechanical testing. No important differences were found between these two repair methods. The purpose of this study was to compare traditional rotator cuff fixation devices with bioabsorbable press-fit tacks. Sixteen sheep were assigned to OBL (n=8) or Suretac (n=8) treatment groups. Four sheep shoulder joints were used as unoperated controls. Treated sheep underwent general anesthesia and a lateral arthrotomy using aseptic technique to allow transection of the supraspinatus tendon insertion. The tendon-bone interface was repaired with two fixation devices according to the manufacturer’s directions. After recovery from anesthesia the sheep were maintained in small pens for twelve weeks. After sacrifice, muscle-tendon-bone blocks were prepared for mechanical testing. The specimen underwent a preload of 25N, followed by cyclic loading (10–50N x10), then loading at 480mm/min until failure. The remaining bone-tendon interface was fixed, embedded in plastic and 100μ undecalcified histological sections were cut, polished and stained. All tendons had healed to the humerus and the repair site was two to three times larger than unoperated controls. There were no significant differences between the two treatment groups with respect to maximum load, modulus, and energy per unit area. Histological analysis is ongoing. These data suggest that these two fixation methods are functionally equivalent in this model. Press-fit fixation devices do not knot tying and they can be inserted arthroscopically so they are a convenient fixation method. This study confirms that press fit anchors and metallic anchors with sutures are equivalent for repair of bone-tendon interfaces. Funding: Smith & Nephew supplied the fixation devices for this project. Thanks to Deb McWade for technical assistance

Introduction. Long-term success of the cementless acetabular component has been depends on amount of bone ingrowth around porous coated surface of the implant, which is mainly depends on primary stability, i.e. amount of micromotion at the implant-bone interface. The accurate positioning of the uncemented acetabular component and amount of interference fit (press-fit) at the rim of the acetabulum are necessary to reduce the implant-bone micromotion and that can be enhancing the bone ingrowth around the uncemented acetabular component. However, the effect of implant orientations and amount of press-fit on implant-bone micromotion around uncemented acetabular component has been relatively under investigated. The aim of the study is to identify the effect of acetabular component orientation on implant-bone relative micromotion around cementless metallic acetabular component. Materials and Method. Three-dimensional finite element (FE) model of the intact and implanted pelvises were developed using CT-scan data [1]. Five implanted pelvises model, having fixed antiversion angle (25°) and different acetabular inclination angle (30°, 35°, 40°, 45° and 50°), were generated in order to understand the effect of implant orientation on implant-bone micromotion around uncemented metallic acetabular component. The CoCrMo alloy was chosen for the implant material, having 54 mm outer diameter and 48 mm bearing diameter [1]. Heterogeneous cancellous bone material properties were assigned using CT-scan data and power law relationship [1], whereas, the cortical bone was assumed homogeneous and isotropic [1]. In the implanted pelvises models, 1 mm diametric press-fit was simulated between the rim of the implant and surrounding bone. Six nodded surface-to-surface contact elements with coefficient of friction of 0.5 were assigned at the remaining portion of the implant–bone interface [1]. Twenty-one muscle forces and hip-joint forces corresponds to peak hip-joint force of a normal walking cycle (13%) were used for the applied loading condition. Fixed constrained was prescribed at the sacroiliac joint and pubis-symphysis [1]. A submodelling technique was implemented, in order to get more accurate result around implant-bone interface [1]. Results and Discussions. The peak implant-bone sliding interfacial micromotion was observed around 75 microns around superior and supero-posterior regions of the acetabulum, whereas, micromotion was below 50 microns around other regions (area). As compared to other regions, less implant-bone micromotions were observed at the central region of the acetabulum and anterior part of the acetabulum, where micromotions were varied in the range between 5 microns to 30 microns. Although, the generated peak implant-bone sliding micromotion around the uncemented acetabulum was not vary notably due to change in inclination angle of the acetabular component, changes in patterns of implant-bone micromotions were observed and as shown [Fig.1]. Results of the present study indicated that the positioning of the uncemented acetabular component have influence on patterns of implant-bone micromotion and that might have influence on bone ingrowth and long-term success of uncemented acetabular component

Testing wear durability of UHMWPE joint replacement bearings under abrasive conditions (mimicking in vivo conditions when metallic components become scratched from bone or cement debris) is useful in screening new bearing materials or alternative processing methods. Adding third body particle debris in testing brings the complications of minimal (if any) increase in wear with particles lodging into the plastic bearings potentially causing unknown errors for gravimetric wear measurements. Alternatively, testing those bearings against already scratched metallic components may provide a cleaner route without such complications. This requires a method to reproducibly create scratches resembling the damage seen on retrievals. This study introduces such a method, and investigates wear of UHMWPE bearings against metallic femoral hip components that have been intentionally scratched. In this technique, femoral hip heads were pressed and sunk into a bed of abrasive beads under a known load (712N, one body weight), and this created longitudinal scratches. Latitudinal scratches were generated by rotating the sunken femoral heads ± 90° about their polar axis while under the same load. This process (pressing into the abrasive beads and then turning ± 90°) was repeated 10 times on each femoral component which resulted in thousands of random scratch patterns, but with statistically repeatable overall severity and similar visually to retrievals (Fig. 1). We then evaluated the technique through a hip wear study. Twelve UHMWPE liners (40 mm I.D.) were tested against CoCrMo femoral heads on a 12-station hip simulator (AMTI). Liners were three materials: a) Three conventional (GUR1020, gamma-sterilized 3.5 Mrad), b) Three highly cross-linked (HXL) (GUR1020, 10 Mrad, annealed, EtO-sterilized, artificially aged), and c) Six HXL w/vitamin-E (GUR1020, 12 Mrad, annealed, EtO-sterilized, aged). The test comprised three phases. Phase-I: standard clean (non-abrasive, non-scratched) test for 5 Mc; Phase-II: Pulverized PMMA was added to serum at 700 mg/L (to introduce abrasive conditions); however, effects were minimal after 2 Mc (7 Mc total). Phase-III: Femoral heads were scratched using our method. Phase-III lasted for 1 Mc, for a testing total of 8 Mc (ISO-14242-1 waveforms). All specimens were lubricated with bovine serum (37°C, 30g/L protein). Plastic liners were cleaned and weighed at standard intervals, and wear was corrected with active loaded soak controls. The wear results are shown in Fig. 2. The conventional liners showed the highest wear (Phase-I: 55.7 ± 3.00 mg/Mc, Phase-II: 49.2 ± 0.520 mg/Mc, Phase-III: 124 ± 28.9 mg/Mc) while HXL liners displayed much lower wear (Phase-I: 2.58 ± 0.969 mg/Mc; Phase-II: 4.93 ± 1.22 mg/Mc; Phase-III: 9.92 ± 4.64 mg/Mc). Vitamin-E HXL liners also showed very low wear (Phase-I: 5.97 ± 0.50 mg/Mc, Phase-II: 8.89 ± 1.40 mg/Mc, Phase-III: 11.9 ± 2.70 mg/Mc). Addition of the PMMA powder during Phase-II increased liner wear, but the surfaces did not appear damaged like retrievals. Wear rates between Phase-I and Phase-III doubled due to scratching the femoral heads for all material types, a statistically significant increase (p < 0.05). Our results confirm that the scratching procedure successfully created a severe wear situation for the bearings. Future work will involve abrasive testing on knee components to determine if the method is successful there too

AM specifically allows for cost-efficient production of patient-specific Orthopaedic medical devices with unusual designs and properties. A porous design allows to adjust the stiffness of metallic implants to that of the host bone. Beyond traditional metals, like titanium alloys, this talk will review the present state-of-the-art of directly printed absorbable metal families. Physicochemical, mechanical and biological properties of standardized design prototypes from all currently available metal families will be compared and their clinical application potential discussed. The impact of in vitro test environments on comparative corrosion behavior, post manufacturing aspects, and the recent status quo in biocompatibility testing and present knowledge gaps will be addressed.

Purpose of the study: Long-term outcome of Charnley low-friction arthroplasty in young active patients is impaired worldwide due to wear of the polyethylene (PE) component and osteolysis. In the late eighties, reports of possible low wear with some former metal on metal total hip arthroplasties led to the reintroduction of metallic bearings. The aims of this work were to examine the rationale for using metal on metal bearings in primary total hip arthroplasty (THA) and report preliminary results obtained with cementless Metasul™-Alloclassic™ hips. Materials and methods: From January 1994 to March 1997, 64 cementless primary Alloclassic-THA (grit-blasted titanium SL stems and CSF treaded cups) with 28 mm Metasul bearings were performed. Mean age at surgery was 60 years (range, 36–73). Diagnoses were usual, mainly primary osteoarthrosis in 70 p. 100 of the hips. Two bearing surfaces were exchanged for late dislocation at 2.6 and 2.9 years. Thus, 62 hips in 58 active patients (4 bilateral) were reviewed after a minimum 2-year follow-up (mean 3.2 years, range 24–66 months). Results: Clinical results according to the Merle d’Aubigne and Charnley rating system were graded excellent or good in all 62 hips. Radiologically, calcar, atrophy and spot welds were noted in 93 p. 100 and 82 p. 100 of hips respectively. Proximal reactive and lucent lines and mild proximal stress shielding were observed in 8 p. 100 and 4.8 p. 100 of hips respectively. No osteolysis granuloma has thus far been observed in the vicinity of any component. Cobalt blood level remained normal, except in 6 cases due to occupational exposure (n = 1), possible impingement (n = 1) or an unknown cause (n = 4). All elevated cobalt levels (range 7 to 25 mg/l) were nevertheless far below the toxic limit. Discussion: Dislocation may be due either to the posterolateral surgical approach and/or early impingement with the first Metasul bearing design (head sleeve). Metasul acetabular component fixation is not restricted to only cementless metal-backing, unlike alumina-ceramic cups. The concern about the toxicity of metallic wear debris dissemination and the hematocarcinogenic risk must be taken into consideration as for any metallic THA. Follow-up is too short for the new polys for significant comparisons. Conclusion: Metal on metal tribology is well known in vitro and Metasul™ bearings have functioned in vivo for 12 years (120 000 Metasul hips worldwide) as was expected from laboratory tests. Obviously, this friction couple is not the unique answer to PE-wear and THA longevity, but, in light of current data, appears as a trustworthy solution available today

Aim: To evaluate the results of arthroscopic repair of anterior and superior glenoid labral tears in the shoulder with metallic knotless suture anchors with an average follow up of 31 months. Material and methods: Between 2000 and 2002, 55 patients with labral tears underwent arthroscopic repair with metallic knotless suture anchors (Mitek, Ethicon Ltd). Their average age was 36 years (range 16 to 67). Thirty-seven patients presented with anterior instability. Twenty-one patients presented with painful shoulder without instability. In the instability group there were eight acute dislocations and twenty-nine recurrent dislocations. All patients underwent examination under anaesthesia, arthroscopic repair of labral tears using the metallic knotless suture anchors, thermal capsulorraphy and closure of the rotator interval. Subacromial decompression was performed when indicated. Rehabilitation consisted of sling immobilisation for four weeks followed by gradual strengthening program over three months with the physiotherapist. Contact sports were allowed at 1 year. Evaluation: Patients were evaluated preoperatively and at the time of final follow-up using Constant score and Modified Rowe – Zarin score system. Results: Three out of the thirty-seven patients in the instability group had recurrent dislocation. A fourth patient had pain with a positive anterior apprehension test thus making the overall recurrence rate of 11%. In the painful shoulder group, good and excellent results were recorded in twenty out of twenty-one patients (95%). Of the fifty five patients who had labral repair, five had poor functional outcome secondary to pain in their shoulder (9%). One patient had a fall and required further surgery to replace one dislodged anchor. Conclusions: We found the metallic knotless suture anchor easy to use and stabilised the torn labrum well. The success rate for instability compares well with the published literature. However, we have some concern of our observation of early degenerative changes in some of our patients treated for recurrent dislocation

Alloys of titanium, aluminium, vanadium, iron and other metals are traditional materials used in bone tissue surgery. The anchorage of the metallic materials into the surrounding tissue depends of their mechanical and other physical and chemical properties. The integration of metallic material with the surrounding tissue can be markedly improved by appropriate physicochemical surface properties of the material, such as roughness, topography, wettability or presence of certain chemical functional groups. In the present study the first step the surface roughness of samples of pure Ti or Ti6Al4V alloy. In order to influence the adhesion, growth and presence of bone differentiation markers in human osteoblast-like MG 63 cells, we modified as machining or subsequent polishing by diamond paste was performed. In addition, we investigated the interaction of these cells with a newly developed material for construction of bone-anchoring parts of bone implants. These tested materials were treated either with electro-erosion or plasma-spraying with Ti. After the cells seeding (MG63, human osteoblast-like cells of the line MG 63, derived from osteosarcoma of a 13-year-old boy, on different surfaces, the basic parametrs of adhesion and the viability of bone cells were detected, the cell were analysed and cultered for 1–8 days, during 3 different time intervals(expl.1. 4. and 7 day). Cells number, were detected and analyzed in a ViCell XR analyzer. The concentration of molecules participating in cell adhesion, osteoblastic differentiation, was determined semi-quantitatively by the enzyme-linked immunosorbent assay (ELISA) in cell. In addition we performed a reconstruction curve of population density of human osteoblast-like MG 63 cells on day 1, 4 and 8. including calculation of doubling time(DT)in human osteoblast-like MG 63 cells grown on metallic materials with different surface treatments. From the tested surfaces Ti Alloys electroerosion surfaces seem promising materials. They show the best osteointegration parameters in vitro. Nevertheles further in vivo experiments must be performed prior to clinical use

Due to increased life expectancy of human population, the amount of total knee replacements (TKR) is expected to increase. TKR reached a high grade of quality and safety, but most often it fail because of aseptic implant loosening caused by polyethylene (PE) wear debris. Wear is generated at the articulating surfaces, e.g. caused by three body particles, like bone fragments or bone cement particles. The aim of this experimental study was to compare the wear of tibial PE inserts combined with metallic and ceramic femoral components at three body wear situation induced by polymethylmethacrylate (PMMA) and zirconia (ZrO2) particles from the bone cement. Wear testing was performed for 5 Mio load cycles, using tibial standard PE inserts combined with the same CR femoral component, in two different materials, Cobalt Chromium (CoCrMo) and Biolox delta ® ceramic (Multigen Plus Knee System, Lima Corporate, Italy). A knee wear simulator, according to ISO 14243 (EndoLab GmbH, Rosenheim, Germany), was used to carry out the tests. The tests were performed in temperature-controlled test chambers at 37 °C, containing calf serum with a protein content of 30 g/l. Polymethylmethacrylate (PMMA) and zirconia (ZrO2) bone cement particles (Palacos R ®) were manufactured to a size of 30 μm. The three body particles were added at all stations onto the articulating surface of the tibial PE insert (7mg per condyle) at every 500,000 cycles. Wear was determined gravimetrically and the surfaces of tibial inserts were analysed by scanning electron microscope (SEM) after finishing the 5 million cycles. Furthermore, roughness of the PE insert surfaces and the articulating surfaces of the different femoral components were detected and the PE wear particles were analysed by SEM. The average gravimetrical wear rates of the tibial PE inserts in combination with CoCr and Biolox delta ® ceramic femoral components amounted to 6.4 ± 0.9 mg and 2.6 ± 0.4 mg per million cycles, respectively. Beside bone cement particles on the articulating surface of the PE inserts, polished surfaces and scratches were detected by SEM. In comparison to the untreated surfaces of the PE inserts at both material pairings the surface roughness at the articulating areas showed deep scratches and polished regions. Analyses of the metallic femoral components showed scratches at the articulating surfaces, none on ceramics. The present study pointed out the effect of femoral component material in an abrasive three body wear situation on the wear properties of TKR. The wear simulator tests showed that wear of PE inserts under three body wear conditions, in combination with ceramic femoral components, was significantly lower than with metallic femoral components. With regard to anti-allergic properties, ceramic femoral components are promising products for TKR

Introduction: The aim of this prospective, randomized, monocentric study was to compare wear of polyethylene when using a 28 mm diametre ceramic head versus a metallic head. Material and Method: 226 THR performed between 1988 and 1990 were evaluated in 2005: 111 patients had died, 28 were lost of follow up and in 17 cases radiological assessment was not possible. 74 arthroplasties have been analyzed. In all cases, a straight femoral stem in protasul 10 (Zimmer), and a polyethylene cup sterilized under gamma radiation were used. In 37 cases the bearing surface used a metal head and in 37 cases a ceramic head. Radiolucent lines were analysed on AP x-rays. Aseptic loosening was defined according to Hodgkinson and Harris criteria. The penetration of the femoral head was measured with a special software (M.P.H. Wear) on digitalised x-rays. Results: The two groups were statistically comparable (p = 0.0857). For metallic heads, linear wear was 0,102 mm/year (62.8 mm3/year volumetric wear). For ceramic heads, linear wear was 0,058 mm/year (volumetric wear 35.7 mm3/year. It represents a significant reduction (p = 0.0004) 44% of penetration. There was a penetration higher than 0.1 mm per year in thirteen cases of metal heads and in only one case of ceramic head. It was noted four aseptic loosening. In these four cases penetration was greater than 0.2 mm per year. In three cases, it was a metal head and in one case, a ceramic head. Discussion: Our results are comparable to those found in the literature when the follow up is more than ten years as reported by Schuller, Oonichi and Hernigou. For authors with follow up shortest than ten years, it is reported identical outcomes between ceramic head and metal head (as reported Jenni, Devane and Sychterz). Conclusion: This is the first randomized prospective study with two identical populations, showing a statistical significant difference of wear of polyethylene between ceramic and metallic prosthesis head

We present a review of 97 consecutive BioPro. ®. metallic hemiarthroplasties performed in 80 patients for end-stage hallux rigidus, with a minimum of five years follow-up. The mean age of the cohort was 55 (22 to 74) years. No patient was lost to follow-up. There were 15 revisions performed, one for infection, two for osteolysis, and 12 for pain. The all cause survival rate at five years was 85.6% (95% confidence interval (CI) 83.5 to 87.9). Younger age was a significant predictor of revision (odds ratio 1.09, 95% CI 1.02 to 1.17, p=0.014) on excluding infection and adjusting for confounding variables (Cox regression). Significant improvements were demonstrated at 5 years in the Manchester Oxford foot questionnaire (13.9, 95% CI 10.5 to 17.2) and in the physical component of the short form 12 score (6.5, 95% CI 4.1 to 8.9). The overall satisfaction rate was 72%. The cost per quality-adjusted-life-year at 5 years, accounting for a 3% per year revision rate, was £3,714. The BioPro offers good short to mid-term functional outcome and is a cost effective intervention. The relative high revision rate is associated with younger age and the use of this implant may be limited to older patients

Prosthetic joint infections represent complications connected to the implantation of biomedical devices, they have high incidence, interfere with osseointegration, and lead to a high societal burden. The microbial biofilm, which is a complex structure of microbial cells firmly attached to a surface, is one of the main issues causing infections. Biofilm- forming bacteria are acquiring more and more resistances to common clinical treatments due to the abuse of antibiotics administration. Therefore, there is increasing need to develop alternative methods exerting antibacterial activities against multidrug-resistant biofilm-forming bacteria. In this context, metal-based coatings with antimicrobial activities have been investigated and are currently used in the clinical practice. However, traditional coatings exhibit some drawbacks related to the insufficient adhesion to the substrate, scarce uniformity and scarce control over the toxic metal release reducing their efficacy. Here, we propose the use of antimicrobial silver-based nanostructured thin films to discourage bacterial infections. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture, allow tuning silver release, and avoid delamination. To mitigate interference with osseointegration, here silver composites with bone apatite and hydroxyapatite were explored. The antibacterial efficacy of silver films was tested in vitro against gram- positive and gram-negative species to determine the optimal coatings characteristics by assessing reduction of bacterial viability, adhesion to substrate, and biofilm formation. Efficacy was tested in an in vivo rabbit model, using a multidrug-resistant strain of Staphylococcus aureus showing significant reduction of the bacterial load on the silver prosthesis both when coated with the metal only (>99% reduction) and when in combination with bone apatite (>86% reduction). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses.

Impaction bone grafting has become an established technique in restoring acetabular and femoral bone stock loss during hip replacement surgery. This study presents our preliminary results using this technique to restore acetabular bone stock loss during cemented total hip replacement, with particular reference to the use of a preformed perforated metallic mesh to contain major acetabular defects. In 52 patients (55 hips), acetabular reconstruction with impaction bone grafting was undertaken during total hip replacement (7 primary and 48 revision, of which 13 had previously undergone multiple revisions). The mean age at the time of surgery was 68 (range 34 to 88). In 31 cases (30 segmental or combined acetabular deficiencies, and one case of pelvic discontinuity) a pre-formed stainless steel mesh was utilised to contain the impacted morsellised bone graft. There were no perioperative deaths or deep infections and few complications (2 non-recurrent dislocations and 2 deep vein thromboses). At a mean follow-up of 40 months (range 18 to 91 months) there have been no revisions for any reason. Three patients who died before a minimum follow-up of 18 months have been excluded. Of the 49 patients (52 hips) remaining, clinical hip scores (Merle d’Aubigne and Postel) averaged 5.3 for pain, 4.2 for walking ability, and 5.3 for range of movement (with 16 patients in Charnley group A, 14 in group B, and 19 in group C). There was one case of radiographic loosening, with a radiolucent line > 2mm diameter in all 3 zones of DeLee and Charnley, although the cup has not migrated and the patient remains pain-free. All other cases show radiographic changes suggestive of ongoing graft incorporation. We consider that the use of preformed metallic meshes extends the scope of impaction bone grafting to include cases where major segmental acetabular deficiencies are encountered, allowing restoration of bone stock and an anatomical centre of hip rotation, with encouraging preliminary clinical and radiological results

INTRODUCTION. A detailed clinical examination and investigations are required to evaluate the cause of persisting groin pain following a metal on metal (MoM) hip replacement. Adverse reaction to metallic debris (ARMD) is an emerging problem with MoM hip replacements. It is an umbrella term encompassing metallosis, pseudo-tumors and aseptic lymphocytic vasculitis associated lesions (ALVAL). The role of imaging in the diagnosis of this complex problem is still unclear. A study was undertaken to evaluate the efficacy of ultrasound in diagnosis of ARMD following a MoM hip replacement. METHODS. The study group included 35 patients with a clinical and histological diagnosis of ARMD, who had a preoperative ultrasound. All ultrasound procedures were performed on the anterior and lateral aspects of the painful hip with a high frequency probe of 9–13 MHz (Sonoline Antares – Siemens). RESULTS. All patients diagnosed with ARMD had abnormalities identified on ultrasound. Fluid inside the joint was noted in 30 out of 35 procedures (85.7 %). Fluid outside the joint was noted in 33 procedures (94.3 %). Amongst the patients with fluid outside the joint, 32 had iliopsoas and 30 had trochanteric bursitis. Echogenic reflections were noted in 31 out of 35 procedures (88.6 %). Considerable attenuation or absence of iliopsoas and gluteus tendon reflection was seen in many patients with echogenic fluid collections on the anterior and trochanteric aspects of hip. Progression of such changes was noted on further 5 patients, who had a repeat ultrasound within an interval of 3–6 months. 1 patient had a progression from anechogenic to echogenic joint effusion. DISCUSSION. Different radiological investigations including MRI scan have been used for evaluation of painful MoM hip arthroplasty. To our knowledge, this is the first study to demonstrate the efficacy of ultrasound in diagnosis of ARMD. Floating echogenic reflections and fluid collections around iliopsoas and gluteus medius/minimus tendons is highly suggestive of ARMD. Ultrasound is a cheap, non-invasive and dynamic investigation and has been shown to be reliable in diagnosis of ARMD

Biodegradable metals as orthopaedic implant materials receive substantial scientific and clinical interest. Marketed cardiovascular products confirm good biocompatibility of iron. Solid iron biodegrades slowly in vivo and has got supra-physiological mechanical properties as compared to bone and porous implants can be optimized for specific orthopaedic applications. We used Direct Metal Printing (DMP)3 to additively manufacture (AM) scaffolds of pure iron with fine-tuned bone-mimetic mechanical properties and improved degradation behavior to characterize their biocompatibility under static and dynamic 3D culture conditions using a spectrum of different cell types.

Atomized iron powder was used to manufacture scaffolds with a repetitive diamond unit cell design on a ProX DMP 320 (Layerwise/3D Systems, Belgium). Mechanical characterization (Instron machine with a 10kN load cell, ISO 13314: 2011), degradation behavior under static and dynamic conditions (37ºC, 5% CO2 and 20% O2) for up of 28 days, with μCT as well as SEM/energy-dispersive X-ray spectroscopy (EDS) (SEM, JSM-IT100, JEOL) monitoring under in vivo-like conditions. Biocompatibility was comprehensively evaluated using a broader spectrum of human cells according to ISO 10993 guidelines, with topographically identical titanium (Ti-6Al-4V, Ti64) specimen as reference. Cytotoxicity was analyzed by two-way ANOVA and post-hoc Tukey's multiple comparisons test (α = 0.05).

By μCT, as-built strut size (420 ± 4 μm) and porosity of 64% ± 0.2% were compared to design values (400 μm and 67%, respectively). After 28 days of biodegradation scaffolds showed a 3.1% weight reduction after cleaning, while pH-values of simulated body fluids (r-SBF) increased from 7.4 to 7.8. Mechanical properties of scaffolds (E = 1600–1800 MPa) were still within the range for trabecular bone, then. At all tested time points, close to 100% biocompatibility was shown with identically designed titanium (Ti64) controls (level 0 cytotoxicity). Iron scaffolds revealed a similar cytotoxicity with L929 cells throughout the study, but MG-63 or HUVEC cells revealed a reduced viability of 75% and 60%, respectively, already after 24h and a further decreased survival rate of 50% and 35% after 72h. Static and dynamic cultures revealed different and cell type-specific cytotoxicity profiles. Quantitative assays were confirmed by semi-quantitative cell staining in direct contact to iron and morphological differences were evident in comparison to Ti64 controls.

This first report confirms that DMP allows accurate control of interconnectivity and topology of iron scaffold structures. While microstructure and chemical composition influence degradation behavior - so does topology and environmental in vitro conditions during degradation. While porous magnesium corrodes too fast to keep pace with bone remodeling rates, our porous and micro-structured design just holds tremendous potential to optimize the degradation speed of iron for application-specific orthopaedic implants. Surprisingly, the biological evaluation of pure iron scaffolds appears to largely depend on the culture model and cell type. Pure iron may not yet be an ideal surface for osteoblast- or endothelial-like cells in static cultures. We are currently studying appropriate coatings and in vivo-like dynamic culture systems to better predict in vivo biocompatibility.

Abstract

Aim: Impaction bone grafting is an established technique for the restoration of bone loss at revision hip surgery. Preformed stainless steel meshes have been recently introduced to augment graft containment. We present our results of acetabular impaction grafting at a mean of 4 years, with particular reference to the use of preformed steel meshes. Methods: 72 consecutive total hip replacements (7 primary and 65 revision) in 69 patients underwent acetabular impaction grafting with morsellised fresh frozen allograft through a posterior approach. In 47 cases there were uncontained defects (46 segmental or combined deficiencies, one pelvic discontinuity) necessitating the use of a preformed steel mesh, secured with multiple small fragment screws to contain the impacted bone graft. All the operations were done by the senior author in a district general hospital. Results: At mean follow-up of 4 years (range 18 to 92 months), no case has been lost to follow up. The Merle d’Aubigne Postel hip scores averaged 5.3 (pain), 4.2 (walking ability), and 5.3 (range of movement). (Charnley group A -26 patients, group B -19, group C -24). There were no peri-operative deaths or deep infections. There have been no revisions for septic or aseptic loosening. There were 2 cases of early post operative dislocation which stabilised after closed reduction. One case of recurrent disclocation required cup revision. There was one case of radiographic loosening without cup migration. This patient remains pain free and there are no plans for revision. In all other cases, radiographs suggest graft incorporation, with no significant radiolucent lines, acetabular component or mesh migration. There have been no complications relating to the use of the preformed mesh. Conclusion: The results of this study are encouraging. By using preformed metallic meshes it is possible to manage all cases of acetabular loss, irrespective of severity, encountered during total hip replacement with acetabular impaction grafting

Introduction

The accumulation of proteins and bacteria on implant surfaces is a critical concern in the biomedical field, especially with respect to the potential of biofilm formation on implant surfaces. Material surface wettability is often used as a predictor of potential colonization of specific bacterial strains. Surface roughness has also been shown to have a strong relationship with biofilm formation, as rougher surfaces tend to have a stronger affinity to harbor bacterial colonies. The modification of implant surfaces to impart a biofilm resistant layer can come at the expense of increasing surface roughness however, and it is therefore important to determine how the variables of wettability and roughness are affected by any new surface coating technologies. In the current work, a novel CoBlast (C) process that impregnates alumina (A) at 50 μm grit (5) or 90 μm grit (9) sizes, with the possible addition of polytetrafluoroethylene (P) onto titanium surfaces, combined with a plasma coating process called BioDep, that coats the surface with chitosan (X) with the possible addition of vancomycin (V), were evaluated for wettability and surface roughness to determine their potential as biofilm resistant treatments on implants.