Background. Intramedullary nailing is a widely accepted treatment method for femoral fractures. Failure of locking screws is often a threatening complication, particularly on comminuted fractures. For comminuted fractures, the locking nails are load-bearing devices. The load transfer between fractured fragments is made through especially the locking screws for these load bearing situations. Nonunion, malunion, delayed union, shortening, and nail migration are the expected results if early failure of locking screws is present with comminuted fractures. In this study our aim was to compare the bending resistance of titanium and stainless steel locking screws. Methods. We tested 60 locking screws in six groups (titanium, stainless steel, unthreaded, low threaded and high threaded) in a steel tube that has 30 mm inner diameter, which imitates the lesser trochanter level. We determined the yield points at three-point bending tests that permanent deformation started in the locking screws using an axial compression testing machine. Results. The three-point bending resistance of 5 mm low threaded titanium locking screws (bending at 1413 N loading) was 46.5 % less than the three-point bending resistance of 5 mm low threaded stainless steel locking screws (bending at 2171 N loading) (p < 0.001). Five mm stainless steel locking screws are 29–57 % more resistant to three-point bending deformation than titanium ones. Conclusions. Therefore, stainless steel locking screws instead of titanium ones must be preferred in comminuted femur shaft fractures. In intramedullary nailing of comminuted or long oblique femur fractures, a locking screw should be 5 mm low threaded or unthreaded stainless steel or 5 mm unthreadedtitanium. Five mm high threaded titanium or stainless steel screws must not ever be used as a locking screw. Level of Evidence. 5. Disclosure. Authors declare that there is no conflict of interest related to the present study

Using an osteotomy of the olecranon as a model of a transverse fracture in 22 cadaver elbows we determined the ability of three different types of suture and stainless steel wire to maintain reduction when using a tension-band technique to stabilise the bone. Physiological cyclical loading simulating passive elbow movement (15 N) and using the arms to push up from a chair (450 N) were applied using an Instron materials testing machine whilst monitoring the osteotomy site with a video extensometer. Each osteotomy was repaired by one of four materials, namely, Stainless Steel Wire (7), No 2 Ethibond (3), No 5 Ethibond (5), or No 2 FiberWire (7). There were no failures (movement of > 2 mm) with stainless steel wire or FiberWire and no significant difference in the movements measured across the site of the osteotomy (p = 0.99). The No. 2 Ethibond failed at 450 N and two of the five of No. 5 Ethibond sutures had a separation of > 2 mm at 450 N. FiberWire as the tension band in this model held the reduction as effectively as stainless steel wire and may reduce the incidence of discomfort from the hardware. On the basis of our findings we suggest that a clinical trial should be undertaken

Summary Statement

Innovative nanocomposite carbon coating doped with Si can significantly improve the osseintegration of orthopaedics implants. Additionally, this kind of coating increases the mechanical resistance of the implants, what is especially important on case of joints (frictional pairs).

Summary Statement. Routine metal allergy screening prior to joint arthroplasty is not essential and the use of cobalt chromium or stainless steel implants is recommended regardless of the patient's metal allergy status. Introduction. This study was undertaken to obtain a consensus amongst joint arthroplasty experts with regards to metal allergy screening prior to joint arthroplasty and the choice of implant in patients with potential metal allergy. Patients & Methods. A web based Delphi consensus study was used including orthopaedic surgeons that had previously published on the topic of knee, hip or shoulder arthroplasty. Two rounds of questionnaires were sent via electronic mail. Consensus was considered if agreement was 60% or higher. Results. 18 surgeons responded to the first and 17 to the second round of questionnaires. There was consensus that patients having metal arthroplasty surgery should not be routinely questioned about metal allergy prior to surgery. There was consensus that patch testing is not necessary even if metal allergy is suspected. Most respondents agreed in proceeding with cobalt chromium or stainless steel implant in patients suspected of metal allergy regardless of the results of cutaneous patch testing. Discussion/Conclusion. This consensus study suggests that routine metal allergy screening prior to joint arthroplasty is not essential. The use of traditional cobalt chromium/stainless steel implants is recommended regardless of the patient's metal allergy status

Intramedullary nails (IMNs) are the current gold standard for treatment of long bone diaphyseal and selected metaphyseal fractures. Their design has undergone many revisions to improve fixation techniques, conform to the bone shape with appropriate anatomic fit, reduce operative time and radiation exposure, and extend the indication of the same implant for treatment of different fracture types with minimal soft tissue irritation. The IMNs are made or either titanium alloy or stainless steel and work as load-sharing internal splints along the long bone, usually accommodating locking elements – screws and blades, often featuring angular stability and offering different configurations for multiplanar fixation – to secure secondary fracture healing with callus formation in a relative-stability environment. Bone cement augmentation of the locking elements can modulate the construct stiffness, increase the surface area at the bone-implant interface, and prevent cut-through of the locking elements. The functional requirements of IMNs are related to maintaining fracture reduction in terms of length, alignment and rotation to enhance fracture healing. The load distribution during patient's activities is along the entire bone-nail interface, with nail length and anatomic fit being important factors to avoid stress risers

In 2011, approximately 1.6 million total hip arthroplasties (THAs) were conducted in 27 of the 34 member countries in the Organization for Economic Cooperation and Development (OECD) However, approximately 10–15% of patients still require revision surgery every year. Therefore, new technologies are required to increase the life-spam of the prosthesis from the current 10–15 years to at least 20–30 years. Our strategy focuses on surface modification of the bearing materials with a hydrophilic coating to improve their wear behaviour. These coatings are biocompatible, with high swelling capacity and antifouling properties, mimicking the properties of natural cartilage, i.e. wear resistance with permanent hydrated layer that prevents prosthesis damage. Clear beneficial advantages of this coating have been demonstrated in different conditions and different materials, such as UHMWPE, PEEK, CrCo, Stainless steel, ZTA and Alumina. Using routine tribological experiments, the wear for UHMWPE substrate was decreased by 75% against alumina, ZTA and stainless steel. For PEEK-CFR substrate coated, the amount of material lost against ZTA and CrCo was at least 40% lower. Further experiments on hip simulator adding abrasive particles (1-micron sized aluminium particles) during 3 million cycles, on a total of 6 million, showed a wear decreased of around 55% compared to uncoated UHMWPE and XLPE. In conclusion, CIDETEC‘s coating technology is versatile and can be adapted to protect and improve the tribological properties of different types of surfaces used for prosthesis, even in abrasive conditions

Aim. The aim of this study is to outline the steps and techniques required to create a patient specific 3D printed guide for the accurate placement of the origin of the femoral tunnel for single bundle ACL reconstruction. Introduction. Placements of the femoral tunnels for ACL reconstruction have changed over the years. Most recently there has been a trend towards placing the tunnels in a more anatomic position. There has been subsequent debate as to where this anatomic position should be. The problem with any attempt at consensus over the placement of an anatomic landmark is that each patient has some variation in their positioning and therefore a fixed point for all has compromise for all as it is an average. Our aim was to attempt to make a cost effective and quick custom guide that could allow placement of the center of the patients’ newly created femoral tunnel in the mid position of their contralateral native ACL femoral footprint. Materials & Methods. We took a standard protocol MRI scan of a patient's knee without ACL injury transferred the DICOM files to a personal computer running OsiriX (Pixmeo, Geneva, Switzerland.) and analysed it for a series of specific anatomical landmarks. OsiriX is an image processing software dedicated to DICOM images. We marked the most posterior edge of the articular cartilage on the lateral wall of the notch (1), the most anterior edge of the articular cartilage of the lateral wall of the notch (2), the most inferior edge of the articular cartilage of the lateral wall of the notch (3) and the center of the femoral footprint of the native ACL. Distances were then calculated to determine the position relative to the three articular cartilage points of the center of the ACL footprint. These measurements and points were then utilised to create a 3D computer aided design (CAD) model of a custom guide. This was done using the 3D CAD program 123Design (Autodesk Ltd., Farnbourgh, Hampshire). This 3D model was then exported as an STL file suitable for 3D printing. The STL file was then uploaded to an online 3D printing service and the physical guide was created in transparent acrylic based photopolymer, PA220 plastic and 316L stainless steel. The models created were then measured using vernier calipers to confirm the accuracy of the final guides. Results. The MRI data showed point 1 (AP), point 2 (distal-ACL), point 3 (Ant-ACL) and point 4 (Post-ACL) at a distance of 59.83, 15, 45.8 and 13.9 respectively. For the 3D CAD model, points 1, 2, 3 and 4 were at a distance of 59.83, 15, 45.8 and 13.9 respectively. For the PA220 plastic model, points 1, 2, 3 and 4 were at a distance of 59.86, 14.48, 45.85 and 13.79 respectively. For the 316L stainless steel model, points 1, 2, 3 and 4 were at a distance of 59.79, 14.67, 45.64 and 13.48 respectively. Lastly, for the photopolymer model, points 1, 2, 3 and 4 were at a distance of 59.86, 14.2, 45.4 and 13.69 respectively. The p-value comparing MRI/CAD vs. PA220 was p=0.3753; for the comparison between MRI/CAD vs. 316L, p=0.0683; lastly for the comparison between MRI/CAD Vs. Photopolymer, p=0.3450. The models produced were accurate with no statistical difference in size and positioning of the center of the ACL footprint from the original computer model and to the position of the ACL from the MRI scans. The costs for the models 3D printed were £3.50 for the PA220 plastic, £15 for the transparent photopolymer and £25 for the 316L stainless steel. The time taken from MRI to delivery for the physical models was 7 days. Discussion. Articles regarding the creation of 3D printed custom ACL guides from the patients contralateral knee do not feature in current literature. There has been much research on custom guides for other orthopaedic procedures such as in total knee arthroplasty for the accurate placement of implants. There has also been research published on the creation of custom cutting jigs from CT for complex corrective osteotomy surgery. This study serves as the first step and a proof of concept for the accurate creation of patient specific 3D printed guides for the anatomical placement of the femoral tunnel for ACL reconstruction. The guides were easy to create and produce taking only a week and with a cost of between £3.50 and £25. The design of the guides was to allow the tip of a standard Chondro Pick (Arthrex inc., Naples, Florida.) (3mm) used to mark the starting point of the femoral tunnel to enter through the guide. The next step for this research is to create guides from cadaveric matched knees and utilise the guides to carry out the creation of the femoral tunnels and to analyse of the placement of the tunnel in relation to the contralateral knee

Many orthopaedic procedures require implants to be trialled before definitive implantation. Where this is required, the trials are provided in a set with the instrumentation. The most common scenario this is seen in during elective joint replacements. In Scotland (2007) the Scottish Executive (. http://www.sehd.scot.nhs.uk/cmo/CMO(2006)13.pdf. ) recommended and implemented individually packed orthopaedic implants for all orthopaedic sets. The premise for this was to reduce the risk of CJD contamination and fatigue of implants due to constant reprocessing from corrosion. During many trauma procedures determining the correct length of plate or size of implant can be challenging. Trials of trauma implants is no longer common place. Many implants are stored in closed and sealed boxes, preventing the surgeon looking at the implant prior to opening and contaminating the device. As a result many implants are incorrectly opened and either need reprocessed or destroyed due to infection control policy, thus implicating a cost to the NHS. With even the simplest implants costing several hundreds of pounds, this cost is a very significant waste in resources that could be deployed else where. My project was to develop a method to produce in department accurate, cheap and disposable trials for implants often used in trauma, where the original manufacturer do not offer the option of a trial off the shelf. The process had to not involve contaminating or destroying the original implant in the production of a trial. Several implants which are commonly used within Glasgow Royal Infirmary and do not have trials were identified. These implants were then CT scanned within their sealed and sterile packaging without contamination. Digital 3D surface renders of the models were created using free open source software (OsiriX, MeshLab, NetFabb). These models were then processed in to a suitable format for 3D printing using laser sintering via a cloud 3D printing bureau (. Shapeways.com. ). The implants were produced in polyamide PA220 material or in 316L stainless steel. These materials could be serialized using gamma irradiation or ethylene oxide gas. The steel models were suitable for autoclaving in the local CSSU. The implants produced were accurate facsimiles of the original implant with dimensions within 0.7mm. The implants were cost effective, an example being a rim mesh was reproduced in polyamide PA220 plastic for £3.50 and in 316L stainless steel for £15. The models were produced within 10 days of scanning. The stainless steel trials were durable and suitable for reprocessing and resterilisation. The production of durable, low cost and functional implant trials all completed in department was successful. The cost of production of each implant is so low that it would be offset if just one incorrect implant was opened during a single procedure. With some of the implants tested, the trials would have paid for themselves 100 times. This is a simple and cost saving technique that would help reduce department funding and aid patient care

Abstract. Objectives. The outcomes from patella fracture have remained dissatisfactory despite advances in treatment, especially from operative fixation1. Frequently, reoperation is required following open reduction and internal fixation (ORIF) of the patella due to prominent hardware since the standard technique for patella ORIF is tension band wiring (TBW) which inevitably leaves a bulky knot and irritates soft tissue given the patella's superficial position2. We performed a systematic review to determine the optimal treatment of patella fractures in the poor host. Methods. Three databases (EMBASE/Medline, ProQuest and PubMed) and one register (Cochrane CENTRAL) were searched. 476 records were identified and duplicates removed. 88 records progressed to abstract screening and 73 were excluded. Following review of complete references, 8 studies were deemed eligible. Results. Complication rates were shown to be high in our systematic review. Over one-fifth of patients require re-operation, predominantly for removal of symptomatic for failed hardware. Average infection rate was 11.95% which is higher than rates reported in the literature for better hosts. Nevertheless, reported mortality was low at 0.8% and thromboembolic events only occurred in 2% of patients. Average range of movement achieved following operative fixation was approximately 124 degrees. Upon further literature review, novel non-operative treatment options have shown acceptable results in low-demand patients, including abandoning weight-bearing restrictions altogether and non-operatively treating patients with fracture gaps greater than 1cm. Regarding operative management, suture/cable TBW has been investigated as a viable option with good results in recent years since the materials used show comparable biomechanics to stainless steel. Additionally, ORIF with locking plates have shown favourable results and have enabled aggressive post-operative rehabilitation protocols. TBW with metallic implants has shown higher complication rates, especially for anterior knee pain, reoperation and poor functional outcomes. Conclusion. There is sparse literature regarding patella fracture in the poor host. Nevertheless, it is clear that ORIF produces better outcomes than conservative treatment but the optimal technique for patella ORIF remains unclear. TBW with metallic implants should not remain the standard technique for ORIF; low-profile plates of suture TBW are more attractive solutions. Non-operative treatment may be considered for low-demand individuals however any form of patellectomy should be avoided if possible. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objectives. Additive manufacturing (AM) enables fine control over the architecture of porous lattice structures, and the resulting mechanical performance. Orthopaedic implants may benefit from the tailored stiffness/elastic modulus of these AM biomaterials, as the stiffness can be made to closer match the properties of the replaced trabecular bone. Methods. This study used laser powder bed fusion (PBF) to create stochastic porous lattice structures in stainless steel (SS316L) and titanium alloy (Ti6Al4V), with modifications that aimed to overcome PBF manufacturing limitations of build angles. The structures were tested in uni-axial compression (n = 5) in 10 load orientations relative to the structure, including the three orthogonal axes. Results. The testing verified that no hidden peaks in elastic modulus existed in the stochastic structure. The standard deviation of the 10 elastic modulus values in the final structure decreased from 249 MPa to 101 MPa when made in SS316L and from 95.9 MPa to 52.5 MPa for Ti6Al4V, indicating the structures were more isotropic. Conclusions. These modified stochastic lattices have similar stiffness to cancellous bone and have controllable anisotropy, giving them the potential to be used within implants which match the stiffness of trabecular bone. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Resistance to infection may be influenced by foreign bodies such as devices for fracture fixation. It is known that stainless steel and commercially-pure titanium have different biocompatibilities. We have investigated susceptibility to infection after a local bacterial challenge using standard 2.0 dynamic compression plates of either stainless steel or titanium in rabbit tibiae. After the wounds had been closed, various concentrations of a strain of Staphylococcus aureus were inoculated percutaneously. Under otherwise identical experimental conditions the rate of infection for steel plates (75%) was significantly higher than that for titanium plates (35%) (p < 0.05)

The Capital Hip implant was a Charnley-based system which included a flanged and a roundback stem, both of which were available in stainless steel and titanium. The system was withdrawn from the market because of its inferior performance. However, all four of the designs did not produce poor rates of survival. Using a simulated-based, finite-element analysis, we have analysed the Capital Hip system. Our aim was to investigate whether our simulation was able to detect differences which could account for the varying survival between the Capital Hip designs, thereby further validating the simulation. We created finite-element models of reconstructions with the flanged and roundback Capital Hips. A loading history was applied representing normal walking and stair-climbing, while we monitored the formation of fatigue cracks in the cement. Corresponding to the clinical findings, our simulation was able to detect the negative effects of the titanium material and the flanged design in the Capital Hip system. Although improvements could be made by including the effect of the roughness of the surface of the stem, our study increased the value of the model as a predictive tool for determining failure of an implant

Proponents of the biological theory of aseptic loosening have in recent years tended to concentrate on the production and distribution of particulate ultra-high-molecular-weight polyethylene (UHMWPE) debris around the potential joint space. However, mechanical loading of cemented implants with the differing elastic moduli of metal stems, polymethylmethacrylate (PMMA) cement and bone can result in relative micromotion, implying the potential for production of metal and PMMA particles from the stem-cement interface by fretting wear. In order to investigate the production and biological reactivity of debris from this interface, PMMA and metal particulate debris was produced by sliding wear of PMMA pins containing barium sulphate and zirconium dioxide against a Vaquasheened stainless steel counterface. This debris was characterised by SEM, energy-dispersive analysis by X-ray (EDAX) and image analysis, then added to cell cultures of a human monocytic cell line, U937, and stimulation of pro-osteolytic cytokines measured by ELISA. Large quantities of PMMA cement debris were generated by the sliding wear of PMMA pins against Vaquasheened stainless steel plates in the method developed for this study. Both cements stimulated the release of pro-osteolytic TNFα from the U937 monocytic cell line, in a dose-dependent fashion. There was a trend towards greater TNFα release with Palacos cement than CMW cement at the same dose. Palacos particles also caused significant release of IL-6, another pro-osteolytic cytokine, while CMW did not. The particulate cement debris produced did not stimulate the release of GM-CSF or IL1β from the U937 cells. These results may explain the cytokine pathway responsible for bone resorption caused by particulate PMMA debris. Radio-opaque additives are of value in surgical practice and clinical studies to quantify the relevance of these in vitro findings are required before the use of cement containing radio-opacifier is constrained

Coronoid fractures account for 2 to 15% of the cases with elbow dislocations and usually occur as part of complex injuries. Comminuted fractures and non-unions necessitate coronoid fixation, reconstruction or replacement. The aim of this biomechanical study was to compare the axial stability achieved via an individualized 3D printed prosthesis with curved cemented intramedullary stem to both radial head grafted reconstruction and coronoid fixation with 2 screws. It was hypothesized that the prosthetic replacement will provide superior stability over the grafted reconstruction and screw fixation. Following CT scanning, 18 human cadaveric proximal ulnas were osteotomized at 40% of the coronoid height and randomized to 3 groups (n = 6). The specimens in Group 1 were treated with an individually designed 3D printed stainless steel coronoid prosthesis with curved cemented intramedullary stem, individually designed based on the contralateral coronoid scan. The ulnas in Group 2 were reconstructed with an ipsilateral radial head autograft fixed with two anteroposterior screws, whereas the osteotomized coronoids in Group 3 were fixed in situ with two anteroposterior screws. All specimens were biomechanically tested under ramped quasi-static axial loading to failure at a rate of 10 mm/min. Construct stiffness and failure load were calculated. Statistical analysis was performed at a level of significance set at 0.05. Prosthetic treatment (Group 1) resulted in significantly higher stiffness and failure load compared to both radial head autograft reconstruction (Group 2) and coronoid screw fixation, p ≤ 0.002. Stiffness and failure load did not reveal any significant differences between Group 2 and Group 3, p ≥ 0.846. In cases of coronoid deficiency, replacement of the coronoid process with an anatomically shaped individually designed 3D printed prosthesis with a curved cemented intramedullary stem seems to be an effective method to restore the buttress function of the coronoid under axial loading. This method provides superior stability over both radial head graft reconstruction and coronoid screw fixation, while achieving anatomical articular congruity. Therefore, better load distribution with less stress at the bone-implant interface can be anticipated. In the clinical practice, implementation of this prosthesis type could allow for early patient mobilization with better short- and long-term treatment outcomes and may be beneficial for patients with irreparable comminuted coronoid fractures, severe arthritic changes or non-unions

Osteosynthesis of high-energy metaphyseal proximal tibia fractures is still challenging, especially in patients with severe soft tissue injuries and/or short stature. Although the use of external fixators is the traditional treatment of choice for open comminuted fractures, patients' acceptance is low due to the high profile and therefore the physical burden of the devices. Recently, clinical case reports have shown that supercutaneous locked plating used as definite external fixation could be an efficient alternative. Therefore, the aim of this study was to evaluate the effect of implant configuration on stability and interfragmentary motions of unstable proximal tibia fractures fixed by means of externalized locked plating. Based on a right tibia CT scan of a 48 years-old male donor, a finite element model of an unstable proximal tibia fracture was developed to compare the stability of one internal and two different externalized plate fixations. A 2-cm osteotomy gap, located 5 cm distally to the articular surface and replicating an AO/OTA 41-C2.2 fracture, was virtually fixed with a medial stainless steel LISS-DF plate. Three implant configurations (IC) with different plate elevations were modelled and virtually tested biomechanically: IC-1 with 2-mm elevation (internal locked plate fixation), IC-2 with 22-mm elevation (externalized locked plate fixation with thin soft tissue simulation) and IC-3 with 32-mm elevation (externalized locked plate fixation with thick soft tissue simulation). Axial loads of 25 kg (partial weightbearing) and 80 kg (full weightbearing) were applied to the proximal tibia end and distributed at a ratio of 80%/20% on the medial/lateral condyles. A hinge joint was simulated at the distal end of the tibia. Parameters of interest were construct stiffness, as well as interfragmentary motion and longitudinal strain at the most lateral aspect of the fracture. Construct stiffness was 655 N/mm (IC-1), 197 N/mm (IC-2) and 128 N/mm (IC-3). Interfragmentary motions under partial weightbearing were 0.31 mm (IC-1), 1.09 mm (IC-2) and 1.74 mm (IC-3), whereas under full weightbearing they were 0.97 mm (IC-1), 3.50 mm (IC-2) and 5.56 mm (IC-3). The corresponding longitudinal strains at the fracture site under partial weightbearing were 1.55% (IC-1), 5.45% (IC-2) and 8.70% (IC-3). From virtual biomechanics point of view, externalized locked plating of unstable proximal tibia fractures with simulated thin and thick soft tissue environment seems to ensure favorable conditions for callus formation with longitudinal strains at the fracture site not exceeding 10%, thus providing appropriate relative stability for secondary bone healing under partial weightbearing during the early postoperative phase

The angle of acetabular inclination is an important measurement in total hip replacement (THR) procedures. Determining the acetabular component orientation intra-operatively remains a challenge. An increasing number of innovators have described techniques and devices to achieve it. This paper describes a mechanical inclinometer design to measure intra-operative acetabular cup inclination. Then, the mechanical device is tested to determine its accuracy. The aim was to design an inclinometer to measure inclination without existing instrumentation modification. The device was designed to meet the following criteria: 1. measure inclination with acceptable accuracy (+/− 5o); 2. easy to use intra-operatively (handling & visualization); 3. adaptable and useable with majority of instrumentation kits without modification; 4. sterilizable by all methods; 5. robust/reusable. The prototype device was drafted by computer aided design (CAD) software. Then a prototype was constructed using a 3D printer to establish the final format. The final device was CNC machined from SAE 304 stainless steel. The design uses an eccentrically weighted flywheel mounted on two W16002-2RS ball bearings pressed into symmetrical housing components. The weighted wheel is engraved with calibrated markings relative to its mass centre. Device functioning is dependent on gravity maintaining the weighted wheel in a fixed orientation while the housing can adapt to the calibration allowing for determining the corresponding measurement. The prototype device accuracy was compared to a digital device. A digital protractor was used to create an angle. The mechanical inclinometer (user blinded to digital reading) was used to determine the angle and compared to the digital reading. The accuracy of the device compared to the standard freehand technique was assessed using a saw bone pelvis fixed in a lateral decubitus position. 18 surgeons (6 expert, 6 intermediate, 6 novice) were asked to place an uncemented acetabular cup in a saw bone pelvis to a target of 40 degrees. First freehand then using the inclinometer. The inclination was determined using a custom-built inertial measurement unit with the user blinded to the result. Comparison between the mechanical and digital devices showed that the mechanical device had an average error of −0.2, a standard deviation of 1.5, and range −3.3 to 2.6. The average root mean square error was 1.1 with a standard deviation of 0.9. Comparison of the inclinometer to the freehand technique showed that with the freehand component placement 50% of the surgeons were outside the acceptable range of 35–45 degrees. The use of the inclinometer resulted all participants to achieve placement within the acceptable range. It was noted that expert surgeons were more accurate at achieving the target inclination when compared to less experienced surgeons. This work demonstrates that the design and initial testing of a mechanical inclinometer is suitable for use in determining the acetabular cup inclination in THR. Experimental testing showed that the device is accurate to within acceptable limits and reliably improved the accuracy of uncemented cup implantation in all surgeons

Prosthetic joint infections (PJI) occur infrequently, but they represent the most devastating complication with high morbidity and substantial cost. Staphylococcus aureus and coagulase-negative S. epidermidis are the most common infecting agents associated with PJI. During the past decades, novel materials have been developed to improve osseointegration of implants. Recently has been demonstrated that by using nanosized hydroxyapatite (HA) coatings, since it combines nanoroughness and bone-like chemistry in a synergistic effect, it promotes better osseointegration when compared to uncoated metal implants. In a further step, due to the known bactericidal properties of fluor, the aim of this study is to evaluate the biofilm development on fluorohydroxyapatite (FHA) compared to HA. Coatings were grown on stainless steel substrates by Pulsed Laser Deposition (PLD) technique using fluorohydroxyapatite targets of marine origin. A comprehensive physicochemical characterization of the coatings was performed using SEM, EDS, XPS and XRD. Biological in vitro tests using the pre-osteoblastic cell line (MC3T3-E1) demonstrated the non-cytotoxicity of FHA coatings, the healthy cell proliferation and their osteogenic activity. The S. aureus 15981 (Valle et al.) and S. epidermidis ATCC 35984 strains adherence study was performed introducing each probe in a well of 96-well plate with 200 µl containing 106 colony forming units (CFU/mL) intryptic soy broth supplemented with 1% glucose and was incubated at 37°C 5% CO2 for 24 hours. After incubation, the medium was removed and three washes with 0.9% NaCl sterile saline were performed. The biofilm was disrupted by sonication at 50–60 Hz for 5 min. The CFU/cm2 was estimated by drop plate method. All of the experiments were performed in triplicate. Statistical analysis was performed by non-parametric unilateral Wilcoxon”s test with a level of statistical significance of 0.05. The results showed a significant (p=0.02475) 2.4-fold reduction in S. epidermidis biofilm formation on FHA (logUFC/cm2 = 6.87) compared to HA (logUFC/cm2 = 7.25); and also a significant (p=0.042) 3.7-fold reduction in S. aureus 15981 biofilm formation. In conclusion, according our results FHA is a promising biomaterial that promotes osseointegration and decreases the staphylococcal biofilm that could avoid PJI. Further studies will be necessary

Background. External fixation is a method of osteosynthesis currently required in traumatology and orthopaedic surgery. Pin tract infection is a common problem in clinical practice. Infection occurs after a bacterial colonisation of the pin due to its contact with skin and local environment. To prevent such local contamination, one way to handle this issue is to create a specific coating using method which could be applied in the medical field. In this work we develop a surface coating for external fixator pins based on photocatalytic TiOα properties, producing a bactericidal effect with sufficient mechanical strength to be compatible with surgical use. Method. The morphology and structure of the sol-gel coating layers were characterised using, respectively, scanning electron microscopy and X-ray diffraction. Resistance properties of the coating were investigated by mechanical testing. Photo-degradation of acid orange 7 in aqueous solution was used as a probe, to assess the photo-catalytic activity of titanium dioxide layers under UV irradiation. The bactericidal effect induced by the process was evaluated against 2 strains: a Staphylococcus aureus and a multiresistant Staphylococcus epidermidis. Results. The coated pins showed good mechanical strength and efficient antibacterial effect after 1 hour of UV irradiation. Conclusion. Our study allowed to develop an antibacterial coating for stainless steel commonly used in surgical practice. The process using photoactive TiO2 exposed to UV irradiation is actually well known and applied in many disinfection fields, and exhibited efficiency against the two main bactericidal strains involved in pin tract infections. Mechanical tests confirmed the coating's ability to resist to important stresses. Moreover, this kind of coating created by sol-gel dip-coating techniques is not expensive and quite easy to do. As a consequence, we can hope that this new option would treat preventively pin tract infection, even if there is an important optimisation task to be done in order to amplify bactericidal properties. Level of evidence. II

INTRODUCTION. Staphylococci species account for ∼80 % of osteomyelitis cases. While the most severe infections are caused by Staphylococcus aureus (S. aureus), the clinical significance of coagulase negative Staphylococcus epidermidis (S. epidermidis) infections remain controversial. In general, S. epidermidis was known to be a protective commensal bacterium. However, recent studies have shown that intra-operative low-grade S. epidermidis contamination prevents bone healing. Thus, the purpose of this study is to compare the pathogenic features of S. aureus and S. epidermidis in an established murine model of implant-associated osteomyelitis. METHODS. All animal experiments were performed on IACUC approved protocols. USA300LAC (MRSA) and RP62A(S. epidermidis) were used as prototypic bacterial strains. After sterilization, stainless steel pins were implanted into the tibiae of BALB/c mice (n=5 each) with or without Staphylococci. Mice were euthanized on day 14, and the implants were removed for scanning electron microscopy (SEM). Tibiae were fixed for mCT prior to decalcification for histology. RESULTS. The histology of S. aureus infected tibiae demonstrated massive osteolysis and abscesses formation. In contrast, the histology from S. epidermidis infected tibiae was indistinguishable from uninfected controls. Gross mCT analyses revealed massive bone defects around the infected implant with reactive bone formation only in the S. aureus group. The osteolysis findings were confirmed by quantitative analysis, as the medial hole area of S. aureus infected tibiae (1.67 ± 0.37 mm2) was larger than uninfected (0.15 ± 0.10 mm2) (p < 0.001) and S. epidermidis (0.19 ± 0.14 mm2) (p < 0.001) groups. Consistently, the %biofilm area on the implants of the S. aureus group (39.0 ± 13.7 %) was significantly larger than uninfected (6.3 ± 2.3 %) (p < 0.001) and S. epidermidis (12.9 ± 7.4 %) (p < 0.001). Although the amount of biofilm of S. epidermidis was much smaller than S. aureus, the presence of bacteria on the implant were confirmed by SEM. In addition, the empty lacunae, which is a feature of mature biofilm and evidence of bacterial emigration, were also present on both S. epidermidis and S. aureus infected implants. DISCUSSION. In this study, we confirmed the aggressive pathologic features S. aureus on host bone, soft tissues and biofilm formation. In contrast, we show that S. epidermidis is incapable of inducing osteolysis, reactive bone formation or soft tissue abscesses, even though it colonizes the implant in small biofilms. Collectively, the results support a potential role for S. epidermidis in implant loosening and fracture non-unions, as the bacteria can form small biofilms that could interfere with osseous integration and bone healing. However, future studies are warranted to assess the effects of S. epidermidis biofilm on implant loosening

Due to its avascular nature, articular cartilage exhibits a very limited capacity to regenerate and to repair. Although much of the engineered cartilage grafts so far proposed have successfully shown to mimic the morphological and biochemical appearance of hyaline cartilage, they are generally mechanically inferior to the natural tissue. 1. In this study a new bioreactor device was realized to test innovative scaffolds under physiological stimulation (i.e. perfusion fluid flow and dynamic compression), with the aim to produce a more functional engineered tissue construct for articular applications. The computer-controlled bioreactor system has been properly designed to simultaneously provide static or dynamic compression and/or continuous perfusion to 3D engineered constructs, reproducing the physiological loads to which the articular cartilage is subjected. The specifically designed bioreactor comprises a chamber where the grafts are accommodated, a porous piston connected to a linear stepper motor (Dings, Model 34-2080-4-300), which controls its movement to provide mechanical stimulation and a peristaltic pump (Watson-Marlow, Model 323S), connected by joints and pipes to the culture chamber to ensure a continuous media perfusion. As piston for compression, a sintered stainless steel filter (43% of porosity) was adopted to allow the perfusion of the culture media during physical stimulation. The culture chamber is composed by a hollow cylinder (30 mm × 40,5 mm) and a base realized as a single object. They are made in polycarbonate for its characteristics of transparency and infrangibility and linked to a Nylon cover through four brass tie rods unscrewable from above. The chamber has been designed to accommodate simultaneously different constructs of any size and shape and stimulate them with perfusion and/or dynamic compression. A finites elements program was used to mimic the effects of perfusion and compression regime on the scaffolds cultured within the bioreactor chamber. The bioreactor was properly designed and developed. Particular attention has been paid to the implementation of a simple, compact and economical system. It was then tested by using different polymeric porous scaffolds (PVA, collagen, Gelatin grafts, both porous and not) cultured with mesenchymal cells up to two weeks. The system has been validated in terms of sterility, experimental reproducibility and ease to use. The structural stability of grafts over time has been observed; moreover cells adhesion, proliferation and matrix production under different chemical-physical stimuli conditions is under investigation. We have realized a novel bioreactor system representing an artificial articular niche, where a dynamic compression combined with fluid perfusion allows to functionally and mechanically validate tissue substitutes, besides investigating the response of engineered cartilaginous tissues to physical stimuli mimicking the natural cartilage micro-environment. Such bioreactor may be in fact adopted as a sort of articular simulator for promoting and standardizing the new tissue formation in vitro, preconditioning cell fate through the application of proper artificial stimuli. Moreover, they can be valid tools to investigate physiological processes and novel therapeutic approaches avoiding controversial animal models