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Background: Although the Pinnacle Acetabular Hip System (DePuy Synthes) has demonstrated excellent survivorship results since it was first introduced in 2003, there have been a growing number of cases indicating that Pinnacle liners may be subject to a higher-than-expected rate of early dissociation failure. Between 2006 and 2020, our Centre received 212 retrieved Pinnacle liners from Western Australian hospitals. Of these, 26 were removed due to liner dissociation. Methods: To better understand the frequency and cause of this complication we assessed all retrieved Pinnacle acetabular components for type, damage modes and patient demographics. The leverage force required to dissociate Pinnacle liners was also measured and compared with another commonly used acetabular system, the Trident (Stryker Orthopaedics). Results: The estimated minimum incidence of liner dissociation from our data was 0.35%. Characterisation of dissociated Pinnacle cases (n = 26) revealed 73% were female with an average age of 59 compared to all retrieved Pinnacle cases (n = 212) where 58% were female with an average age of 66. Retrieval analysis indicated plastic deformation of the liner into an ovoid shape, signs of impingement on the rim postero-superiorly and shearing of the liner’s anti-rotation tabs was common. Mechanical testing indicated that the dissociation strength of Pinnacle cups decreases at approximately 6.6 N/year in situ (p = 0.01). Conclusion: The survival rate of Pinnacle acetabular cups is exceptional with only 5% revised at 10 years. However, surgeons should be aware of the clinical symptoms and high-risk demographics when assessing patients with polyethylene Pinnacle liners.

Aims The aim of this study was to conduct the largest low contact stress (LCS) retrieval study to elucidate the failure mechanisms of the Porocoat and Duofix femoral component. The latter design was voluntarily recalled by the manufacturer. Materials and Methods Uncemented LCS explants were divided into three groups: Duofix, Porocoat, and mixed. Demographics, polyethylene wear, tissue ingrowth, and metallurgical analyses were performed. Results In 104 implants, a decrease in the odds of loosening and an increase in metallosis and tissue staining in the Duofix group relative to Porocoat group was detected (p = 0.028). There was an increased presence of embedded metallic debris in the Duofix group (p < 0.001). Decreased tissue ingrowth was associated with the Duofix surface (p < 0.001). The attached beads had reduced microhardness, indicative of adverse thermal processing, which resulted in bead shedding, particulate debris, and metallosis. Conclusion Hydroxyapatite coating of the LCS femoral component produced unexpected results and led to its recall. The root cause was likely a combination of retained alumina grit and a reduction in bead microhardness (mechanical strength) resulting in increased particle debris, metallosis, and early revision. The Duofix LCS femoral component was not equivalent to the Porocoat version despite its approval through the Food and Drug Administration (FDA) 510(k) equivalance approval process. Regulation of the introduction of modified existing devices needs to be improved and the Duofix LCS should have been considered to be a new device for which equivalence had not been demonstrated at the point of introduction. Cite this article: Bone Joint J 2019;101-B:1248–1255

Mechanical failure of intramedullary nails is rare. This investigation was prompted by a series of cases of observed breakage of the recently introduced TFNA Proximal Femoral Nailing System (TFN [Trochanteric Fixation Nail]-Advanced; DePuy Synthes) in our region. Laboratory analysis and case data are presented, in contribution to post-market surveillance.Medical and imaging records from the 3 public tertiary orthopaedic trauma hospitals in Western Australia were reviewed. Relevant data of patients in whom breakage of the TFNA implant occurred between 2016 and 2018 were collected and analyzed. Laboratory review of retrieved implants was conducted at the Centre for Implant Technology and Retrieval Analysis (CITRA) in Western Australia.A total of 16 cases of TFNA implant breakage were recorded and analyzed. The predominant OTA/AO fracture classification was 31A3 (12 cases, 75%). The reduction quality was good in 10 cases, acceptable in 4 cases, and poor in 2 cases. The mean time to failure (and standard deviation) was 5.0 ± 2.2 months (range, 2.2 to 9.8 months). The treatment modality for the breakage was revision nailing in 11 cases, arthroplasty in 3, and nonoperative management in 2. All nails broke at the proximal screw aperture, with 1 nail additionally breaking at the distal aperture. Of 8 patients treated with a second TFNA implant for nail breakage, 3 (38%) returned with breakage of the revision implant. Laboratory analysis of the broken nails demonstrated a unique fracture pattern, with a stepped propagation pathway.This study represents the largest series, to our knowledge, of proximal femoral nail breakages in the published English literature and is the first that we are aware of to involve laboratory analysis of the TFNA implant. Changes to the nail design and/or alloy may have contributed to the observed cases of breakage, and this study will be followed by an evaluation of breakage rates in comparison with those of previous generations of nailing systems. We advise close clinical and radiographic surveillance of patients with unstable hip fracture patterns who undergo osteosynthesis with use of a TFNA implant.Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Tuneable, bioactive hydrogels present an attractive option as cell-instructive substrates for tissue regeneration. Properties mimicking the extracellular matrix at the site of injury are sought after, in particular the ability to regulate growth factors that are key to the regeneration process. This study demonstrates the successful formation of hydrogels with heparin functionalities and fibroblast growth factor-2 (FGF-2). Poly(2-hydroxyethyl methacrylate)-heparin hydrogels were capable of retaining FGF-2 by specific binding to heparin and subsequently showed sustained presentation of the growth factor to mesenchymal stromal cells (MSC). Heparin acted as stable anchoring molecules for FGF-2 on the substrate and the synergistic effect of the ensuing heparin-FGF-2 complex was evident in supporting long term cell growth. The presence of heparin during 3D scaffold formation was also found to introduce surface roughness and microporosity to the resulting hydrogels. While FGF-2 has been known to encourage MSC growth and maintain their multilineage potential, other heparin-binding ligands such as bone morphogenetic proteins are potent differentiation stimuli for MSC. Therefore preserving MSC multipotency or a push toward a differentiation pathway may be pursued by the choice of ligand applied to and bound by the heparin functionalities on the current substrate.

Cranioplasty is necessary for patients that have undergone craniectomy following trauma, stroke or other causes of elevated intracranial pressure. This study assessed the effectiveness of treating cranial defects with allogeneic mesenchymal stromal cells (MSC) on a ceramic carrier and polymer scaffold, to produce viable bone and healing of a cranial void. Patients underwent a baseline computed tomography (CT) scan for construct design. Two sets of interlocking moulds were three-dimensional printed to enable shaping of two polymer meshes, which formed the boundaries of the construct corresponding to restoration of the skull interna and externa. In vitro expanded donor MSC were seeded onto ceramic granules in a good manufacturing practices facility. The inner mesh was placed in theatre, followed by the cell-loaded granules, and the outer mesh. Patients were followed-up at 3, 6 and 12 months and cosmesis assessed visually, while bone formation was assessed by CT scans at 1 day, 3 months and 12 months. Manufacture of the construct and surgery was uneventful for all three patients. Initial cosmesis was excellent with no complications. New bone formation was demonstrated by analysis of CT data; however, bone resorption was noted in all 3 cases on the 12-month CT scan. The lack of rigidity of the construct in an environment with continuous pulsatile movement may be preventing the formation of solid bone. It is possible to produce a customized allogeneic MSC construct for cranial reconstruction to replace cranial bone with good cosmesis, using a combination of medical computer modelling, rapid-prototyping and tissue engineering.

We report a case of metallosis following a shoulder hemiarthroplasty with a humeral component resurfacing shoulder replacement.

Case: We present a case of systemic cobalt toxicity secondary to third-body wear of a cobalt-chromium (CoCr) femoral head following revision of a fractured ceramic bearing. Removal of the CoCr head was followed by resolution of much of the systemic symptoms. Conclusion: This case supports previous reports of cobalt toxicity secondary to catastrophic third-body wear of a CoCr femoral head following a fractured ceramic bearing. It also demonstrates the potential reversibility of many systemic sequelae associated with cobalt toxicity. To our knowledge, this case represents the highest documented blood cobalt level (45,840 nmol/L).

Since the first use of ultra-high-molecular-weight polyethylene as a bearing material, research and development efforts have sought to improve wear resistance, increase longevity and lessen the potential for debris mediated adverse tissue responses. A series of second generation sequentially cross-linked and annealed tibial bearings were analysed after several bearings sent for routine retrieval analysis showed oxidative degradation including subsurface whitening, cracking and gross material loss. Evaluation incorporated visual and white banding assessment, mechanical testing and spectroscopy analysis. Whilst visual observation and white banding assessment confirmed oxidative changes, a decrease in mechanical properties and increasing ketone oxidation index as a function of time in vivo suggest time dependent oxidative degradation. Clinically relevant degradation of the sequentially cross-linked and annealed tibial bearings was observed.

Introduction Retrievable inferior vena cava (IVC) filters have been increasingly used in patients with major trauma who have contraindications to anticoagulant prophylaxis as a primary prophylactic measure against venous thromboembolism (VTE). The benefits, risks and cost-effectiveness of such strategy are uncertain. Methods and analysis Patients with major trauma, defined by an estimated Injury Severity Score >15, who have contraindications to anticoagulant VTE prophylaxis within 72 hours of hospitalisation to the study centre will be eligible for this randomised multicentre controlled trial. After obtaining consent from patients, or the persons responsible for the patients, study patients are randomly allocated to either control or IVC filter, within 72 hours of trauma admission, in a 1:1 ratio by permuted blocks stratified by study centre. The primary outcomes are (1) the composite endpoint of (A) pulmonary embolism (PE) as demonstrated by CT pulmonary angiography, high probability ventilation/perfusion scan, transoesophageal echocardiography (by showing clots within pulmonary arterial trunk), pulmonary angiography or postmortem examination during the same hospitalisation or 90-day after trauma whichever is earlier and (B) hospital mortality; and (2) the total cost of treatment including the costs of an IVC filter, total number of CT and ultrasound scans required, length of intensive care unit and hospital stay, procedures and drugs required to treat PE or complications related to the IVC filters. The study started in June 2015 and the final enrolment target is 240 patients. No interim analysis is planned; incidence of fatal PE is used as safety stopping rule for the trial. Ethics and dissemination Ethics approval was obtained in all four participating centres in Australia. Results of the main trial and each of the secondary endpoints will be submitted for publication in a peer-reviewed journal. Trial registration number ACTRN12614000963628; Pre-results.

Background: Artificial ligaments have been developed and used in the treatment of ligamentous injuries since the 1970s. The early generation of artificial ligaments showed promising short-term results but resulted in high rates of rupture and inflammatory reaction in the surrounding tissues. Purpose: To determine whether the use of Ligament Augmentation and Reconstruction System (LARS) ligaments is associated with the development of intra-articular foreign body reaction. Study Design: Case series; Level of evidence, 4. Methods: LARS ligaments were explanted from 15 patients under 6 consultant orthopaedic surgeons at 8 surgical centers. Of these, 14 explanted samples were sent for macroscopic and histological analysis, with the 1 remaining sample sent for scanning electron microscopy, to assess for inflammatory change as well as the degree of fibrous tissue ingrowth. Results: We observed a foreign body reaction in 10 of 14 explanted LARS ligaments. Seven samples demonstrated fibrous tissue ingrowth, with 5 producing only focal or incomplete ingrowth. The 2 samples with extensive fibrous coverage were completely free of any foreign body reaction, while all 5 remaining samples with only focal or partial fibrous ingrowth were associated with at least some degree of harmful immune response. Conclusion: The LARS ligament is still associated with a clinically significant degree of foreign body reaction despite the LARS Company’s efforts to reduce complications through improved design. The development and completion of fibrous tissue ingrowth may work to reduce the occurrence of a foreign body reaction.

Bead shedding has been reported in both hip and knee arthroplasties and can result in increased polyethylene wear and metal ion release. The rates of bead loss were recorded for each device type, and the interfacial bead-substrate shear load to failure and contact areas of the beads were determined. The 3 components with the highest rate of bead loss, namely, S-Rom, Omnifit, and Optifix acetabular shells, recorded the lowest shear loads to failure. Percentage bead-substrate contact area ranged between 7% and 37% and was the most important factor affecting bead shedding. Other factors influencing bead loss in decreasing order of importance were bead fusion, bead size, component type (acetabular or knee), component loosening, and time in situ.

While modular femoral heads have been used in THA for decades, a recent innovation is a second neck-stem taper junction. Clinical advantages include intraoperative adjustment of leg length, femoral anteversion, and easier revision, all providing flexibility to the surgeon; however, there have been reports of catastrophic fracture, cold welding, and corrosion and fretting of the modular junction.We asked whether (1) the neck-stem junction showed the same degradation mechanisms, if any, as the head-neck junction, (2) the junction contributed to THA revision, (3) the alloy affected the degree of degradation, and (4) the trunion machine finish affected the degradation mechanisms.We compared 57 retrievals from seven total hip modular designs, three cobalt-chromium-molybdenum and four titanium based: Bionik(®) (four), GMRS(®) (four), Margron(®) (22), Apex(®) (five), M-series(®) (five), ZMR(®) (two), and S-ROM(®) (15). Macroscopic inspection, microscopy, and micro-CT were conducted to determine the effects of materials and design.The cobalt-chromium-molybdenum components showed crevice corrosion and fretting of the neck-stem taper, whereas the titanium components had less corrosion; however, there were several cases of cold welding where disassembly could not be achieved in theater.Even with modern taper designs and corrosion-resistant materials, corrosion, fretting, and particulate debris were observed to a greater extent in the second neck-stem junction. Titanium-based modular arthroplasty may lessen the degree of degradation, but cold welding of the components may occur.Degradation of the second junction contributed to 8 cases of metallosis and two cases of aseptic lymphocyte-laminated vascular-associated lesions contributing to revision.

Background Corrosion has been documented in modular knee implants, but it has not been related to negative patient outcomes. We performed an observational retrieval investigation of 13 Stryker Triathlon TS modular knee implants, 3 of which were revised because of osteolysis and adverse local tissue reactions secondary to fretting corrosion at the modular junctions. Methods Modular surfaces were examined for the presence and severity of corrosion, and factors that may influence the development of corrosion were investigated. Scanning electron microscopy and energy-dispersive x-ray spectroscopy were performed to evaluate implants with severe corrosion, and tissue samples were sent for histopathological analysis. Results Mild to severe corrosion was present in association with 62% of modular tibial components and 75% of modular femoral components. Although tibial corrosion was less prevalent than femoral corrosion, it occurred earlier and with greater severity. Scanning electron microscopy and energy-dispersive x-ray spectroscopy demonstrated the appearances of fretting and corrosion of the modular junctions. Histopathological analysis of specimens from the 3 patients with adverse local tissue reactions demonstrated severe reactions to metal debris, including 1 reaction that was consistent with an aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). Conclusions To our knowledge, ALVAL and pseudotumors have not previously been reported secondary to corrosion of modular knee replacements. The threaded taper design and the release of cobalt-chromium ions and/or debris are implicated in the occurrence of the adverse local tissue reactions, osteolysis, and soft-tissue damage that we observed in our investigation. Clinicians should be aware of this possible complication associated with modular knee implants. Clinical relevance This article should raise clinician awareness of adverse local tissue reactions secondary to corrosion, potentially resulting in earlier recognition of this complication.

Since the early 1990s, there has been a dramatic increase in modular total hip designs ranging from a stem with a proximal taper and modular head, to a distal stem, double taper proximal neck, and modular head. Clinical advantages of the modular neck include intraoperative adjustment of leg length via the neck-head taper and femoral anteversion via the neck-stem taper. Sixteen cases of a double tapered cone, Margron hip prosthesis, were presented for retrieval analysis. Macroscopic inspection, corrosion testing, light microscopy, and scanning electron microscopy were conducted to elucidate mechanisms of failure. In this regard, 6 neck components showed significant fretting, and crevice corrosion of the neck-stem taper with an average implantation time of 39 months compared with the remaining retrievals, which showed no corrosion with and average time in situ of 2.7 months. This retrieval study demonstrates that even with a modern taper design and corrosion-resistant materials, increased modularity can lead to fretting and crevice corrosion, metal ion generation, and particulate debris that may contribute to periprosthetic osteolysis and loosening.

PurposeThe purpose of this paper is to describe a preliminary investigation into the heat treatment of Ti‐6Al‐7Nb components that had been produced via selective laser melting (SLM).Design/methodology/approachBars of Ti‐6Al‐7Nb were produced using SLM by MCP‐HEK Tooling GmbH in Lubeck, Germany. These bars were then subjected to a range of heat treatments and the resultant microstructure evaluated with respect to its likely effect on fatigue.FindingsIt was found that the as received material consisted of an α′ martensitic structure in a metastable β matrix. Evidence of the layer‐wise thermal history was present, as were large (up to ∼500 μm) pores. Solution treatment at 955°C (below the β transus) did not completely disrupt this layered structure and is therefore not recommended. When solution treatment was performed at 1,055°C (above the β transus) a homogeneous structure was produced, with a morphology that depended on the post‐solution treatment cooling rate. It was concluded that the most promising heat treatment consisted of a moderate cooling rate after solution treatment at 1,055°C.Research limitations/implicationsThe study had only limited material and therefore it was not possible to perform any mechanical property testing.Practical implicationsThe paper presents the initial findings of a project which is aimed at optimising the mechanical properties of Ti‐6Al‐7Nb components produced using SLM.Originality/valueCurrently, little is known about the heat treatment and subsequent mechanical properties of this Ti‐6Al‐7Nb alloy when produced using rapid manufacturing techniques. Such lack of knowledge limits the potential applications, especially in the biomedical field where the consequences of implant failure are high. The paper presents the first step in developing this understanding.

Femoral component neck fracture is an uncommon type of failure in total hip arthroplasty. We present a report on 4 retrieved cobalt-chrome femoral components that fractured at the neck, where we investigated the mechanisms of failure.The 4 retrieved implants were analyzed with regard to their macro- and microstructures and the fracture surfaces were examined using electron microscopy. The medical record of each patient was also examined for any history of complications prior to failure of the implant.These fractures occurred immediately adjacent to the base of the modular head. Skirted modular heads were used in 3 of the 4 failed components. This constructs promotes corrosion. Cyclic fatigue-loading in combination with the material factors of course grain microstructure and extensive carbide precipitation along the grain boundaries were also identified as the cause of implant failure.Our findings suggest that a solution annealing step could be introduced into the manufacturing process to improve the microstructure of the cobalt chrome alloy. We also advise caution in using a skirted modular head in combination with a device of known suboptimum microstructure, for a greater margin of safety.

Oxinium exhibits 4900 times less volumetric wear and 640 times less deep scratches in laboratory wear testing compared with traditional cobalt-chromium alloys. Despite the superior wear resistance because of the thin ceramic surface, the zirconium alloy substrate is relatively soft (Hv = 285) when compared with cobalt-chrome alloy femoral heads (ISO 5832-12; Hv = ~420,) and may deform in contact with acetabular shell materials (ISO5832-3; Hv = 350) in the case of dislocation. Three retrieval cases highlight the damage that may occur during dislocation and/or when performing closed reduction maneuvers. It is recommended that closed reduction be attempted with caution because significant head damage can occur. This may lead to accelerated polyethylene wear. In the case of successful reduction, close patient follow-up is recommended. Open reduction with femoral head inspection and exchange may be preferable if difficulty is encountered in closed reduction maneuvers.

Routine qualitative observations of more than 850 polyethylene fixed and mobile bearings at our institution have noted minimal wear of mobile bearings. The APG mobile bearing is the most recent design variant of the LCS knee, allows multi-directional movement at the tibiofemoral articulation, and is posterior cruciate sparing. Even though it is difficult to perform, quantitative wear measurement is important in determining the likely longevity of new arthroplasty devices, and is especially relevant because of increasing numbers of new mobile bearing designs.We analyzed 10 retrieved APG and 7 retrieved RP tibial bearings (De Puy) with a mean implantation period of 33 (9-70) months. We used coordinate-measuring techniques to quantitatively determine linear penetration, and optical and scanning electron microscopy to assess wear mechanisms qualitatively.The mean total volume loss (superior and inferior articulations) of the APG and RP designs was 85 mm((3))/year and 77 mm((3))/year, respectively. Burnishing was the predominant wear mechanism, and to a lesser extent scratching, abrasion and pitting. Multidirectional scratching and abrasion were noted on the APG inserts inferiorly, whereas there was circumferential scratching on the RP inserts.Our short-term results for the APG and RP mobile bearing designs are similar and compare more than favorably with reported values for fixed-bearing designs. However, increased backside wear due to multidirectional movement may predispose the APG design to greater wear in the long term.

Background Many exchangeable neck hip systems have been withdrawn because of fretting corrosion at the neck/stem coupling. Method Our prospective randomized study evaluating stem stability (Roentgen stereophotogrammetric analysis, dual-energy x-ray absorptiometry) and clinical outcomes between the K2/Apex hip systems was ceased early because of a withdrawal of the stems which had an unfavorably high early revision rate reported in the Australian Orthopaedic Association National Joint Registry (9.3% at 3 years). Results At 2 years, there are no clinical differences between the stems. Roentgen stereophotogrammetric analysis has identified a high proportion of potentially concerning subsidence and retroversion in both groups, more marked in the K2 stem, although mostly in asymptomatic patients. Dual-energy x-ray absorptiometry has shown similar bone density around the stems. Retrieval analysis of 3 study patients showed fretting corrosion of the antirotation pin and aseptic lymphocyte-dominated vasculitis-associated lesion, with no relationship to bearing type or size. Analysis of 7 further nonstudy K2/Apex stems confirmed similar corrosion. Conclusion This study shows potentially concerning subsidence of both stems and is the first to describe corrosion at the neck-stem interface and a relationship to metal-related pathology.

Before the widespread use of silicone implants various foreign substances were injected directly into the breasts. The nature of these materials sometimes remains unknown and can cause various complications requiring surgical intervention. Preoperative diagnostic imaging can help characterise the type and distribution of the injected material, thereby assisting in making decisions regarding treatment. We report a case of breast augmentation with an unknown substance, aiming to highlight some imaging characteristics of different breast augmentation substances.

Bone ingrowth into uncemented acetabular components requires intimate cup-bone contact and rigid fixation, which can be difficult to achieve in revision hip arthroplasty. This study compares polyaxial compression locking screws with non-locked and cancellous screw constructs for acetabular cup fixation. An acetabular cup modified with screw holes to provide both compression and angular stability was implanted into a bone substitute. Coronal lever out, axial torsion and push-out tests were performed with an Instron testing machine, measuring load versus displacement. Polyaxial locking compression screws significantly improved construct stiffness compared with non-locked or cancellous screws. This increased construct stiffness will likely reduce interfacial micromotion. Further research is required to determine whether this will improve bone ingrowth in vivo and reduce cup failure.

Poly Implant Prothèse implants were recalled in Australia in April of 2010 following concerns of higher than expected rupture rates and the use of unauthorized industrial grade silicone as a filler material. Although subsequent investigations found that the gel filler material does not pose a threat to human health, the important question of what caused a relatively modern breast implant to have such a poor outcome compared with contemporary silicone breast implants is yet to be addressed.From a cohort of 27 patients, 19 ruptured Poly Implant Prothèse breast implants were subjected to a range of mechanical tests and microscopic/macroscopic investigations to evaluate possible changes in properties as a result of implantation. New Poly Implant Prothèse implants were used as controls.All samples, explanted and controls, complied with the requirements for shell integrity as specified in the International Organization for Standardization 14607. Compression testing revealed rupture rates similar to those reported in the literature. Shell thickness was highly variable, with most shells having regions below the minimum thickness of 0.57 mm that was specified by the manufacturer. Potential regions of stress concentration were observed on the smooth inner surfaces and outer textured surfaces.The high incidence of Poly Implant Prothèse shell rupture is most likely a result of inadequate quality control, with contributory factors being shell thickness variation and manufacturing defects on both inner and outer surfaces of the shell. No evidence of shell degradation with implantation time was determined.

Bead shedding has been reported in both hip and knee arthroplasties and can result in increased polyethylene wear and metal ion release. The rates of bead loss were recorded for each device type, and the interfacial bead-substrate shear load to failure and contact areas of the beads were determined. The 3 components with the highest rate of bead loss, namely, S-Rom, Omnifit, and Optifix acetabular shells, recorded the lowest shear loads to failure. Percentage bead-substrate contact area ranged between 7% and 37% and was the most important factor affecting bead shedding. Other factors influencing bead loss in decreasing order of importance were bead fusion, bead size, component type (acetabular or knee), component loosening, and time in situ.

b o oyal Perth Hospital designs and manufactures 40–50 ustom-made titanium cranioplasty plates each year, and they ange in size from roughly 50 mm to complete bifrontal craial replacements. The method has evolved over the past ecade into a robust procedure that incorporates computer odelling, rapid-prototyping, and highly-skilled production ngineering. A high resolution helical multislice computed tomoraphic (CT) scan (1.0 mm slice thickness, 1.0 mm slice pacing) is taken of the patient. The CT data are stored and ransferred by PACS in DICOM format. The software packge Mimics (Materialise®, NV Leuven, Belgium) is used to reate a virtual three-dimensional model of the skull. Care s taken to remove the segments of any resorbed bone flap r other metalwork that will be excised during operation hen the titanium plate is implanted (Fig. 1A). The model is xported from Mimics in the .STL format. A rapid-prototype model of the defect is created from he .STL file using the Catalyst EX software (Stratasys®, den Prairie, Minnesota, USA) and a Dimension SST1200es hree-dimensional printer. The .STL file is imported into he software package FreeForm® Modeling PlusTM (Sens

Six fractured high nitrogen stainless steel (HNSS), polished, tapered hip stems have been reviewed for analysis. Clinical data suggests that poor proximal support (loosening), varus positioning, and canal morphology are implicated in the failure of these stems. Metallurgical assessment reveals a number of microstructural deficiencies contributing to failure. Of significance is poor grain homogeneity and larger grain size near the surface of the fractured stems. It appears some polished, tapered HNSS stems are at risk when combinations of these clinical and metallurgical features occur. As the control of grain size, microstructural uniformity, and inclusion content are critical for optimum mechanical performance, it is important the manufacturers review processing methods to further minimize the risk of component failure.

Background: The Australian Joint Registry records that there are approximately 84 hip stem designs, 71 acetabular designs and 45 knee systems in common use in Australia, giving the surgeon an extensive and often bewildering choices. Methods: Since the 1990s, there have been several attempts to rationalize the supply of the products of primary hip and knee arthroplasties to the public hospitals in Western Australia. To continue and improve the rationalization process, the recently awarded ‘whole of health’ tender was based on a thorough clinical and laboratory evaluation process. The method included commercial analysis by Health Supply Western Australia, clinical evaluation by a committee comprised of senior surgeons and technical assessment by biomedical engineers and scientists. The evaluation process was subdivided into qualitative criteria; being the commercial aspects of the tender (50%) and a fitness for purpose assessment comprising clinically based evidence (40%) and laboratory assessment of product quality (10%). Result: The tendering process concluded with the recommendation of 12 hip and 5 knee systems. Conclusions: A comprehensive method primarily based on clinical evidence was used to assess arthroplasty products tendered to Western Australia public hospitals. Generally, there was good compliance with the commercial aspects of the tender. In contrast, however, clinically based evidence assessment of many arthroplasty devices was difficult because of a distinct lack of quality published work. Inadequate quality control of several devices is also of concern. Evaluation of key performance indicators, including cost savings, acceptance by surgeons, tender compliance and revision rates, will determine the success of the tender.

Oxinium exhibits 4900 times less volumetric wear and 640 times less deep scratches in laboratory wear testing compared with traditional cobalt-chromium alloys. Despite the superior wear resistance because of the thin ceramic surface, the zirconium alloy substrate is relatively soft (Hv = 285) when compared with cobalt-chrome alloy femoral heads (ISO 5832-12; Hv = ~420,) and may deform in contact with acetabular shell materials (ISO5832-3; Hv = 350) in the case of dislocation. Three retrieval cases highlight the damage that may occur during dislocation and/or when performing closed reduction maneuvers. It is recommended that closed reduction be attempted with caution because significant head damage can occur. This may lead to accelerated polyethylene wear. In the case of successful reduction, close patient follow-up is recommended. Open reduction with femoral head inspection and exchange may be preferable if difficulty is encountered in closed reduction maneuvers.