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Clinical Perspective on Dual Energy Computed Tomography
Published in Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski, Spectral, Photon Counting Computed Tomography, 2020
Charis McNabney, Shamir Rai, Darra T. Murphy
Metal within prosthesis causes streak artefacts in CT imaging due to photon starvation, photon scatter, and excessive beam hardening. Beam hardening is due to the absorption or scatter of x-rays from the scanning beam by the metallic prosthesis, so less x-rays are registered at the detector (Barrett & Keat 2004). Conventional CT acquisition and reconstruction techniques can be applied to minimize artefact from metallic prosthesis, often at the expense of an increased radiation dose. Despite best attempts, artefacts related to metallic prosthesis in conventional CT still remain problematic (Nicolaou et al. 2012). For example, in patients with hip prosthesis, visualization of tissue adjacent to the prosthesis becomes impaired, including pelvic organs which potentially results in missed findings (Elmpt et al. 2016). Radiologists are frequently asked to assess metallic prosthesis for periprosthetic fractures, infection, aseptic loosening, metallic failure and fractures, pseudotumors, and recurrence of tumors (sarcomas) (Roth et al. 2012). MRI is also beneficial for assessment of metallic prosthesis due to superior soft tissue detail surrounding the prosthesis and sensitivity for bone edema; however, images are also prone to distortion related to metallic prosthesis (Suh et al. 1998).
Polymers for Artificial Joints
Published in Severian Dumitriu, Valentin Popa, Polymeric Biomaterials, 2020
Masayuki Kyomoto, Toru Moro, Kazuhiko Ishihara
Table 25.2 illustrates the reasons for revision in the 14,081 first revisions for THA performed in the previous study [2]. The majority (75.3%) of the revision surgeries were performed because of aseptic loosening with or without focal osteolysis, 7.6% were performed to treat primary or secondary infection, and 8.8% were performed for technical reasons and dislocation that could have been mainly related to misalignment of the implants. Periprosthetic fractures (5.1%), implant fractures (1.5%), and a number of less prevalent reasons constituted the balance of the reasons.
Metallic Biomaterials
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Joon B. Park and Young Kon Kim
Titanium derives its resistance to corrosion by forming a solid oxide layer to a thickness of 10 nm. Under in vivo conditions, the oxide (TiO2) is the only stable reaction product. However, micromotion at the cementprosthesis and cement-bone are inevitable and consequently, titanium oxide and titanium alloy particles are released in cemented joint prosthesis. Sometimes this wear debris accumulates as periprosthetic uid collections and triggers giant cell response around the implants. is cystic collection continued to enlarge and aspiration revealed a “dark” heavily stained uid containing titanium wear particles and histiocytic cells. Histological examination of the stained so tissue showed “brin necrotic debris” and collagenous, brous tissue containing a histiocytic and foreign body giant cell inltrate. e metallosis, black staining of the periprosthetic tissues, has been implicated in knee implant (Breen and Stoker, 1993).
Synthesis, characterization and applications of endophytic fungal nanoparticles
Published in Inorganic and Nano-Metal Chemistry, 2020
Ranjani S, Shariq Ahmed M, Mohd Adnan, Senthil Kumar N, Ruckmani K, Hemalatha S
The EDX analysis (Figure 4b) confirmed the synthesis of nanoparticles by showing a strong signal at 3 kev where the presence of silver is observed and other metal ions such as Si, S, Mg, Cl, N could be from the natural moieties such as phytocompounds, enzymes, proteins present in the aqueous extract of the endophytic fungi. There were previous reports supporting that silicon has potent antibacterial activity against tested Staphylococcus aureus and Escherichia coli.[18] Sulfur has good antibacterial, antifungal activity, which has been widely used for dermatological application.[19] Magnesium has very good antibacterial activity which has been used as Magnesium implants to prevent Periprosthetic infection.[20] Chlorination is the important method for disinfecting water, since chlorine is the best antimicrobial agent.[21] Nitrogen in the form of Nitric oxide is the best agent to kill the pathogens by invading the cell membrane.[22] Along with all these elements endophytic fungal silver nanoparticles works synergistically as a potent bactericidal agent.
The treatment of periprosthetic joint infection: safety and efficacy of two stage versus one stage exchange arthroplasty
Published in Expert Review of Medical Devices, 2020
Joseph R. Palmer, Tejbir S. Pannu, Jesus M. Villa, Jorge Manrique, Aldo M. Riesgo, Carlos A. Higuera
As early as 1983, two-stage exchange arthroplasty has been the gold standard treatment in the United States for chronic PJI [13]. However, there is a lack of consensus in the literature as to what constitutes a success or a failure of this procedure, which makes it difficult to compare different management strategies and success rates [14]. Moreover, due to the comorbidity associated with two surgeries versus one, two-stage might not be the best option for infections caused by susceptible organisms or those patients with either minimal comorbidities or unable to withstand two surgeries. One-stage exchange might be the best answer in those scenarios. Also, two-stage revision has been demonstrated to be associated with five-year mortality of 26% [15]. Therefore, we performed a thorough literature review of two-stage exchange arthroplasty in the setting of periprosthetic joint infection. The aim was to analyze the safety and efficacy of two-stage exchange arthroplasty, to compare the clinical outcomes reported 10 years ago with ones recently reported, and to contrast those results with the ones of one-stage arthroplasty.
Effect of posterior tibial slope and implant material on the bone-implant system following TKA: A finite element study
Published in Cogent Engineering, 2018
Ravishanker Baliga B, Raghuvir Pai B, Satish Shenoy, Atmananda Hegde K, Sharath Rao K, Shubham Swaroop, Abhijeet Shetkar
The strain distribution in the periprosthetic bone post-TKR, considering two implant materials and four different PTS were analyzed. MB components have been found to have significant consequences for stress shielding (68% volumeof bone in the flange region under reduced stresses for MB vs only 10% volumein AP) than those of AP components for the three load cases considered. Similarly, the impact of PTS (63% variation in stress patterns around the flange and keel region) on stress shielding appears to be of secondary or less significance in comparison with the implant material. AP material seems to reduce the effect of stress shielding to a large extent (60% reduction in stress shielding), compared to MB trays. Our inference, for the said loading conditions and observed strain distribution pattern, that neutral position or a 3° PTS for AP trays may be preferred have also been widely reported by clinicians and other FE studies.