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Artifact appearance in 3 T MRI PDw TSE (FS) in two positions of the screw (0°/90°)

Artifact appearance in 3 T MRI PDw TSE (FS) in two positions of the screw (0°/90°)

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Background Magnesium alloys have recently been rediscovered as biodegradable implants in musculoskeletal surgery. This study is an ex-vivo trial to evaluate the imaging characteristics of magnesium implants in different imaging modalities as compared to conventional metallic implants. MethodsA CE-approved magnesium Herbert screw (MAGNEZIX®) and a t...

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... It has mechanical properties more similar to that of bone than other metals used for fixation screws [16]. In radiographic images, magnesium metal screws have been shown to have a good visibility and produce fewer artifacts than alternative metallic screws, which could be beneficial during the post-operative follow-up [17][18][19]. As magnesium degrades, its metallic structure is transformed from metallic magnesium into magnesium salts, which are subsequently resorbed by the body [20,21]. ...
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Nowadays, the most commonly used fixation systems are non-resorbable, but new re-sorbable magnesium alloy fixation screws have been introduced recently. Therefore, the aim of this study was to compare the magnesium fixation screw and the commonly used non-resorbable titanium screw in an animal model. Four 3-wall defect sites were covered with collagen membranes in the mandible of twenty beagle dogs (two sites on the left and two on the right). Each membrane was fixed with either four magnesium screws or four titanium screws. Post-operative follow-up revealed the expected observations such as transient inflammation and pain. Both groups showed a good healing response, with no differences between groups. Micro-CT analysis showed no significant difference between groups in terms of BV/TV or soft tissue volume. The void volume in the magnesium fixation screw group continued to decrease on average between the different timepoints, but not significantly. Furthermore, a gradual progression of the degradation process of the magnesium screws was observed in the same group. Magnesium screws and titanium screws showed equal performance in tissue regeneration according to GBR principles. An additional advantage of magnesium screws is their resorbable nature, which eliminates the need for a second surgical step to remove the screws.
... computed tomography (MDCT), and magnetic resonance imaging (MRI). All help with post-operative follow-up [10,11]. A variety of plasma electrolytic oxidation (PEO) coating procedures were developed in order to improve corrosion resistance and cytocompatibility and bioactivity of Mg alloys. ...
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Magnesium (Mg)-based degradable alloys have attracted substantial attention for tissue engineering applications due to their biodegradability and potential for avoiding secondary removal surgeries. However, insufficient data in the existing literature regarding Mg’s corrosion and gas formation after implantation have delayed its wide clinical application. Since the surface properties of degradable materials constantly change after contact with body fluid, monitoring the behaviour of Mg in phantoms or buffer solutions could provide some information about its physicochemical surface changes over time. Through surface analysis and spectroscopic analysis, we aimed to investigate the structural and functional properties of degradable disks. Since bubble formation may lead to inflammation and change pH, monitoring components related to acidosis near the cells is essential. To study the bubble formation in cell culture media, we used a newly developed Mg alloy (based on Mg, zinc, and calcium), pure Mg, and commercially available grade 2 Titanium (Ti) disks in Dulbecco’s Modified Eagle Medium (DMEM) solution to observe their behaviour over ten days of immersion. Using surface analysis and the information from near-infrared spectroscopy (NIRS), we concluded on the conditions associated with the medical risks of Mg alloy disintegration. NIRS is used to investigate the degradation behaviour of Mg-based disks in the cell culture media, which is correlated with the surface analysis where possible.
... Magnesium is a nontoxic biodegradable material that has a certain mechanical strength [8,16]. Magnesium, however, undergoes rapid corrosion when in contact with chloride ions in body fluids, causing hydrogen gas formation and deterioration of strength [8,17,18]. Its resorption rate is difficult to control and, as such, magnesium has little to no clinical value as a bone fixation material. ...
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Background Resorption of magnesium-based alloy bioabsorbable screws produces hydrogen gas, which can be mistaken as a sign of infection and may affect the physis or fixed bone fragment. Objective We evaluated the temporal and spatial occurrence of gas and the occurrence of a breakage of the fixed bone fragment or screw following magnesium screw fixation. Materials and methods Radiographs of paediatric patients treated with magnesium screws were retrospectively reviewed. Temporal occurrence and distribution of gas in the bone, the physis and soft tissues, breakage of the screw or fixed bone fragment and joint effusion were assessed. Results One hundred and three radiographs in 35 paediatric patients were reviewed (mean age: 10.6 years). Follow-up ranged from 1 to 730 days. Gas in the bone increases up to week 5, remains constant up to week 16 and then decreases. Gas in soft tissues, intra-articular gas and joint effusions gradually reduce over time. In 1/23 (4.3%) patients with an open physis, gas intrusion into the physis occurred. Breakage of the bone fragment fixated by the screw was observed in 4/35 (11.4%) patients within the first 6 weeks. Screw breakage was observed in 16/35 (45.7%) patients, with a median time to first detection of 300 days. Conclusion Gas bubbles in bone and soft tissue are normal findings in the context of screw resorption and should not be confused with soft-tissue infection or osteomyelitis. Gas is rarely visible in the physis. Breakage of the fixed bone fragment and/or screw can occur.
... In addition, traditional implants generate significantly more artifacts in common imaging modalities (e.g., digital radiography, magnetic resonance imaging, and computed tomography) and can create more artifact-induced noise and signal distortion in postoperative imaging [9,10]. Prior research has attempted to overcome these limitations, the most effective of which is the utilization of biodegradable metallic devices. ...
Article
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Magnesium alloys exhibit superior biocompatibility and biodegradability, which makes them an excellent candidate for artificial implants. However, these materials also suffer from lower corrosion resistance, which limits their clinical applicability. The corrosion mechanism of Mg alloys is complicated since the spontaneous occurrence is determined by means of loss of aspects, e.g., the basic feature of materials and various corrosive environments. As such, this study provides a review of the general degradation/precipitation process multifactorial corrosion behavior and proposes a reasonable method for modeling and preventing corrosion in metals. In addition, the composition design, the structural treatment, and the surface processing technique are involved as potential methods to control the degradation rate and improve the biological properties of Mg alloys. This systematic representation of corrosive mechanisms and the comprehensive discussion of various technologies for applications could lead to improved designs for Mg-based biomedical devices in the future.
... 4,5 Actually there are not enough commercially available magnesium devices, but research is highly concentrated on their development. 6 Improving the corrosion resistance property of this metal requires an in-depth understanding of the mechanism of corrosion. 7−9 Corrosion scientists have applied several corrosion-monitoring techniques to study the degradation pattern of Mg and its alloys in physiological systems. ...
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Dynamic electrochemical impedance spectroscopy (dynamic EIS) has the capacity to track changes on surfaces in a changing corrosive system, an advantage it holds over classical EIS. We used the dynamic EIS approach to provide insight into the corrosion behavior of the AZ91D Mg alloy in simulated body fluid for 30 h at 25 °C. The results reveal that the impedance response of the alloy is influenced by the immersion time. Between 0 and 7 h, impedance with three-time constants was obtained, whereas two-time-constant impedance spectra were obtained between 8 and 30 h of immersion. The results confirm the breakdown of the corrosion product at longer immersion times.
... The elastic modulus of magnesium is closer to that of bone than that of other metals used for implants; approximately 45 GPa, which is closer to cortical bone (5-23 GPa) than for example titanium (100-125 GPa) [31]. A common issue with the implantation of titanium implants is the production of artefacts during post-operative radiographic analysis [9], however in comparison, magnesium screws generate significantly fewer image artefacts in common imaging modalities of radiography, CT and MRI [32]. Therefore, the use of magnesium screws may facilitate the post-operative follow-up. ...
Article
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An ideal fixation system for guided bone (GBR) regeneration in oral surgery must fulfil several criteria that includes the provision of adequate mechanical fixation, complete resorption when no longer needed, complete replacement by bone, as well as be biocompatible and have a good clinical manageability. For the first time, a biodegradable magnesium fixation screw made of the magnesium alloy WZM211 with a MgF 2 coating has been designed and tested to fulfill these criteria. Adequate mechanical fixation was shown for the magnesium fixation screw in several benchtop tests that directly compared the magnesium fixation screw with an equivalent poly-meric resorbable device. Results demonstrated slightly superior mechanical properties of the magnesium device in comparison to the polymeric device even after 4 weeks of degradation. Biocompatibility of the magnesium fixation screw was demonstrated in several in vitro and in vivo tests. Degradation of the magnesium screw was investigated in in vitro and in vivo tests, where it was found that the screw is resorbed slowly and completely after 52 weeks, providing adequate fixation in the early critical healing phase. Overall, the magnesium fixation screw demonstrates all of the key properties required for an ideal fixation screw of membranes used in guided bone regeneration (GBR) surgeries.
... At this point, it should be noted that titanium (and even more so chromium-cobalt) fixations significantly degrade the CT image and reduce its diagnostic power. It is noteworthy that magnesium, as a lighter metal alloy, causes fewer artifacts in CT images [48]. This allows for a more accurate analysis of CT images, especially subtle changes around the screw heads such as resorption (which often determines their removal). ...
Article
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Titanium alloys are used in skeletal surgery. However, once bone union is complete, such fixation material becomes unnecessary or even harmful. Resorbable magnesium materials have been available for several years (WE43 alloy). The aim of this study was to clinically compare magnesium versus titanium open reduction and rigid fixations in mandible condylar heads. Ten patients were treated for fractures of the mandibular head with magnesium headless compression screws (2.3 mm in diameter), and 11 patients were included as a reference group with titanium screws (1.8 mm in diameter) with similar construction. The fixation characteristics (delay, time, and number of screws), distant anatomical results (mandibular ramus height loss, monthly loss rate, and relative loss of reconstructed ramus height), basic functional data (mandibular movements, facial nerve function, and cutaneous perception) and the influence of the effects of the injury (fracture type, fragmentation, occlusion, additional fractures, and associated diseases) on the outcome were evaluated. The long-term results of treatment were evaluated after 18 months. Treatment results similar to those of traditional titanium fixation were found with magnesium screws. Conclusions: Resorbable metal screws can be a favored option for osteosynthesis because surgical reentry can be avoided. These materials provide proper and stable treatment results.
... In conventional radiography, Mg screws show a reduced attenuation of X-rays compared to titanium screws. In computed tomography (CT) and magnetic resonance imaging (MRI), Mg screws generate substantially fewer artifacts compared to titanium screws and may therefore facilitate postoperative imaging follow-up [19,20]. Especially in the first postoperative months, the expected (hydrogen) gas formation can be observed within the bone and the soft tissues around the implant due to the corrosion process of the Mg implant. ...
... The lower mass magnetic susceptibility of Mg (6.9 × 10 −9 m 3 /kg) compared to titanium (4.01 × 10 −8 m 3 /kg) [24] explains why the screw borders appeared sharply demarcated and the artifact was mainly limited to a signalloss area with a thin bright pile-up margin without significant geometric distortions or blooming artifacts in all postoperative controls in the present study. These findings correspond to ex vivo studies that reported Mg screws generating significantly fewer artifacts in MRI compared to conventional titanium [19,20]. ...
Article
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Objectives This study aimed to examine the alterations in magnetic resonance imaging (MRI) characteristics of bioabsorbable magnesium (Mg) screws over time in a single center study in humans. Methods Seventeen patients who underwent medial malleolar (MM) fracture or osteotomy fixation using bioabsorbable Mg screws and had at least one postoperative MRI were included in this retrospective study. Six of them had more than one MRI in the postoperative period and were subject of the artifact reduction measurements. 1.5T or 3T MRI scans were acquired in different periods in each patient. The size and extent of the artifact were assessed independently by two experienced radiologists both quantitatively (distance measurement) and qualitatively (Likert scale). Results In the quantitative measurements of the six follow-up patients the screw’s signal loss artifact extent significantly decreased over the time, regardless of the MRI field strength (p<0.001). The mean artifact reduction was 0.06 mm (95% confidence interval [CI]: 0.05–0.07) for proton density weighted [PDw] and 0.04 mm (95% CI: 0.03–0.05) for T1 weighted (T1w) sequences per week. The qualitative assessments similarly showed significant artifact reduction in all MRI sequences. Different imaging findings, like bone marrow edema (BME), liquid collections, and gas formation were reported. The overall inter-reader agreement was high (κ=0.88, p<0.001). Conclusions The time-dependent artifact reduction of Mg screws in postoperative controls might indicate the expected self-degradation of the Mg implants. In addition, different MRI findings were reported, which are characteristic of Mg implants. Further MRI studies are required to get a better understanding of Mg imaging properties.
... A few years after this trial was completed, extra supportive findings and results were published into a further descriptive research article by Sonnow et al. where the experiments are discussed in greater detail [36]. ...
... Of the studies mentioned in this review, only Li et al., Plaass et al., and Lai et al. successfully observe the presence of gas in their MRI results, or lack thereof. Although no reports on gas formation in their study, Sonnow et al. suggest that future investigations be aimed at further differentiation of air, gas formation, and artifacts around implant site [36]. The ability to observe gas formation around Mg implants promote MRI as a compatible imaging modality. ...
... Artifact production of Magnesium and Titanium in two views of the screw using 3T MRI[36]. ...
Article
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Magnesium-based implants are re-emerging as a substantial amendment to standard orthopaedic implants. A brief introduction of magnesium (Mg) as a biodegradable material and basic magnetic resonance imaging (MRI) principles are discussed. This review aims to highlight the current performance of these implants during examinations with MRI. We also aim to summarise comparisons between Mg-based implants with current standards to emphasise the promotion of biodegradable implants in clinical practice. A comprehensive search of current literature on Mg-based implants and the utilisation of MRI in the studies was performed. Additionally, recorded artefact behaviour of Mg-based implants during MRI was investigated. A total of nine studies were included in which MRI was employed to image Mg-based implants. Of those studies, four of the nine discuss artefact production caused by the implants. MRI successfully imaged regions of interest over all and produced fewer artefacts than other materials used in the studies. MRI was employed in contrast angiography, bone growth observation, bone infection healing, and blood perfusion. Imaging capabilities of an implant material are vital to translating products into clinical application. Positive findings presented in this review suggest and support the use of Mg-based implants due to their successful visual compatibility with MRI techniques.
... One of them is the biodegradation of Mg, which exhibits gas formation upon implantation [9]. There are many technologies to measure the Mg degradation and its effects including computed tomography (CT) [10], synchrotron-radiation-based computer microtomography (SRµCT) [11], positron emission tomography (PET) [12], magnetic resonance imaging (MRI) [13], and ultrasound photoacoustic (USPA) [14]. However, the bubble formation needs to be investigated extensively. ...