Visibility of Transcondylar Screw Fractures in Standard and Extended Scale Computed Tomography Images

Objective Application of extended computed tomography scale (ECTS) reconstruction to diagnose metal implant failure has been described in a single case report. The purpose of this study was to compare the features and visibility of humeral transcondylar screw fractures in standard CT scale (SCTS) and ECTS images. Study Design Case series: CT images of dogs with fractured transcondylar screws were retrospectively reviewed and described in both SCTS and ECTS images. Results Five dogs with a total of six transcondylar screw failures (five right and one bilateral) were reviewed. All cases had an ongoing humeral intercondylar fissure with varying degrees of stress remodelling. The fracture was seen in all screws on ECTS images, however only in three implants on SCTS images. The measured fracture gap was larger in ECTS images in all cases (range: + 0.14 mm to + 0.28mm). The three smallest fracture gaps were not seen on SCTS images. A subtle hypoattenuating streak (artefact) was visible adjacent to the screw fracture in 5/6 of cases using SCTS images. All screw fractures occurred parallel and often slightly medial to the humeral intercondylar fissure. Conclusion Implant failure is only seen with larger fracture gaps in SCTS images, with 3/6 screw fractures not visible in SCTS compared with ECTS. A hypoattenuating streak extending perpendicular to the implant in SCTS images is suggestive of screw fracture even if this is not directly visible.

Performance Comparison Study of Several Interpolation Methods on Streak Metal Artifacts Reduction of CT Images

In the course of generating the CT images, the streak metal artifacts emerge from the reconstructed images, often degraded the quality of the images and blur the fringe information around the metal implant. Although a number of attempts had been reported, among them, our proposed interpolation-based method is the simplest and most efficient approaches. In this paper, three interpolation approaches are compared with subjective and objective criterion based on both simulation and clinical cases. Our results have shown an improvement from the original images. As for the comparison with NRMSD and MAD. For the execution time, the L-MAR possesses the shortest time with S-MAR time being the slowest among the interpolation-based methods. For NRMSD and MAD, the digits from small to large are P-MAR, S-MAR, L-MAR and original. This shows that among interpolation-based methods the image corrected by P-MAR approach is the closest to the ideal image, followed by S-MAR correction, L-MAR correction, and the gap between the original image and the ideal image is the largest.

Non-contact induction heating and SAAP-148 eliminate persisters within MRSA biofilms mimicking a metal implant infection

Implant-associated infections are the primary cause of complications following orthopaedic surgery. Due to biofilm and persister formation, current treatments, i.e. surgical debridement followed by antibiotics, often fail. There is an urgent need for alternative strategies to combat such infections. Therefore, the present study investigated the effects of non-contact induction heating (NCIH), the antimicrobial peptide SAAP-148 and combinations thereof on bacterial counts in 7 d mature biofilms and in persister-enriched biofilms of methicillin-resistant Staphylococcus aureus (MRSA) on titanium-aluminium-niobium (TAN) discs. Enrichment of persisters was achieved by daily exposure of mature biofilms to high doses of rifampicin and ciprofloxacin for 3 consecutive days. To heat up the TAN discs, a miniaturised induction heater was built and successfully validated. Using this apparatus, NCIH resulting in surface temperatures up to 85 °C eradicated all the bacteria in immature biofilms but not in mature biofilms, whereas persisters were already eliminated at surface temperatures ≥ 70 °C. SAAP-148 at concentrations > 25.6 µmol/L reduced the persister counts in antibiotics-exposed, mature biofilms. As surface temperatures > 60 °C can have detrimental effects on the surrounding tissues, the maximum temperature of NCIH used in combination with SAAP-148 on persisters was set to 60 °C. Results revealed that this combination was slightly more effective than the peptide or NCIH alone in eliminating biofilm-embedded persisters. NCIH and SAAP-148 can be applied both invasively and non-invasively in various treatment scenarios. Together, combinations of NCIH and SAAP-148 might be a promising treatment strategy to combat metal-implant-associated infections.

Study on Mechanical Property and Biocompatibility in Vitro of 3D Printing Tantalum- Niobium Alloy Implants.

tooth defects or deletions. Tantalum (Ta) has been widely used in the biomedical field, but its application in artificial dental implants is rarely reported. In this study, Tantalum-Niobium alloy (TaNb40) implant prepared by 3D printing—SLS was used as the research subject. Its mechanical properties in vitro and the biocompatibility by utilizing human Oral Mucosa Fibroblasts (hOMF) were studied. Results: The mechanical property test results were that the Tensile Strength, Yield Strength, Elongation, and Vickers hardness of TaNb40 implant was 548 ± 50MPa, 420 ± 30MPa, 40%, and 425HV, respectively, manifesting the two indicators met the requirements of dental metal implant, and had good mechanical properties of wear resistance and not easy to brittle fracture. The cytocompatibility test showed that TaNb40 did not inhibit cell proliferation and produce cell cycle arrest. The cytotoxicity grade was 1, there was almost no metal ion release in the culture medium, and the surface had fine cell early adhesion, which met the requirements of biomedical materials. Conclusion: The TaNb40 prepared by domestic 3D printing—SLS has excellent mechanical properties and cytocompatibility in vitro, which is expected to replace the Titanium metal implant prepared by the traditional casting method, having a leading significance for the formation of implants with independent intellectual property rights.