Guidelines for Accurate Multi-Temporal Model Registration of 3D Scanned Objects.

Changes in object morphology can be quantified using 3D optical scanning to generate 3D models of an object at different time points. This process requires registration techniques that align target and reference 3D models using mapping functions based on common object features that are unaltered over time. The goal of this study was to determine guidelines when selecting these localized features to ensure robust and accurate 3D model registration. For this study, an object of interest (tibia bone replica) was 3D scanned at multiple time points, and the acquired 3D models were aligned using a simple cubic registration block attached to the object. The size of the registration block and the number of planar block surfaces selected to calculate the mapping functions used for 3D model registration were varied. Registration error was then calculated as the average linear surface variation between the target and reference tibial plateau surfaces. We obtained very low target registration errors when selecting block features with an area equivalent to at least 4% of the scanning field of view. Additionally, we found that at least two orthogonal surfaces should be selected to minimize registration error. Therefore, when registering 3D models to measure multi-temporal morphological change (e.g., mechanical wear), we recommend selecting multiplanar features that account for at least 4% of the scanning field of view. For the first time, this study has provided guidelines for selecting localized object features that can provide accurate 3D model registration for 3D scanned objects.

In vitro method to quantify and visualize mechanical wear in human meniscus subjected to joint loading.

The mechanical wear and tear of soft connective tissue from repetitive joint loading is a primary factor in degenerative joint disease, and therefore methods are needed to accurately characterize wear in joint structures. Here, we evaluate the accuracy of using a structured light 3D optical scanning system and modeling software to quantify and visualize volume loss in whole human meniscus subjected to in vitro joint loading. Using 3D printed meniscus replicas with known wear volumes, we determined that this novel imaging method has a mean accuracy of approximately 13 mm3, corresponding to a mean error of less than 7% when measuring meniscal volumetric changes of 0.2 cm3 (size of a pea). The imaging method was then applied to measure the in vitro wear of whole human menisci at four time points when a single cadaveric knee was subjected to one million cycles of controlled joint loading. The medial and lateral menisci reached steady state volumetric reductions of 0.72 cm3 and 0.34 cm3 per million cycles, respectively. Colorimetric maps of linear wear depth revealed high wear and deformation in the posterior regions of both the medial and lateral menisci. For the first time, this study has developed a method to accurately characterize volume loss in whole meniscus subjected to in vitro joint loading. This 3D scanning method offers researchers a new investigative tool to study mechanical wear and joint degeneration in meniscus, and other soft connective tissues.

A Cold Atmospheric Pressure Plasma Discharge Device Exerts Antimicrobial Effects.

A cold atmospheric pressure plasma device was developed using two parallel plates of Low Temperature Co-fired Ceramic with embedded electrodes. The 2.4 cm wide by 1 mm deep plasma discharge operates at 20 kHz with a 2-5 kV AC drive signal across a 0.25 mm gap. Mixed Argon/oxygen plasmas were directed between the plates to flow toward a bacterial biofilm sample for treatment. Results showed that at 4-5 kV the plasma etched away a bacterial biofilm on glass in 10 minutes. In addition, we showed that short plasma treatments rapidly killed biofilm resident bacteria with ED90 values of <15 s.

Adverse effects of spinal manipulative therapy in children younger than 3 years: a retrospective study in a chiropractic teaching clinic.

OBJECTIVE: The purpose of this study is to identify any adverse effects to chiropractic care occurring in the pediatric patient and to evaluate the risk of complications arising in the pediatric patient resulting from chiropractic care. METHODS: A 3-year retrospective study of pediatric case files from the Anglo-European College of Chiropractic (AECC) (Bournemouth, England) teaching clinic practice in Bournemouth, England. All files (n = 781) of pediatric patients younger than 3 years of age were selected manually in sequential order from current files stored in the AECC clinic presenting to the AECC clinic during a specific period. Most (73.5%) patients presenting were 12 weeks of age or younger (n = 574). RESULTS: Six hundred ninety-seven children received a total of 5242 chiropractic treatments, with 85% of parents reporting an improvement. Seven parents reported an adverse effect. There was a reaction rate of approximately 1 child in 100, or one reaction reported for every 749 treatments. There were no serious complications resulting from chiropractic treatment (reactions lasting >24 hours or severe enough to require hospital care). CONCLUSION: This study shows that for the population studied, chiropractic manipulation produced very few adverse effects and was a safe form of therapy in the treatment of patients in this age group.