Fixed-angle locking proximal humerus plate: an evaluation of functional results and implant-related outcomes

Background
Displaced and unstable proximal humeral fractures are challenging injuries to treat. Proximal humeral locking plates are a recent development for the treatment of these complex fractures.

Methods
Retrospective analysis of 23 patients with 23 proximal humeral fractures treated with the Synthes locking proximal humerus plate. These were Neer two-, three- and four-part fractures. Follow-up was at a mean of 22 months and included clinical assessment using the Constant score (CS) and the Short Form-12 health questionnaire. Radiographic assessment was performed to assess implant-related complication in relation to the initial fracture pattern and the presence of adequate medial support.

Results
The mean CS for all patients was 60.4 (range, 29–85). The mean adjusted CS was 82% (range, 30–117), active forward flexion 127 degrees and the active abduction 115 degrees. Initial fracture pattern, the presence or absence of adequate medial support and age did not significantly influence the clinical scores. Complications included one infection, two cases of avascular necrosis, two cases of varus collapse with screw penetration and one non-union. The overall reoperation rate was 26%. There was an increased rate of complications in those with inadequate medial support (P = 0.0183) and a trend to higher complication rates in four-part fractures.

Conclusion
Using the locking proximal humerus plate for the treatment of proximal humeral fractures is an acceptable procedure with comparable outcomes with historical controls, but with a complication rate of 30%. More important than implant selection, however, is the ability to achieve a stable reduction with calcar support.

Corticomotor responses to attentionally demanding motor performance: a mini-review

Increased attentional demand has been shown to reduce motor performance, leading to increases in accidents, particularly in elderly populations. While these deficits have been well documented behaviorally, their cortical correlates are less well known. Increased attention has been shown to affect activity in prefrontal regions of the cortex. However there have been varying results within past research investigating corticomotor regions, mediating motor performance. This mini-review initially discusses past behavioral research, before moving to studies investigating corticomotor areas in response to changes in attention. Recent dual task studies have revealed a possible decline in the ability of older, but not younger, adults to activate inhibitory processes within the motor cortex, which may be correlated with poor motor performance, and thus accidents. A reduction in cortical inhibition may be caused by neurodegeneration within prefrontal regions of the cortex with age, rendering older adults less able to allocate attention to corticomotor regions.

Ti-SrO metal matrix composites for bone implant materials

Titanium-strontia (Ti-SrO) metal matrix composites (MMCs) with 0, 1, 3 and 5% (weight ratio) of SrO have been fabricated through the powder metallurgy method. Increasing the weight ratio of SrO from 0 to 5%, the compressive strength of Ti-SrO MMCs increased from 982 MPa to 1753 MPa, while the ultimate strain decreased from 0.28 to 0.05. The elastic moduli of Ti-3SrO and Ti-5SrO MMCs were higher than those of Ti and Ti-1SrO MMC samples. Additionally, the micro hardness of Ti-SrO MMCs was enhanced from 59% to 190% with the addition of SrO. The enhanced compression strength and micro hardness of Ti-SrO MMCs were attributed to the Hall-Petch effect and the SrO dispersion strengthening in the Ti matrix. MTS assay results demonstrated that Ti-SrO MMCs with 3% SrO exhibited enhanced proliferation of osteoblast-like cells. Alkaline phosphatase activity of cells was not influenced significantly on the surface of Ti-SrO MMCs compared with pure Ti in a term longer than 10 days. The cell morphology on the Ti-SrO MMCs was observed using confocal microscopy and scanning electron microscopy, which confirmed that the Ti-3%SrO MMCs showed optimal in vitro biocompatibility. This journal is © the Partner Organisations 2014.

Mini-micro unmanned aerial vehicle intelligence: a threat to land vehicles

Increasing use of commercial off-the-shelf Mini-Micro Unmanned Aerial Vehicle (MAV) systems with enhanced intelligence methodologies can potentially be a threat, if this technology falls into the wrong hands. In this study, we investigate the level of threat imposed on critical infrastructure using different MAV swarm artificial intelligence traits and coordination methodologies. The critical infrastructure in consideration is a moving commercial land vehicle that may be transporting for example an important civil servant or politician. Non-dimensional fitness functions used for measuring MAV mission effectiveness have been established for the case studies considered in this paper. The findings indicated that increased in intelligent and coordination level elevate teams' efficiency, therefore poses a higher degree of threat to targeted land vehicle. Observations from the study have suggested that memory-based cooperative technique provides a consistent efficiency compared to other methods for the mission objectives considered in this paper. © 2014 The authors and IOS Press. All rights reserved.

Mechanical properties and microstructure of powder metallurgy Ti-xNb-yMo alloys for implant materials

In this study, a series of Ti-xNb-yMo (x = 5-40 wt.% in 5 wt.% increments; and y = 3, 5, 10 wt%) alloys were fabricated by powder metallurgy and studied with respect to their microstructures, compressive mechanical properties and hardness. Increases in Nb and Mo content led to decreases in compressive and yield strengths, elastic modulus and hardness of the sintered alloys. Among the studied alloys, Ti-10Nb-3Mo alloy exhibited the optimum combination of strength and ductility. Alloys with a lower amount of Nb (≤ 25 wt.%) and Mo (≤ 5 wt.%) developed Widmanstätten structure, while further increase in Nb and Mo additions led to the microstructure predominantly consisting of β phase with varying regions of α + β phase. The effects of sintering temperature on elastic modulus and hardness were also investigated for Ti-xNb-3Mo alloys.

Effects of zirconium and strontium on the biocorrosion of Mg-Zr-Sr alloys for biodegradable implant applications

The successful applications of magnesium (Mg) alloys as biodegradable orthopedic implants are mainly restricted due to their rapid degradation rate in the physiological environment, leading to a loss of mechanical integrity. This study systematically investigated the degradation behaviors of novel Mg-Zr-Sr alloys using electrochemical techniques, hydrogen evolution, and weight loss in simulated body fluid (SBF). The microstructure and degradation behaviors of the alloys were characterized using optical microscopy, XRD, SEM, and EDX. The results indicate that Zr and Sr concentrations in Mg alloys strongly affected the degradation rate of the alloys in SBF. A high concentration of 5 wt% Zr led to acceleration of anodic dissolution, which significantly decreased the biocorrosion resistance of the alloys and their biocompatibility. A high volume fraction of Mg17Sr2 phases due to the addition of excessive Sr (over 5 wt%) resulted in enhanced galvanic effects between the Mg matrix and Mg17Sr2 phases, which reduced the biocorrosion resistance. The average Sr release rate is approximately 0.15 mg L^-1 day^-1, which is much lower than the body burden and proves its good biocompatibility. A new biocorrosion model has been established to illustrate the degradation of alloys and the formation of degradation products on the surface of the alloys. It can be concluded that the optimal concentration of Zr and Sr is less than 2 wt% for as-cast Mg-Zr-Sr alloys used as biodegradable orthopedic implants.

Microstructure and mechanical properties of Ti-15Zr alloy used as dental implant material

Ti-Zr alloys have recently started to receive a considerable amount of attention as promising materials for dental applications. This work compares mechanical properties of a new Ti-15Zr alloy to those of commercially pure titanium Grade4 in two surface conditions - machined and modified by sand-blasting and etching (SLA). As a result of significantly smaller grain size in the initial condition (1-2µm), the strength of Ti-15Zr alloy was found to be 10-15% higher than that of Grade4 titanium without reduction in the tensile elongation or compromising the fracture toughness. The fatigue endurance limit of the alloy was increased by around 30% (560MPa vs. 435MPa and 500MPa vs. 380MPa for machined and SLA-treated surfaces, respectively). Additional implant fatigue tests showed enhanced fatigue performance of Ti-15Zr over Ti-Grade4.

Validation of the SenseWear Mini activity monitor in 5-12-year-old children

OBJECTIVES: This study aimed to validate SenseWear Mini software algorithm versions 2.2 (SW2.2) and 5.2 (SW5.2) for estimating energy expenditure (EE) in children. DESIGN: Laboratory-based validation study. METHODS: 57 children aged 5-12 y completed a protocol involving 15 semi-structured sedentary (SED), light-intensity (LPA), and moderate- to vigorous-intensity (MVPA) physical activities. EE was estimated using portable indirect calorimetry (IC). The accuracy of EE estimates (kcal·min(-1)) from SW2.2 and SW5.2 were examined at the group level and individual level using the mean absolute percentage error (MAPE), Bland-Altman plots and equivalence testing. RESULTS: MAPE values were lower for SW5.2 (30.1±10.7%) than for SW2.2 (44.0±6.2%). Although mean differences for SW5.2 were smaller than for SW2.2 during SED (-0.23±0.22 vs. -0.61±0.20kcal·min(-1)), LPA (-0.69±0.76 vs. -1.07±0.46kcal·min(-1)) and MVPA (-2.22±1.15 vs. -2.57±1.15kcal·min(-1)), limits of agreement did not decrease for the updated algorithms. For all activities, SW2.2 and SW5.2 were not equivalent to IC (p>0.05). Errors increased with increasing intensity. CONCLUSION: The current SenseWear Mini algorithms SW5.2 underestimated EE. The overall improved accuracy for SW5.2 was not accompanied with improved accuracy at the individual level and EE estimates were not equivalent to IC.

Fabrication of biocompatible enclosures for an electronic implant using 3D printing

A variety of different approaches have been employed to enableimplantation of electronic medical microdevices. A novel method of producing low-cost, rapidly fabricated implantable enclosures from biocompatible silicone is presented in this paper. This method utilises 3D computer-aided design software to design and model the enclosures prior to fabrication. The enclosures are then fabricated through additive manufacturing from biocompatible silicone using a 3D bioprinter. In this paper, four different implantable enclosure designs are presented. A prototyping stage with three different prototypes is described, these prototype enclosures are then evaluated through submersion and operation tests. A final design is developed in response to the obtained results, and then evaluated in a long term temperature controlled submersion test. The evaluation results are presented and discussed.Several areas of future works are identified and discussed.