965 Complication Rates in Operatively Managed Ankle Fracture/Dislocations - The Effect of Pre-Reduction Imaging and Compliance with BOAST 12 Guidance

Aim

The BOAST-12 guidelines for the management of ankle fractures aims to optimise functional recovery and reduce complications. They advise against having radiographs prior to urgent reduction of clinically deformed ankles as it could cause an unacceptable delay to subsequent management. Our study aimed to assess the effect of time to acceptable reduction on the risk of complications and time to definitive reduction.

Method

This was a retrospective observational study of patients with ankle fracture-dislocations between 2013 to 2017 at the Northern General Hospital’s Emergency Department (ED). Information collected from 2 patient groups (with and without pre-reduction radiographs), included patient demographics, time to accepted reduction, number of manipulations, operations, and subsequent complications.

Results

242 patients were identified. Time from arrival in ED to acceptable reduction was significantly longer in patients with pre-reduction radiographs versus patients without (184.5 vs 82 minutes, p < 0.00), but did not increase the overall risk of complications (p = 0.62). Pre-reduction radiographs were associated with insignificantly higher rates of post-traumatic osteoarthritis (p = 0.17) and slightly longer wait time for definitive intervention (1 vs 2 days, p = 0.72). However, this had no relationship with the number of manipulations (p = 0.53).

Conclusions

The use of pre-reduction radiographs significantly increased time to acceptable reduction of ankle fracture-dislocations. However, this was not associated with increased risk of complications or time to definitive management.

A novel behavioral model of the pasture-based dairy cow from GPS data using data mining and machine learning techniques

A better understanding of the behavior of individual grazing dairy cattle will assist in improving productivity and welfare. Global positioning systems (GPS) applied to cows could provide a means of monitoring grazing herds while overcoming the substantial efforts required for manual observation. Any model of behavioral prediction using GPS needs to be accurate and robust by accounting for inter-cow variation as well as atmospheric effects. We evaluated the performance using a series of machine learning algorithms on GPS data collected from 40 pasture-based dairy cows over 4 mo. A feature extraction step was performed on the collected raw GPS data, which resulted in 43 different attributes. The evaluated behaviors were grazing, resting, and walking. Classifier learners were built using 10 times 10-fold cross validation and tested on an independent test set. Results were evaluated using a variety of statistical significance tests across all parameters. We found that final model selection depended upon level of performance and model complexity. The classifier learner deemed most suitable for this particular problem was JRip, a rule-based learner (classification accuracy=0.85; false positive rate=0.10; F-measure=0.76; area under the receiver operating curve=0.87). This model will be used in further studies to assess the behavior and welfare of pasture-based dairy cows.

An optimized individual target brain in the Talairach coordinate system

The goal of regional spatial normalization is to remove anatomical differences between individual three-dimensional brain images by warping them to match features of a single target brain. Current target brains are either an average, suitable for low-resolution brain mapping studies, or a single brain. While a single high-resolution target brain is desirable to match anatomical detail, it can lead to bias in anatomical studies. An optimization method to reduce the individual anatomical bias of the ICBM high-resolution brain template (HRBT), a high-resolution MRI target brain image used in many laboratories, is presented. The HRBT was warped to all images in a group of 27 normal subjects. Displacement fields were averaged to calculate the "minimal deformation target" (MDT) transformation for optimization. The greatest anatomical changes in the HRBT, following optimization, were observed in the superior precentral and postcentral gyri on the right, the right inferior occipital, the right posterior temporal lobes, and the lateral ventricles. Compared with the original HRBT, the optimized HRBT showed better anatomical matching to the group of 27 brains. This was quantified by the improvements in spatial cross-correlation and between the group of brains and the optimized HRBT (P < 0.05). An intended use of this processing is to create a digital volumetric atlas that represents anatomy of a normal adult brain by optimizing the HRBT to the group consisting of 100+ normal subjects.

Transmission electron and high-voltage electron microscopy of osteocyte cellular processes extending to the dental implant surface

Examination of the morphology of osteocytes within the bone supporting endosteal dental implants was performed using conventional transmission and high-voltage transmission electron microscopy (HVEM). The in vivo dog model used 72 implants inserted into the premolar region of 18 experimental animals. Forty-eight implants in 12 dogs were used as anterior abutments for fixed bridges for periods up to 12 months. The mineralized matrix of the supporting bone was either directly apposed to the implant surface or was separated from the implant by a narrow region of unmineralized matrix. Osteocytes were routinely observed to be closely associated with the bone-implant interface, as well as at a distance from the implant. Osteocytes were found to extend cellular processes directly to the implant surface through canaliculi. The osteocyte processes contained microfilaments. The three-dimensional capabilities of HVEM elucidated the nature of these cell processes at the point of exit from the osteocyte, as the processes extended through the mineralized matrix, and as the processes terminated at the implant interface. This report suggests that avenues of communication may exist between the implant and the osseous cells, providing intriguing hypotheses regarding biomechanical forces and osteogenesis at the implant interface. Furthermore, an electron-dense deposit was observed upon the inner confines of the canalicular wall, upon the outer aspects of the osteocyte lacuna, and upon the outer aspect of the bone interfacing the implant.

Osteoblast activity at the dental implant-bone interface: transmission electron microscopic and high voltage electron microscopic observations

The purpose of this report is to present transmission electron microscopic and high voltage transmission electron microscopic (HVEM) observations of a longitudinal investigation examining the activities of osteoblasts and associated tissues apposing titanium and alumina oxide ceramic endosteal dental implants. The HVEM permitted 3-dimensional stereologic observations. All observations were obtained from undecalcified interfacial tissues from this in vivo experimental dog model using commercially available implants placed into the mandible. Two similar implants were placed in both sides of the mandible, with implants in 12 of the 18 dogs supporting fixed bridges for either 6 or 12 months. From the study, we observed that a mineralized matrix exists in direct apposition to the implant. Since bone does not interface the entire length of the implant, other interfacial zones were found to exist which consisted of unmineralized tissues. In such zones, we observed that osteoblasts were routinely found directly at the implant interface to the mandibular bone. These interfacial tissues included unmineralized collagen fibers, proteinaceous material, a finely fibrillar matrix, and the osteoblasts. This study has reinforced the concept that the oral tissue-dental implant interface is a dynamic zone consisting of remodeling activities of the osseous cells and extracellular matrices.

Osteogenesis at the dental implant interface: high-voltage electron microscopic and conventional transmission electron microscopic observations

The osteogenesis of mandibular bone to endosteal dental implants was examined using an in vivo dog model. One half of the implants examined were unloaded implants, with the remaining one half prosthodontically loaded for 6 months. Undecalcified mandibular implant samples were examined with both high-voltage electron microscopy (HVEM) stereology and routine transmission electron microscopy. The osseous interface to integrated implants was shown to vary in its morphology. Mineralized bone was observed directly apposing the implant, often separated from the implant by an electron-dense deposit of approximately 50 nm. Within this densely mineralized matrix, osteocytes were routinely observed. Adjacent areas were shown to contain slightly wider zones of either a less dense mineralized matrix or, alternatively, unmineralized tissue. Other zones consisted of wider unmineralized matrices containing collagen fibers and osteoblasts. These latter zones were consistent with the appearance of an appositional type of bone growth. Because bone is a dynamic, actively remodeling tissue, a varied morphology of the support tissues to dental implant is not unexpected. Areas of mature bone interfacing with successfully integrated implants were demonstrated, as well as areas adjacent to the mature bone that were undergoing remodeling or mineralization. This study has also shown that HVEM stereology is a valuable research tool to investigate the oral tissue interface with dental implants.

The mechanism of antler casting in the fallow deer

The process by which antlers are detached from their pedicles was examined histologically in fallow deer castrated in the autumn to induce precocious casting. Osteoclastic erosion across an abscission line between the dead bone of the antler and the living bone of the pedicle was found to be responsible for the separation of the 2. As early as 3 days after castration, osteoclasts and associated lacunae were present on the sides of the pedicle bone. These were then found in progressively deeper locations, by 2 weeks extending across the entire width of the pedicle. Concomitant with the centripetal spread of osteoclasts was the enlargement of Haversian canals, the surfaces of which became lined with osteoclasts. These widening vascular channels within the bone were filled with connective tissue, which in precasting stages formed a mesodermal pad about 1 mm thick. In later stages, a circumferential cleft was excavated beneath the antler burr, and connective tissues from the surrounding pedicle skin invaded the space between the antler and pedicle. After casting, the ingrowing integumental tissues fused with the mesodermal tissues derived from the vascular channels of the pedicle to give rise to an incipient antler bud beneath the scab. The ingrowth of epidermis capable of de novo hair follicle formation gave rise to the future velvet skin that envelops the elongating antler.

High-voltage electron microscopy and conventional transmission electron microscopy of the interface zone between bone and endosteal dental implants

The interface between mandibular bone and endosteal dental implants was examined with an in vivo dog model. Undecalcified mandibular implant samples were observed with both conventional transmission electron microscopy and high-voltage transmission electron microscopy (HVEM). Results demonstrated the variable nature of the interfacial support tissues. Mineralized bone was often found within 50 nm of the implant surface, separated from that surface only by an electron dense deposit. Osteocytes were observed close to the interface encased within lacunae extending numerous cellular processes through canaliculi. An osteoblast was also observed directly at the interface within a developing lacuna. Other interfacial areas exhibited a finely fibrillar and more electron lucent morphology. Furthermore, other areas were shown to be composed of wider zones of extracellular products containing collagen fibrils, ground substance, and calcified inclusions. Because bone is an actively growing and remodeling tissue, these different morphological zones around the entire area of the implants would appear to confirm the dynamic tissue response to endosteal dental implants. Further, HVEM stereology was shown to be an exciting research tool to investigate this tissue response.

Liquid chromatography at 3-methoxy-4-hydroxyphenylethylene glycol in urine with fluorescence detection

We describe a liquid-chromatographic procedure for determining low concentrations of 3-methoxy-4-hydroxyphenylethylene glycol in urine. After liquid-liquid extraction and cleanup of the sample, an aliquot of the extract is injected onto a reversed-phase chromatographic column, with isocratic elution with an acetonitrile/acetate buffer mobile phase. An on-line fluorescence detector is used for measuring the natural fluorescence of the compound. The method gives a relatively clean extract, which is suitable for measuring the less-than-normal concentrations associated with mentally depressed patients. Although a liquid-chromatographic technique has been recently described for measuring this compound in urine, the method involves electrochemical detection, which may not be available in many clinical laboratories, and, because of its nonspecificity, the method is only suitable for detecting the increased amounts of 3-methoxy-4-hydroxyphenylethylene glycol excreted by patients with pheochromocytoma.

Liquid chromatography at 3-methoxy-4-hydroxyphenylethylene glycol in urine with fluorescence detection

We describe a liquid-chromatographic procedure for determining low concentrations of 3-methoxy-4-hydroxyphenylethylene glycol in urine. After liquid-liquid extraction and cleanup of the sample, an aliquot of the extract is injected onto a reversed-phase chromatographic column, with isocratic elution with an acetonitrile/acetate buffer mobile phase. An on-line fluorescence detector is used for measuring the natural fluorescence of the compound. The method gives a relatively clean extract, which is suitable for measuring the less-than-normal concentrations associated with mentally depressed patients. Although a liquid-chromatographic technique has been recently described for measuring this compound in urine, the method involves electrochemical detection, which may not be available in many clinical laboratories, and, because of its nonspecificity, the method is only suitable for detecting the increased amounts of 3-methoxy-4-hydroxyphenylethylene glycol excreted by patients with pheochromocytoma.

Effect of puromycin on the ultrastructure of keratohyalin granules

Keratohyalin granules (KHG) from control and puromycin-treated hamster cheek pouch epithelium were studied by electron microscopy. The animals were killed 1-4 hours after injection with 75-100 microgram puromycin per gram body weight; controls were injected with saline. The KHG from control animals were round or oval and consisted of a finely granular background matrix containing many small, round, homogeneous electron-dense deposits. The KHG from puromycin-treated animals showed marked variation in morphology and size. They consisted of a coarse granular or speckled matrix and round, club-shaped or comma-shaped electron-dense deposits. Since puromycin is known to inhibit protein synthesis, alterations in KHG structure support previous reports suggesting the protein nature of KHG.