Assessing the Use of DNA Detection Platforms Combined with Passive Wind-Powered Spore Traps for Early Surveillance of Potato and Tomato Late Blight in Canada.

Quantitative PCR (qPCR), loop-mediated amplification (LAMP), and lateral flow strip-based recombinase polymerase amplification (RPA-LFS) assays were assessed for early detection of Phytophthora infestans, the global causal agent of potato and tomato late blight, on passive wind-powered spore traps known as Spornados. Spore traps were deployed in potato and tomato fields during the 2018, 2019, and 2020 growing seasons in the provinces of Alberta, British Columbia, Manitoba, Prince Edward Island, and Ontario. All assays used DNA extracts from Spornado cassette membranes targeting the P. infestans nuclear ribosomal internal transcribed spacer. A total of 1,003 Spornado samples were qPCR tested, yielding 115 positive samples for P. infestans spores. In further assessment of these samples, LAMP detected P. infestans in 108 (93.9%) of 115 qPCR positive samples, and RPA-LFS detected it in 103 (89.6%). None of the assays showed cross-reaction with other Phytophthora species or pathogenic fungi known to infect potato and tomato. The qPCR detected ≤1 fg of P. infestans DNA, and LAMP and RPA-LFS amplified 10 fg in as little as 10 min. All assays detected P. infestans before the first report of late blight symptoms in commercial potato or tomato fields within each region or province. The combination of Spornado passive samplers with qPCR, LAMP, or RPA-LFS proved a valuable spore trapping system for early surveillance of late blight in potato and tomato. Both LAMP and RPA-LFS showed potential as alternative approaches to qPCR for in-field monitoring of P. infestans.

Limb lengthening by the Vilarrubias method: the Sheffield Children's Hospital experience.

The Vilarrubias method of limb lengthening is a percutaneous procedure with soft tissue releases. This reduces soft tissue tension and prevents joint contractures during longer lengthenings. This method has been used for 99 lower limb lengthenings. The mean length gained was 92 mm and the mean Bone Healing Index was 41.3 days/cm. There were 45 pin site problems, 33 flexion contractures, 33 angular deformities and 15 stress fractures. This complication rate compares well with other techniques. We recommend that the Vilarrubias method can be considered for lengthenings, where the aim is greater than 15% of the bone length with potential soft tissue problems.

The radiographic classification of the bone-screw interface in paediatric tibial lengthening.

Bone-screw loosening in monolateral external fixators is a significant problem. This study classifies the radiographic appearance of the bone-screw interface and predicts which screws will become loose and those that will remain solidly fixed to bone. Five radiographic features were identified at the bone-screw interface. The classification of these features was validated using interobserver and intraobserver studies. The reliability of the classification was improved by image enhancement with simple filters. Some radiographic features predicted which screws would eventually become loose, allowing the clinician to make earlier management decisions regarding the adjustment of screws.

Radiographic classification of osteogenesis during bone distraction.

Successful limb lengthening requires serial radiological evaluation of the progression of healing of the regenerate bone. However, there is no radiographic classification system that shows how the regenerate should progress during treatment in adults. The study aimed to address this need.A series of radiographs were studied from 92 patients (125 segments) who had undergone bone lengthening. A radiographic classification of osteogenesis was developed based on callus shape and radiographic features that occur between osteotomy and fixator removal. This classification system used both shape and type of feature to condense and record the radiographic information, but type of feature alone was sufficient to predict outcome. The concurrence and reproducibility of the classification system was tested by inter- and intra-observer studies. The degree of consistent repetition and agreement between observers suggests that the classification system is reliable, reproducible, and therefore should be robust in use. This classification system provides an insight into osteogenesis; it allows the progress of the bone healing to be assessed against a successful pattern of healing. Hence, potential problems can be predicted and clinical changes made to improve outcome. The classification can be simplified to make it more appropriate for clinical use.

Influence of bone quality on the strength of internal and external fixation of tibial plateau fractures.

We studied the influence of different parameters of bone quality on the fixation strength of bicondylar tibial plateau fractures and examined the relationship between these parameters. Bone quality was measured in the plateau of 16 cadaveric tibias using three modalities: dual-energy X-ray absorptiometry (DXA), peripheral quantitative computer tomography (pQCT), and spectral analysis of digitized radiographs (SADR). The tibias were divided into two groups by the median bone mineral density (BMD) and randomized to receive either dual plating or external fixator for the stabilization of a standardized bicondylar tibial fracture. The fixed fractures were subjected to axial compression until failure. DXA BMD correlated most significantly with the failure load (r>or=0.79, p<0.001), followed by the pQCT parameters of cancellous bone (0.52>or=r>or=0.73, p<0.01). Similar strong correlations were also evident in both fixation methods. For parameters derived from SADR, only those including both longitudinal and transverse trabecular orientations had modest correlation with the fixation strength (0.53>or=r>or=0.71, p<0.01). The failure loads of the two fixation techniques were not significantly different (mean+/-SD=3522+/-1386 N and 3710+/-1356 N, respectively, p=0.78). However, BMD in the dual-plating group influenced the failure load significantly (p=0.03), whereas in the external fixation group this was less evident (p=0.100). The majority of bone quality parameters that correlated with fixation strength were also strongly correlated with each other, particularly the BMDs measured by DXA and pQCT. This is the first study that relates fixation strength of bicondylar tibial plateau fractures to bone quality assessed at the same anatomical site. BMD around the fracture site had the best correlation with the failure load regardless of the fixation technique. The two fixation methods tested performed equally well, and the choice between them depends on the soft tissue condition and surgeon preference.

Tensioning technique and fixator stability of a circular external fixator with threaded fine wires.

Hybrid external fixators have become more popular over recent years, and although biomechanical tests show varying results from paper to paper, a consistent finding is shear motion occurring at the fracture/osteotomy site during loading. This can be reduced to some extent by frame configuration, and with the use of olive stop wires, but both of these have limitations. We have investigated the use of threaded fine wires in a circular hybrid fixator. A reliable tensioning method is described which minimises movement at the wire-bone interface during tensioning, and threaded wires are seen to offer a significant improvement in fracture site shear stiffness when compared to smooth fine wires.

Experimental model of tibial plateau fracture for biomechanical testing.

Although adequate reduction and stable fixation have been recognized to be the prime goals in the treatment of displaced tibial plateau fractures, the optimal fixation technique remains controversial. The lack of a reliable model and a standard methodology contribute to this situation. The purpose of this study is to develop an experimental model of a tibial plateau fracture and a testing methodology that reproduces the failure mode commonly seen in the clinical setting. Using solid-foam and composite Sawbones tibiae, three different models of bi-condylar tibial plateau fracture (solid-foam, reinforced solid-foam and composite), six specimens for each model, were created and stabilized with double plating. The specimens were subjected to cyclic axial compression with increasing maximum load until failure. A femoral component of a total knee replacement of similar size and shape to the synthetic tibial surface was used as a load applicator. The experiment was repeated on six specimens of human cadaver tibiae. Among the Sawbones specimens, only the reinforced solid-foam model was found to produce a consistent failure mode (collapse in the medial plateau) comparable to that reported clinically in the literature. This mode of failure was also confirmed by the cadaver experiments. The failure load of the reinforced solid-foam model ranged from 4150 to 4260 N with a mean +/- SD of 4201 +/- 44 N and a coefficient of variance of 0.01, whereas for the cadaver model the failure load ranged from 1675 to 6096 N with a mean +/- SD of 3768 +/- 1482 N and a coefficient of variance of 0.39. We recommend the reinforced-foam model for future mechanical tests to compare different fixation methods for tibial plateau fractures.

Asymmetrical fracture fixation: stability of oblique fractures is influenced by orientation.

BACKGROUND: Although clear differences in fracture site displacement have previously been demonstrated between transverse and oblique fracture models stabilised by an asymmetrical method, the direction of the obliquity has not been examined biomechanically. METHODS: Eight Sawbones tibiae were cut to represent oblique fractures: four ran from antero-inferior to postero-superior and four from antero-superior to postero-inferior. These were fixed with a Sheffield Ring Fixator and cyclically loaded in axial and off-axis compression. Direct measurements were taken of inter-fragmentary displacement. RESULTS: Significant differences were detected between the fracture directions (P < 0.01) and inter-fragmentary displacements were generally reduced in antero-superior to postero-inferior fractures compared with antero-inferio to postero-superior fractures. INTERPRETATION: Fixation asymmetries need to be tailored to specific fracture orientation to improve fracture site mechanics.

A radiographic technique for the assessment of ankle and midfoot equinus.

BACKGROUND: Both clinical and radiographic techniques have been used to evaluate foot and ankle position and orientation. Clinical measurements have been shown to be less reliable than radiographic measurements. Because midfoot equinus deformity may coexist with ankle joint equinus deformity, a radiographic method of separating and measuring these two components is desirable. The purpose of this study was to evaluate a new radiographic technique, the Lateral Mid-Tibia to Toes (LMTT), weightbearing view of the foot and ankle. METHOD: Twenty LMTT images were randomly selected from the study population of patients treated in our center for lower limb equinus deformity. Validation was achieved by a study involving three observers, assessing 20 images on two consecutive occasions, 4 weeks apart. Analysis was performed using Kappa statistics. RESULTS: The plantigrade and midfoot equinus angles provided substantial (p = 0.000) and moderate (p = 0.005) agreement, respectively. CONCLUSIONS: Awareness of midfoot equinus and its correction may avoid residual deformity when surgery is performed to correct equinus deformity of the ankle.

Knee joint reaction force during tibial diaphyseal lengthening: a study on a rabbit model.

The in vivo passive knee joint reaction force was measured in a rabbit model of tibial diaphyseal lengthening. This was based on the assumption that limb lengthening creates soft tissue tension that compresses the joint surface and generates the joint contact force. A measurement method was developed that involved the distraction of the joint and the determination of the distraction force that just separates the joint surfaces. Sixteen immature (mean+/-SD age=9+/-0.6 weeks) New Zealand White rabbits underwent 30% (left) tibial diaphyseal lengthening at a rate of two 0.4mm incremental lengthenings per day. The knee joint reaction force was measured at the end of lengthening (8 rabbits, mean+/-SD age=14+/-0.6 weeks) and five weeks after lengthening (8 rabbits, mean+/-SD age=19+/-0.7 weeks). An instrumented bilateral distractor and an extensometer were fixed cross the knee joint. The joint distraction force and distraction displacement were measured when the joint was distracted in steps and after the section of the Achilles tendon. The joint reaction force on the lengthened side was significantly higher than the control side at both time points (mean+/-SD 44.4+/-7.8 N v. 27.2+/-4.0 N at the end of lengthening, 44.3+/-S6.5 N v. 31.3+/-3.0 N at 5 weeks after lengthening). The contribution of the gastrocnemius to the joint reaction force on the lengthened side was also significantly higher than the control side at both time points (mean+/-SD 9.0+/-1.3N v. 2.8+/-0.8 N at the end of lengthening, 5.3+/-1.4N v. 2.7+/-0.5N at 5 weeks after lengthening). There were significant knee and ankle joint contractures at the end of lengthening, as evidenced by decreased range of motion (mean+/-SD 27+/-8 degrees and 36+/-13 degrees, respectively), which remained 5 weeks after lengthening (mean+/-SD 26+/-6 degrees and 35+/-8 degrees, respectively). The gastrocnemius contributed about 20% of the joint reaction force, indicating that changes in the other intra- and extra-articular structures due to joint contracture may be more important in generating the joint reaction force.

Acute correction of lower limb deformity and simultaneous lengthening with a monolateral fixator.

We have reviewed, retrospectively, all children with a lower limb deformity who underwent an acute correction and lengthening with a monolateral fixator between 1987 and 1996. The patients were all under the age of 19 years and had a minimum follow-up of eight months after removal of the fixator. A total of 41 children had 57 corrections and lengthening. Their mean age was 11.3 years (3.2 to 18.7) and there were 23 girls and 18 boys. The mean maximum correction in any one plane was 23 degrees (7 to 45). In 41 bony segments (either femur or tibia) a uniplanar correction was made while various combinations were carried out in 16. The site of the osteotomy was predominantly diaphyseal, at a mean of 47% (17% to 73%) of the total bone length and the mean length gained was 6.4 cm (1.0 to 17.0). Univariate analysis identified a moderately strong relationship between the bone healing index (BHI), length gained, maximum correction and grade-II to grade-III complications. For logistic regression analysis the patients were binary coded into two groups; those with a good outcome (BHI < or = 45 days/cm) and those with a poor outcome (BHI > 45 days/cm). Various factors which may influence the outcome were then analysed by calculating odds ratios with 95% confidence intervals. This analysis suggested a dose response between increasing angular correction and poor BHI which only reached statistical significance for corrections of larger magnitude. Longer lengthenings were associated with a better BHI while age and the actual bone lengthened had little effect. Those patients with a maximum angulatory correction of less than 30 degrees in any one plane had an acceptable consolidation time with few major complications. The technique is suitable for femoral deformity and shortening, but should be used with care in the tibia since the risk of a compartment syndrome or neurapraxia is much greater.

Outcome of complex fractures of the tibial plateau treated with a beam-loading ring fixation system.

Fine-wire external fixation is accepted as a minimally invasive technique, which can provide better outcomes than traditional open methods in the management of complex fractures of the tibial plateau. Available fixators vary in their biomechanical stability, and we believe that a stable beam-loading system is essential for consistently good outcomes. We assessed, prospectively, the clinical, radiological and general health status of 20 of 21 consecutive patients with complex fractures of the tibial plateau who had been treated using a standard protocol, with percutaneous screw fixation and a neutralisation concept with a fine wire beam-loading fixator allowing early weight-bearing. Bony union was achieved in all patients, with 85% having good or excellent results. Full weight-bearing started during the first six weeks in 60% of patients. The general health status assessment correlated well with the knee scores and reflected a satisfactory outcome.

Treatment of displaced bicondylar tibial plateau fractures (OTA-41C2&3) in patients older than 60 years of age.

OBJECTIVE: To investigate the outcome (clinical, radiographic, and general health status) of the surgical treatment of displaced bicondylar tibial plateau fractures (OTA-41C) in patients >60 years old. DESIGN: Prospective cohort study. SETTING: Limb reconstruction service, university teaching hospital. PATIENTS: Eleven consecutive patients >60 years old with a mean age of 72 years (range 60 to 90 years). The indications for surgery were displaced bicondylar tibial fractures, open fractures, and fractures with severe soft tissue injury. INTERVENTION: All patients were treated according to a standard protocol, which involved limited articular reconstruction and percutaneous intrafragmentary screw fixation, followed by neutralization with a stable beam-loading external fixator and early mobilization. MAIN OUTCOME MEASUREMENTS: The clinical outcome was assessed using Rasmussen's system and the Iowa knee score. For general health assessment, the anglicized SF-36 was used. Radiographic assessment was performed for redisplacement and angulation on digitized radiographs. RESULTS: After a mean follow-up of 38 months (range 18 to 51 months), bony union was achieved in all patients. Seven of 11 patients started full weight bearing 2 to 6 weeks postoperatively. According to Rasmussen's system, 9 of 11 (82%) scored satisfactory results. Radiographic redisplacement was found in three severely comminuted cases resulting in >/=10 degrees of valgus malunion. One patient received a corrective osteotomy while still in the fixator. Another needed TKA. Limited knee flexion was found in three patients with cross knee fixation. Superficial pin site infection occurred in five patients, but there were no cases of deep infections or septic arthritis. CONCLUSIONS: All-ring external fixation, as a beam-loading system applied in a neutralizing mode, is a safe, stable, and reliable technique for the treatment of displaced bicondylar tibial plateau fractures in elderly patients.

Stiffness characteristics and inter-fragmentary displacements with different hybrid external fixators.

OBJECTIVES: To determine how the different approaches of constructing a hybrid external skeletal fixator affect the mechanical environment at the fracture site. DESIGN: A comparative biomechanical analysis of external fixators that represent a spectrum of designs from unilateral to circular fixators. BACKGROUND: The most pertinent parameter that affects fracture healing is the inter-fragmentary displacement. Most studies on the mechanical performance of external fixators have concentrated on the overall stiffness of the fixators. METHODS: Mechanical testing was performed on four types of hybrid fixators in which the overall stiffness of the fixator as well as the axial, transverse shear and angular displacements at the fracture site were measured. RESULTS: The Ilizarov hybrid fixator with one wire and one screw on each ring behaved more like a unilateral fixator than a circular fixator. The bar-ring hybrid fixator that simply connected a unilateral fixator body to a wire/ring assembly was too flexible. Reinforcing the bar-ring hybrid system with diagonally placed struts eliminated the deformation associated with the unilateral body and the resulting construct performed considerably better. The two-ring hybrid fixator most closely resembled the Ilizarov fixator. CONCLUSIONS: Depending on the construction characteristics hybrid fixators possess a spectrum of mechanical characteristics of both unilateral and circular fixators. The constructions using two rings in which at least one bone segment is supported entirely by wires appears to have the best mechanical characteristics. RELEVANCE: Understanding how the different approaches of constructing a hybrid fixator affect the mechanical environment at the fracture site will enable surgeons to chose or build the most appropriate fixator for each clinical situation.

Distraction-resisting force during tibial diaphyseal lengthening and consolidation--a study on a rabbit model.

BACKGROUND: Distraction-resisting force is generated in the soft tissues and callus during limb lengthening. Monitoring this force may offer a method of studying the behaviour of soft tissue and detecting the distraction osteogenesis related problems, and help to prevent complications. Changes in the post distraction period have not been previously investigated and there are no reports on the contribution of gastrocnemius to the distraction-resisting force. METHODS: Sixteen immature New Zealand White rabbits underwent 30% (left) tibial diaphyseal lengthening at a rate of two 0.4 mm increments per day. Using an instrumented bilateral fixator, the passive distraction-resisting force and the contribution made by gastrocnemius were measured at the end of lengthening and 5 weeks after lengthening. FINDINGS: The distraction-resisting force at the end of lengthening (mean 44 N (SD 10)) was statistically higher (p < 0.01) than that five weeks after lengthening (mean 20 N (SD 8)), so was the contribution of the gastrocnemius to the force (mean 11 N (SD 5 N) or 25% (SD 7) at the end of lengthening and 3 N (SD 1) or 13% (SD 5.2) five weeks later). INTERPRETATION: The callus rather than the surrounding muscles generates most of the passive DRF and its share of the force increased during consolidation period.

The strength of different fixation techniques for bicondylar tibial plateau fractures--a biomechanical study.

OBJECTIVE: To compare the mechanical strength of fixation of bicondylar tibial plateau fractures using internal and external fixation techniques. DESIGN: A randomised laboratory testing of fixation methods currently in clinical use. BACKGROUND: To reduce the high complication rate associated with the double plating, many surgeons have started to use less invasive techniques. However the literature comparing the mechanical performance of these methods is still scarce. METHODS: Bicondylar tibial plateau fractures were simulated on Sawbones tibiae and fixed with one of the five fixation methods: dual plating, a two-ring hybrid fixator with inter-fragmentary screws, a ring-bar hybrid fixator with inter-fragmentary screws, lateral plate and medial monolateral external fixator, lateral plate and medial inter-fragmentary screws. Following statistical power calculations, seven tibiae were used for each fixation method. The specimens were tested in cyclical compression to failure. The vertical subsidence in the medial or lateral plateau was measured using extensometers. RESULTS: In all cases the mode of failure was consistent with collapse occurring in the medial plateau. There was no significant difference in the failure load between dual plating and the two-ring hybrid fixator (4218 N and 4184 N respectively; P=0.28, t-test). Failure was seen at significantly lower loads with the other fixation systems. CONCLUSION: Weight-bearing mobilisation of the patient may be undertaken earlier with more confidence by using the double plating or two-ring hybrid fixator rather than other less strong techniques. The choice on which of these two methods to use may depend on tissue viability and surgeon preference.

Tibial shortening for correction of leg length discrepancy and deformity: a new technique.

Where length discrepancy occurs in the skeletally mature lower leg, there may be a benefit in using the technique of tibial shortening. Existing techniques have not been widely adopted and are associated with a high incidence of soft tissue complications. We describe a technique of progressive shortening, which we believe is a safe method, having adapted this from techniques for dealing with traumatic bone loss.

Tibial lengthening: does the fibula migrate?

A retrospective study of 32 patients who underwent tibial lengthening was performed in order to establish the need for distal tibio-fibular fixation. In 16 patients stabilization of the inferior tibio-fibular joint was carried out and in the other 16 no stabilization was performed. Three established and one new radiographic index of the tibio-fibular relationship at the ankle were used to assess proximal fibular migration. All patients showed proximal migration of the distal fibula, but those without stabilization demonstrated marked migration of the fibula associated with a valgus tendency. The difference between the groups was statistically significant ( <0.001), confirming the need for fibular fixation.

MedEdPORTAL: a report on oral health resources for health professions educators.

MedEdPORTAL is a unique web-based peer-reviewed publication venue for clinical health educators sponsored by the Association of American Medical Colleges (AAMC). The open exchange of educational resources promotes professional collaboration across health professions. In 2008, the American Dental Education Association (ADEA) collaborated with AAMC to allow dental educators to use the platform to publish dental curriculum resources. Oral health is integral to general health; hence, collaboration among health care professionals brings enormous value to patient-centered care. The aim of this study was to conduct a current survey of metrics and submission statistics of MedEdPORTAL resources. The data were collected using the MedEdPORTAL search engine and ADEA and AAMC staff. The data collected were categorized and reported in tables and charts. Results showed that at the time of this study there were over 2,000 medical and dental resources available to anyone worldwide. Oral health resources constituted approximately 30 percent of the total resources, which included cross-indexing with information relevant to both medical and dental audiences. There were several types of dental resources available; the most common were the ones focusing on critical thinking. The usage of MedEdPORTAL has been growing, with participation from over 190 countries and 10,000 educational institutions around the world. The findings of this report suggest that MedEdPORTAL is succeeding in its aim to foster global collaborative education, professional education, and educational scholarship. As such, MedEdPORTAL is providing a new forum for collaboration and opens venues for promising future work in professional education.

Characteristics of simulation activities at North American medical schools and teaching hospitals: an AAMC-SSH-ASPE-AACN collaboration.

SUMMARY STATEMENT: In September 2011, the Association of American Medical Colleges released the results of a survey conducted in 2010 on simulation activities at its member medical schools and teaching hospitals. In this commentary, we offer a synthesis of data and conclude that (1) simulation is used broadly at Association of American Medical Colleges member institutions, for many types of learners, including other health care professionals; (2) it addresses core training competencies and has many educational purposes; (3) its use in learner assessment is more prevalent at medical schools but is still significant at teaching hospitals; and (4) it requires a considerable investment of money, space, personnel, and time. These data confirm general perceptions about the state of simulation in North America for physician training. Future endeavors should include a more granular examination of how simulation is integrated into curricula, a similar survey of other health care-related institutions and professions, and a periodic assessment to characterize trends over time.