Postoperative periprosthetic femoral fracture around total hip replacements: current concepts and clinical outcomes

The rising incidence of postoperative periprosthetic femoral fracture (PFF) presents a significant clinical and economic burden. A detailed understanding of risk factors is required in order to guide preventative strategies. Different femoral stems have unique characteristics and management strategies must be tailored appropriately. Consensus regarding treatment of PFFs around well-fixed stems is lacking, but revision surgery may provide more predictable outcomes for unstable fracture patterns and fractures around polished taper-slip stems. Future research should focus on implant-related risk factors, treatment of concurrent metabolic bone disease and the use of large endoprostheses

Comparison of artificial neural network and logistic regression models for prediction of mortality in head trauma based on initial clinical data

BACKGROUND: In recent years, outcome prediction models using artificial neural network and multivariable logistic regression analysis have been developed in many areas of health care research. Both these methods have advantages and disadvantages. In this study we have compared the performance of artificial neural network and multivariable logistic regression models, in prediction of outcomes in head trauma and studied the reproducibility of the findings. METHODS: 1000 Logistic regression and ANN models based on initial clinical data related to the GCS, tracheal intubation status, age, systolic blood pressure, respiratory rate, pulse rate, injury severity score and the outcome of 1271 mainly head injured patients were compared in this study. For each of one thousand pairs of ANN and logistic models, the area under the receiver operating characteristic (ROC) curves, Hosmer-Lemeshow (HL) statistics and accuracy rate were calculated and compared using paired T-tests. RESULTS: ANN significantly outperformed logistic models in both fields of discrimination and calibration but under performed in accuracy. In 77.8% of cases the area under the ROC curves and in 56.4% of cases the HL statistics for the neural network model were superior to that for the logistic model. In 68% of cases the accuracy of the logistic model was superior to the neural network model. CONCLUSIONS: ANN significantly outperformed the logistic models in both fields of discrimination and calibration but lagged behind in accuracy. This study clearly showed that any single comparison between these two models might not reliably represent the true end results. External validation of the designed models, using larger databases with different rates of outcomes is necessary to get an accurate measure of performance outside the development population

From sleep spindles of natural sleep to spike and wave discharges of typical absence seizures: is the hypothesis still valid?

The temporal coincidence of sleep spindles and spike-and-wave discharges (SWDs) in patients with idiopathic generalized epilepsies, together with the transformation of spindles into SWDs following intramuscular injection of the weak GABAA receptor (GABAAR) antagonist, penicillin, in an experimental model, brought about the view that SWDs may represent ‘perverted’ sleep spindles. Over the last 20 years, this hypothesis has received considerable support, in particular by in vitro studies of thalamic oscillations following pharmacological/genetic manipulations of GABAARs. However, from a critical appraisal of the evidence in absence epilepsy patients and well-established models of absence epilepsy it emerges that SWDs can occur as frequently during wakefulness as during sleep, with their preferential occurrence in either one of these behavioural states often being patient dependent. Moreover, whereas the EEG expression of both SWDs and sleep spindles requires the integrity of the entire cortico-thalamo-cortical network, SWDs initiates in cortex while sleep spindles in thalamus. Furthermore, the hypothesis of a reduction in GABAAR function across the entire cortico-thalamo-cortical network as the basis for the transformation of sleep spindles into SWDs is no longer tenable. In fact, while a decreased GABAAR function may be present in some cortical layers and in the reticular thalamic nucleus, both phasic and tonic GABAAR inhibitions of thalamo-cortical neurons are either unchanged or increased in this epileptic phenotype. In summary, these differences between SWDs and sleep spindles question the view that the EEG hallmark of absence seizures results from a transformation of this EEG oscillation of natural sleep

Muscle function and functional outcome following standard antegrade reamed intramedullary nailing of isolated femoral shaft fractures

OBJECTIVE: To evaluate the functional outcomes and long-term effects on muscle strength of femoral shaft fractures treated with intramedullary (IM) antegrade nailing using a standard piriformis start point. DESIGN: Retrospective Outcome Study. SETTING: Tertiary Level Teaching Hospital and Referral Centre for the Province of British Columbia. PATIENTS/PARTICIPANTS: Twenty-one patients (7 female, 14 male; mean age 34.5 years, range 16-56 years) with isolated femoral shaft fractures who were treated with standard antegrade reamed interlocking IM nailing and who had a minimum 1-year follow-up were identified through the Orthopaedic Trauma Database. All patients had isokinetic muscle testing of their hip abductors, hip extensors, and knee extensors using the KinCom muscle testing machine. Of the patients, 10 underwent formal gait lab analysis. All of the patients answered a questionnaire and completed the Short Form (SF)-36 and Musculoskeletal Functional Assessment outcome measures. INTERVENTION: Antegrade reamed interlocking IM nailing of femoral shaft fractures using a standard trochanteric fossa (also referred to as piriformis fossa) starting point. MAIN OUTCOME MEASUREMENTS: Examination of muscle strength, using 2 different objective measures (KinCom and gait analysis). The KinCom muscle testing machine was used for isokinetic muscle testing of hip abductors, hip extensors, and knee extensors. Outcome questionnaires were used to evaluate function (Musculoskeletal Functional Assessment) and general health (SF-36). RESULTS: Isokinetic muscle testing showed a statistically significant lower peak torque generation by the hip abductors (P=0.003) and hip extensors (P=0.046) from the uninjured contralateral side. The gait lab analysis did not show important changes in gait pattern. Scores for the SF-36 were 51.77+/-7.55 and 53.73+/-8.70. Scores for the Short Musculoskeletal Functional Assessment (S-MFA) were 7.74 and 8.66. Both scores did not indicate any significant disability. CONCLUSIONS: Antegrade reamed interlocking IM nailing of femoral shaft fractures using a standard trochanteric fossa starting point is associated with a mild hip abductor muscle-strength deficit. Gait pattern returns to normal following femoral shaft fracture treated with this technique, and functional outcomes are good

Functional architecture of eye position gain fields in visual association cortex of behaving monkey

In the behaving monkey, inferior parietal lobe cortical neurons combine visual information with eye position signals. However, an organized topographic map of these neurons' properties has never been demonstrated. Intrinsic optical imaging revealed a functional architecture for the effect of eye position on the visual response to radial optic flow. The map was distributed across two subdivisions of the inferior parietal lobule, area 7a and the dorsal prelunate area, DP. Area 7a contains a representation of the lower eye position gain fields while area DP represents the upper eye position gain fields. Horizontal eye position is represented orthogonal to the vertical eye position across the medial lateral extents of the cortices. Similar topographies were found in three hemispheres of two monkeys; the horizontal and vertical gain field representations were not isotropic with a greater modulation found with the vertical. Monte Carlo methods demonstrated the significance of the maps, and they were verified in part using multiunit recordings. The novel topographic organization of this association cortex area provides a substrate for constructing representations of surrounding space for perception and the guidance of motor behaviors

International guide to the circus

An easy-to-read publication defining 100 key circus terms translated in nine languages. The 24-page full color Guide (A4 size) is categorized by aerial acts, acrobatics, balancing, juggling, daredevil and specialty acts, clowning and performing animals. Terms are illustrated by photographs supplied by circuses and participants in the Federation’s annual World Circus Photo Contest. Perfect for circuses and organisations to give to visiting media. Edited by R. Huey, Ph.D