Factors predictive of patient outcome following total wrist arthrodesis.

AIMS: Total wrist arthrodesis (TWA) produces a spectrum of outcomes. We investigated this by reviewing 77 consecutive TWA performed for inflammatory and post-traumatic arthropathies, wrist instability and as a salvage procedure. PATIENTS AND METHODS: All operations were performed by a single surgeon using a specifically designed pre-contoured dorsally applied non-locking wrist arthrodesis plate at a single centre. RESULTS: Median post-operative Buck-Gramcko Lohman (BGL), Disabilities of the Arm, Shoulder and Hand and Patient Rated Wrist Evaluation scores at six years (interquartile range (IQR) 3 to 11) were 9 (IQR = 6 to 10), 19 (IQR = 7 to 45) and 13 (IQR = 1 to 31) respectively. Polyarticular inflammatory arthritis and female gender were associated with poorer patient-reported outcomes, although the effect of gender was partly explained by higher rates of inflammatory disease among women. Return to work was negatively influenced by workers' compensation and non-inflammatory wrist pathology. There was no difference in complication rates for inflammatory and non-inflammatory indications. TAKE HOME MESSAGE: Polyarticular inflammatory arthritis is a risk factor for adverse patient-reported outcomes in TWA. Furthermore, when compared with patients without inflammatory arthritis, dorsally applied pre-contoured plates can be used for wrist arthrodesis in patients with inflammatory arthritis without an increased risk of complications. Cite this article: Bone Joint J 2016;98-B:647-53.

An estimation of the incidence of squeaking and revision surgery for squeaking in ceramic-on-ceramic total hip replacement: a meta-analysis and report from the Australian Orthopaedic Association National Joint Registry.

Squeaking arising from a ceramic-on-ceramic (CoC) total hip replacement (THR) may cause patient concern and in some cases causes patients to seek revision surgery. We performed a meta-analysis to determine the incidence of squeaking and the incidence of revision surgery for squeaking. A total of 43 studies including 16,828 CoC THR that reported squeaking, or revision for squeaking, were entered into the analysis. The incidence of squeaking was 4.2% and the incidence of revision for squeaking was 0.2%. The incidence of squeaking in patients receiving the Accolade femoral stem was 8.3%, and the incidence of revision for squeaking in these patients was 1.3%.

Comparison of the rheological properties of Advantage-S and Replens.

The rheological properties of Advantage-S and Replens were measured at body (37 degrees C) and room temperature (25 degrees C) over a range of physiologically relevant shear rates. The viscosity of Replens was found to differ from that of Advantage-S, particularly at room temperature. In addition, the two materials differed in their miscibility with a vaginal fluid simulant.

Rheological properties of contraceptive gels.

The rheological properties of 4 commercially available contraceptive drug delivery gels and their dilutions with a vaginal fluid simulant were measured. These properties govern the critical functions of spreading and retention of these gels over the vaginal surfaces. Measurements made on Conceptrol, KY Plus, Gynol II, and Advantage-S included stress growth, stress relaxation and residual stress, and the shear rate dependence of viscosity. All gels exhibited non-Newtonian behavior including shear thinning and viscoelasticity. Conceptrol and Gynol II had no residual stress, while both KY Plus and Advantage-S did. The gels differed in their response to dilution with vaginal fluid simulant.

Factors influencing nonoxynol-9 permeation and bioactivity in cervical mucus.

The effects of delivery gel pH and osmolarity on both the mass transport and 'biodiffusion' of the spermicide nonoxynol-9 (N9) in bovine cervical mucus were evaluated. Delivery gels were calcium chloride crosslinked alginate containing 3% N9, and were manufactured over a pH range of 3.4 to 5.9 and an osmolarity range of 300 to 900 mosmol. Mass transfer parameters (diffusion coefficients and total drug loading) were determined using a new UV spectrophotometric technique while biodiffusion (the diffusion distance into mucus at which sperm are killed) was assessed using the Double Ended Test. It was found that delivery gel pH had a significant effect on spermicidal efficacy of the alginate-N9 system; biodiffusion increased with decreasing pH. Actual N9 diffusion into mucus was found to be influenced by both the delivery gel pH and osmolarity. At high N9 concentration (near the gel/mucus interface), mass transport tended to decrease with decreasing pH at the highest osmolarity. At low concentration, mass transport tended to decrease with increasing osmolarity and decrease with increasing pH at the highest osmolarity. The difference between low and high concentration behavior can be attributed to N9 micelle formation. These findings are interpreted in the context of the design of intravaginal drug delivery vehicles for spermicides.

A vaginal fluid simulant.

A fluid medium was developed to simulate the fluid produced in the human vagina. The composition of the medium was based on an extensive review of the literature on constituents of human vaginal secretions. In choosing the ingredients for this medium, the goal was to emphasize properties that influence interactions of vaginal fluid with topical contraceptive, prophylactic, or therapeutic products. Among these properties, pH and osmolarity play a dominant role in physicochemical processes that govern drug release and distribution.

PIP: This article investigates a vaginal fluid simulant intended to model the fluid properties originating in the vagina--specifically the vaginal transudite found in healthy, nonpregnant premenopausal women. Methods of volume measurement of vaginal fluid fell into two categories: those that measured the quantity of vaginal fluid present at any one time and those that measured production over an extended interval. A volume of 0.75 ml vaginal fluid simulant was used. The proposed simulant was designed to incorporate information about chemical composition determined by previous researchers; this information emphasized pH modeling and the osmolarity of the material. Consequently, the specific "recipe" for 1 liter of this simulant given as compound and weight (g) was as follows: NaCl, 3.51; KOH, 1.40; Ca(OH)2, 0.222; borine serum albumin, 0.018; lactic acid, 2.00; acetic acid, 1.00; glycerol, 0.16; urea, 0.4; glucose, 5.0. The simulant was designed to have the same physical and chemical properties as those known to influence intravaginal gel efficacy. Further efforts by other researchers are needed if improved simulants are to be developed.

The utility of motion parallax information for the perception and control of heading.

Two experiments in which participants were given control over the direction of computer-simulated self-motion were conducted. Environments were designed to evaluate the functionality of simple and multiple motion parallax as well as a separation ratio (sigma; indexing the separation of 2 objects in depth) for the perception and control of heading. Results provide a 1st indication of optimizing performance in the top end of the global optical flow velocity range available during human bipedal self-motion. The introduction of sigma, developed to explain performance improvements with decreasing distance to the target, was able to account for most of the performance differences among all simulated environments. The rate of change in horizontal optical separation between at least 2 discontinuities was identified as a likely candidate for the optical foundation of the perception and control of heading during target approach.

Sampling factors influencing accuracy of sperm kinematic analysis.

Sampling conditions that influence the accuracy of experimental measurement of sperm head kinematics were studied by computer simulation methods. Several archetypal sperm trajectories were studied. First, mathematical models of typical flagellar beats were input to hydrodynamic equations of sperm motion. The instantaneous swimming velocities of such sperm were computed over sequences of flagellar beat cycles, from which the resulting trajectories were determined. In a second, idealized approach, direct mathematical models of trajectories were utilized, based upon similarities to the previous hydrodynamic constructs. In general, it was found that analyses of sampling factors produced similar results for the hydrodynamic and idealized trajectories. A number of experimental sampling factors were studied, including the number of sperm head positions measured per flagellar beat, and the time interval over which these measurements are taken. It was found that when one flagellar beat is sampled, values of amplitude of lateral head displacement (ALH) and linearity (LIN) approached their actual values when five or more sample points per beat were taken. Mean angular displacement (MAD) values, however, remained sensitive to sampling rate even when large sampling rates were used. Values of MAD were also much more sensitive to the initial starting point of the sampling procedure than were ALH or LIN. On the basis of these analyses of measurement accuracy for individual sperm, simulations were then performed of cumulative effects when studying entire populations of motile cells. It was found that substantial (double digit) errors occurred in the mean values of curvilinear velocity (VCL), LIN, and MAD under the conditions of 30 video frames per second and 0.5 seconds of analysis time. Increasing the analysis interval to 1 second did not appreciably improve the results. However, increasing the analysis rate to 60 frames per second significantly reduced the errors. These findings thus suggest that computer-aided sperm analysis (CASA) application at 60 frames per second will significantly improve the accuracy of kinematic analysis in most applications to human and other mammalian sperm.

Evidence for the function of hyperactivated motility in sperm.

After insemination, mammalian sperm undergo a striking change in flagellar beat pattern, termed hyperactivation. In low-viscosity culture medium, nonhyperactivated sperm flagella generate relatively symmetrical, low-amplitude waves, while hyperactivated sperm flagella generate an asymetrical beating pattern that results in nonprogressive movement. Since sperm encounter highly viscous and viscoelastic fluids in the female reproductive tract, the progress of hyperactivated sperm was compared with that of nonhyperactivated and transitional sperm in media of increasing viscosity. Hamster sperm obtained from the caudal epididymis were incubated in a medium that promotes capacitation. After 0, 3, and 4 h of incubation, the majority of the sperm exhibited, respectively, activated, transitional, and hyperactivated motility. At each of these time points, aliquots of sperm were removed from incubation and added to solutions of 0, 5%, 10%, 20%, and 30% Ficoll in medium. Samples containing mostly hyperactivated sperm (4 h) maintained higher swimming and flagellar velocities and were able to generate greater forces in response to increased viscous loading than activated sperm (0 h). Transitional sperm (3 h) showed an intermediate response. The paths of hyperactivated sperm through solutions of 20% and 30% Ficoll were considerably straighter than those made through medium alone. This is the first demonstration that hyperactivation can confer a mechanical advantage upon sperm in the oviduct where they may encounter viscous oviductal fluid and a viscoelastic cumulus matrix.

Maintaining posture and avoiding tripping. Optical information for detecting and controlling orientation and locomotion.

In attempting to understand the role of visual perception in falls and their prevention, the relationship between the locomoting individual and the surrounding environment must be considered. Falls will occur when necessary properties of the environment and visual sources of information about them are inadequate, or when the individual is not adequately sensitive to or attentive to them. Body sway and tripping, two major problems contributing to falls, are examined. In regard to the prevention of falls, implications for the design of environments and training of the individuals who must move about in them are discussed.

Functional optical invariants: a new methodology for aviation research.

The application to aviation psychology of Gibson's (4) "ecological approach to visual perception" demands information-rich visual displays to adequately and unambiguously enable a pilot to perform flight maneuvers. Optical information often takes the form of invariant properties of a changing optic array, and functional invariants are defined as psychologically effective optical invariants. Their effectiveness is determined by empirical test, but standard experimental paradigms are shown to be inappropriate for testing the effectiveness of information-rich displays. This is due to the presence of inherent and unavoidable confounding factors that are here termed "secondary independent variables" in contradistinction to the "primary independent variables" manipulated by the experimenter. Recommendations for a new methodology and statistical treatment are offered, and the implications for aviation psychology are discussed.

Optical information for detecting loss in one's own forward speed.

An experiment was conducted to determine whether accuracy and efficiency of detecting loss in one's own forward speed are constant when optical information is invariant over a wide range of environmental variables. Deceleration rate, initial forward velocity, and altitude were varied so as to isolate initial optical flow rate, optical flow deceleration, and optical flow damping invariants specified in observer-relevant metrics. The candidate resulting in the most consistent effect on performance was global damping, which specifies a contrast of flow deceleration with initial flow rate. The finding is a first step toward validating a procedure for identifying functional invariants by assessing the usefulness of mathematically specified optical information for the perception of egomotion. The research represents both a methodological development and empirical support for the broader program of ecological functionalism.

Bias-free improvement in wine discrimination.

Over three test sessions alternated with two training sessions, accuracy of 'same'/'different' judgments of four dry, white wines improved 14%. Confidence ratings were obtained so that the area under the isosensitivity curve could be computed as a bias-free measure of accuracy while the wine used for same pairs was held constant. An initial bias for 'different' judgments persisted, rather than disappearing as Walk found. While perceptual learning did occur, the problem of attending to irrelevant differences was not overcome.