bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical implications of interfacial defects between femoral hip implants and cement: A finite element analysis of interfacial gaps and interfacial porosity
Authors: Scheerlinck T , Broos J , Janssen D , Verdonschot N
Published: November 2008

Two types of defect between femoral hip implants and cement have been identified. Interfacial porosity arises from cement shrinkage during curing and presents as pores randomly located along the stem. Interfacial gaps are much larger stem—cement separations caused by air introduced during stem insertion. To investigate the mechanical consequences of both types of defect, a finite element analysis model was created on the basis of a computed tomography image of a Charnley—Kerboul stem, and alternating torsional and transverse loads were applied. The propagation of fatigue cracks within the cement and the rotational stability of the stem were assessed in models simulating increasing amounts of interfacial gaps and pores. Anterior gaps covering at least 30 per cent of the implant surface promoted cement cracks and destabilized the stem. Anterolateral gaps were less destabilizing, but had more potential to promote cracks. In both cases, cracks occurred mainly outside gap regions, in areas where the stem contacted the cement during cyclic loading. Although random interfacial pores did not destabilize the implant, they acted as crack initiators even at low fractions (10 per cent). In conclusion, random interfacial pores were more harmful for the cement mantle integrity than were larger regions of interfacial gaps, although gaps were more detrimental for the rotational stability of the stem.
Fuzzy clustering analysis of microarray data
Authors: Han Lixin , Zeng Xiaoqin , Yan Hong
Published: November 2008

Fuzzy clustering is a useful tool for identifying relevant subsets of microarray data. This paper proposes a fuzzy clustering method for microarray data analysis. An advantage of the method is that it used a combination of the fuzzy c-means and the principal component analysis to identify the groups of genes that show similar expression patterns. It allows a gene to belong to more than a gene expression pattern with different membership grades. The method is suitable for the analysis of large amounts of noisy microarray data.
Comparison of wear of ultra-high molecular weight polyethylene acetabular cups against surface-engineered femoral heads
Authors: Galvin A , Brockett C , Williams S , Hatto P , Burton A , Isaac G , Stone M , Ingham E , Fisher J
Published: November 2008

Alumina ceramic heads have been previously shown to reduce polyethylene wear in comparison to cobalt chrome (CoCr) heads in artificial hip joints. However, there are concerns about the brittle nature of ceramics. It is therefore of interest to investigate ceramic-like coatings on metallic heads. The aim of this study was to compare the friction and wear of ultra-high molecular weight polyethylene (UHMWPE) against alumina ceramic, CoCr, and surface-engineered ceramic-like coatings in a friction simulator and a hip joint simulator. All femoral heads tested were 28 mm diameter and included: Biolox™ Forte alumina, CoCr, arc evaporative physical vapour deposition (AEPVD) chromium nitride (CrN) coated CoCr, plasma-assisted chemical vapour deposition (PACVD) amorphous diamond-like carbon (aDLC) coated CoCr, sputter CrN coated CoCr, reactive gas controlled arc (RGCA) AEPVD titanium nitride (TiN) coated CoCr, and Graphit-iC™ coated CoCr. These were articulated against UHMWPE acetabular cups in a friction simulator and a hip joint simulator. Alumina and CoCr gave the lowest wear volumes whereas the sputter coated CrN gave the highest. Alumina also had the lowest friction factor. There was an association between surface parameters and wear. This study indicates that surface topography of surface-engineered femoral heads is more important than friction and wettability in controlling UHMWPE wear.
Indirect selective laser sintering of apatite—wollostonite glass—ceramic
Authors: Xiao K , Dalgarno K W , Wood D J , Goodridge R D , Ohtsuki C
Published: November 2008

This paper develops an indirect selective laser sintering (SLS) processing route for apatite—wollastonite (A—W) glass—ceramic, and shows that the processing route, which can create porous three-dimensional products suitable for bone implants or scaffolds, does not affect the excellent mechanical and biological properties of the glass—ceramic. ‘Green parts’ with fine integrity and well-defined shape have been produced from glass particles of single-size range or mixed-size ranges with acrylic binder in various ratios by weight. A subsequent heat treatment process has been developed to optimize the crystallization process, and an infiltration process has been explored to enhance mechanical strength. Three-point bending test results show flexural strengths of up to 102 MPa, dependent on porosity, and simulated body fluid (SBF) tests show that the laser sintered porous A—W has comparable biological properties to that of conventionally produced A—W.
An investigation on the biodynamic foundation of a rat tail vibration model
Authors: Welcome D E , Krajnak K , Kashon M L , Dong R G
Published: November 2008

The objectives of this study are to examine the fundamental characteristics of the biodynamic responses of a rat tail to vibration and to compare them with those of human fingers. Vibration transmission through tails exposed to three vibration magnitudes (1 g, 5 g, and 10 g r.m.s.) at six frequencies (32 Hz, 63 Hz, 125 Hz, 160 Hz, 250 Hz, and 500 Hz) was measured using a laser vibrometer. A mechanical-equivalent model of the tail was established on the basis of the transmissibility data, which was used to estimate the biodynamic deformation and vibration power absorption at several representative locations on the tail. They were compared with those derived from a mechanical-equivalent model of human fingers reported in the literature. This study found that, similar to human fingers, the biodynamic responses of the rat tail depends on the vibration magnitude, frequency, and measurement location. With the restraint method used in this study, the natural frequency of the rat tail is in the range 161–368 Hz, which is mostly within the general range of human finger resonant frequencies (100–350 Hz). However, the damping ratios of the rat tail at the unconstrained locations are from 0.094 to 0.394, which are lower than those of human fingers (0.708–0.725). Whereas the biodynamic responses of human fingers at frequencies lower than 100 Hz could be significantly influenced by the biodynamics of the entire hand—arm system, the rat tail biodynamic responses can be considered independent of the rat body in the frequency range used in this study. Based on these findings it is concluded that, although there are some differences between the frequency dependences of the biodynamic responses of the rat tail and human fingers, the rat tail model can provide a practical and reasonable approach to examine the relationships between the biodynamic and biological responses at midrange to high frequencies, and to understand the mechanisms underlying vibration-induced finger disorders.
Development of a nasal cast model to test medicinal nasal devices
Authors: Hughes R , Watterson J , Dickens C , Ward D , Banaszek A
Published: November 2008

Bespak, a division of Consort Medical plc, and Queen's University Belfast have developed a viable and unique in-vitro testing capability for nasal drug delivery devices. The aim was to evaluate and optimize current and conceptual drug delivery devices by quantifying the deposition of drug in the various distinct regions of the nasal cavity. The development of this test apparatus employed computed tomography (CT) scan data of the human nasal cavity to construct an accurate representation of the human nasal airways. An investigation of suitable materials and manufacturing technologies was required, together with extensive analytical method development. It is possible for this technique to be further developed in an attempt to create a standardized apparatus based on nasal geometry that can be used to compare accurately deposition from drug delivery devices. This paper presents the issues encountered in the development of this test apparatus, including manufacturing and material limitations, investigation and choice of suitable materials, laboratory testing considerations, and the steps required to validate the analytical process.
Wear simulation of ultra-high molecular weight polyethylene hip implants by incorporating the effects of cross-shear and contact pressure
Authors: Kang L , Galvin A L , Brown T D , Fisher J , Jin Z-M
Published: November 2008

The effect of multi-directional cross-shear (CS) motion and contact pressure on ultra-high molecular weight polyethylene (UHMWPE) wear was investigated in this study, based on an integrated experimental and computational approach. The wear factor as a function of CS was determined experimentally from a multi-directional pin-on-plate wear tester under a nominal contact pressure of 1 MPa. A computational wear model was developed which included the effects of CS as well as the load and sliding distance imposed on the hip joint employing a UHMWPE cup against a metallic femoral head under both gait and Leeds ProSim hip joint simulator conditions. The CS ratios were quantified over the articular surface of the UHMWPE cup and the CS-dependent wear factors derived from multi-directional pin-on-plate studies were applied in the computational wear model. Outputs from the computational wear model were validated independently against an experimental hip simulator study. Comparisons of linear and volumetric wear were made between the computational wear model and the hip simulator testing for a nominal conventional (0 MRad) UHMWPE cup of 28 mm diameter and a highly cross-linked (10 MRad) UHMWPE cup. The difference between the computed and experimental volumetric wear was approximately 30 per cent for the 0 MRad UHMWPE, although the worn areas between the prediction and the measurement were similar. For the 10 MRad UHMWPE, the discrepancy was reduced to 16 per cent. In both cases, the computational model predicted a lower wear rate than the experimental simulator testing. The effect of using alternative wear factors under a different nominal contact pressure of 3 MPa was also considered. The input wear factor to the computational model, derived from a constant loaded pin-on-plate test configuration, may underestimate the dynamic effect due to the variation in the load in the hip joint simulator.
A finite element model on effects of impact load and cavitation on fatigue crack propagation in mechanical bileaflet aortic heart valve
Authors: Mohammadi H , Klassen R J , Wan W-K
Published: November 2008

Pyrolytic carbon mechanical heart valves (MHVs) are widely used to replace dysfunctional and failed heart valves. As the human heart beats around 40 million times per year, fatigue is the prime mechanism of mechanical failure. In this study, a finite element approach is implemented to develop a model for fatigue analysis of MHVs due to the impact force between the leaflet and the stent and cavitation in the aortic position. A two-step method to predict crack propagation in the leaflets of MHVs has been developed. Stress intensity factors (SIFs) are computed at a small initiated crack located on the leaflet edge (the worst case) using the boundary element method (BEM). Static analysis of the crack is performed to analyse the stress distribution around the front crack zone when the crack is opened; this is followed by a dynamic crack analysis to consider crack propagation using the finite element approach. Two factors are taken into account in the calculation of the SIFs: first, the effect of microjet formation due to cavitation in the vicinity of leaflets, resulting in water hammer pressure; second, the effect of the impact force between the leaflet and the stent of the MHVs, both in the closing phase. The critical initial crack length, the SIFs, the water hammer pressure, and the maximum jet velocity due to cavitation have been calculated. With an initial crack length of 35 μm, the fatigue life of the heart valve is greater than 60 years (i.e. about 2.2×109 cycles) and, with an initial crack length of 170 μm, the fatigue life of the heart valve would be around 2.5 years (i.e. about 9.1×107 cycles). For an initial crack length greater than 170 μm, there is catastrophic failure and fatigue cracking no longer occurs. A finite element model of fatigue analysis using Patran command language (PCL custom code) in MSC software can be used to evaluate the useful lifespan of MHVs. Similar methodologies can be extended to other medical devices under cyclic loads.
Engineering of clinical glioma treatment: Prediction of pro-invasive molecular events in treated gliomas
Authors: Trog D , Yeghiazaryan K , Schild H H , Golubnitschaja O
Published: November 2008

The diffusely infiltrative nature of malignant gliomas is the main obstacle to successful treatment approaches. Advanced simulation models of the in vivo response to therapy conditions are expected to improve malignant glioma treatment substantially. In parallel experiments, human malignant glioma cells underwent either radiation or chemotherapy treatment (chemotreatment) with temozolomide alone, or combined chemoradiation. Cells were treated according to diverse, clinically relevant, therapeutic algorithms. Quantitative ‘real-time’ polymerase chain reaction (PCR) measurements were performed for target genes, namely vascular endothelial growth factor, p53, and cyclooxygenase-2, which allow a comparative evaluation of pro-invasive molecular events in treated gliomas. The proof-of-principle study simulated variable intratumoural regional conditions. Pro-invasive molecular patterns were strongly dependent on the treatment algorithm, cellular density, and drug delivery. The highest pro-invasive potential was demonstrated for simulated peripheral regions under continued chemoradiation. This result strongly supports the clinical observations of increased aggressiveness and relatively poor response to second-line therapies in post-operatively chemoradiation-treated malignant gliomas at the time of relapse. Individualized and potentially the most effective treatment algorithms can be designed using established gene expression patterns applied on primary cell cultures obtained from individual patients. Individual drug toxicity and response to anti-cancer therapy can be predicted.
Study of the multi-injection combustion process in a transparent direct injection common rail diesel engine by means of optical techniques
Authors: Mancaruso E , Merola S S , Vaglieco B M
Published: November 2008

A combination of ultraviolet—visible optical diagnostics has been applied in the combustion chamber of a diesel engine in order to study the fuel injection, autoignition, and soot formation processes. Measurements were made in an optically accessible diesel engine equipped with a multivalve cylinder head and a common rail (CR) high-pressure injection system. Several multi-injection strategies, characteristic of new generation CR diesel engines, were tested. They consisted of two (pre + main) and three (pre + main + post) injections per cycle. Fuel injection and visible combustion were studied by imaging the natural flame luminosity, and soot formation and evolution were evaluated by means of the two-colour pyrometry method. The reactions that occur during autoignition and soot formation were investigated by chemiluminescence imaging, while the broadband ultraviolet—visible extinction and scattering spectroscopy (BUVESS) technique was used in order to measure the soot particle size and number concentration.

For all the injection strategies investigated, pre injection has contributed to the reduction of the ignition delay of the main injection. Moreover, the present study showed that autoignition can be characterized to some degree by the presence of the OH radical. The effect of post injection on combustion development and soot particle diameter has also been observed and discussed.
Thermodynamic requirements for maximum internal combustion engine cycle efficiency. Part 1: Optimal combustion strategy
Authors: Teh K-Y , Miller S L , Edwards C F
Published: November 2008

This is the first of a two-part study that examines, from the exergy management standpoint, the fundamental thermodynamic requirements for maximizing internal combustion (IC) engine cycle efficiency. The optimal cycle is shown to comprise three distinct engine architectural elements — reactant preparation, combustion, and work extraction from the products — each of which can be analysed separately. This study shows, based on dynamical system optimization, that it is the equilibrium thermodynamics (specifically, the constant-internal energy—volume ( UV) product state at the end of combustion) and not chemical kinetics (i.e. reactions taking place during combustion) that ultimately dictates the amount of exergy destroyed due to combustion. The strategy for minimizing this destruction term reduces to carrying out reactions at the highest possible internal energy state — following what may be called the ‘extreme state’ principle — so as to minimize the corresponding constant- UV entropy change from reactants to equilibrium products. The extreme state principle remains unaltered when system inhomogeneity (from fuel vaporization and mixing with air) and heat loss are accounted for. Based on this optimal combustion strategy, the companion paper examines the remaining elements of the engine cycle (reactant preparation and work extraction) so as to improve overall cycle efficiency.
What influences rigid inflatable boat motions?
Authors: Townsend N C , Wilson P A , Austen S
Published: November 2008

This paper presents results of full-scale and model-scale rigid inflatable boat (RIB) experiments identifying the influences of speed, ballast, wave height, encounter frequency, and tube pressure on the motion responses of Royal National Lifeboat Institution (RNLI) Atlantic RIBs. A discussion of the results and the influences on the motions is made with a description of the typical motion responses, measures to describe the motion, the function of a RIB tube, and the effect of the motions on the occupants.
Simulation study of a ship's engine behaviour running with a periodically immersed exhaust
Authors: Tauzia X , Chessé P , Maiboom A
Published: November 2008

This paper presents a simulation study of a marine diesel engine equipped with an exhaust system periodically immersed by sea waves. The engine is simulated with an existing, filling and emptying zero-dimensional thermodynamic model. The exhaust system is described with capacitive and inertial elements, and the modelling can take into account water penetration into the exhaust system. An extensive parametric study is conducted to check the influence of exhaust backpressure on engine performances, efficiency, and reliability. A constant water height is first studied and then sinusoidal waves of various periods are analysed, for several engine loads from idle to full load. Results show that the turbine inlet temperature, air/fuel (A/F) ratio, or scavenging process can become critical in some situations. Simulation can help to design an exhaust system that avoids these situations.
Structural risk analysis of an NO96 membrane-type liquified natural gas carrier in Baltic ice operation
Authors: Han S , Lee J-Y , Park Y-I , Che J
Published: November 2008

The present study considers the results of a structural risk analysis for a 170 000 m3 vessel with Ice Class IA classification operating from the Baltic Sea to Quebec, Canada. The target vessel is characterized by a Gaz Transport/Technigas (GTT) NO96 containment system for liquified natural gas (LNG) cargo. The capacity of the double-hull structure has been assessed considering inner hull deflection as the critical factor for the safety of the containment system. This capacity is compared with accidental ice load, termed as ‘demand’ to the LNG carrier, from ice hazards that can occur during Baltic Sea operation in winter or while operating on the Canadian east coast. Risk analysis has been performed to evaluate the risks of the considered ice features in the operation route, based on the study of capacity and demand.
Assessment of operational risks to personnel on board fixed offshore structures
Authors: Elsayed T , Leheta H , Shehadeh M , Sherede M
Published: November 2008

An overview of the causes and frequency of incidents occurring on a fixed offshore structure, handling petroleum, is presented in this paper. Results are based on an analysis of a database of incident data covering a period of 2 years. The database is compiled by the operating company of the platform, which is located about 100 km offshore from Libya. The analysis provides important information on incident modes and rates of occurrence for fixed offshore structures. Platform incident data can also be used to develop probabilities of future incidents, a key input for quantitative risk assessment. Personnel risk assessment is carried out to assess the safety of offshore workers on board the platform. Potential loss of life, fatal accident rate, and average individual risk are computed for personnel working on board the platform. These values are then compared with acceptable standard values to assess the current safety level on board the platform. Activity-based risk assessment is also carried out for six potentially risk-increasing activities. The results could be a valuable tool for improving personnel safety on board the platform and for setting up inspection and maintenance strategies for the platform.
Development of an emission assessment scheme for a fishing vessel diesel propulsion engine
Authors: Latorre R G , Cardella V J P
Published: November 2008

While a significant effort has been made to reduce marine diesel exhaust emissions, there is a need to examine the world fleets and assess the current levels of engine emissions. This paper introduces an emission assessment scheme that the authors have applied to analyse the US fishing fleet with length L>22.9 m. The present results give an estimate that the 1051 vessels in the US fishing fleet produce 306 tonnes/day of nitrous oxides (NO x). The largest power values are found in the decades of 1960 to 1980. The actual power (kW) is compared with a reference power (kWo) using the powering index ratio (PIR = kW/kWo). It was found that 50–80 per cent of the power in seiners, trawlers, and crabber/trapper/clam vessels have a PIR>2.5. Based on this assessment, it is clear that a large number of trawlers and seiners are overpowered – resulting in high diesel engine NO x emissions.
Measuring Brand Value in an Equilibrium Framework
Authors: Goldfarb Avi , Lu Qiang , Moorthy Sridhar
Published: November 2008

We propose a structural approach to measuring brand and subbrand value using observational data. Brand value is defined as the difference in equilibrium profit between the brand in question and its counterfactual unbranded equivalent on search attributes. Our model allows us to make this computation rigorously, taking into account competitors' and retailers' reactions in the real and counterfactual situations. We illustrate our method using quarterly city-level data on ready-to-eat breakfast cereals, and compare our brand value estimates with those obtained from previously used reduced-form methods. A key advantage of our methodology is that it provides estimates of the value of brands to firms—manufacturers and retailers—taking into account the brand's value to consumers as well as its impact on firm decisions.
Optimal Bundling Strategies in Multiobject Auctions of Complements or Substitutes
Authors: Subramaniam Ramanathan , Venkatesh R.
Published: November 2008

We consider a problem at the interface of auctions and bundling. Our revenue-maximizing seller seeking to auction one unit each of two complements or substitutes in the best-of-three formats: the auction of the bundle, separate auctions of the individual items, and a combinatorial auction. We draw on an analytical model to address the following questions: (i) Which of the auctioning strategies is optimal under the second-price, sealed-bid format? (ii) What is the optimal strategy for the bidders? (iii) When the objects are asymmetrically valued (e.g., Super Bowl ticket versus souvenir), what is the optimal auctioning sequence under the pure components strategy? Our results suggest that separate auctions of the two objects are superior to the auction of the bundle for most substitutes and even moderate complements when there are at least four bidders. The auction of the pure bundle is better suited for strong complements or with too few bidders. When the combinatorial auction is an available option, it weakly dominates the auction of the pure bundle but has domains of inferiority relative to the separate auctions. When the objects are asymmetric in value, it is optimal to auction the higher-valued object first.
The Benefits of Downstream Information Acquisition
Authors: Guo Liang
Published: November 2008

This study investigates the effects of turning terabytes of raw retail data into managerial insights (i.e., downstream information acquisition) in a strategic channel setting. Two effects of information acquisition are identified—the efficiency effect that improves retail pricing decision making in an uncertain environment, and the strategic effect whereby the retailer voluntarily discloses the acquired private information to influence the upstream manufacturer's wholesale pricing behavior. It is shown that the efficiency effect benefits the retailer without affecting the manufacturer, while the strategic effect works to the detriment of the retailer but to the advantage of the manufacturer. Nevertheless, unobservable information acquisition can mitigate the retailer's loss and the manufacturer's benefit from the strategic effect of information disclosure. Moreover, an increasing expected information acquisition cost may benefit the retailer, when that cost is low and information acquisition is unobservable to the manufacturer. The implications of this paper can shed light on how firms interact in a channel where the downstream market is data intensive, but information gleaning is costly.
Asymptotic Behavior of Total Times for Jobs That Must Start Over if a Failure Occurs
Authors: Asmussen Søren , Fiorini Pierre , Lipsky Lester , Rolski Tomasz , Sheahan Robert
Published: November 2008

Many processes must complete in the presence of failures. Different systems respond to task failure in different ways. The system may resume a failed task from the failure point (or a saved checkpoint shortly before the failure point), it may give up on the task and select a replacement task from the ready queue, or it may restart the task. The behavior of systems under the first two scenarios is well documented, but the third (RESTART) has resisted detailed analysis. In this paper we derive tight asymptotic relations between the distribution of task times without failures and the total time when including failures, for any failure distribution. In particular, we show that if the task-time distribution has an unbounded support, then the total-time distribution H is always heavy tailed. Asymptotic expressions are given for the tail of H in various scenarios. The key ingredients of the analysis are the Cramér–Lundberg asymptotics for geometric sums and integral asymptotics, which in some cases are obtained via Tauberian theorems and in some cases by barehand calculations.
On the Low Rank Solutions for Linear Matrix Inequalities
Authors: Ai Wenbao , Huang Yongwei , Zhang Shuzhong
Published: November 2008

In this paper we present a polynomial-time procedure to find a low-rank solution for a system of linear matrix inequalities (LMI). The existence of such a low-rank solution was shown in the work of Au-Yeung and Poon and the work of Barvinok. In the approach of Au-Yeung and Poon an earlier unpublished manuscript of Bohnenblust played an essential role. Both proofs in the work of Au-Yeung and Poon and that of Barvinok are nonconstructive in nature. The aim of this paper is to provide a polynomial-time constructive procedure to find such a low-rank solution approximatively. Extensions of our new results and their relations to some of the known results in the literature are discussed.
On the Solutions of Discrete Nonlinear Complementarity and Related Problems
Authors: Yang Zaifu
Published: November 2008

This paper concerns the existence of solutions to the discrete nonlinear complementarity problem. The problem is that of finding an integer vector x in the n-dimensional Euclidean space such that both x and f(x) are nonnegative, and the inner product of x and f(x) is equal to zero, where f is a nonlinear function mapping from the n-dimensional Euclidean space into itself. Several sufficient conditions are introduced to show the existence of solutions or a unique solution to the problem. Meanwhile, we study the closely related discrete fixed point problem and provide sufficient conditions for the existence of discrete fixed points. In addition, two economic applications are discussed.
Auditing Orthopaedic Audit
Authors: Guryel E , Acton K , Patel S
Published: November 2008

INTRODUCTION

Clinical audit plays an important role in the drive to improve the quality of patient care and thus forms a cornerstone of clinical governance. Assurance that the quality of patient care has improved requires completion of the audit cycle. A considerable sum of money and time has been spent establishing audit activity in the UK. Failure to close the loop undermines the effectiveness of the audit process and wastes resources.

PATIENTS AND METHODS

We analysed the effectiveness of audit in trauma and orthopaedics at a local hospital by comparing audit projects completed over a 6-year period to criteria set out in the NHS National Audit and Governance report.

RESULTS

Of the 25 audits performed since 1999, half were presented to the relevant parties and only 20% completed the audit cycle. Only two of these were audits against national standards and 28% were not based on any standards at all. Only a third of the audits led by junior doctors resulted in implementation of their action plan compared to 75% implementation for consultant-led and 67% for nurse-led audits.

CONCLUSIONS

A remarkably large proportion of audits included in this analysis failed to meet accepted criteria for effective audit. Audits completed by junior doctors were found to be the least likely to complete the cycle. This may relate to the lack of continuity in modern medical training and little incentive to complete the cycle. Supervision by permanent medical staff, principally consultants, and involvement of the audit department may play the biggest role in improving implementation of change.
Dislocation Following Total Hip Replacement: The Avon Orthopaedic Centre Experience
Authors: Blom Ashley W , Rogers Mark , Taylor Adrian H , Pattison Giles , Whitehouse Sarah , Bannister Gordon C
Published: November 2008

INTRODUCTION

The aim of this study was to determine the incidence and outcome of dislocation after total hip arthroplasty at our unit.

PATIENTS AND METHODS

In total, 1727 primary total joint arthroplasties and 305 revision total hip arthroplasties were performed between 1993 and 1996 at our unit. We followed up 1567 (91%) of the primary hip arthroplasties and 284 (93%) of the revision hip arthroplasties at 8–11 years after surgery. Patients were traced by postal questionnaire, telephone interview or examination of case notes of the deceased.

RESULTS

The dislocation rates by approach were 23 out of 555 (4.1%) for the posterior approach, 0 out of 120 (0%) for the Omega approach and 30 out of 892 (3.4%) for the modified Hardinge approach. Of dislocations after primary total hip arthroplasty, 58.5% were recurrent. The mean number of dislocations per patient was 2.81. Overall, 8.1% of revision total hip arthroplasties dislocated. 70% of these became recurrent. The mean number of dislocations per patient was 2.87. The vast majority of dislocations occurred within 2 months of surgery.

DISCUSSION

To our knowledge, this is the largest multisurgeon audit of dislocation after total hip arthroplasty published in the UK. The follow-up of 8–11 years is longer than most comparable studies. The results of this study can be used to inform patients as to the risk and outcome of dislocation, as well as to the risk of further dislocation.
An Audit of Orthopaedic Referrals via Multi-Professional Triage Teams
Authors: Rogers BA , Kabir C , Bradley N
Published: November 2008

INTRODUCTION

Multi-Professional Triage Teams (MPTTs) were created to reduce the caseload of hospital orthopaedic clinics and this prospective study evaluated referrals made to a district general hospital orthopaedic department from a lower limb MPTT clinic.

PATIENTS AND METHODS

Over 9 months, 277 referrals to a lower limb hospital orthopaedic clinic were assessed. The temporal delay to hospital clinic review between patients seen at the MPTT clinic and those referred directly by their general practitioner (GP) was analysed using an ANOVA test. A qualitative assessment of diagnoses given to patients reviewed at the MPTT clinic was performed.

RESULTS

The 132 patients initially reviewed at the MPTT clinic and subsequently referred to a hospital consultant waited significantly longer (140 days compared to 62 days by direct GP referral; P < 0.05) to see an orthopaedic consultant. Over three-quarters of this patient cohort incorrectly identified the healthcare professional conducting their consultation at the MPTT clinic. One-third of cases (31%) had no diagnosis made and 22% were assessed as having an incorrect diagnosis.

CONCLUSIONS

Time delays, patient confusion regarding professional roles and diagnostic indecision are significant problems for patients referred to hospital orthopaedic clinics from MPTT clinics. This risks sub-optimal patient care and may lead to future medicolegal implications.
Pelvic Fasciae in Urology
Authors: Raychaudhuri B , Cahill D
Published: November 2008

INTRODUCTION

Despite the vast literature on pelvic fascia, there is confusion over the periprostatic structures and their nomenclature, including their orientation, the neurovascular bundles and the existence of the prostatic ‘capsule’. In this review, we seek to clarify some of these issues.

MATERIALS AND METHODS

Review of published medical literature relating to the anatomy of the pelvic fascia including a Pubmed search using the terms – pelvic fascia, Denonvilliers' fascia, prostate capsule, neurovascular bundle of Walsh, pubo-prostatic ligament and the detrusor apron.

CONCLUSIONS

The findings of the study were as follows: The ‘capsule’ of the prostate does not exist. Rather, the fibromuscular band surrounding the prostate forms an integral part of the gland. The prostate is surrounded by fascial structures – anteriorly/anterolaterally by the prostatic fascia and posteriorly by the Denonvilliers' fascia. Laterally, the prostatic fascia merges with the endopelvic fascia. The posterior longitudinal fascia of the detrusor comprises a ‘posterior layer’ of the detrusor apron, extending from the bladder neck to the prostate base. The neurovascular structures tend to be located posterolaterally, but may not always form a bundle. A significant proportion of fibres may lie away from the main nerve structures, along the lateral/posterior aspects of the prostate.
Adult Morgagni Hernia: The Need for Clinical Awareness, Early Diagnosis and Prompt Surgical Intervention
Authors: Arora S , Haji A , Ng P
Published: November 2008

We report an unusual case of strangulated diaphragmatic (Morgagni) hernia resulting in ischaemia of the small and large bowel, which was initially diagnosed as a pneumonia. This case highlights the importance of being aware of this rare, but potentially fatal condition when assessing patients with respiratory symptoms and abdominal pain.
Skin Puckering as a Sign of Humeral Neck Fracture
Authors: Alshryda SJ , Odak S , Patel AD
Published: November 2008

To the best of our knowledge, this is the first clinical report of skin puckering associated with fractured neck of humerus. Its significance may vary in different locations and its presence should be added to other physical and radiological signs to aid decision making.
The Effect of Operating Time on Surgeons' Muscular Fatigue
Authors: Slack PS , Coulson CJ , Ma X , Webster K , Proops DW
Published: November 2008

INTRODUCTION

A study was completed to determine if operating has an effect on a surgeon's muscular fatigue.

SUBJECTS AND METHODS

Six head and neck surgery consultants, two ENT registrars, 20 normal controls from two tertiary referral centres in the West Midlands participated in the study. Electromyography (EMG) measurements were taken throughout a day of operating and fatigue indices were compared to controls performing desk work.

RESULTS

The percentage changes in mean frequency of muscular contractions were examined; there was no significant difference in fatigue levels between consultants and registrars. Operating led to an increase in fatigue in all subjects, compared to no increase in controls performing desk work. It was also found that the brachioradialis muscle is used more than the mid-deltoid muscle and, hence, fatigues at a faster rate.

CONCLUSIONS

Surgeons should be aware that their muscular fatigue levels will increase as an operation progresses; therefore, if possible, more complex parts of the operation should be performed as early as possible, or, in the case of a very long operation, a change in surgeon may be necessary.
Can magical intervention affect subjective experiences? Adults' reactions to magical suggestion
Authors: Subbotsky Eugene
Published: November 2008

In three experiments, undergraduates' subjective experiences were affected by positive magical intervention. A large number of participants accepted the offer of magical help, yet the outcomes they reported were contrary to the aims of the magical intervention. In Experiment 1, participants were offered magical help that aimed to improve their practical skills. However, in the magical‐suggestion condition, they reported no improvement significantly more frequently than in the control no‐suggestion condition. In Experiment 2, participants who accepted the offer of magical help aimed at improving their general life satisfaction reported a significant decrease in this satisfaction. Those who declined the offer of magical help reported a significant increase in satisfaction. In Experiment 3, in the magical‐suggestion condition, participants experienced bad dreams significantly more frequently than in the control condition. In conclusion, the data suggest that adult participants protect their subjective experiences against magical intervention.
Using an extended theory of planned behaviour to inform interventions aimed at increasing breastfeeding uptake in primiparas experiencing material deprivation
Authors: McMillan Brian , Conner Mark , Green Josephine , Dyson Lisa , Renfrew Mary , Woolridge Mike
Published: November 2008

Objectives The theory of planned behaviour (TPB) was employed to investigate infant feeding intentions and subsequent behaviour in women from selected areas of economic hardship in the UK. Underlying beliefs were examined in order to inform future interventions aimed at increasing breastfeeding uptake among women living in such areas, which is associated with low rates of breastfeeding.

Design Midwives recruited women from areas meeting study criteria. TPB measures were obtained from 303 primiparas via postal questionnaires completed during pregnancy, and feeding method was subsequently obtained from 286 of these women.

Results A model containing age, education, deprivation, attitude, subjective norm (SN), and perceived behavioural control (PBC) predicted intention to breastfeed (R2=.44) and intention to formula feed (R2=.45). A model controlling for age, education and deprivation predicted ever having breastfed (86.1% correctly classified) and ever having formula fed (77.1% correctly classified). MANCOVAs differentiated those who intended to breastfeed and subsequently did (inclined actors), those who intended to breastfeed but did not (inclined abstainers), and those who did not intend to breastfeed and did not (disinclined abstainers). Differentiating outcome beliefs, normative beliefs, and control beliefs are presented.

Conclusions The TPB provided a useful framework with which to examine the factors underlying breastfeeding intentions and behaviour amongst primiparas. A grouping system based on the congruence between intentions and subsequent behaviour revealed important differences between beliefs of the three groups. Further research might usefully test the effectiveness of interventions targeting the beliefs identified here in increasing breastfeeding uptake and duration.
What predicts post‐traumatic stress following spinal cord injury/
Authors: Hatcher Mal B. , Whitaker Chris , Karl Anke
Published: November 2008

Objectives. Spinal cord injury (SCI) is a severe, traumatic event and recently research into the role of post‐traumatic stress disorder (PTSD) subsequent to the injury has become of increasing interest. This study has been conducted in order to investigate potential risk factors for the development of post‐traumatic stress disorder symptoms in those with SCI.

Design. This cross‐sectional study used multiple regression analysis to look for associations between post‐traumatic stress symptom severity, SCI‐related factors and previously identified risk factors for PTSD such as dysfunctional cognitions, demographic factors and personality predispositions (neuroticism, alexithymia).

Method. A total of 102 participants with SCI completed measures of post‐traumatic stress severity, acceptance of injury, post‐traumatic cognitions, social support, neuroticism and alexithymia. In addition, information about type, level and cause of the SCI was assessed.

Results. High levels of post‐traumatic stress symptoms were found. Potential risk factors for the development of PTSD were negative cognitions of self and neuroticism. Variables that added to the variance explained by the models included time since injury and difficulty identifying feelings. Acceptance of injury was mediated by negative cognitions of the self and neuroticism.

Conclusions. The study highlights the need for services to be aware of the psychological difficulties experienced by this client group. An important finding is that the acceptance of the injury is mediated by negative cognitions of the self which need to be identified as potential risk factors in order to prevent the development of post‐traumatic symptoms in this population.
Plasticity of Cloned Canine Mammary Spindle Cell Tumor, Osteosarcoma and Carcinoma Cells
Authors: Wensman H. , Flama V. , Pejler G. , Hellmén E.
Published: November 2008

Female dogs are frequently affected by mammary tumors, both carcinomas and sarcomas. The mechanisms behind mammary-tumor formation and the high degree of heterogeneity are not understood. To provide insight into this issue, it is important to determine the properties of the cells forming the different types of tumors. One question is if individual neoplastic cells can give rise to phenotypically distinct tumor types, i.e., show plasticity. We studied 3 different tumors (a spindle-cell tumor, an osteosarcoma, and a carcinoma) and followed the change of lineage marker expression between the primary canine mammary tumors, the clones derived from the corresponding tumors and in tumors generated after inoculation of tumor clones into nude mice ( n = 75). Inoculation of clones derived from the spindle-cell tumor gave rise to spindle-cell tumors in nude mice. Several of these contained bone tissue, a sign of plasticity. Clones derived from the osteosarcoma were negative for a panel of lineage markers but, when inoculated into nude mice, they were able to form bone, again a sign of plasticity. In contrast to the primary carcinoma, most of the clones derived thereof lacked keratin expression, but keratin expression was recovered in most of the tumors formed after inoculation of clones into nude mice. Moreover, tumors generated from the carcinoma clones, in contrast to the primary tumor, were positive for smooth-muscle-cell markers. Our results point to plasticity in canine mammary tumors, as shown both by morphologic criteria and by expression patterns for lineage specific markers.
Cyclooxygenase-2 Expression in Equine Tumors
Authors: Thamm D. H. , Ehrhart E. J. , Charles J. B. , Elce Y. A.
Published: November 2008

The enzyme cyclooxygenase-2 (COX-2) is expressed in some tumor and stromal tissues, and catalyzes production of prostaglandins with growth stimulatory, antiapoptotic, proangiogenic, and immunosuppressive properties. Pharmacologic inhibition of COX-2 is associated with antitumor activity in various human and canine malignancies. The purpose of this study was to assess COX-2 expression in a series of equine sarcoids, melanomas, and squamous-cell carcinomas (SCC). COX-2 expression was assessed in formalin-fixed paraffin-embedded tissues from 14 sarcoids, 11 melanomas, and 37 SCC that represent various anatomic sites by using standard immunohistochemical methods. COX-2 was expressed in 2 of 14 sarcoids, 7 of 11 melanomas, and 32 of 37 SCC, 56% of which demonstrated moderate-to-strong immunoreactivity. There were no differences in expression between anatomic sites. In conclusion, most equine SCC and many melanomas appear to express COX-2 and thus could respond to COX-2 inhibitor therapy.
A Pregnant Mouse Model for Bovine Tritrichomonas foetus Infection
Authors: Agnew D. W. , Corbeil L. B. , Munson L. , Byrne B. A. , BonDurant R. H.
Published: November 2008

The economically important effects of Tritrichomonas foetus infection in cattle are abortion and infertility, yet there has not been an animal model to examine the parasite-host interactions during gestation. In this study, 5- and 7- to 8-week-old BALB/cAnNCr, BALB/cJ, and SCID/NCr mice on a BALB/c background were intravaginally infected with T. foetus. All BALB/ cAnNCr and BALB/cJ mice, and 89% of SCID/NCr mice sustained infections for 13 weeks, if inoculated before 5 weeks of age. Infection rates were lower in all mouse strains inoculated at 7 weeks of age, although BALB/cAnNCr mice were significantly more susceptible than BALB/cJ or SCID/NCr mice. Vaginal bacterial flora did not account for the variation in mouse-strain susceptibility, although coagulase-negative staphylococci in vaginal flora were associated with failure of T. foetus to infect. As with infected cattle, T. foetus-specific vaginal immunoglobulin (Ig) G and IgA antibodies were elevated after infection. The number and viability of day-10 fetuses were reduced in mice infected at 5 weeks of age and bred 12 weeks after infection. Lesions in pregnant and nonpregnant infected mice, including suppurative and eosinophilic vaginitis; cervicitis; endometritis with distension of the uterine lumen; endometrial ulceration; and glandular ectasia, with neutrophils in the glandular lumen and loss of gland epithelium, were similar to those in cattle. The decidua and placenta were multifocally necrotic. Immunohistochemistry demonstrated trichomonads in vaginal folds and uterine glands, and adjacent to fetal tissues. In summary, experimentally infected BALB/cAnNCr mice showed many pathologic similarities to cattle and may serve as a model to study host-trichomonad interactions.