bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Inertial Factors on Spinal Stress when Lifting
Authors: Leskinen T P J , Stålhammar H R , Kuorinka I A A , Troup J D G 
Published: February 2007

Biomechanical models used for the evaluation of spinal stress have mostly been static: they reveal the postural stress caused by gravity but ignore the inertial forces and torques induced by the accelerations of body segments and the load handled. In this study both static and dynamic models for determining lumbosacral compression were used, and the results from different models were compared. Twenty subjects lifted a 15 kg box from a 10 cm high shelf to knuckle height with four lifting techniques: the conventional back and leg lifts and two kinetic' lifts with which the subjects gave kinetic energy either to the horizontally moving load or to the vertically moving body before lifting the load itself vertically. The results showed that the inertial factors increase the spinal load considerably. Comparison between the lifting techniques showed that the dynamic peak stress was clearly smaller in the leg lift than in the back lift, although the static peak stress was smaller in the back lift. The L5/S1-compression × time integral, describing the total stress of a lift, was smallest in the back lift with both models.
The use of Strain Gauges for Biometrics in Europe
Authors: Calderale P M 
Published: February 2007

Strain gauges have a relevant role in mechanical measurements, and it is therefore quite natural that they find widespread use in biomechanics. They are used for the evaluation of the strain and stress distribution in particular points of structures of biomechanical interest, and, moreover, for the validation of numerical analyses. This work reviews the use that European researchers make of this technique, mainly in orthopaedics, dentistry, and sport biomechanics.
Cartilage-Bone Interface
Authors: Millington P F 
Published: February 2007

Although cartilage and bone are considered to be rigid tissues they are nevertheless living and changing throughout life. One of the retrogressive processes in cartilage is calcification, but calcification also occurs as a temporary strengthening during the replacement of cartilage by bone. Studies of the zone of calcification have shown that crystalline calcium phosphate is deposited alongside the collagen fibres. A morphometric study of the zone has now been made using novel techniques in which the surface of an epoxy-embedded thick section of undecalicified tissue is polished, stained with toluidine blue, and inspected by reflection light microscopy. Measurement of the area of stain deposition in normal tissue has led to an estimate of the area ratio for the section and, hence, the volume of calcified cartilage in the femoral head. Studies on osteoarthritic heads have revealed smaller area ratios as well as differences in distribution in the boundary layer. The significance of the data is discussed in relation to physical properties and possible remedial treatments in severe arthritis.
A Finite Element Stress Analysis of an Endodontically Restored Tooth
Authors: Williams K R , Edmundson J T 
Published: February 2007

Previous work has indicated that teeth restored with posts and pins of non-noble metals can fail by longitudinal fracture. In particular, teeth restored by the Wiptam method have shown significant demineralization of the dentine by metallic salts due to corrosion of the Ni–Co–Cr post. This investigation concentrated on the stress distribution within a Wiptam restored tooth for a variety of mechanical and thermal loads calculated using the finite element method. It is shown that the dentine is more highly stressed in restorations with long posts than short posts for a given load. The maximum tensile stresses exist in the vicinity of the bottom of the post and the FEM calculations indicate a similar pattern of stress distribution to the observed cracking pattern. In no case were the calculated stresses above the fracture stress for dentine. However, by simulating the gradual leaching of cement from the dentine/gold-porcelain interface, it is shown that significant tensile stresses well above the fracture stress develop in the zinc phosphate cement in the pulp chamber. Subsequent breakdown of this layer, with the consequent ingress of oral fluids to the Ni–Co–Cr post, then leads to corrosion and demineralization of the dentine. The demineralized dentine is then readily fractured by normal masticatory forces. Thermal transients of the order of 25 C and above also generate high stresses in the cementing medium in the pulp chamber. Normal thermal cycling can also lead to cement breakdown and subsequent tooth fracture by the processes already described.
A Comparison of Knee Joint and Muscle Forces in Women 36 Weeks Pregnant and Four Weeks after Delivery
Authors: Ellis M I , Seedhom B B , Wright V 
Published: February 2007

Knee joint and muscle forces were determined for three women when they were 36 weeks pregnant and again four weeks after delivery, for the activity of rising from a seated position. The knee joint forces were determined by kinesiological techniques using a high speed cine camera, a force platform, a specially constructed dynamometerized chair, and emg recorders. A comparison of knee joint and muscle forces was made for rising from a normal chair both with and without the aid of arms for the same three women Before Childbirth (b.c.) and After Delivery (a.d.). For rising from the seated position without the aid of arms, the knee joint forces parallel to the long axis of the tibia at the point of contact between the tibia and the femur, were found to be 33 per cent greater b.c. compared to those a.d. Other knee joint and muscle forces were also dramatically increased due to pregnancy.
Theoretical Determination of Damage Risk Criteria for Impulse Noise
Authors: Chatham Robina 
Published: February 2007

It is widely accepted that for continuous noise, a relationship exists between the energy of sound (A-weighted) and its deleterious effects on hearing. However, when the exposure is to high intensity short duration impact or impulse noise, a hitherto unpredictable degree of damage can occur to the inner ear. The present study has set out to establish damage risk criteria for a variety of impulsive waveforms. A mathematical model of the auditory periphery has been developed and verified for sinusoidal stimulation using existing experimental data. Experimental results, obtained using guinea pigs under impulsive stimulation, were used to calibrate the model. Once calibrated the model was used to give information as to the damage likely to occur from other types of impulsive stimuli, hence reducing the need for extensive animal experimentation. It has been shown that the model can predict the potential auditory hazard from various impulsive stimuli, quantitatively in the guinea pig and qualitatively in man. Both the experimental and theoretical results indicated that the intensity of the first pressure wave of an impulse, above a certain value, is the most significant determinator of hearing damage. The machine designer thus has guide lines as to where to concentrate his efforts in reducing potentially traumatic machine noise.
Experimental Arthrosis by Hyperpressure
Authors: Bejui J , Harmand M F , Duphil R , Roussouly P , Comtet J J , Anania G 
Published: February 2007

The frequent occurrence of degenerative joint disease (DJD) pathology and the high degree of functional prejudice associated with it, justify the search for experimental models with a view to a better understanding of this pathology and its treatment. The models most commonly used resort to a sudden mechanical degradation by shock (post-contusive osteoarthritis) or to a kinematic disruption of the joint through more or less extensive menisco-capsulo-ligamentary lesions or lesions induced by toxic substances. Cartilaginous lesions met with in human pathology are often secondary to a morphological anomaly at the origin of a hyperpressure. Maquet (1977) has suggested the bringing forward of the anterior tibial tubercle (ATT) in order to reduce the retro-patellar pressure. The drawing back by hollowing of this ATT appeared to us a suitable model for experimental osteoarthritis by hyperpressure.
The DHSS Evaluation Programme for Infusion Control Instruments
Authors: Auty B 
Published: February 2007

The DHSS commissioned the Bath Institute of Medical Engineering (BIME) to carry out a comparative evaluation of instruments for the control of intravenous infusions. This project commenced six years ago. To date, six reports have been published in the DHSS‘ Health Equipment Information series and more are in preparation. Some three dozen different instruments have been assessed. The programme proceeds in three independent phases: technical, clinical, and safety testing. The technical phase includes performance testing in the laboratory, assessment of ease of operation and assessment of design and production techniques used, ease of servicing, and reliability. The clinical evaluation is designed to check the capability of the instrumentation under actual ward usage and questionnaires are completed by medical staff. Safety testing to BS 5724 Part 1 is undertaken at the British Standards Test House at Hemel Hempstead. There are four different types of instrument for infusion control: gravity controllers, drip-rate pumps, volumetric pumps, and syringe pumps. Each type has different performance characteristics to cater for specific applications. During the course of the evaluation, much has been learnt and many different aspects of performance have been studied, including drop size variations, air embolism, delivery pressure, and alarm response times.
Body Surface Measurement and Replication by Photogrammetry and Computer Aided Design
Authors: Vergeest Joris S M , Broek Johan J , Van Voorden A 
Published: February 2007

This article presents and demonstrates a method of measuring the shape of the human skin and of reproducing the form as a real three-dimensional object at any scale. The working system consists of two parts, each normally in use for different disciplines at Delft University of Technology. The two parts, that we have interfaced, are a photogrammetric stereo restitution system and a CAD system integrated with a numerically controlled 3D milling machine. One stereopicture of (an arbitrary part of) the human body is sufficient to obtain any number of digitized points of the visible surface. Our system does not necessarily rely on reference grids, calibration frames, or surface marking points. Repeated measurements have shown that a measurement precision of 0.06 per cent of the observation distance is achieved. The data allow a complete surface representation by the CAD system, which in turn provides facilities for fast interactive viewing, for high quality colour image generation, and reproduction of the shape in foam material.
Quantitative Approach to Osteoarthritic Gait Assessment
Authors: Khodadadeh Soussan 
Published: February 2007

Measurements of the gait of 42 patients with osteoarthritis of the hip are made using only a pair of small force plates with computer interfacing. The use of more complex and expensive television systems is thus avoided. The force between the foot and plate is measured during gait, resolved into vertical, horizontal, and lateral force components, and graphs of the time variations of these components produced. It is shown that an accurate on-line assessment of pre- and post-operative gait can be made, but only by reference to all three force component curves. A numerical assessment of the gait condition is obtained as the total of scores for clearly identified separate features of each curve. This helps the clinician to arrive at a firm value and should reduce subjective variations arising from attempts to assign a single overall number for the ‘quality’ of each curve.
Hydrodynamic Advantages and Disadvantages of Mechanical Bileaflet Valves and Tilting Disc Valves No. 29
Authors: Heiliger R 
Published: February 2007

In order to determine the effectiveness of mechanical heart valves two different types of mechanical heart valves, three tilting disc valves (BS–SD, BS–CCD, BS–M) and two bileaflet valves (St Jude Medical, Duromedics) with the same size of annulus diameter dA = 29 mm have been investigated in the mitral position of a mock circulation under pulsatile flow conditions. Flow, pressure and orifice area have been measured. Insufficiency, mean orifice area, discharge coefficient, performance index, and efficiency index have been calculated. The investigated tilting disc valves show smaller reflux volume and smaller insufficiency when comparing with the bileaflet valves. The bileaflet valves show higher values of orifice areas—that is to say smaller pressure drops—than the tilting disc valves. The St Jude Medical shows the biggest orifice areas, but also the highest reflux volume and insufficiency. Insufficiency of the Duromedics is slightly higher than that of the tilting disc valves. The orifice area of the Duromedics is bigger than that of the tilting disc valves and smaller than that of the St Jude Medical. The different pivot and the different profile of the disc of the BS–CCD and the BS–M are responsible for the more constant behaviour of the opening of these tilting disc valves when comparing with the BS–SD. Though the bileaflet valves show the better efficiency index, none of the valve types is superior in all hydrodynamic criteria. Both valve types, the bileaflet valves and the tilting disc valves, show different hydrodynamic advantages and disadvantages.
A Leg Positioning and Holding Mechanism for Use during Knee Surgery
Authors: Churches A E , Walsh M J , Fisher W E , Anderson J B 
Published: February 2007

The paper describes a novel leg positioning and support mechanism for use during knee surgery. The limb is positioned by controlling hip flexion–extension and hip abduction–adduction, using the normal thigh tourniquet as an attachment point for the mechanism. The knee joint and the lower leg are not impeded by the device and the surgeon may freely test knee joint movements. Early experience in the operating theatre indicates significant advantages in freeing the assistant surgeon for other duties, reduced physical effort, and firmer retention of the leg. The use of the leg positioning and support mechanism may permit ergonomically improved operating techniques to be developed.
Assessment of a New Hip Dynamometer
Authors: Greena J , Mckenna F , Ellis M , Helliwell P , Howe A , Chamberlain M A 
Published: February 2007

A new system for measuring power and endurance of muscles around the hip joint is described. The system is designed to be used in a study involving patients with osteoarthritis of the hip joint. The system is compared with previous work in this field. The method of use and a study to evaluate reproducibility are described. Ten patients with osteoarthritis of the hip joint, and eleven volunteers were tested. Results show reasonable levels of reproducibility for power; endurance was less reproducible.
A Clinical Gait Analysis System
Authors: Ellis Malcolm , Howe Adrian 
Published: February 2007

A gait analysis system has been devised that is not only relatively inexpensive, but is also quick to use, requires no expertise to run, and does not need any special laboratory facilities. The system monitors the subject's knee and hip movements during ambulation using electro-goniometers. Foot contact data are obtained using lightweight, flexible, foot switches. The data are sent to a computer via an eight channel telemetry system carried by the subject on a waist belt. The software is designed to simplify analysis and be ‘user friendly’. After a simple calibration routine, the system prompts the operator to ask the subject to walk a number of steps. The computer ignores the initial steps taken as these are not typical of normal gait. It then collects data from the consequent steps, averages the data and then displays them in both graphical and numerical form. A patient can be tested and a printout provided for insertion in the patient's notes within ten minutes. Only one hours training is required to learn to operate the system. A patient can be tested in a physiotherapy department, corridor, or in any area where a few consecutive steps can be taken.
The Role of Gait Analysis in Clinical Medicine: A Survey of UK Centres
Authors: Messenger N , Bowker P 
Published: February 2007

This paper reports the results of a survey carried out to assess the clinical usage currently being made of gait analysis facilities within the UK. Thirty-five centres were circulated with a questionnaire which requested information under four main headings: (i) equipment, (ii) research projects, (iii) clinical service commitments, and (iv) subjective views of the ultimate clinical value of the service. Of the 25 completed questionnaires returned, 16 were suitable for inclusion in the final analysis of data. The survey provided useful data on the equipment and facilities available in each centre together with details of the service available to prospective referring clinicians. Ten centres were considered as being currently involved in some clinical work, with six of these being routinely involved. The respondents generally felt that gait analysis techniques have a clinical context, if not yet routinely, but the numbers of referrals to the centres is still quite small. A number of areas worthy of further work were identified by the respondents. It is hoped that presentation of these results will stimulate dialogue between centres and between clinicians and bioengineers.
Radiographic Determination of the Angle of Version of the Femoral Component in Total Hip Replacement
Authors: Schmotzer Hans , Learmonth Ian D 
Published: February 2007

This paper describes a simple method to determine stem orientation after total hip replacement. It is based on standard antero-posterior radiographs and computes the angle between prosthesis and film plane from the shortening of predefined distances in the projection. The error of the method is less than 5 per cent for the stem orientation and less than 10 per cent for the neck orientation. The method allows accurate control of stem orientation by means of standard equipment in orthopaedic practice.
Computerized Cheirometer for Assessing Grip-Strength Indices and Classification of Rheumatoid Patients
Authors: Chan Alfred P K , Kamath Markad V , Buchanan W Watson , Ghista Dhanjoo N , Grace Eileen M , Anvari Payman 
Published: February 2007

A computerized Cheirometer has been developed to objectively assess grip strength indices (GSI) of normals and rheumatoid arthritis (RA) patients. The instrument consists of a hand-grip bladder, an LVDT pressure transducer (Schaevitz) interfaced through a 12 bit A/D converter to an Apple II + computer. Software has been developed for data acquisition, display and classification of measured GSI into moderately diseased and severely diseased and normal classes. During the developmental phase of the instrument, it was noted that maximum pressure ( PM) and rate-of-rise (ROR) of pressure during the squeezing of the bladder were the most sensitive indices to distinguish and classify normal and patient hand-grip waveforms. The reproducibility of PM and ROR as useful GS indices was tested in 13 chronic RA patients in the morning, with two measurements per patient, within half-hour intervals. The results indicate that PM and ROR are stable indices with no significant variation between two measurements ( p < 0.05). A Bayes classifier program was developed to recognize and classify normal and pathological signatures of grip strength. The classifier accuracy was evaluated in 79 patients in the Rheumatology clinic at McMaster Hospital. A classification accuracy of 90 per cent was obtained in classifying normals and pathological subjects.
On the Mechanical Function of Marrow in Long Bones
Authors: Bryant J D 
Published: February 2007

Hydraulic strengthening, viscous interaction between marrow and trabecular bone, and viscous resistance by the marrow to shear, appear not to occur in long bones when subjected to non-destructive axially applied compressive loads. These conclusions are based on the following observations. Firstly, volumetric measurements suggest that long bones deform in a way that maintains a near constant volume. Hence the mechanism by which ‘hydraulic strengthening’ could operate seems not to exist. Secondly, with little or no volume change, no significant movement between the marrow and the adjacent trabecular bone is likely to occur. The only mechanism by which the marrow could function mechanically would be by its own viscous resistance to shear deformation. As marrow is near liquid at 37°C (with a measured viscosity of 67 × 10-3 Pa s) this ‘resistance’ is shown to be negligible, even when calculated using values most favourable to the production of large shear forces.
Strength Pattern of Cancellous Bone at the Ankle Joint
Authors: Jensen Niels Christian , Hvid Ivan , Krøner Karsten 
Published: February 2007

The strength pattern of cancellous bone was examined in 17 ankles by a cylinder compression test and in eight distal tibial specimens by an osteopenetration test. With the compression test, 6 mm levels were examined, five levels at the tibia and three levels at the talus. Cylinders were obtained from all levels from corresponding locations. The cylinders were tested at a constant deformation rate of 5 mm/min until failure. From the load deformation curves ultimate strength, yield strength, yield strain, ultimate strain and elastic modulus were calculated. The penetration test involves resection of the joint surface just above the subchondral bone plate at the distal tibia. Measuring force and displacement, a 2.5 mm conical needle was pushed into the bone at 25 locations in a 5 × 5 matrix. The force-displacement curves were integrated at intervals of 2 mm. Three levels were evaluated, corresponding approximately to the first level in the compression test. The study indicates the presence of a strong antero-lateral part and a slightly weaker postero-medial part at all levels in the tibial and talar bone. The compression test at level 1 and the penetration test at levels 1, 2, and 3 in the distal tibia revealed a high strength area crossing the central part, in contrast to the proximal levels of the tibia where the central parts were very weak. At the talus, a high strength area ran along the lateral and posterior border. There were no significant differences in the profiles of ultimate strength, yield strength, and elastic modulus.
Rotational Movement of Femoral Components of Total Hip Replacements in Response to an Anteriorly Applied Load
Authors: Tanner K E , Bonfield W , Nunn D , Freeman M A R 
Published: February 2007

Mechanical testing has been performed on total hip replacements implanted in sections of cadaveric femora. A purpose built transducer has been used to measure the rotation of the implant in the bone under loads applied in the anterior-posterior direction. This has been used to assess the effect of cement and also of retaining more of the femoral neck. The retention of the femoral neck improved stability, as did the bone cement, and in the case of the uncemented prosthesis, longitudinal ridges increased the stability of the prosthesis.
A Numerical Solution to the Elasto-Hydrodynamic Problem
Authors: Dowson D. , Higginson G. R. 
Published: February 2007

This paper presents a solution to the problem of hydrodynamic lubrication of highly loaded clastic cylinders under isothermal conditions. A numerical method is developed which enables a pressure curve to be found which satisfies the elastic and hydrodynamic requirements of the system. Results are presented which take account of elastic distortion and the dependence of viscosity upon pressure for centre-line pressures of 5, 10, 20, and 30 ton/in2. In addition solutions are given for both rigid and elastic solids when the centre-line film thickness is the same in each case.