bluuebunny/crossref_metadata_2025 huggingface dataset:
Hand Function, Biomechanics and Disability
Authors: Purves W K , Berme N , Paul J P
Published: February 2007

A functional assessment and biomechanical analysis of certain joints of the fingers are presented. The functional assessment has been carried out on rheumatoid arthritis patients who were assessed pre- and post-surgically after metacarpophalangeal joint replacement. Twenty normal subjects have been assessed in the biomechanical tests as they carried out two activities, tap turning and jar closing. The load actions applied by the index finger were measured by a six component transducer and the three-dimensional coordinates of the joint centres were derived from external markers attached to the skin of the index finger. From this information the forces and components of moment to be transmitted at the proximal interphalangeal and metacarpophalangeal joints have been calculated.
Biomaterials Activities at the University of Liverpool
Authors: Williams D F
Published: February 2007

Research on biomaterials has been undertaken at the University of Liverpool for the last ten years since the establishment of a Bioengineering Unit in 1969. During recent years involvment in biomaterials research has increased and a considerably greater co-operative effort has developed, leading to the formation of a Centre for Biomaterials Research in 1978. Three different departments are represented in this joint venture, the Department of Dental Sciences within the School of Dental Surgery, the Bioengineering Unit within the Faculty of Medicine and the Metallurgy and Materials Science Department withing the Faculty of Engineering Science. The biomaterials activities of these three departments, which in each case represent one part of the total research activities of that department are directed by Dr D. F. Williams, Mr D. Annis and Professor D. Hull respectively. Each department naturally has its own area of expertise and joint programmes of work are undertaken to maximize this expertise and the facilities that are available.
The Use of a Permutation Approach in the Solution of Joint Biomechanics: The Knee
Authors: Nissan M
Published: February 2007

The internal equilibrium of human joints has been dealt with by many investigators, either as a means for better understanding and treating joint diseases or as a basis for prosthetic design. In all cases there is less information than needed for an accurate solution, and the investigators have to use simplifying geometry and restricting assumptions. In this work a permutation method was used, which takes advantage of big computer facilities in order to reduce the number of assumptions needed. The method was used for the case of the knee joint. The results were compared to those available using a regular method, showing the permutation one to be superior.
A Load Cell and Sole Assembly for Dynamic Pointwise Vertical Force Measurement in Walking
Authors: Frost R B , Cass C A
Published: February 2007

The manufacture, calibration and use of a simple, cheap instrumented sole assembly, suitable for use in a clinical or laboratory environment with normal or pathological feet, is described and discussed.
Wear of Artificial Joint Materials II
Authors: McKellop H
Published: February 2007

A twelve-channel wear machine was designed for the screening of candidate materials for use in prosthetic joints, and for investigating the influence of parameters such as load, cycling rate, surface finish, sterilization dosage, and others, on the wear of conventional materials. The rationale for the design of the machine is discussed In detail with respect to the practice of using data obtained with a simplified specimen geometry to predict wear under the widely varying contact geometries in actual prosthetic joints. Three sets of experiments are described:

(a) a comparison of polyethylene wear properties in the various lubricants used in previous studies, (b) tests of polyethylene against conventional prosthetic alloys to evaluate the accuracy and repeatability of the wear measurement method, and (c) a comparison of the wear properties of several polymers tested in the screening machine to the clinical performance of these materials, to evaluate the clinical significance of the laboratory test protocol.

The wear machine was found to be a very reliable apparatus for providing reproducible data. The simplicity of design and its inherent reliability enabled long-term, multi-specimen tests with a variety of materials to be conducted in a reasonably short time period. Of the lubricants tested, only bovine blood serum produced wear of the same type as that observed on removed prostheses. This was considered to be an essential factor in laboratory wear tests of prosthetic materials.

Wear was determined by direct weighing of the polymer specimens with correction for the effects of fluid absorption. The data thus obtained had a much higher repeatability than has been typical of previous studies of wear properties of prosthetic materials. Nevertheless, tests lasting two to three million cycles were necessary to establish accurately the very low wear rate of the polyethylene specimens, in the order of one micron per year's equivalent use of a prosthesis. This was in contrast to the range of 100-200 microns per year that has been commonly reported in the literature. However, consideration of the potential error, especially due to polymer creep, in previous wear measurement methods suggests that the value of one micron per year may in fact represent a minimum for prostheses under optimal conditions. Polyester, PTFE and Delrin polyacetal all exhibited significantly higher wear rates than polyethylene. A comparison of these results with the available data on prior clinical performance of these polymers strongly indicates that the laboratory wear model developed here provides a first-stage quantitative indication of the potential clinical performance of candidate materials.
A Transducer for the Measurement of Lower Limb Orthotic Loads
Authors: Trappitt A E , Berme N
Published: February 2007

A six channel transducer designed to measure loads in a conventional knee/ankle/foot orthosis is described. Four such transducers are employed to describe fully the orthotic load system. Design considerations, construction and response of the load transducers together with sample test results are presented.
Comparative Display of Dynamic Foot-Ground Pressure Data (Pelmatobarography)
Authors: Johnson F , Kong D M C
Published: February 2007

The acquisition of data about dynamic foot-ground pressures has been possible for some time. The amount of data collected in such studies is large, and a method of data compression is presented which allows rapid comparison between one patient and another, sequential visits, or of left-right asymmetry. Both qualitative and quantitative assessments are provided for and the display is entirely contained within a single A4 size sheet of paper.
Forces Exerted on Gymnasts during Hip Beat Exercises on the Asymmetric Bars
Authors: Robertson E A , Nicol A C , Paul J P
Published: February 2007

The study undertaken investigated the nature of the forces exerted on gymnasts due to thigh contact with the low bar during hip beat exercises on the asymmetric bars.

High speed cine photography and accelerometry techniques were used to obtain the experimental data. The data from the films were analysed using a D-MAC motion analyser and computer programs. A measure of the deflection and acceleration of the low bar due to impact was obtained. A direct measure of acceleration was obtained using two accelerometer transducers attached to the low bar. The method of determining the forces from the values of acceleration is outlined and the results are presented.

The implications of the findings of the study for coaches and researchers are considered and recommendations for further similar study are proffered.
Mechanical Energy Changes and the Oxygen Cost of Running
Authors: Shorten M R , Wootton S A , Williams C
Published: February 2007

The relationship between the oxygen cost of running at submaximal speeds and running mechanics was investigated in a group of trained athletes by means of an energy analysis.

Subjects were filmed while running on a motorized treadmill at speeds of 3.58, 4.02, 4.47, 4.92, 5.36, and 5.81 m/s. Segmental potential and kinetic energies were determined using a three-dimensional link-segmental model. Intra-stride changes in the energy of the whole body were computed with no allowance for energy transfer and with various energy transfer constraints imposed on the model. Oxygen consumption was determined by expired air analysis and used to estimate energy expenditure.

For each transfer condition, net energy expenditure was more highly correlated with the magnitude of intra-stride energy changes than with running speed per se. The more economic running patterns were characterized by greater within-segment energy transfers.

Given the limitations of the kinematic energy model, it is suggested that individual patterns of running are a significant factor in the determination of energy expenditure.
Kinesiologic and Biomechanical Assessment of the Charnley ‘Load Angle Inlay’ Knee Prosthesis
Authors: Minns R J , Day J B , Hardinge K
Published: February 2007

Kinesiologic measurements were conducted on patients with rheumatoid or degenerative arthritis of the knee who had joint replacement using the Charnley ‘load angle inlay’ knee prosthesis. There was an increase in the stance phase flexion-extension and sagittal motion of the knee, thigh and calf three months after surgery but little difference from these three month readings was found at twelve months and a slight decrease two years after operation. However, the walking speed increased twelve months after surgery as did cadence and stride length but further increase did not occur twelve to twenty-four months after surgery. There was little relationship between the clinical examination of total passive movement and the stance and swing phase flexion-extension characteristics obtained from this gait analysis. The loading analysis showed there was a relationship between the total and medial compartment force occurring at the knee and the clinical assessment, higher loading was associated with a low grade of assessment, but no relationship between these loading parameters and gait analysis data was found.
Contourometric Evaluation of Moiré Topograms by Nomographic Techniques
Authors: Drerup B
Published: February 2007

Geometric principles and conditions for the measurement of distances and slopes from moirè topograms are discussed. Perspective is taken into account by a correction formula. A measuring ruler with distance scales, a slope diagram and a logarithmic correction scale is demonstrated.
Biomechanical and Clinical Assessment of Hip Nerve Block in Unilateral Osteoarthrosis
Authors: Bader D L , Khodadadeh S , Turner A , Edmonds-Seal J , Fuller D J
Published: February 2007

This paper combines a biomechanical analysis with a clinical assessment of eighteen patients with unilateral hip osteoarthrosis. A double blind trial was established to evaluate the potential of a regional hip nerve block in relieving pain. The characteristics of the vertical ground-reaction forces were analysed using two Kistler force plates, once before the injection and at three-monthly intervals following it. At the same time pain, mobility and functional activity were assessed clinically.

A significant change in some of the gait parameters for the good leg was recorded for the total patient group one month after the injection. However, no further significant differences were found. When the symmetry of gait was evaluated no significant differences at the 1 per cent level were observed at any period. These results suggest that gait symmetry is not a significant factor in assessment of patients with hip osteoarthrosis.

There was a transient decrease in subjective pain level following the injection, but this rose to pre-injection levels by the fourth week. There were no other significant general improvements after the injection.

It is concluded that the biomechanical/clinical assessment has demonstrated that the hip nerve block does not provide any useful long-term pain relief.
A Dropfoot Brace Mechanism
Authors: Milner J B
Published: February 2007

The kinematic requirements for a dropfoot brace are outlined and an appliance which the author has devised for his own use is described. Constraints in the mechanism requiring ankle joint analogues are identified and the quality of analogue achieved is discussed.
Forces during Squatting and Rising from a Deep Squat
Authors: Dahlkvist N J , Mayo P , Seedhom B B
Published: February 2007

The joint and muscle forces arising from and generated in the knee during the activity of squatting, and rising from a deep squat have been calculated. The analysis involved the consideration of a two-dimensional model. Data was then collected from each of the subjects performing the activity using: a force platform; a ciné film used in conjunction with the X-rays to describe accurately the configuration of the lower limb; EMG data; anthropometric data. A computer program was developed to analyse the data and compute the forces in the leg. Six subjects were tested and graphs of joint and muscle forces versus knee angle were obtained for each of them. A discussion follows. The results for ascent and descent, and slow and fast activities are compared.
Plaster Shears-Overcoming Design Weaknesses
Authors: Shaw A , Paton J S , Aitken J A
Published: February 2007

Plaster shears are often unreliable. This can be overcome by some simple modifications. The modifications involve using a harder material for the pivot pins, securing these pins with set screws and re-locating the existing guide pin.
An Overview of Research on Seating
Authors: Munton J S
Published: February 2007

This review considers the following areas of seating research: anthropometrics (the use of body measurements to determine chair dimensions); anatomy (sitting posture and spinal curvature); muscle activity (the effect of different sitting positions on the muscles of the back); comfort; weight-bearing (prevention of pressure sores); ease of rising; and seating for the disabled (including contoured seating and armchairs). The major contributions in each area will be outlined in turn. If the total requirements for a chair are to be met, aspects of all of these factors may need to be considered in chair design. Despite this body of research many seating problems have not been solved. It is suggested that a bio-engineering approach may be more successful in providing answers than many of the subjective and comparative trials of the past.
Pressures under the Ischium Detected by a Pedobarograph
Authors: Minns R J , Sutton R A
Published: February 2007

Pressure between the ischium and the flat surface of a pressure sensitive device (pedobarograph) are reported. There are no consistent patterns of the pressures detected this way with age, weight, sex or gross anatomy. When sitting on a gel cushion or 3 in foam cushion, the centre of load moves anteriorly and the pressures between the under surface of the cushion and the flat surface of the pedobarograph appear to be both similar and considerably lower than those pressures detected between the ischium and the flat surface.

In spinal cord injured patients with pressure sores, the device indicated areas of high pressures (greater than 300 mm Hg) in the region of the pressure sores as well as a very much reduced contact area (usually less than a third) compared with normal subjects of similar weight.
Two Simple Plantar Pressure Recording Devices in Clinical Use: Evaluation Using a Pedobarograph
Authors: Minns R J
Published: February 2007

A pedobarograph that measures and records plantar pressures has been used to evaluate the possibility of using ‘Shutrak’ as a system to measure pressures under the foot clinically. The Shutrak system is sensitive to pressures of approximately 2.5 kPa, however because of the method of loading, the record cannot be used reliably for standing pressures but can show areas of cumulative contact pressures above 2.5 kPa. Individual areas of high pressure cannot be reliably detected by this system, differentiation between light and dark areas of contact are not discernible, except where the pressures exceed 100 kPa.

Plastazote depth impressions have a better sensitivity but care in heating and applying the load is necessary because of the mechanical and thermal characteristics of the material. If these are standardized, Plastozote could be used to quantify areas of high pressure as well as foot shape, but care has to be taken in interpreting data by this method.

Both devices used in conjunction with a clinical examination would provide dynamic and static plantar pressure data for diagnostic use and plantar pathology investigation.
A Comparative Study of the Properties of Bandage-form Splinting Materials
Authors: Gill J M , Bowker P
Published: February 2007

The physical and mechanical properties of three new bandage-form splinting materials (Baycast, Crystona and Hexcelite) have been compared with those of plaster of Paris. Properties evaluated including working strength, rate of strength development, elastic modulus, exothermic heat and X-ray absorption coefficient. All mechanical testing was carried out on rectangular cross-section specimens in three-point bending. Whilst the three newer materials differed widely they all showed some advantages over plaster of Paris although none could be definitely stated as being superior in all respects. As regards mechanical properties, Baycast was found to be significantly stronger than the other materials and to have a higher strength to weight ratio. The difficulties in formulating laboratory tests which are clinically relevant are discussed and the need to consider other factors, such as ease of application and advantages to the patient, is emphasized.
The Fixation of Femoral Components of Condylar Knee Prostheses
Authors: Walker P S , Granholm J , Lowrey R
Published: February 2007

Although problems with fixation of cemented components have been more common with tibial components than with femoral, there is clinical evidence that femoral loosening may occur but after a longer interval of time. Experimental and theoretical studies were carried out to examine the motions and stresses in the implant-bone assembly. The effect of a central intramedullary stem, and of unbonding the interfaces of the patella flange and the posterior condyles, were particularly examined. Perfect bonding led to severe stress protection of the distal layer of bone. A central stem needed to project considerably above the flange to be effective and was recommended for special indications only.
Reliability of Dynamometry in Patients with a Neuromuscular Disorder
Authors: de Boer A , Boukes R J , Sterk J C
Published: February 2007

The reliability of a measuring method and a dynamometer itself was tested by measuring the maximal torques generated by the flexors and extensors of the elbow in healthy subjects. A similar measuring method on the same dynamometer was also studied in a group of patients suffering from a neuromuscular disorder.

The healthy subjects aged twenty-one to thirty-five years were measured once a week over a period of six weeks and the patients aged twenty-three to fifty-six years once a month over a period of six months. Each measurement consisted of three registrations of three seconds. The maximal registration was taken as the measured value. The measured values of the patients show relatively large variations compared to the measured values of the healthy subjects.

Analysis of the dynamometer shows problems typical for the group of patients studied. A new type of dynamometer is proposed.
Developments in Transducer Stems for Mechanical Coupling Measurements in Endoprosthetics
Authors: Gola M M , Gugliotta A
Published: February 2007

Earlier works, here briefly summarized, described the experimental techniques used for the stress analysis of the stem–femur coupling. Special strain-gauge transducers were constructed in the shape of endoprosthesis stems, to be implanted in test femurs. Four types of such transducers have been evolved, in order to overcome problems encountered during tests. The transducers are described, and results obtained with the third of these are shown in detail.
Biomechanics of the Patello-Femoral Joint. Part I: A Study of the Contact and the Congruity of the Patello-Femoral Compartment and Movement of the Patella
Authors: Fujikawa K , Seedhom B B , Wright V
Published: February 2007

Techniques are described for studying the pattern of contact and congruence of the patello-femoral joint, and the movement of the patella at different angles of knee flexion. The study is carried out on cadaveric knee specimens.
Biomechanics of the Patello-Femoral Joint. Part II: A Study of the Effect of Simulated Femoro-Tibial Varus Deformity on the Congruity of the Patello-Femoral Compartment and Movement of the Patella
Authors: Fujikawa K , Seedhom B B , Wright V
Published: February 2007

This paper investigates the effect of different degrees of varus deformity on the pattern of contact, congruence of the patello-femoral joint, and movement of the patella. Varus deformity of 5, 10, and 15 degrees was imposed on the same cadaveric knee specimen used in the study reported in Part I (Fujikawa, Seedhom, Wright, 1983). This was done by high tibial osteotomy and the introduction of a wooden wedge of the appropriate thickness to effect the deformity. It was found that the contact gradually shifted to the medial side of the knee, and the congruence of the patello-femoral compartment was gradually destroyed as the degree of varus deformity increased to 15 degrees, although the effect of 5 degrees of varus deformity was minimal.

Clinically, contact is shifted to the lateral side of the knee with varus deformity, but this is invariably associated with lateral tibial rotation. This rotation explains the difference between the results of the varus deformity imposed on cadaveric knees and those observed clinically. It is proposed that an adverse change in the congruence of the knee will occur after a sudden correction by high tibial osteotomy, just as that occurring in the normal cadaveric knee after imposing a sudden varus deformity, and therefore it may be useful to consider performing the correction at an early stage of the deformity.

The effect of the varus deformity on the movement of the patella is also described.
A Study of the Wear Characteristics of Sliding Pairs of High Density Polycrystalline Aluminium Oxide with Particular Reference to Their Use in Total Replacement Human Joints
Authors: Wallbridge N , Dowson D , Roberts E W
Published: February 2007

The introduction of ceramic components into total replacement joints for the human body in the last decade has attracted considerable attention. In most cases in which a ceramic component is used a ceramic femoral head is located on a metallic femoral stem, whilst the acetabular cup is made from ultra high molecular weight polyethylene. In some designs a ceramic acetabular cup is used in association with the ceramic femoral head.

A study of the basic wear characteristics of sliding pairs of high density polycrystalline ceramics is reported in this paper. Tests have been carried out under both ‘dry’ and ‘wet’ (distilled water) conditions in a tri-pin-on-disc wear testing machine.

It is shown that sliding pairs of alumina ceramics exhibit remarkably low wear under dry conditions when subjected to small loads, but that high loads lead to rapid deterioration of the interacting surfaces and the onset of very high wear rates.

The presence of distilled water generally permits smooth sliding at higher loads than are possible under dry conditions, but the wear rate increases by a factor of about ten over those encountered at low loads in air.

The slight advantage of sliding pairs of alumina over high density polyethylene sliding on stainless steel as far as wear is concerned is not evident if the comparison is made with high density polyethylene sliding on high density ceramic in the presence of distilled water.
Surface Geometry of the Human Ankle Joint
Authors: Medley J B , Dowson D , Wright V
Published: February 2007

Human ankle joint specimens were dissected and the dimensions required for lubrication analysis were measured. In planes parallel to the principal direction of motion, the radii of curvature of the tibial surfaces were slightly larger than those of the corresponding regions of the talar surfaces. A detailed error analysis was performed to ensure that this result was accurate. Also, length and width of the articulating regions and cartilage thicknesses were recorded. Based on the measurements of the present study an equivalent bearing geometry for the human ankle was proposed which had a reduced radius of 0.35 m for the curved surfaces.
A Practical Dropfoot Brace
Authors: Milner J B
Published: February 2007

The considerations of comfort, appearance, and reliability which governed the design of a dropfoot brace are discussed and the main constructional features of the brace described.
Conference Report: Biomechanical Aspects of the Spine
Authors: Wright V.
Published: February 2007

A report on the annual Day Conference organised by the Bioengineering Group for the Study of Human Joints and the Biological Engineering Society, University of Leeds, January 1983
Functional Differentiation in the Spinal Column
Authors: Klein J A , Hukins D W L
Published: February 2007

The structure of the spine suggests that functional specialisation occurs radially in both the vertebral centra and the intervertebral discs. Vertebrae are covered by a thin layer of cortical bone which is attached to the outer lamellae of the discs. These outer lamellae have a high collagen concentration. Thus the outer margins of both the discs and the vertebral centra are strengthened to withstand the tensile stresses generated by torsion and bending of the spine. Inner lamellae of the disc are attached to cartilage end-plates to form a closed system which can withstand the high pressure generated in the nucleus pulposus during compression of the spine. Compression also deforms the cancellous bone of the vertebrae; the inner regions of the discs and vertebral bodies thus appear to be coupled to form a continuous pressure-bearing column. Blood flow from the cancellous bone provides a possible mechanism for dissipating compressive energy. However under some circumstances compression may fracture the cancellous bone; in contrast the disc is more likely to be damaged by torsion and flexion.
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.
Instrumentation for Analysis of Continuous Neck Rotation
Authors: Rankin I R , Murphy C , Jones B E , Jayson M I V
Published: February 2007

Novel instrumentation is described which enables continuous recording of human neck rotation as a subject goes about normal activities during the day. Subsequent computer analysis and display allows for easy investigation and assessment of results. The system can measure rotation over a range of +90 degrees with an accuracy of ±6 degrees. Initial clinical results indicate that the system should assist in the study of neck problems.
A Study of Antero-Posterior Load Transfer in Total Hip Replacement using a Modelling Technique
Authors: Miles A W , Dall D M , Rivarola M
Published: February 2007

This paper describes the application of a modelling technique to determine the effect of the antero-posterior loading in the hip joint on bone and prosthesis stresses. The technique employs the use of model femora cast in a polyurethane foam and femoral prostheses made from various plastics to simulate titanium and chrome–cobalt. The study showed that antero-posterior forces produce significant stresses in the prostheses and emphasises the importance of considering these forces in the design of femoral prostheses.
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.
A new Approach to the Fixation of a Metacarpophalangeal Joint Prosthesis
Authors: Walker P S , Nunamaker D , Huiskes R , Parchinski T , Greene D
Published: February 2007

A significant problem with rigid prosthetic stems applied in the finger bones, as well as in other bones of the upper and lower extremity, is resorption of bone at the interface. An investigation was carried out using a plastic plug which would more evenly distribute the stresses to the bone, with fine ridges to produce enhanced fixation by bony ingrowth. A total knee prosthesis in the cat was used as the model, radiographic and histological studies being made at up to one year. A finite element analysis identified areas of high interface and material stresses. With a finely grooved plug, bone ingrowth occurred in all regions except for the region near the bone entry, where the finite element analysis showed the highest interface shear stresses and bone material stresses to occur.
Medical Engineering: Meetings on Research Priorities
Authors: Mason E A
Published: February 2007

The importance of ‘workshop’ type meetings to determine research priorities in a range of medical engineering topics has been demonstrated by means of a series of such meetings organised by the Science and Engineering Research Council. Four workshop-type meetings have been held in the past 2 years on topics ranging from incontinence to body access, and these have resulted in new, collaborative research programmes and an increase in the general level of interest in the topic. Further meetings of this type are planned in the coming twelve months.
Biomedical Engineering Training in Dundee
Authors: Hughes S
Published: February 2007

A brief outline of the activities and supporting departments involved in Biomedical Engineering is presented together with a description of existing and potential training facilities.
Medical Biophysics in Manchester
Authors: Pullan B R , Chapman J A , Williams A R , Taylor C J , Hukins D W L , Sharma H
Published: February 2007

The Department of Medical Biophysics in the University of Manchester provides research training in the application of physical and engineering sciences to biomedical problems. A wide range of projects is available for students who wish to work for MSc and PhD degrees.
The Masters Degree in Bioengineering at the University of Strathclyde
Authors: Paul J P
Published: February 2007

This article covers a number of matters relating to University courses in Bioengineering at MSc level. The experience at the University of Strathclyde over the past twenty years is reviewed with regard to entrants and their qualifications, material presented and employment prospects.
Mechanical Strength of the Tibial Resection Surface in total Knee Replacement
Authors: Hvid Ivan , Jensen Jørn
Published: February 2007

A simple laboratory experiment was conducted to investigate the influence of extended proximal tibial resection on the compressive strength of the resection surface. After removal of the tibial joint surface proximal and distal 1 cm slices were cut from the tibial epiphysis and fitted with an Insall/Burstein type of polyethylene tibial component. Proximal and distal resection surfaces were shown to have equal areas. When compressive load was applied through a matching femoral component the distal resection surface was 29 per cent (median) weaker than the proximal one.
On the Choice of Strain Energy Function for Mechanical Characterisation of Soft Biological Tissues
Authors: Sahay K B
Published: February 2007

Constitutive equations that describe stress–strain relations of soft biological tissues require parameters such as the strain energy functions, or certain of their derivatives. An attempt has been made in this paper to examine the suitability of the various strain energy functions reported in the literature. Certain criteria are proposed for the same.
Measuring Mobility of the Metacarpophalangeal Joints II, III, IV, and V in the Dorso-Volar Plane
Authors: Wagner C , Drescher D
Published: February 2007

An electronic gravity goniometer was developed for determining the passive range of movement of the MCP joints II, III, IV, and V in the dorso-volar plane by the use of preset torques. Test–retest measurements on 23 healthy subjects between the ages of 18 and 57 demonstrated high intrarater and interrater agreement for determining the total range. In the determination of the amounts of flexion and extension the measurement of the flexion was less reliable. There was overall evidence of a declining tendency of reliability from MCP joint II to MCP joint V, probably caused by different reactions of the joints to repeated measurements. The higher total range of the MCP joints in women was principally caused by a higher range of extension. In the case of men and women the range of MCP joint V was noticeably greater than that of the other three joints. The mobility of the four MCP joints correlates relatively closely as a whole, however, in the case of the non-adjacent joints less closely than with the adjacent joints. Reliability and validity of the examination method were balanced against one another with regard to testing of the biomechanical pre-conditions for manual dexterity.
Surface Electromyogram (EMG)/Muscle Force: A Muscle Model Based on RMG Peaks
Authors: Wyss U P , Pollak V A
Published: February 2007

In the present study, a muscle model based on EMG peaks and extensive experimental work has resulted in a useful method of correlating the surface EMG with the forces in the muscles under investigation.
The Measurement of Broadband Ultrasonic Attenuation in Cancellous Bone
Authors: Langton C M , Palmer S B , Porter R W
Published: February 2007

We have carried out measurements of the frequency dependence of ultrasonic attenuation in the range 0.2–1 MHz in in vitro samples of bovine cancellous bone and in vivo os calcis heel bones. A comparison of the results allows us to infer that the in vivo measurements are dependent on the bone mineral content of the os calcis. The bone mineral content has been determined in this way for three female populations and indicates that the technique allows determination of bone loss and the study of the onset and progress of osteoporosis. The technique has the great advantage of health safety over radiographic and neutron activation analysis. It may also prove to be more sensitive to small changes in bone mineral content.
The Cervical and Lumbar Vertebrae — An Anthropometric Model
Authors: Nissan M , Gilad I
Published: February 2007

An anthropometric model for human vertebrae in the mid-sagital plane is described, using parameters which were measured from lateral X-rays of the cervical and lumbar regions in normal, healthy men. The data was processed statistically and results are presented. The findings reported are new in the literature. They can be used in many ways, including modelling of the spine, and orthopaedics. Clinically significant parameters are the heights of the vertebral bodies and the intervertebral spacings. The relations between these parameters are presented and discussed.
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.
Transient Elastohydrodynamic Lubrication Models for the Human Ankle Joint
Authors: Medley J B , Dowson D , Wright V
Published: February 2007

An equivalent bearing was proposed to represent the normal human ankle joint. The geometry was based on measurements of dissected ankle joints and tissue properties were obtained from the work of previous investigators. Theoretical models were developed to estimate the cyclic variation in lubricant film thickness and coefficient of friction during repetitive activities such as walking. Solutions were obtained for various combinations of input parameters. For the conditions representing the walking cycle, film thicknesses of about 0.7 μm were calculated. Although this value was smaller than most previous measurements of the rms roughness of cartilage, it was not much smaller and suggested that transient elastohydrodynamic lubrication played a role in synovial joint lubrication. The possibility of full fluid film lubrication was supported only when a very high input viscosity was employed, based on values estimated from the previous experimental studies of the boosted lubrication mechanism. Also, an attempt was made to link the current findings to a published experimental study of whole joint lubrication.
Fibre Reinforcement and Mechanical Stability in Articular Cartilage
Authors: Hukins D W L , Aspden R M , Yarker Y E
Published: February 2007

The gel phase of articular cartilage is reinforced by collagen fibrils. These fibrils have low flexural and torsional stiffness, but are able to provide reinforcement if deformation of the tissue increases their tensile stress. An estimate suggests that the lengths of collagen fibrils in articular cartilage are at least of the same order as their critical length so that tensile stress in the tissue will increase the stress in the fibrils rather than simply pull them out of the gel. In the surface zone the collagen fibrils are oriented so that the efficiency of reinforcement, η, is about 0.6 tangential to the surface; tension in the fibrils is thus able to withstand swelling pressure within the tissue whose condition for stability resembles that of a pressure vessel. Swelling pressure allows the tissue to support applied pressure. An intermediate zone has a roughly isotropic η value of about 0.2, while in the deep zone collagen fibrils appear to tie the cartilage to the subchondral bone; in this deep zone η has a value of about 0.6 perpendicular to the surface direction. There is also some preferred orientation of collagen fibrils in the plane of the articular surface within the surface zone; in patellar cartilage the preferred orientations can be related to the direction of stress which could be generated by movement of the joint.
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.
Intramedullary Fixation of ‘Custom-Made’ Major Endoprostheses with Special Reference to the Bone Response
Authors: Scales J T , Wait M E , Wright K W J
Published: February 2007

The intramedullary response to polymethyl methacrylate cement/metal stem fixation of major femoral and tibial endoprostheses was studied radiologically and histologically. The clinical performance of the fixation of 206 such prostheses is reported.
Experimental Evaluation of the Anchoring Efficiency of Bone Cement under Various Conditions, and Improved Cementing Techniques and Instrumentations for Total Hip Replacement
Authors: Niwa S , Miki S , Sawai K , Hattori T
Published: February 2007

Viscoelastic properties of acrylic bone cement were studied by using a simplified controlled laboratory model simulating a component cementing in total hip replacement surgery. This study also dealt with improved cementing techniques developed through these experimental studies.
A Preliminary Study of the Effects of Medio-Lateral Rotation on Stresses in an Artificial Hip Joint
Authors: Orr J F , James W V , Bahrani A S
Published: February 2007

Photoelastic techniques have been used for some time to model the stresses in bones and orthopaedic implants. Such applications of photoelasticity have not been used widely, so their uses and advantages are discussed. Experiments are described using a two dimensional model of a hip prosthesis to examine stresses in varus and valgus orientations. The results show significantly higher stresses at both the medial and lateral boundaries of the prosthesis stem when it is set in a varus position.
Time Dependent Response of Human Intervertebral Disc to Loading
Authors: Ranu H S
Published: February 2007

Pressures in the nucleus pulposus and under the annulus fibrosus have been measured, using the specially developed miniature pressure transducers when the vertebral segment was subjected to physiological loading. Stress-relaxation of the spinal disc was also measured. Results show that pressures are linear with loading. Pressure variations within the nucleus are due to disc degeneration. The point at which facet joint loading begins has also been pinpointed out by these experiments.
Design of Intramedullary Femoral Stems Using Computer Graphics
Authors: Garg A , Deland J , Walker P S
Published: February 2007

This study describes a method for maximizing the size of an intramedullary stem which can physically be inserted into the canal of the femur. The potential applications of this are for ‘press-fit’ stems where maximizing the area of contact with the endosteal surface is likely to be important, and for cemented stems where a uniform cement layer is desirable. The 3-dimensional shape of a femur is described by using CT data of transverse sections. The computer program uses an algorithm which minimizes the amount of material removed from the stem sections, with preference being given to areas of maximum load transmission. Different parameters are investigated, such as the level and angle of the neck cut, and the length of the stem. Comparisons of percentage of the canal filled are made with standard symmetrical stems. It is shown that computer-generated stems filled substantially more than available symmetrical stems.
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.
Automatic Measurement of Walking Speed and Stride Length
Authors: Crawford R J , Sandford M H , Gillespie G T
Published: February 2007

A step mat has been designed and manufactured for measuring the gait pattern of patients. It is a portable, low profile mat which does not require any attachments to the patient. Information such as stride length and walking velocity during each stride are displayed on a computer VDU and this information may be automatically stored on a computer file for comparison with previous or subsequent performance of the patient. Preliminary trials at the Withers Orthopaedic Unit at Musgrave Park Hospital have shown that the system gives quick, accurate, and reliable results.