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Biomedical subjects

E Stüssi

Publications and source records attributed to E Stüssi.

At least 37 records · Page 2Linked to original sources
PubMed2000

Estimation of geometric properties of cortical bone in spinal cord injury.

OBJECTIVE: To evaluate structural and geometrical properties of the tibia shaft in subjects with spinal cord injury (SCI) and subjects without SCI and to estimate the potential usefulness of a multimodal approach to diagnosing osteoporosis in SCI. DESIGN: A cross-sectional study of randomly selected SCI and non-SCI subjects. METHODS: Measurements of bone geometric indices by computed tomography, and calculated bending stiffness with a biomechanical testing method. SETTING: An SCI center hospital. SUBJECTS: Ten men without known orthopedic or neurologic impairments (controls), 10 men with SCI who had a history of lower extremity pathologic fracture since SCI, and 10 men with SCI who had never had lower extremity pathologic fracture. RESULTS: Analysis of geometric and structural indices of subjects' tibias found a significant difference in all geometric indices between controls and the SCI subjects with pathologic fracture history. Between the controls and the SCI subjects with no fracture history, however, differences were found only in cross-sectional area and calculated bending stiffness. CONCLUSION: Structural analysis of leg bone, combined with measurement of bone density, may improve the ability to assess fracture risk in patients with SCI.

Adult↗
PubMed1999

Changes of tibia bone properties after spinal cord injury: effects of early intervention.

OBJECTIVE: To evaluate the effectiveness of an early intervention program for attenuating bone mineral density loss after acute spinal cord injury (SCI) and to estimate the usefulness of a multimodality approach in diagnosing osteoporosis in SCI. DESIGN: A single-case, experimental, multiple-baseline design. SETTING: An SCI center in a university hospital. METHODS: Early loading intervention with weight-bearing by standing and treadmill walking. PATIENTS: Nineteen patients with acute SCI. OUTCOME MEASURES: (1) Bone density by peripheral computed tomography and (2) flexural wave propagation velocity with a biomechanical testing method. RESULTS: Analysis of the bone density data revealed a marked decrease of trabecular bone in the nonintervention subjects, whereas early mobilized subjects showed no or insignificant loss of trabecular bone. A significant change was observed in 3 of 10 subjects for maximal and minimal area moment of inertia. Measurements in 19 subjects 5 weeks postinjury revealed a significant correlation between the calculated bending stiffness of the tibia and the maximal and minimal area moment of inertia, respectively. CONCLUSION: A controlled, single-case, experimental design can contribute to an efficient tracing of the natural history of bone mineral density and can provide relevant information concerning the efficacy of early loading intervention in SCI. The combination of bone density and structural analysis could, in the long term, provide improved fracture risk prediction in patients with SCI and a refined understanding of the bone remodeling processes during initial immobilization after injury.

Adult↗
PubMed1999

Three-dimensional video analysis of facial movements: a new method to assess the quantity and quality of the smile.

The results of neuromuscular reconstructions of the paralyzed face are difficult to assess. Very sophisticated methods are necessary to measure the motor deficits of facial paralysis or the functional recovery in the face. The aim of this development was a relatively simple system for data acquisition, which is easy to handle and which makes it relatively cheap to delegate data acquisition to centers all over the world, which will not be able to derive a data analysis on their own, but will send their data to a center with specialized equipment. A complex mirror system was developed to get three different views of the face at the same time on the video screen. At each investigation, a digital video is taken from a calibration grid and from standardized facial movements of the patient. Secondary analysis of the digital videofilm is made possible at any time later on by the support of a computer program, which calculates distances and movements three-dimensionally from the frontal image and the right and left mirror images. Pathologies of the mimic movements can be identified as well as improvements after surgical procedures by this system. The significant advantage is the possibility to watch the same movement on the video which is under study and to apply any kind of study later on. Taking the video needs only a few minutes, and fatigue of the patient's mimic system is prevented. Measurements usually at the endpoints of the movements give excellent information on the quantity of the movement or the degree of the facial palsy, whereas the video itself is very informative regarding the quality of the smile. Specific computer software was developed for standardized three-dimensional analysis of the video-documented facial movements and for data presentation. There are options like two-dimensional graphs of single moving points in the face or three-dimensional graphs of the movements of all measured points at the same time during a standardized facial movement. By a comparison of the right- and left-sided alterations of specific distances between two points during the facial movements, the degree of normal symmetry or pathologic asymmetry is quantified. This system is more suitable for detailed scientific multicenter studies than any other system previously established. A very sensitive instrument for exact evaluation of mimic function is now available.

Calibration↗
PubMed1998

Gait asymmetries in patients with idiopathic scoliosis using vertical forces measurement only.

This study aimed at identifying measurable asymmetries during gait and relating them to the spinal deformity in subjects with idiopathic scoliosis. We investigated 21 patients aged between 10 and 26 years for gait asymmetries using force plates. All subjects completed five walking cycles over two force plates measuring vertical ground reaction forces. Among the parameters measured were contact time and magnitude of the two peaks of the vertical forces as well as the rate of application of those forces. Published gait data on normal subjects were used as a control group. In 20 subjects an asymmetry of at least one gait parameter was noted. Multiple regression analysis showed, however, that there was no relation between the noted gait asymmetry and the curve direction, curve magnitude or vertebral rotation. This suggests that although functional asymmetries of the central nervous system have been described in patients with idiopathic scoliosis, they do not appear to have a reproducible effect on gait.

Adolescent↗
PubMed1998

Reliability of phase-velocity measurements of tibial bone.

BACKGROUND AND PURPOSE: The Bone Stiffness Measurement Device-Swing is capable of measuring the propagation velocity of flexural waves in human tibial bone, which relates to bending stiffness. If the interrater and intrarater reliability of measurements obtained with the device are established, it can be used with confidence in assessing changes in bone. The purposes of this study were to detect potential sources of measurement error and to establish the interrater and intrarater reliability of measurements taken with the device. SUBJECTS AND METHODS: In the first part of the study, a random-effects design was used to obtain phase-velocity measurements in subjects without known orthopedic or neurological impairments. The second part of the study consisted of possible applications of the device with mixed designs on subjects with spinal cord injuries. By means of generalizability theory, multiple sources of error (eg, occasion, clinician, repetition) were estimated. For the clinical trial, 17 persons with spinal cord injuries not older than 5 weeks were tested. RESULTS: The standard error of measurement (SEM) for intrarater reliability measurements ranged from 7.3 to 9.8 m x s(-1) . The SEMs for interrater reliability measurements ranged from 5.7 to 9.5 m x s(-1). The SEMs for measurements obtained by a single clinician in a clinical population ranged from 11.9 to 39.7 m x s(-1). CONCLUSION AND DISCUSSION: The reproducibility of measurements obtained with the device is suitably high for the device to be used for evaluation in clinical and research settings.

Adolescent↗
PubMed1998

Techniques and equipment for muscle mechanics.

The individual in vivo mechanical properties of muscle groups are not well known, and these data are important in simulations of a subject's movements, and analysis of measured movements. Discrepancies in the force-velocity relation between in vivo and in vitro measurements have been documented in previous investigations. A powerful, high precision dynamometer was designed and built to make in vivo tests on the elbow and ankle joints. Test data obtained with this machine did not exhibit the same discrepancies observed in previous experiments, which leads to the conclusion that the previous discrepancies resulted from the test method used.

Biomechanical Phenomena↗
PubMed1997

[Sports medicine and rehabilitation. Surface and footwear].

Load on the human body can be influenced by shoes and surfaces which is important both in sports and rehabilitation. The loading which can primarily be influenced are impact situations and friction as well as the stability of the foot. This stability is of main interest in the prevention of pain and injury. However, a certain amount of loading is necessary to improve strength and structure of biological materials. In the past, the development of shoe and surface materials has hardly been perceived under this aspect, but may be increasingly important in the future.

Athletic Injuries↗
PubMed1997

Quantitative gait analysis in patients with medial patellar instability following lateral retinacular release.

Medial patellar instability is a known possible complication following lateral retinacular release. Insufficient passive structures, muscle imbalance and an over-release of the lateral retinaculum with resection of the vastus lateralis tendon have been implied as a major cause of this problem. We report about the findings of quantitative gait analysis consisting of video recordings, three-dimensional motion analysis, dynamic electromyography and sampling of the ground reaction forces in two patients with medial patellar subluxation. Documentation of the gait functions together with observation of the patellar translation revealed the timing of the occurrence of the instability during level gait: a normal gait pattern with a sufficient quadriceps mechanism and a centred patella was seen during loading (weight acceptance), while the quadriceps muscle was active. Abnormal medial translation of the patella was observed during unloading of the leg while the knee was bending in preparation for the swing phase. This is a phase in the gait cycle when the quadriceps muscle is silent and the patella position is guided by the passive structures only. This finding weakens the argument of muscle imbalance as a cause for the patellar instability and stresses the importance of well balanced passive structures. This explains why a muscular rehabilitation programme is likely to fail as long as the passive structures allow the instability to occur.

Adult↗
PubMed1997

Quantitative gait analysis after bilateral total knee arthroplasty with two different systems within each subject.

The functional behavior of two kinematically different knee arthroplasty systems within each subject was studied by gait analysis (three-dimensional kinematics, kinetics, dynamic electromyography) in five elderly patients, 2 to 5 years after bilateral surgery. Clinical results were good, yet gait velocity was reduced (range, 0.57-1.1 m/s), with a shortened stride length and a decreased duration of single-limb stance in all subjects. Force plate recordings revealed an undynamic gait with slow loading, reduced modulation of the vertical forces, and poor fore/aft shears. Sagittal plane knee motion during gait was reduced in all subjects, with trunk and pelvic compensation patterns for foot clearance. Muscle activity around the knee was prolonged bilaterally, with activity modulation related to the motion pattern. Although the stride parameters were quite symmetric, there was a marked asymmetry of the motion pattern, with a side-to-side difference of peak knee flexion during stance and swing phase of up to 15 degrees. This finding, however, was not clearly related to the type of prosthesis. Even within one subject, significant side-to-side variability may persist, which leads to asymmetry of the motion pattern, unrelated to the kinematic design of the implant. Other factors, such as the patella-extensor mechanism, ligament balancing, leg-length discrepancy, proprioception, continuation of a preoperative habit, or a contralateral influence, may explain part of the asymmetry seen in these subjects.

Aged↗
PubMed1996

Lateral stability in sideward cutting movements.

Sideward cutting movements occur frequently in sports activities, such as basketball, soccer, and tennis. These activities show a high incidence of injuries to the lateral aspect of the ankle. Consequently, the lateral stability of sport shoes seems important. The purpose of this study was to show the effect of different shoe sole properties (hardness, thickness, torsional stiffness) and designs on the lateral stability during sideward cutting movements. A film analysis was conducted including 12 subjects performing a cutting movement barefoot and with five different pairs of shoes each filmed in the frontal plane. A standard film analysis was conducted; for the statistical analysis, various parameters such as the range of motion in inversion and the angular velocity of the rearfoot were used. The results showed a large difference between the barefoot and shod conditions with respect to the lateral stability. Two shoes performed significantly better (P < 0.05) than the others with a decreased inversion movement and less slipping inside the shoe. The two shoes differed mainly in the shoe sole design (hollow inner core) and the upper (high-cut). It is concluded that lateral stability may be improved by altering the properties and design of the shoe sole as well as the upper.

Adult↗
PubMed1995

Bone mass at lumbar spine and tibia in young males--impact of physical fitness, exercise, and anthropometric parameters: a prospective study in a cohort of military recruits.

Bone mineral density (BMD) and bone mineral content (BMC) were measured using DXA at lumbar spine and tibial diaphyses at the beginning and at the end of a 15-week training period in 151 military recruits of the Swiss army belonging to 5 different troop categories (infantry grenadiers, tank drivers, tank gunners, signalmen, and privates) who each were exposed to physical training of various intensity. At baseline, height, body mass index, and degree of physical fitness independently correlated with vertebral and tibial BMD. Over the 15 weeks of physical training BMD at tibial diaphyses increased by 2.2 +/- 0.3% at the left leg (p = 0.0001) and by 1.1% at the right leg (p = 0.002) with differences between troop categories. At lumbar spine, BMD decreased significantly in tank drivers (-1.2 +/- 0.4%, p = 0.001) and particularly in infantry grenadiers (-2.1 +/- 0.4%) who had the most strenuous weight-bearing training, but not in other troop categories. This decrease was twice as large at the center of the vertebra than for the whole vertebra. These BMD changes were associated with increments in serum levels of osteocalcin and alkaline phosphatase activity. From the initial cohort, 48 subjects volunteered for a third investigation carried out 2 years after the end of the military training period. At this time, lumbar BMD and BMC had risen back to baseline, whereas at tibial diaphyses bone width and BMC but not BMD increased by 5.8 +/- 1.1% and 6.2 +/- 0.9%, respectively, vs. baseline (p = 0.0001 for both).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

Development of a new documentation system for facial movements as a basis for the international registry for neuromuscular reconstruction in the face.

None of the paresis scoring systems used satisfies an adequate description of all the details necessary to document the degree of facial paresis before and after any treatment. We developed a new documentation system considering all details of the history of the patient and of the treatment that could have any influence on the functional result. The third part of this "international registry for neuromuscular reconstruction in the face" concerns paralysis assessment, including quantitative measurements of the resting and moving face, besides qualitative parameters. A map of standardized static and dynamic points in the face was designed, and three-dimensional measurements of the movements of these facial points were performed with a VICON system in 16 healthy individuals. On the basis of the results, three real static points and representative dynamic points were selected as well as relations of these points most representative for the different facial movements. For data collection, a simple instrument (Frey's faciometer) was developed. A preliminary report is given on the clinical application of this new instrument.

Adult↗
PubMed1994

[Development and adaptation of tensile strength by bones in the extremities in response to physical training exemplified by the tibia].

Results from an in vivo assessment of the bending stiffness of human tibiae with a new method demonstrate that bone mineral measurements are not a suitable predictor to evaluate changes of mechanical properties of long bones. In a study on 559 male military recruits, the bone mineral at tibial shaft resulted in a mean increase of +1.8% during 15 weeks of exercise. The bending stiffness however increased about 25%. An additional test 24 months later on a sample indicated that the increase of bone mineral content was only due to the natural maturation of bone. The bending stiffness however, decreased by about 6% demonstrating the earlier training effect. No correlation between bone mineral and bending stiffness could be found neither in absolute values nor in difference between the three measurements. At the same time first results of a normative study on children (9 to 18 years old, male and female) and on women (up to 80 years old) are presented.

Adolescent↗
PubMed1993

[Control of the rear foot in lateral movements in sports].

The goals of this investigation were to establish the frequency distribution of different movements in various ball sports (1) and to test the influence of altered shoe sole constructions on the stability in lateral breaking movements (2). Firstly, a video analysis was carried out to establish the frequency distribution of different movements in sporting activities such as volleyball, basketball, team handball and football (soccer). It is shown that a selected number of lateral cutting movements can represent more than half of all movements observed in one of the sporting activities. For part 2 an investigation with three systematically varied shoes was undertaken. The results show that with altered shoe sole constructions (torsion and change of shape of the shoe-sole) the supination movement with shoes comes close to the barefoot values. In respect of abduction/adduction of the foot the systematic changes of the shoe soles had no measurable influence.

Adult↗
PubMed1993

[Cushioning versus stability].

Cushioning and stability are still key words for functionally constructed sport shoes. The goal of this investigation is to present and discuss the possibilities and limits of these shoe properties. Here, stability is not regarded as rigidity (like in a ski boot), but as a "dynamic stability" in the sense of functionality which supports the foot under load in such a manner that no unphysiological movements are provoked. Cushioning (in physics terminology: "damping") is defined to reduce and eliminate (kinetic) energy. When considering the impact peak in running, this peak can be reduced by using hard shoe soles with large heel flares. However, by doing that, large levers are introduced which produce an increased distance to decelerate the touchdown. This is basically the opposite of dynamic stability. Current shoe sole materials (homogeneous/isotropic) improve the "cushioning" but enhance the instability. New ways of shoe construction using more sophisticated anisotropic materials may lead out of this dichotomy.

Computer Simulation↗
PubMed1993

[Biomechanical and orthopedic problems of tennis and indoor sports shoe].

In contrast to running, a large number of indoor sports show a variety of body and foot movements with fast changes of direction. These "stop-and-go" movements (including jumps and rotations) produce loads at the joints of the foot, knee and hip in an order of magnitude often underestimated. The goal of this investigation was to provide an overview over various indoor sports movements and to draw conclusions with respect to sport shoe constructions. Reconsideration of the functionality of the foot led to shoe constructions which allow the shoe to rotate about its longitudinal axis (torsion), a movement with which the forefoot can again "reach" for the ground in landing situations. However, the problem of the rear foot stability and cushioning at a rear foot touch down is not yet solved. Therefore it must be postulated that shoes for indoor sports and tennis should be provided with an increased lateral stability at the rear foot.

Athletic Injuries↗
PubMed1993

[External stabilizers for the foot].

The stability in the lateral direction is particularly important in indoor sports as well as tennis, where the frequency of injury at the lateral aspect of the ankle is considerably high (according to various sources between 20-30%). The goal of the present work was to discuss the reasons of instability at the ankle and the effect of external stabilizers. In a number of investigations the stability was measured via film analysis during sports activities in barefoot and shoe conditions. It was concluded that stability and blocking of a movement cannot be regarded as equal. The latter restricts necessary movements of the foot at the ankle and may also provoke large internal forces elsewhere. Negative in respect to stability are stiff and thick shoe soles, positive are: the torsional ability of the sole, softness of the shoe sole edge, the link between the shaft and the sole, shaft height, taping and bracing.

Ankle Injuries↗