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Biomedical subjects

E Stüssi

Publications and source records attributed to E Stüssi.

At least 19 recordsLinked to original sources
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↗
PubMed1992

Heel movement within a court shoe.

Lateral movements of the leg and foot were filmed from behind to evaluate court shoes. Inversion/eversion may be an indicator of potential injuries, but estimates of actual inversion/eversion have typically been measured as the angular displacement of marker pairs on the lower leg and on the shoe. The purpose of this study was to measure the shoe movement versus the heel movement inside the shoe in order to determine the appropriateness of using shoe markers to represent the heel position. Two windows were cut into the heel counter of the shoe to show the heel position in addition to shoe position. The subjects were filmed from behind during a lateral side-stepping movement. The difference between the shoe and heel position was [corrected] statistically significant. The average maximum change in heel inversion inside the shoe was 13.3 +/- 3.8 degrees, compared with 30.7 +/- 6.2 degrees for the shoe. In addition, the maximum change in heel inversion in a barefoot movement was 10.1 +/- 3.1 degrees. The results suggest that for a lateral movement shoe markers do not accurately represent the position of the heel, and heel movement inside a shoe is similar to a barefoot movement. Skin markers on the heel as observed through windows in the shoe give a better indication of the actual position of the calcaneus than do markers placed directly on the shoe.

Adult↗
PubMed1992

[Biomechanical considerations of the load on the ankle joint].

The biomechanical approach to the characteristics of load on the ankle joint and the surrounding structures allows a better understanding of the cause and effect of externally acting forces in human movement (walking, running, jumping). This detailed understanding of the mechanics involved (not only in the functional anatomical sense) makes preventive measures possible that can reduce the risk of distortion at the ankle. With the same mechanical models, clinically applicable methods allow biomechanically monitored rehabilitation. The case studies reported here illustrate that therapeutic success can be measured objectively, leading to improvement in therapy and in the ability to make decisions in the clinical environment.

Achilles Tendon↗
PubMed1992

The movement of the heel within a running shoe.

Most running shoe investigations have used the same standard procedure for the evaluation of the shoes: the runners are filmed from behind and a film analysis is carried out digitizing markers at the heel counter of the shoe and on the lower leg. The angular displacement of these markers relative to the horizontal or the vertical is assumed to be an indicator for various sports injuries. The goal of this investigation was to measure the movement of the heel counter as well as the movement of the heel inside the shoe. First, the influence of the size of different heel counter windows was controlled and found negligible for the test conditions of this study. Second, 15 subjects performed the following procedure: running (a) barefoot, (b) with shoes with windows, and (c) without windows. Overall, the heel was found to move similarly but not identically to the heel counter. The maximum change of pronation was (a) 13.7 +/- 3.7 degrees, barefoot; (b) 14.1 +/- 3.8 degrees for the shoe with windows and 12.1 +/- 3.7 degrees for the heel inside these shoes; and 14.9 +/- 4.2 degrees for the shoes with no windows. To achieve a general impression of a shoe in the sense of a qualitative description, the previous method without heel counter windows still seems adequate. However, for a detailed analysis of quantitative nature, it is important to use the method with heel counter windows.

Adult↗
PubMed1991

The effects of shoes on the torsion and rearfoot motion in running.

Excessive pronation is accepted as a good indicator for various running injuries. The least amount of pronation takes place when running barefoot. The latest investigations show that this is connected to a large torsional movement between forefoot and rearfoot which can be influenced by the shoe sole construction. The shoes which are in use among runners in track and field are basically of two types, running shoes (in general torsionally stiff) and spikes (torsionally flexible). The possibly varying effect of these shoes on the shoe/foot motion in running is not known. The purpose of this investigation was therefore to show whether the pronation angle and the torsion angle differ when running barefoot, with spikes, and with running shoes (forefoot touchdown, N = 9 left and right). A film analysis provided the angular movements of the lower leg, rearfoot, and forefoot as well as pronation and torsion in the frontal plane. The results show that at touchdown the torsional movements with both shoe types are quite different from those of running barefoot. With shoes, the torsion angle is reduced back to zero--with running shoes more than with spikes--and the pronation angle is increased beyond the barefoot values (P less than 0.01). In order to reduce the risk of injury, both shoe types should be improved--the running shoes with respect to torsion and the spikes with respect to pronation.

Achilles Tendon↗
PubMed1989

[Biomechanics in sports].

Sports are often practised nowadays in balance for a non challenging profession or as means to counteract stressful life style. This desirable and reasonable development calls however for a critical assessment of biomechanical factors contributing to stress and admissible load of the human locomotor system. Considerate training renders excessive strain of the skeleton, cartilage and vertebral column virtually impossible. In view of the time required for adaptive processes this statement has to be combined with an appeal for appropriate training to those seeking compensation in physical exercise. Especially young people and middle-aged persons experiencing so called midlife-crisis tend to practise unbalanced and excessive sportive activity.

Adaptation, Physiological↗
PubMed1989

[Torsion --a new concept in construction of sports shoes. Motion excursion of the foot in athletic stress--anatomical and biomechanical observations and their effects on construction of sports shoes].

In recent years several construction elements resulted in an increasing stiffening of the sport shoe so that the foot was partly forced to make its own movements inside the shoe. A new sport shoe concept is presented basing on the results of anatomic and biomechanical studies, its innovative feature being decoupling of the foot movement between the calcaneal part of the foot and the metatarsus (= torsion). The foot is given an opportunity to transmit its freedom of movement in the longitudinal axis of the foot to the shoe without the shoe acting as a lever, this goal being achieved by a limited liberation of the metatarsal pronation/supination and a controlled uncoupling of the metatarsus from the calcaneal part of the foot.

Ankle Joint↗