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Biomedical subjects

L Weh

Publications and source records attributed to L Weh.

At least 19 recordsLinked to original sources
PubMed1997

Marangoni-Stress-Driven "Solitonic" (Periodic) Wave Trains Rotating in an Annular Container during Heat Transfer

Periodic wave trains can be induced at the surface of liquid layers when the liquid is heated from above. These wave trains are an oscillatory regime of the Marangoni-instability. They are studied in a circular annular container, in which a wave synchronization is possible. Two counter-rotating (periodic) wave trains can be observed at a moderate level of supercritical Marangoni-number values. During the head-on collisions of the waves a negative phase shift occurs. This is evidence of the nonlinear interaction of the waves and their "solitonic" properties.

Journal Article↗
PubMed1995

Tissue tightness disposes to disc hernia.

It seems likely that the tightness of tissue influences a patient's disposition to disc hernia. The aim of this study was to compare the mechanical behaviour of tissue from disc hernia patients with that of controls. A computerized finger hyperextensometer was constructed, which allowed the measurement of the viscoelastic properties of the capsule and ligaments at the metacarpophalangeal (MCP) joint. The disc group showed a reduced maximal extension angle of MCP joint II (P < 0.01), reduced tissue recovery value (P < 0.05), reduced relative subsecant area (P < 0.01) and relative integral of the regression curve (P < 0.01). The results indicate that an anulus fibrosus with reduced extension properties, reduced capacity of energy absorption and retarded shape recovery disposes to rupture.

Adolescent↗
PubMed1990

[Sudden hearing loss and the cranio-cervical junction].

Morphological alterations of the craniocervical junction as basilar impressions, a ponticulus posterior, an atlas assimilation, an intervertebral narrowing and spondylosis deformans, were found radiologically in patients with sudden hearing loss. There were no radiological differences to a healthy population. No relationship could be established between static morphological changes of the craniocervical junction of the upper cervical spine and the sudden hearing loss. However, there was a statistically significant reduction of the mobility in the upper cervical spine in patients suffering from sudden hearing loss. Very high standard deviations in the atlanto-occipital and the atlanto-odontoid joints are interpreted as hyper- as well as hypomobile joints. These results indicate a possible correlation between sudden hearing loss and a functional pathology of the craniocervical junction.

Adult↗
PubMed1990

[Functional analysis of the cervical spine in healthy persons].

Radiograms were taken of subjects with no symptoms of cervical spine problems; the cervical spine was evaluated in the spontaneous posture and at maximal flexion and extension. The position and movement of the vertebra, intervertebral height and gliding were calculated. The results showed that (1) lordosis in women occurred less pronounced than in men, and that there was an increase with age; (2) C 2-3 was the least flexible segment and motility increased in the caudal direction; mobility decreased with age and the segments of the lower cervical spine with the highest mobility decreased the most; (3) all posterior and ventral intervertebral heights showed a decrease with age at C 5-6 and C 6-7; (4) vertebral gliding decreased with age.

Adult↗
PubMed1989

[Sudden deafness and the craniocervical transition].

Morphological alterations of the cranio-cervical junction as a basilar impression, a ponticulus posterior, an atlas assimilation, an intervertebral narrowing, and spondylosis deformans were found radiologically. There was no difference to a healthy population. This means there are no correlations between static morphological changes of the craniocervical junction and sudden deafness. However, there was a statistically significant reduced mobility in the upper cervical spine in patients suffering from sudden deafness. Especially very high standard deviations in the atlanto-occipital and the atlanto-dental joint are interpreted as hypermobile as well hypomobile atlas joints. These results indicate a correlation between sudden deafness and functional pathology of the craniocervical junction.

Adult↗
PubMed1988

[The overstretched patellar tendon in patellar apex syndrome].

Pain syndromes of the patella in persons active in sports are extremely frequent. The most important subgroup (by incidence rate) is the apex patellae syndrome (jumper's knee). Since all attempts at ascribing objective diagnostic criteria with satisfactory reproducibility to this syndrome, have failed to date, we have tried to define this disease pattern by means of analysis of the patellar movement. 35 patients with primary apex patellae syndrome (56 painful knee joints) and 15 healthy subjects (30 knee joints) were examined. The movement of the patella while stretching the knee in the posterior-anterior ray path was recorded on x-ray film and on magnetic tape. Assessment of the vertical movements of the patellae--in relation to the angle of extension of the knee joints--yielded the following results: 1. Initial and final positions of the patella in the apex patellae syndrome were the same as those of the control group. 2. If the knee was stretched from a 30 degree angle, the path travelled by the patella was significantly longer in case of apex patellae syndrome. The mobile performance of the patella in the apex patellae syndrome is seen as an expression of an elongated patellar ligament. Enhanced long-term longitudinal stretch is considered to be the cause of such elongation. The principal sign of the syndrome, namely, pain at the apex patellae, can be explained by: 1. an elongation of the patellar tendon with formation of an angle between the patellar ligament and the patella on the sagittal plane during flexing and strain, 2. deterioration of the plastic ligament properties and impulse absorption capacities due to overstretching.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

[Advances in the early diagnosis of congenital hip dysplasia by real-time sonography].

Twenty-four infants and children aged five days to three years had their hips examined by ultrasound, and in 17 the findings were compared with the radiographic appearances. Real-time sonography, because of its flexibility, is a suitable screening method for the early diagnosis of hip dysplasia. It has the typical characteristics of a screening method: so far there have been no false negative findings. False positive results are rare, but cannot be completely excluded. The patients examined so far were mostly abnormal, and a final assessment of false positive findings will have to await larger clinical material, including normals.

Child, Preschool↗
PubMed1983

[Alteration of the mechanical properties of cartilage after intra-articular administration of drugs in vitro].

In this study the biomechanical effect of intra-articularly applicable drugs on the articular cartilage was analyzed in vitro. Arthrotic cartilage cylinders from tibia plateaus were used, which were removed during endoprosthetic joint replacement. The elasticity of these specimens were measured before and after a 12-day incubation in a medium containing Hank's solution and serum. Five successive loading and unloading cycles from 0 to 10 N were applied, using an indenter with a diameter of 3 mm. The indentation velocity was 0.2 mm/s. Drugs with different postulated influence on the cartilage metabolism were added in various concentrations. A change in the mechanical behavior of the cartilage in relation to drug concentration could be seen in most of the medications; the change could be described using a 3rd-degree polynoma. The possible influence of this biomechanical alteration on arthrotic pain and arthrotic progression is discussed.

Aged↗
PubMed1983

[Neurologic component and resulting therapeutic concept of patellar chondropathy and chondromalacia].

Observations of nerve root lesions in spontaneous peripatellar pain led to new aspects concerning the etiology of periarticular pain and chondromalacia patellae. We regard the spontaneous peripatellar pain as an enthesiopathia resulting from an innervation disorder. We believe that also chondromalacia can be caused by nerve root lesions. As a consequence, a change in conservative and operative management is necessary. The aim is a balanced gliding and rotational stability of the patella. This means a muscular compensation of the weakened muscle part and stabilisation of the lumbar and hip region. Surgical techniques should only be applied to normalize the gliding of the patella. There is no indication for ventralisation of tuberositas tibiae.

Cartilage Diseases↗
PubMed1982

[Free bodies in the knee joint. Etiology, clinical course and therapeutic plan].

Free bodies are supposed to induce degenerative joint disease. The etiological mechanism, as far as known, of the most important and frequent diseases with corpora libera osteochondrosis dissecans, osteochondral and chondral fracture, chondromatosis and osteoarthrosis are discussed. The diagnostic and therapeutic methods are described. The need for surgical therapy is obvious in cases with chronical synovial irritation. The opportunity to reimplant a loose body into the joint surface should be taken. The technique and the results of sticking the fragments to reconstruct the joint surface are demonstrated.

Adolescent↗
PubMed1982

[Correlation between compression characteristics and CAT densitometry values of vertebral bodies (author's transl)].

The compression characteristics of 25 fresh cadaveric vertebrae of different height had been analysed in static compression tests and related to CAT densitometry values. A relationship between fracture load and CAT densitometry values of the vertebral body (spongiosa and corticalis) had been found, which can be described as a logarithmical function (r2 = 0.91). Separated CAT measurements of spongiosa also showed a logarithmical function (r2 = 0.89). Consequently, the thin corticalis of vertebral waist is of subordinate importance in correlation to fracture load. An analogously explored average CAT densitometry value showed no definite dependence on corticalis capacity. The graphic description of analysed spongiosa areas in absorption profile (CAT histogram) almost resulted in a Gauss distribution.

Adult↗
PubMed1982

Correlations between breaking load and CT absorption values of vertebral bodies.

Computed tomography was performed in 25 freshly isolated thoracic and lumbar vertebral bodies of different heights. Their breaking strength was analyzed in a static compression test and compared to the obtained absorption values. It was possible to demonstrate a correlation between absorption values and breaking load which is represented as a logarithmic function. Absorption by cancellous bone in the various vertebrae of one and the same individual was constant. It was dependent upon age. Absorption by cortical bone increased from cranially to caudally and was barely influenced by age in our test material. The sum of the cancellous and cortical absorption values increased from cranially to caudally like the load carrying capacity. The absorption values showed a normal distribution, and the error of reproducibility was approx. 2%.

Absorption↗
PubMed1981

[Osteomyelitis after BCG-vaccination (author's transl)].

BCG-osteomyelitis is a rare complication of BCG-vaccination. The diagnosis is difficult and undiagnosed cases can be assumed. After adequate treatment a benign course is typical. There is quite a difference of morbidity in various European countries. Possible reasons are discussed.

BCG Vaccine↗