Search PubMed⌕ Search

Biomedical subjects

H Graichen

Publications and source records attributed to H Graichen.

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

Magnetic resonance-based motion analysis of the shoulder during elevation.

Changes in shoulder motion patterns are relevant in various shoulder diseases, but no in vivo information exists about the relative positions in vivo of the shoulder girdle bones and the supraspinatus muscle in three-dimensional space. Thus, the objective of this study was to perform a motion analysis of these structures during passive arm elevation using open magnetic resonance imaging and three-dimensional image processing. Fourteen volunteers were examined in five positions of abduction (30 degrees-150 degrees) with an open magnetic resonance system. After segmentation and three-dimensional reconstruction, the axis of the supraspinatus, humerus, clavicle, and the plane of the glenoid were determined, and the relative movements were calculated. The ratio for glenohumeral to scapulothoracic motion was 1.5:1 at 60 degrees and 2.4:1 at 120 degrees abduction. At 30 degrees, the axis of the supraspinatus was nearly horizontal, and during abduction a continuous elevation (+123 degrees at 150 degrees abduction) was measured. In the transverse plane, the angle between the supraspinatus and the clavicle axes became larger during abduction because of an increasing retroversion of the clavicle. The study shows specific three-dimensional motion patterns for each bone of the shoulder girdle and the supraspinatus muscle during passive elevation. The technique and results can be used for future studies in patients with pathologic changes of shoulder girdle motion.

Adult↗
PubMed2000

[A new in vivo technique for 3-dimensional analysis of the translation of femoral condyles and the menisci responding to antagonistic muscle forces].

The aim of our study was to develop a 3-D MR-based technique for the analysis of meniscal and femoral translations during flexion of the knee, and under the influence of antagonistic muscle forces in healthy subjects. In an open MR system, 5 knees were examined at 30 degrees and 90 degrees flexion using a T1-weighted 3-D gradient echo sequence. A force of 30 Newtons, first in the extending and then in the flexing direction, was applied to the distal lower leg. After three-dimensional reconstruction, the minimal distances between the centre of the tibial plateau and the posterior edge of the menisci and femoral condyles were determined. At 30 degrees flexion, the minimum distance for the meniscus was larger medially than laterally (23.2 +/- 1.8 mm vs. 16.2 +/- 3.3 mm), and this also applied to the condyles (25.1 +/- 1.5 vs. 19.0 +/- 3.0 mm). During flexion to 90 degrees, a posterior translation of 0.5 +/- 0.2 mm was observed for the lateral, and of 3.4 +/- 1.2 mm for the medial, meniscus. The condyles demonstrated a different posterior translation (lateral 2.2 +/- 0.56 mm; medial 1.8 +/- 1.9 mm). No obvious differences were found between extension and flexion muscle activity for the different positions of the knee. In the present study, a new 3-D technique is presented for the analysis of the femoral and meniscal translation at various positions of the knee, and under muscle activity. The results suggest different translation for the menisci and condyles.

Adult↗
PubMed1999

Subacromial space width changes during abduction and rotation--a 3-D MR imaging study.

The objectives of this study were to determine systematic changes of the normal subacromial space width during abduction and rotation, and to analyze the spatial relationship of the supraspinatus muscle with the acromion and clavicle. 12 healthy volunteers were imaged by an open MR scanner in 5 different positions of abduction and in 3 positions of rotation. After three dimensional (3D) reconstruction and 3D Euclidian distance transformation, the minimal spatial distances between the humerus and the acromion and the humerus and clavicle were computed. The minimal acromio-humeral distance decreased significantly from 30 degrees of abduction (mean 7.0 mm +/- 1.6 mm) to 120 degrees (mean 3.9 mm; +/- 1.8 mm; p < 0.0001). At 30 degrees, the minimal distance penetrated the supraspinatus, whereas at 120 degrees it was always located lateral to the supraspinatus tendon. At 90 degrees with internal rotation (7.6 mm, +/- 2.3 mm) the minimal acromio-humeral distance was larger than in neutral rotation (5.4 mm, +/- 2.3 mm) or external rotation (4.4 mm, +/- 2.2 mm; p < 0.05), but it penetrated the supraspinatus tendon at its most vulnerable part, reaching the acromion at its anterior inferior border. We conclude that the subacromial space width changes during abduction and rotation and that the supraspinatus is in closest contact to the anterior inferior border of the acromion in 90 degrees of abduction with 45 degrees internal rotation. These values obtained in volunteers can be used as a basis for further investigations in patients with the impingement syndrome.

Acromion↗
PubMed1999

[Anatomical and functional aspects of the thoracic and lumbar spine].

The vertebral bodies and vertebral arches show a characteristic distribution of cortical and cancellous bone. The pedicles are loaded by uniplanar bending that is reflected by the arrangement of the Corticalis. The ligaments of the vertebral column consist of longitudinal and (with exception of the lig. longitudinal anterius) horizontal/oblique segmental ligament bundles. In combination with the anulus fibrosus, the ligaments work as a kind of gear system. They regulate the process of movements of adjacent vertebral bodies in a very precise manner and control the final phase of motion. Besides maintaining the necessary amount of pretension the intervertebral disc distributes the loads uniformly onto the adjacent vertebral bodies. The intervertebral joints are important for guided motion, by restricting the extent in specific planes and directions. Because of their position, they are able to take up the shear forces and to simultaneously restrict them in different planes. The integrity of the fascia thoracolumbalis warrants the protective function of the autochthonuos muscles.

Fascia↗
PubMed1999

Effectiveness of glenoid osteotomy in atraumatic posterior instability of the shoulder associated with excessive retroversion and flatness of the glenoid.

In this investigation, patients with atraumatic posterior instability of the shoulder were appraised in order to evaluate the effectiveness of glenoid osteotomy in the correction of excessive retroversion and flatness of the glenoid. In a series of 32 patients, 17 with posterior instability had no history of trauma. Posterior glenoid osteotomy was performed to correct excessive retroversion and to deepen the glenoid; 95% were re-examined after 5 years. In 81% the results were rated as good or excellent (Constant-Murley and Rowe scores), only 12.5% having had a recurrence. The glenoid could be deepened and on average the angle could be altered from -9.35 degrees to -4.62 degrees. In comparison, 50 volunteers had average angles of -4.4 degrees, thus differing significantly from the preoperative group. Twenty-five per cent of the patients showed postoperative degenerative changes in the glenohumeral joint. The study shows that excessive retroversion and flatness of the glenoid in persons with atraumatic posterior instability can be successfully treated by a posterior glenoid osteotomy. Nevertheless, the high rate of postoperative degenerative changes must be taken into account.

Anthropometry↗
PubMed1999

A non-destructive technique for 3-D microstructural phenotypic characterisation of bones in genetically altered mice: preliminary data in growth hormone transgenic animals and normal controls.

A non-destructive, three-dimensional technique for microstructural phenotypic characterisation of skeletal elements in genetically altered mice is presented. Preliminary data in bovine growth-hormone transgenic animals and control littermates are shown. The technique is based on microcomputed tomography (microCT) and digital postprocessing and allows for a differential quantitative analysis of the cortical and trabecular bone compartments in the axial and peripheral skeleton. The distal femora and the first lumbar vertebral bodies of six animals were CT scanned in the axial plane with an isotropic resolution of 20 microm. The periostal surface and the marrow spaces were segmented fully automatically, and the trabecular and cortical compartments were separated interactively. After 3-D reconstruction, various regions of interest (diaphyseal, metaphyseal and epiphyseal) were selected for the analysis. The femora and vertebrae of the transgenic animals showed obvious differences in size, shape, and trabecular arrangement compared with the control animals. The total bone mass was increased by a factor of two to three, but the trabecular bone was increased much more (up to 12 times) than the cortical bone. The transgenic animals showed an increased ratio of trabecular vs cortical bone (0.90 to 1.27 vs 0.14 to 0.36 in the femoral diaphysis) and an elevated trabecular bone volume fraction (49% to 73% vs 18% to 43% in the femoral metaphysis). The mean 3-D cortical thickness was similar in the normal and transgenic animals (values between 93 microm and 232 microm in the dia- and metaphyses), but the minimal cortical thickness was lower in the transgenic animals (22 to 31 microm vs 54 microm to 110 microm in the diaphysis). The technique presented is suitable for phenotypic characterisation of bone structure in genetically altered mice.

Animals↗
PubMed1999

Three-dimensional analysis of the width of the subacromial space in healthy subjects and patients with impingement syndrome.

OBJECTIVE: The aim of this study was to per form a three-dimensional analysis of the width of the subacromial space during passive and active arm abduction in healthy volunteers and patients with impingement syndrome. SUBJECTS AND METHODS: The shoulders of 10 healthy subjects and 10 patients with impingement syndrome were imaged with an open MR system during abduction, with and without activation of the shoulder muscles. An apparatus was designed for applying an adduction force of 10 N to the distal humerus during image acquisition, and the minimal acromiohumeral distance was measured after three-dimensional reconstruction. RESULTS: In the 10 healthy volunteers, muscle activity led to a significant decrease (-32%; p < .05) of the acromiohumeral distance at 60 degrees of abduction, whereas at 120 degrees of abduction the distance was significantly increased (+44%; p < .05). In these volunteers, muscle activation caused no significant effect at 90 degrees of abduction. However, in the 10 patients with impingement syndrome, muscle activity led to a significant decrease in the width of the subacromial space compared with that of the healthy contralateral side (-68%; p < .05). CONCLUSION: Muscle activity and arm position were found to cause systematic changes in the width of the subacromial space. However, functional deficits of the supraspinous muscle in patients with early-stage impingement syndrome were not apparent during muscle relaxation.

Acromion↗
PubMed1998

A technique for determining the spatial relationship between the rotator cuff and the subacromial space in arm abduction using MRI and 3D image processing.

An MR imaging-based technique for three-dimensional determination of subacromial space width in relation to the rotator cuff in arm abduction is presented. Five volunteers were examined in an open MRI in seven arm positions, and coronal images were obtained with a gradient-echo sequence. 3D reconstruction of the bones and the supraspinatus was performed, and the minimal spatial distances between acromion, clavicle, and humerus were calculated. The closest contact between the supraspinatus and the anterior inferior part of the acromion occurred at 90 degrees abduction in internal rotation. The technique presented allows investigation of the morphological basis of the impingement syndrome.

Acromion↗
PubMed1998

[Noninvasive analysis of cartilage volume and cartilage thickness in the human elbow joint using MRI].

The aim of the study was to non-invasively analyse the cartilage volume and thickness in the human elbow joint with magnetic resonance imaging. 12 fresh frozen specimens (ages 20 to 69 yrs.) were investigated using a 1.5 T magnet, and a water-excitation FLASH-3D sequence at a resolution of 1 x 0.25 x 0.25 mm3. After linear interpolation to 0.125 x 0.125 mm2 in the image plane, the cartilages were segmented interactively with a Snake algorithm. Following three-dimensional reconstruction, the cartilage volumes were determined, and the mean and maximal cartilage thickness computed by Euclidean distance transformation. The total cartilage volume of the human elbow joint amounted to between 3.90 and 7.17 ml (mean 5.5 ml +/- 20%). The humerus occupied 49 to 60%, the radius 15 to 27% and the ulna 20 to 29% of the total volume. The mean cartilage thickness ranged from an average of 0.9 (proximal part of the ulna) to 1.4 mm (capitulum humeri), and the maximal thickness from 2.3 mm (proximal part of the ulna) to 2.9 mm (distal part of the ulna). The ulnar cartilage showed a more inhomogeneous distribution than that of the humerus and radius. The interindividual variability of the cartilage thickness was less than that of the volume. There was no significant relationship of the volume with age (r = 0.11) or body weight (r = 0.51). However, based on the joint size (r = 0.71-medio-lateral extension of the articular surfaces) about 50% of the variability of the total cartilage volume could be predicted. The technique presented is suitable for designing computer models to investigate the load transmission and functional adaptation of diarthrodial joints, and for diagnosing and monitoring joint disease.

Adult↗
PubMed1982

Automatic dew-point temperature sensor.

A device is described for measuring dew-point temperature and water vapor pressure in small confined areas. The method is based on the deposition of water on a cooled surface when at dew-point temperature. A small Peltier module lowers the temperature of two electrically conductive plates. At dew point the insulating gap separating the plates becomes conductive as water vapor condenses. Sensors based on this principle can be made small and rugged and can be used for measuring directly the local water vapor pressure. They may be installed within a conventional ventilated sweat capsule used for measuring water vapor loss from the skin surface. A novel application is the measurement of the water vapor pressure gradients across layers of clothing worn by an exercising subject.

Body Surface Area↗
PubMed1981

New thermal method for evaluating vaginal blood flow.

The goal of this study was the development noninvasive technique for measurement of vaginal blood flow. A vaginal probe (diameter 1.84 cm; length 7.0 cm) was constructed by winding 23 m of 34-gauge enameled copper wire around a hollow cylinder of epoxy-impregnated glass wool. Resistance of the wire was 20 omega at 40 degrees C. Surface area of coil was 40.5 cm2. The temperature of the wire midway along the coil was measured continuously with a thermcouple. Temperature difference (delta T) between coil and vagina was raised by delivery of 300 mA with a resultant production of 1.8 W. In ewes treated with 1 mg estrone im., delta T fell significantly (p less than 0.025) by 90 min and (p less than 0.005) by 120 min after injection. There was a significant correlation between delta T and vaginal blood flow as measured by the radiolabeled microsphere technique.

Animals↗
PubMedDate not supplied

[MRI-based 3-D analysis of the glenohumeral translation in patients with shoulder instability].

AIM: Until now, pathological translation of the glenohumeral joint could not be assessed three-dimensionally and in functionally important arm positions in the living. The objektive of this study was therefore to develop an MR-based technique for determining the three-dimensional glenohumeral translation in functionally relevant positions in vivo. METHOD: In an open MR scanner both shoulder joints of 5 volunteers with an unilateral traumatic instability were examined in different positions of abduction and rotation. After semiautomatic segmentation, 3D reconstruction of the bony structures of the shoulder girdle was performed and the center of mass of the glenoid cavity was determined and used as reference point. In a virtual reality, the midpoint of the humeral head was assessed and its position relative to the center of mass of the glenoid cavity was calculated. RESULTS: At 30 degrees of abduction, in both shoulders, the humeral head was positioned inferior and posterior relative to the glenoid cavity (healthy: 0.42 +/- 1.1 inf., 0.75 +/- 1.0 mm post.; unstable: 1.31 +/- 0.87 mm inf., 0.51 +/- 1.28 mm post.) The maximal translation (to anterior and inferior) was observed both on the healthy side (mean 1.0 mm, max. 1.8 mm) and in the unstable shoulders (mean 2.5 mm, max. 4.6 mm) with the arm in 90 degrees of abduction and external rotation, thus being 1.7 to 2.5 times higher in the pathological shoulders. CONCLUSIONS: With this technique the glenohumeral translation can be quantified three-dimensionally in functionally important positions and without projectional artefacts. In the future, this method can be applied to patients with different entities of shoulder instability.

Adolescent↗
PubMedDate not supplied

[MR-based 3D-analysis of the pathomechanics of traumatic and atraumatic shoulder instability].

AIM: Until now it is unknown to what extent malpositioning of the scapula is a relevant factor in shoulder instability that should be considered in therapy. The objective was to analyse 3D-scapular kinematics and humeral head (de-)centering in patients with atraumatic and/or traumatic shoulder instability and to investigate the correlation between the two factors. METHOD: The shoulders of 28 healthy volunteers and of 14 patients each with atraumatic or traumatic instability were examined in various arm positions - with and without muscle activity - using open MR imaging. After 3D reconstruction, analyses of scapular kinematics and glenohumeral translation were performed. RESULTS: In atraumatic unstable shoulders, the scapular position [30 degrees of abduction: scapulo-humeral rhythm: 3.5 +/- 2.6 : 1 vs. healthy 2.4 +/- 1.3 : 1; internal rotation: 59 +/- 9 degrees vs. healthy 49 +/- 3 degrees (p < 0.05)] and humeral head position was significantly decentered in both planes (p < 0.05). While the correlation between the two factors was high during passive elevation (r = 0.60-0.87), it was low during muscular activity (r = 0.25-0.62). In patients with traumatic instability no alterations of the scapula kinematics were observed. Significant humeral head decentering (p < 0.05) occurred only during abduction and external rotation. CONCLUSIONS: Patients with atraumatic instability demonstrated significant alterations of scapular kinematics and decentering of the humeral head. In traumatic instability a decentering occurred only in specific arm positions with no changes in scapula position. Because of the high correlation between the two factors, physiotherapeutic strategies for the scapula-stabilising muscles should be adapted to the direction of instability.

Adolescent↗