Biomedical subjects

J Koebke

Publications and source records attributed to J Koebke.

At least 91 records · Page 5Linked to original sources

PubMed1993

[Stress fractures of the navicular bone--biomechanical and densitometry studies].

One of the most important pathogenetic mechanisms regarding stress fractures of the navicular bone lies in the hyperpronation movement of the foot. For recording the impacts of the pronation movement on the talonavicular joint, stress and pressure experiments are carried out and the radii of curvature as well as the bone density are measured. The stress experiments show a rotation movement of the talar head in a medioplantar direction of about 20 degrees. The radii of curvature of the articulating joint surfaces do not differ to a great extent. A possible incongruency in the joint therefore has to be attributed to the rotation movement of the talus during pronation of the foot. The pressure experiments show a very irregular distribution of pressure in the joint presenting a lateral and medial pressure maximum. Fractures preferably occur in the area in between these maxima. Areas of high subchondral bone density in the densitometric results are found in the central part of the talar head as well as in the medial part of the navicular bone. Within the functional adaptation the distribution of bone density expresses the rotation movement of the talus during pronation of the foot.

Absorptiometry, Photon↗

PubMed1993

[The functional anatomy of the lower extremity, especially the foot].

The skeletal elements as well as the muscles of the human foot are functionally adapted to bearing body load. The arrangement of the hindfoot bones is essential for establishing the longitudinal foot arch. This and the transverse arch, too, must be supported by the passively acting plantar ligaments and the active plantar muscles. The total muscle force is needed for support to 80%; 20% will serve for articular mobility. Insufficiency or loss of stabilizing factors will lead to unphysiological high stress of the skeletal elements. In consequence, the arch system will be weakened and stress fractures may occur.

Adolescent↗

PubMed1993

[Absorption properties of supporting tissues in low-energy molybdenum spectrum as basis for a material-qualitative roentgen image in mixed color coding].

The absorption properties of bone and cartilage tissue in the molybdenum spectrum are studied firstly according to Bragg and secondly by means of radiographs taken with different sections of the spectrum, revealing differences substance-specifically dependent on the radiation frequency. These differences can be utilised for imaging by means of substance-specific color-coded radiography.

Absorptiometry, Photon↗

PubMed1993

Plastination: a new approach to morphological research and instruction with excised larynges.

Impregnation of biologic materials with curable polymer (plastination) allows wider use of human tissue for both basic and clinical research and instruction. The aim of this study was to determine for the first time the potential of this method in the field of laryngology. A feasibility study on 54 pig larynges established a detailed methodology for larynx plastination and determined the extent of shrinkage by using computer-assisted morphometry. The process involves dehydration, saturation with an appropriate intermediate solvent, and infiltration with cured polymer in vacuo. In the main study 20 fresh, intact human larynges and 12 laryngectomy specimens were submitted to plastination. The resulting resin blocks were cut with a diamond band saw into 0.8-mm sections in the transaxial plane. The resulting specimens are dry, odorless, and durable, and do not deteriorate with time. The subtle features of soft tissue pathology are well preserved. Shrinkage of plastinated larynges is less than 10%. The complete process is accomplished within 5 weeks. Staining of sections with toluidine blue provides an enhanced contrast between different types of tissue, allowing a clear identification of tumor invasion. Plastination is considerably faster than celloidin embedding and causes minor anatomic changes. It provides durable specimens of high quality for teaching purposes. In research, it allows the investigation of all tissue components in their undisturbed context in the borderline area between gross anatomy and histology.

Anatomy↗

PubMed1993

[Functional anatomy of the fifth carpometacarpal joint].

Apart from the first carpometacarpal joint, the fifth carpometacarpal joint is of importance in gripping and cupping the hand. The present study describes the functional anatomy of the fifth carpometacarpal joint considering morphological and experimental findings. Shape and extension of the cartilaginous articular surface of 50 metacarpal bases show characteristics of a saddle joint. The differences between the dorso-palmar and ulno-radial curvature of the articular surface suggest a main direction of motion in the fifth carpometacarpal joint around an ulno-radial axis. Flexion in this joint ranges from 10 to 15 degrees. After maximal flexion, a supinatory rotation of the metacarpal bone ranging from 10 to 15 degrees is measured. Because of the transverse arched configuration of the carpal bones, the flexion of the fifth metacarpal bone produces opposition towards the thumb. A simultaneous supinatory rotation supports this opposition movement.

Adolescent↗

PubMed1993

[Ontogeny of the human temporomandibular joint].

An analysis of the human temporomandibular joint is done regarding to the appearance of secondary cartilage formations during the prenatal development of condylus and temporal joint elements. Sagittal sections of nine human fetuses (49 mm CRL to 315 mm CRL) show a closed relationship between the development of the bony and soft tissues of the joint. The temporary appearance of secondary cartilage in the temporal joint area is induced by the functional loading of the capitulum. This process requires the genesis of the two free articular cavities on the one side and the functional attachment of the lateral pterygoid muscle to the discus and the collum mandibulae on the other. Pointing out the clear relationship of the articulating joint surfaces and the in between discuss, a left temporomandibular joint of a fetus (125 mm CRL) is reconstructed in a medioventral view with the help of a three dimensional drawing. The location of the temporal secondary cartilage formation within the centre of the temporal loading area of the condyle assures its functional genesis during the embryological development of the human temporomandibular joint.

Cartilage, Articular↗

PubMed1993

[The ulnar recess in the arthrogram of the proximal wrist joint].

Arthrography of the proximal wrist joint does not provide details regarding the shape and the extension of the recessus ulnaris. The recessus located between the ulnocarpal disc and the meniscus homologue as a diverticulum of the articular lining was examined in 61 wrists by arthrography and dissection. Using the Pleximon-injection technique, specimens of the proximal wrist cavity allowed a systematic description of morphology and topography of the ulnar recessus. The shape and location of the ulnar recessus show variations, but a sacciform recessus, which usually bears a close relationship to the ulnar styloid process, is the most common. The comparison of arthrographic and morphologic findings allows an assessment of the credibility of arthrographic depictions of the wrist as regards the clinically relevant close relationship to the recessus ulnaris.

Adult↗

PubMed1993

The pedicled pisiform transposition in Kienböck's disease. An anatomical and functional analysis.

Anatomic characteristics of the lunate and the pisiform were compared in order to support the use of a pisiform transposition in advanced stages of Kienböck's disease. Fifty lunate and pisiform bone pairs served for morphological and functional investigations. In view of the present results, the pisiform, after a rotation of 90 degrees, should be implanted in the lunate cavity with its longitudinal diameter oriented in the dorsopalmar plane. Despite the small pisiform volume, maintenance of carpal height is assured by its relatively large dorsopalmar diameter. The rotated position takes advantage of existing cancellous structures and improves the conditions of force transmission. Measurements comparing the radii of curvature of the original lunate and the substitute pisiform surfaces show a good correspondence proximally and a reduction of the articular congruity distally, due to the flatness of the pisiform surface.

Biomechanical Phenomena↗

PubMed1992

Anatomical bases of the pediculated pisiform transplant and the intercarpal fusion by Graner in Kienböck's disease.

Anatomic characteristics of the lunate, the pisiform and the capitate were compared in order to support the use of a pisiform transplant or the intercarpal fusion by Graner in advanced stages of Kienböck's disease. Fifty lunate and pisiform bone pairs and 20 wrist specimens served for morphological and functional investigations. In view of the present results, the pisiform, after a rotation of 90 degrees, should be implanted in the lunate box with its longitudinal diameter oriented to the dorsopalmar plane. Despite the small pisiform volume, maintainance of carpal height is assured by its relatively large dorsopalmar diameter. The rotated position permits use of existing soft tissue structures and improves the conditions of force transmission. Measurements comparing the radii of curvature of the original lunate and the substitute pisiform surfaces show a good correspondence proximally and a reduction of the articular congruity distally, due to the flatness of the pisiform surface. The palmar convexity of the pisiform adapts better to the distal radius facet than the capitate head, which replaces the lunate in Graner's surgical procedure.

Arthrodesis↗

PubMed1992

[Structure of the palmar plate of the proximal interphalangeal joint with reference to the typical injury pattern in hyperextension trauma of the finger. A morphometric, densitometry and histologic study].

The palmar plates of the PIP of the fingers are examined in 43 hands. Apart from macroscopic morphometric studies special attention is paid to the density of bone in the areas of insertion, measured with the help of a computerized image analysing system. Especially the distal area of insertion in the basis of the medial phalanx shows a low density of bone. The consequent low adaptation to stress explains clinical findings, describing most frequent osseous ruptures of the palmar plates in case of hyperextension injuries to the fingers. The fibrous structure of the palmar plate is studied in histological sections. A palmar layer of transversally running collagenous fibres, as well as a medial layer of diagonally and a dorsal layer of longitudinally running fibres can be differentiated. The distal area of the palmar plate mostly consists of transversal, the proximal area of longitudinal collagenous fibres. Therefore a hyperextension stress, hitting the fibres in a right angle distally, cannot be neutralized sufficiently. This result is closely linked to clinical observations describing mostly distal ruptures of the palmar plate in spite of its proximal region being of weaker structure.

Athletic Injuries↗

PubMed1992

[Vascular supply of the unsheathed segment of the extensor tendons of the 2d to 5th fingers of the dorsum of the hand].

The dorsal approach to the metacarpal bones is through the peritendinous connective tissue of the extensor tendons. Knowledge of the vascular supply of the distal parts of these tendons, between the distal end of the tendon sheath and the tendon's osseous insertion is important, especially with respect to atraumatic technique. The course and distribution of the vessels to the extensor tendons II-V were investigated. Superficial and deep layers of connective tissue were found to contain blood vessels. The superficial vessels reach the dorsal aspect of the extensor tendon, originating from subcutaneous arteries and the large arteries of the hand. The deep vessels reach the lateropalmar aspect of the tendons and originate from the peritendinous muscular arteries. Vessel distribution suggests a direct relationship between the number of nourishing arteries and the tendon surface area. The vascular supply to the unsheathed parts of the extensor tendons shows morphological adaptations to differential mechanical stress during tendon excursion.

Aged↗

PubMed1992

[Anomalous course and anomalous division of the median nerve in the distal forearm].

An anatomic variation of the median nerve is demonstrated in a female patient suffering from carpal tunnel syndrome subsequent to a distal radius fracture with malalignment and reflex sympathetic dystrophy. The median nerve coursed anterior to the superficial flexor tendons from proximal ulnar toward the distal radial region of the distal forearm, giving off an ulnar branch just 2.5 cm proximal to the flexor retinaculum. This case proves that in the distal forearm, branches of the median nerve can be found both radial and ulnar to the midline.

Carpal Tunnel Syndrome↗

PubMed1992

[The temporal bone].

Imaging of the temporal bone by high resolution CT scan has become more and more accurate in recent years. Coronal slices are particularly important. We present the anatomy of four temporal bones embedded in plastic material. Coronal sections with a thickness of 2 mm were taken, radiographed and their density measured. Particular interest was given to the three-dimensional relations as well as to the density of bone of important morphological structures such as the labyrinth, middle ear, facial canal, sigmoid sinus, carotid canal and the mastoid. A low density of bone corresponds to the colour blue, a high density to black. Because of the high resolution of the method it was possible to image small and fine structures such as the auditory ossicles, and the perilymphatic and endolymphatic ducts. A three-dimensional reconstruction may well be possible in the future, and the possibilities of this method are discussed.

Carotid Artery, Internal↗

PubMed1991

[Significance of shape differences between medial and lateral knee joint menisci for functional change of position].

The attachments of the anterior and posterior horn of the menisci to the tibial plateau are of a most important functional value. At the medial meniscus the circumference is more widely configurated, because of the greater distance between anterior and posterior horns. The areas of sagittal cuts through the menisci slightly differ regarding medial and lateral side. A higher area momentum of inertia of the medial meniscus, related to a vertical axis within the examinated sagittal plane, is found. It derives from a geometrical distribution of partial areas more distant from the axis. The medial meniscus therefore has a higher stiffness against sagittal bending stress. Experiments and theoretical stress simulation prove these results. According to them, the medial meniscus is less mobile in comparison to the lateral. These findings are discussed as a basic geometrical cause for the higher incidence of injuries of the medial meniscus.

Biomechanical Phenomena↗

PubMed1991

[Alloplastic replacement of the anterior cruciate ligament. Comparative studies of ruptured Dacron, Trevira and Ligapro ligaments].

Histological investigations were performed on 24 polyethylene terephthalate ligaments (eight Dacron, eleven Trevira and five Ligapro) which had served as substitute for the human anterior cruciate ligament. Because of rupture or loosening they had been explanted six to 48 months after operation. Only in one Trevira ligament a longitudinal direction of collagenous lamellae could be seen, all other ligaments had only few collagenous fibers, mainly orientated in circular direction. In the fibrous tissue of all three kinds of ligaments there were signs of inflammation. Foreign body giant cells have immigrated--they mainly enclose the graft fibres in Dacron and Ligapro ligaments. In Trevira and Ligapro ligaments the foreign body giant cells phagocyte particles of graft fibers after increasing implantation times. The inflammatory reaction to graft fibers and their particles may also damage host tissue. Regarding these results we conclude that the Polyethylene terephthalate ligaments are not qualified as substitutes for the anterior cruciate ligament.

Adolescent↗

PubMed1991

[Clinical morphology of the sternum].

The length, width and thickness of the sternum were measured in 74 adult specimens with the aim of optimizing the dimensions of staples used after sternotomy. This article describes the experimental procedure and presents the results. Sex differences were confined mainly to the length, with males measuring 16.5 cm, and females 15 cm. Width and thickness maxima (7.4 cm and 1.7 cm, respectively) are measured at the proximal and distal ends of the manubrium, while the width and thickness of the corpus (2.7-3.5 cm and 1.0-1.4 cm, respectively) show relatively minor differences.

Aged↗

PubMed1991

[Diagnosis of torsion malposition of the radius and ulna after healed distal fracture].

Assessing radial and ulnar rotational deformities quantitatively by routine diagnosis after healed distal forearm fractures is very difficult. A method to obtain information about direction and graduation of malrotation is described. This method is based on discovering topographic changes of skeletal points by CT. Rotational angles of intact forearm bones are measured on anatomic specimen and in vivo using epiphyseal and diaphyseal axes of the radius and the ulna. Normal rotation of intact forearm bones varies in a specific manner. The radius presents less variations than the ulna. A morphological index of radial and ulnar rotation is not given because of the great individuality of diaphyseal rotation. Both radii of a single individuum show a very small rotational difference. Therefore a verification of malrotation is indicated by comparison to the intact opposite radius. Higher rotational graduations on the left side have to be noted.

Follow-Up Studies↗

PubMed1990

[Functional aspects of embryonic secondary cartilage development in the human TMJ].

The development of the temporomandibular joint was studied histologically in sagittal sections of four human fetuses with a crown-to-rump length of 49 mm to 315 mm. Special attention was paid to the appearance of secondary cartilage in the condylar and glenoidal joint elements. There was a close relationship between the development of both the soft tissue and bony elements. It is the purpose of this paper to report histologic observations made in humans regarding the functional genesis of the temporal secondary cartilage.

Cartilage, Articular↗