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Biomedical subjects

J Koebke

Publications and source records attributed to J Koebke.

At least 19 recordsLinked to original sources
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↗
PubMed1990

[Controlling and supporting apparatus of the deep finger flexor tendon and the long extensor tendon of the thumb. Clinico-anatomical analysis].

Full function of finger flexion requires an intact pulley system. After destruction of the pulleys, reconstruction over the metacarpal head (A1) and over the center of the proximal and middle phalanges (A2, A4) should be carried out. Calculations on a computer model suggest that the reconstructed pulley must hold the tendon close to the underlying bone. Width of the pulley and distance from the next proximal or distal joint of the inserted pulley are of minor functional importance. The amount of maximum load on the pulley, exceeding the tension of the tendon, must be considered in operation and postoperative treatment. The extensor pollicis longus tendon lies at the dorsal tubercle (tubercle of Lister) within an osseous gliding surface, where it changes direction. The deviation angle depends on the radiocarpal position and causes, in addition to the usual tension, a pressure stress to that part of the tendon. A graphical analysis of statics, based on X-rays, demonstrates maximum loads on the gliding surface. They can increase in relation to the tension force of the tendon to about 50% in the antero-posterior and to 100% in the radioulnar projection. Densitography of the distal radius shows a maximum of density where the dorsal tubercle is most prominent. Nutritional problems of that tendon are predisposed by that particular mechanical stress. Therefore spontaneous rupture of the extensor pollicis longus tendon in patients with rheumatoid arthritis or after fracture of the distal radius occurs, though infrequently. In the case of immobilization, slight ulnar abduction within the radiocarpal joint remarkably reduces the tension and pressure stresses on the tendon.

Computer Simulation↗
PubMed1990

[Torsion of the metacarpals II to V. Functional and clinical significance].

Torsion of the metacarpals II to V was measured in 50 pairs of human hand skeletons. The in-situ position of the metacarpals was reconstructed and the influence of the torsion of the morphological radioulnar head axes analysed. It is shown that during flexion of the metacarpophalangeal joint these morphological radioulnar axes serve as functional axes. Because of the specific position of the radioulnar axes through the metacarpal heads, the hand can be divided into three functional units: the thumb; the index and middle fingers; the fourth and fifth fingers. Within such a functional unit, lines perpendicular to the aforementioned radioulnar axes converge. In contrast to earlier investigations, these lines do not intersect at one common point. There are two separate intersections: one for the metacarpals II and III and another for the metacarpals IV and V. The torsion of right and left metacarpals shows significant differences. The lines perpendicular to the radioulnar metacarpal head axes in left hands generally show a more radial deviation, whereas in right hands they run more parallel to the metacarpals' longitudinal axes. This investigation shows that the precision grip of the right hand and the power grip of the left is supported by the morphology of the metacarpal bones. Finally, the clinical significance of our results is pointed out.

Biomechanical Phenomena↗
PubMed1989

[Stress on the normal and pathologic wrist joint].

The wrist joint is generally stressed by external forces. The resultant of these external forces produces the pressure in the joint which evokes pressure stresses within the supporting tissues of the joint. As was shown by Pauwels (1973) the density of the subchondral bone is adapted to articular stress distribution. The zone of subchondral bone can be seen as the morphological equivalent of the specific joint stress. This paper shows by means of density analyses and pressure measurements that in contrast to earlier opinions joint pressure is transmitted both by the lunate and the scaphoid bones. It seems that the physiological stress is even higher in the scaphoid than in the lunate bone. The force transmission between the lunate and the ulnar disc is less pronounced. The analysis of the lunatal trabecular architecture leads to the suggestion that the lunate is stressed differentially in the radio-ulnar plane. In pathological conditions of the wrist joint (perforation of the disc, ulnar shift, Kienböck's disease, ulna minus variant) the pressure and the density distribution are adapted to the pathomorphology in each case.

Aged↗
PubMed1989

[Rhizarthrosis and thenar muscles. A clinico-anatomic study].

Advanced osteoarthrosis of the first carpometacarpal joint is characterized by a subluxation (luxation) of the joint, by an adduction deformity and by hyperextension of the metacarpophalangeal joint of the thumb. This morphological and functional investigation aims to underline the importance of the intrinsic thumb muscles in this complex deformity of the thumb. The vector of the M. abductor pollicis brevis and the physiological cross-section of the thenar muscles were determined in eight osteoarthrotic and ten healthy hands. The superficial head of the M. flexor pollicis brevis and the M. abductor brevis were investigated electromyographically in patients as well as in healthy controls. There is disturbed function of the M. abductor pollicis brevis in cases of arthrosis, caused by a changed vector of the muscle. The physiological cross-section of the superficial head of the M. flexor pollicis brevis is diminished by about fifty per cent. The electromyographic records of patients lead to the conclusion that there is a particular loss of activity in the short flexor and abductor muscles. The muscular alterations taken together cause functional imbalance of the thenar muscles. The abductor muscle is not able to maintain the coordinating system that consists of two straight and one oblique muscle and the Z-deformity of the thumb results.

Aged↗
PubMed1988

[Functional importance of the m. extensor carpi ulnaris for distal radioulnar articulation].

Any analysis of the stability of the distal radio-ulnar joint should consider the extensor carpi ulnaris tendon. The static and kinematic function of this tendon depends on its relationship to the sigmoid notch of the radius. Morphological studies indicate the existence of a gliding surface in the sulcus of the tendon on the dorsal side of the ulnar head.

Biomechanical Phenomena↗
PubMed1988

[Anatomy of the wrist joint and carpus].

A systematic anatomical representation of the carpal area is not an adequate means to show its way of function. This paper describes the functional correlations between the distal radio-ulnar joint and the wrist joint. The proximal wrist joint is composed of two mechanically equivalent compartments. Within the ulnocarpal joint, the disk fulfills a most important function as a surface adapting and pressure transmitting element. Its perforation is a pre-arthrotic deformity. The column conception of the carpus is supported by cinematic studies as well as by analyses of the subchondral bone density and the spongy structure of the ossa carpi. This conception presumes a radial scaphoid column, a central lunate column, and an ulnar triquetrum column.

Carpal Bones↗
PubMed1988

[Radiologic determination of the length of the distal end of the radius and ulna].

The influence of inaccurate positioning of the hand and forearm upon the relative lengths of the ulna and radius is investigated systematically in anatomical specimens and living persons. Increased or decreased ulnar lengths could be produced by moving up and down, by tilting or by pronation of the forearm. Extension of the elbow also influences the ulnar variance measurement.

Biomechanical Phenomena↗