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Biomedical subjects

J Koebke

Publications and source records attributed to J Koebke.

At least 109 records · Page 6Linked to original sources
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↗
PubMed1987

The function of the antebrachial interosseous membrane.

The relationship between the fibers of the interosseous membrane and the muscle fibers of the deep extensor and flexor muscles was investigated on the basis of 33 forearms. The angle between muscle and membrane fibers was determined radiologically in the dorso-ventral and radio-ulnar planes. The spatial angle of origin can be determined immediately in areas where the membrane is covered by a flexor or extensor muscle alone. In areas where the membrane is covered on both sides, the angle between the muscle force resultant and the membrane fibers is measured. The obtained results lead to the following conclusion: the muscle fibers or the resultant form a specific angle with the membrane fibers which results in the typical functionally predisposed orientation of the membrane fibers.

Aged↗
PubMed1987

[MR of the shoulder joint with surface coils at 1.5 tesla. Its anatomy and possible clinical use].

High spatial resolution magnetic resonance images of the shoulder were obtained in axial, sagittal and coronal orientations using a 1.5 T imaging system and anatomically shaped, wrap-around surface coils. Variations in scapular position induced by patient positioning change the relationship of the planes to the shoulder anatomy and make reproducibility of sagittal and coronal planes difficult. We, therefore, use--after axial orientation--image-oblique planes perpendicular and parallel to the glenoid fossa. In this manner MRI can visualise the anatomic structures of the shoulder including rotator cuff, long biceps tendon, articular capsule, articular cartilage, muscles and bones due to the high soft tissue contrast of MRI.

Humans↗
PubMed1986

Neck extension as a cause of SIDS.

The intradural sagittal diameter at the second cervical vertebra (SD/C2) of 62 SIDS cases was measured myelographically. This SD/C2 proved to be dependent on body size, body weight, and age. A clear, age-dependent difference is to be found in the primarily narrow spinal canal. This parameter (SD/C2), which is more precisely defined in adults on the basis of clinical, radiological, and autopsical findings is assumed to have the value of 0.5 cm in the first 2 months, 0.6 cm in the third month, and 0.65 cm in the fourth month. The resulting potential danger to infants is dependent upon their position. The SD/C2, was significantly decreased in extension as compared to a neutral posture. With consideration of the primarily narrow spinal canal in the infant, there is, according to our measurements, a potential hazard for the infant in any further, significant shortening of the SD/C2. This is independent of the width of the spinal canal under maximal extension. We found individual cases in which the SD/C2 was decreased by almost 50% from the normal value in neutral position. No correlation was found between the primary width of the spinal canal and the degree of luminal reduction upon extension.

Age Factors↗
PubMed1986

[Bladder diverticulum at an atypical site].

An atypically located diverticulum of the bladder was found in five anatomical dissection specimens. The diverticulum with a depth of about 1-3 cm developed in the bladder's lateral wall. The diverticulum seems to be caused by a strong fibrous cord originating from the bladder's wall and penetrating the canalis obturatorius. Within the channel the cord is anchored by a voluminous fat body. Histologically the wall of the diverticulum reveals typical signs of chronic inflammation.

Adipose Tissue↗
PubMed1986

[The fat body of the obturator canal].

In addition to the obturator nerve and vessels a fat body in the obturator canal is found in the majority of cases investigated. The fat body, small and isolated in newborns, is part of the subperitoneal mass of fat and loose areolar tissue in adults. In the 2 cases of obturator hernia the fat body has no connection with the peritoneum which constitutes the sac of the hernia. A strong fibrous cord running from the urinary bladder to the fat body of the obturator canal is observed in 46 cases. In 5 of these the cord causes a small pouch in the wall of the bladder.

Adipose Tissue↗
PubMed1986

Histological observations on muscles from cases with aplasia of the tibia.

Muscles of the lower leg and foot from 3 cases with aplasia of the tibia were investigated by light microscopy. The crural muscles are atrophied in all cases, whereas the small muscles of the foot are quite normal. The histological appearance of the degenerated muscles is characterized by atrophied muscle fibers and fatty infiltration. There are no signs of hypertrophy or regeneration. These observations suggest that the atrophy is caused selectively by inactivity of the crural muscles.

Adolescent↗
PubMed1984

[The quadrate pronator muscle--a morphological and functional analysis].

Based upon the findings of dissections and of histological investigations, the m. pronator quadratus was found to be composed of 2 heads. In the majority of the cases an oblique superficial head entirely covered a deep head, whose fasciculi were oblique from the ulnar origin to the distal volar surface of the radius. The fibers of both heads were arranged obliquely to the axis of rotation. From this both heads by contraction will develop a rotatory and a shunt force, the shunt components acting antagonistically. The superficial head is the rotator for pronation, whereas the deep head is well located for maintenance of transverse forces at the distal radioulnar joint. Moreover, the two heads insert into the capsule of the articulatio radioulnaris distalis.

Adult↗