Biomedical subjects

J M Kauer

Publications and source records attributed to J M Kauer.

At least 37 records · Page 2Linked to original sources

PubMed1993

Carpal bone kinematics and ligament lengthening studied for the full range of joint movement.

Present data on carpal kinematics and carpal ligament behaviour are limited to flexion and deviation movements of the hand. These motions do not represent all the wrist-joint motions which are important for the activities of daily living. The goal of this project was to obtain insight into carpal kinematics and carpal ligament behaviour during motions of the hand covering the full range of motion of the wrist joint. The carpals and the ligaments of four wrist-joint specimens were provided with radiopaque markers. These joints were subjected to Röntgenstereophotogrammetric experimentation in a large number of hand positions to determine carpal positions and ligament lengths. The movements of the carpal bones were described by means of finite helical axes (FHA). It was found that the movements of the carpals in the distal row closely resemble those of the hand. Conversely, the motions of the carpals of the proximal row appeared not to be directly proportional to the hand motions and exhibited clear out-of-plane movements. Furthermore, it could be shown that movements of the hand into the ulnodorsal quadrant of the full range of hand motion corresponds to larger helical rotations and translations for most of the carpals than when the hand was moved into any other quadrant. The maximal ligament length changes determined did not exceed the length changes reported for pure flexion and pure deviation movements of the hand.

Aged↗

PubMed1993

An indirect method to assess wrist ligament forces with particular regard to the effect of preconditioning.

A method has been developed to calculate the forces that are developed in the ligaments of a joint specimen during motions. This indirect method is needed since direct measurements fail in the case of small ligaments. As an example the small ligaments of the carpal joint are considered. The rationale of the method is that the force generated in a ligament depends on the amount of strain to which it is subjected and on its material characteristics. In the method presented the lengths of the ligaments are determined in vitro at several joint positions by means of röntgenstereophotogrammetry. The zero-force length and the force-elongation relationship are determined on the same ligaments isolated in a materials testing machine. Over a considerable part of the strain range the measurement errors are relatively small compared to the forces determined, less than 10%. The method is applicable to joints in situations where other measuring methods cannot be used. The present analysis shows, however, that the force values determined are susceptible to preconditioning of the ligaments. In preconditioned ligaments the forces could be up to 50% lower than in the non-preconditioned situation. This suggests that ligament forces may vary considerably in vivo, depending on the extent of preconditioning provoked by a particular function.

Biomechanical Phenomena↗

PubMed1993

The Kleinert dynamic splint: where it fails and how it can be modified.

After primary tenoraphy of flexor tendons one often finds a hampered function of the DIP-joint. Analysis of the pattern of early mobilization exercised by our patients in the Kleinert splint and analysis of the excursions of the flexor tendons of fresh unembalmed specimens brought us to the conclusion that the Kleinert dynamic splint fails in maintaining a sliding movement of the deep and the superficial flexor tendons along each other because the splint excludes motion at the distal interphalangeal joint. Based on our observations we modified the Kleinert dynamic splint. Our experience with 37 patients shows that this modified splint gives a better function in the DIP-joint.

Biomechanical Phenomena↗

PubMed1993

Neuritis of the lateral femoral cutaneous nerve in leprosy.

Neuritis of the lateral femoral cutaneous nerve (meralgia paresthetica) is observed more frequently in leprosy than in nonleprosy patients, and its symptoms can easily be confused with those suggesting, e.g., ischialgia. The diagnosis can be confirmed by a diagnostic block with a local anesthetic solution. Analgesics, antiinflammatory drugs, bed rest and, in severe cases, therapeutic blocks were successfully applied in the treatment of the neuritis, and no surgical intervention was needed. Three leprosy patients with severe meralgia paresthetica are presented.

Adult↗

PubMed1992

Strains and forces in selected carpal ligaments during in vitro flexion and deviation movements of the hand.

The forces induced in tiny wrist joint ligaments must be estimated in order to understand their role in the mechanism of the joint. We estimated forces in a number of selected ligaments in seven human wrist joint specimens, using a noninvasive method. The method is based on the rationale that the force generated in a ligament depends on its change of length with the joint under load. In vitro length changes of the ligaments were determined during flexion and deviation movements of the hand, using a roentgenstereophotogrammetric analysis technique. Subsequently, bone-ligament-bone (BLB) preparations were dissected from the specimens. From these BLB preparations the zero-force length and the force-elongation relationship were determined in a material testing machine. The forces generated in the ligaments during flexion and deviation were calculated by combining results on the in vitro ligament length changes, the zero-force length, and the force-elongation relationship. Large interspecimen variations of the force patterns were found. Due to this variability, it is not possible to obtain quantitative models for the kinetic behavior of the ligaments. However, qualitative trends could be distilled from the strain and force patterns. It is clear that for most ligaments, the zero-force lengths were not equal to the lengths they possessed in the neutral position of the hand. Furthermore, it could be shown which motions of the hand would most likely strain a particular ligament. It could be shown that the variations in the force patterns originate mainly from variations in the zero-force lengths, and from variations in the force-strain relationship between specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

Stiffness of the ligaments of the human wrist joint.

In the present study the stiffness of the superficial ligaments of 14 human cadaver wrist joints have been determined. In these experiments the tested, fresh-frozen carpal joints are divided into a number of bone-ligament-bone complexes, which are loaded in a tensile testing machine at a rate of 66% of the ligaments' initial length per second to a maximal strain of 15%. From the force-elongation curves and ligament dimensions the tangent moduli for the ligament-bone strips are derived. The results show that, with regard to the tangent modulus, there is not a clear differentiation among ligament strips. Only the dorsal radiotriquetrum ligament (RTD) and the palmar radiocapitate ligament (RCP) appear to consist of a material of a relatively high tangent modulus, about 93 and 83 MPa, respectively. The other seven ligaments tested have similar tangent moduli, ranging from 25 to about 50 MPa.

Aged↗

PubMed1992

An unusual ulnar nerve-median nerve communicating branch.

Branching of the ulnar nerve distal to the origin of the dorsal cutaneous branch was investigated in 25 hands in one of which an anatomical variation was observed. This finding may be of importance in the evaluation of certain entrapment phenomena of the ulnar nerve or unexplained sensory loss after trauma or surgical intervention in that particular area.

Humans↗

PubMed1992

The distal radioulnar joint. Anatomic and functional considerations.

The distal radioulnar joint is functionally coupled with the proximal radioulnar joint, thus forming a mechanism for the longitudinal rotation of the hand. Distal radioulnar mobility is derived from the geometry of the joint, joint surfaces, and radioulnar connections. There is a structural and functional separation between the distal radioulnar and carpal joints, giving the possibility of pronation and supination in every position of the hand to the forearm. As for the stability of the joints involved, the ulnar articular disk plays an essential role. Being part of both distal radioulnar and carpal joints, the disk has very specific morphologic features that not only are individualized to the function of both joints but also stabilize the joints in their independent movements. Developmental data give the strong impression of an architectural scheme, of which the distal radioulnar joint is only a part. Traumatic lesions at the distal radioulnar joint and disturbances in normal distal radioulnar alignment have to be viewed, therefore, in a wider context.

Cartilage, Articular↗

PubMed1991

Human carpal ligament recruitment and three-dimensional carpal motion.

In five fresh human cadaver wrist joints six carpal ligaments and seven carpal bones were marked with small, radio-opaque pellets. Using a roentgenstereophotogrammetric measuring system, the ligamentous length changes and the kinematics of carpal bones were determined in different flexion and deviation positions of the hand. The data generated by this method differ significantly from lengthening data predicted by current concepts on carpal ligament functioning. The motions of carpal bones and the lengthening of the carpal ligaments were related to each other. It appeared that most carpal ligaments lengthen only during one half of a full movement cycle. Hence, ligaments seem to constrain either a dorsal- or a palmar-directed motion of the hand, or an ulnar- or a radial-directed motion of the hand. When the hand is in maximal radial deviation or maximal palmar flexion, none of the ligaments has a greater length than in the neutral situation. The tested parts of the lunatotriquetrum palmar ligament do not lengthen during any movement of the hand. Significant lengthening relative to the neutral situation was found for the radiocapitate palmar ligament (6.5% in maximal ulnar deviation and 11.7% in maximal dorsal flexion of the hand), and for the distal string of the radiolunate palmar ligament (6.4% in maximal ulnar deviation). It was confirmed that the carpals, apart from moving in the plane in which the hand motion takes place, also execute considerable out-of-plane motions during hand motions. The combination of these experimentally and simultaneously determined data on length change and on the movements of carpal bones are found to be necessary in order to give suitable explanations for the observed separate kinematical phenomena.

Carpal Bones↗

PubMed1991

Radioscapholunate ligament: a gross anatomic and histologic study of fetal and adult wrists.

The radioscapholunate ligament was studied using fifty-four dissected adult cadaver wrists. Four of these wrists had arterial perfusions with colored latex and serial sections were made of twenty-one wrists from fetuses ranging in size from 23 to 230 millimeters crown-rump length. The radioscapholunate ligament was consistently identified between the long and short radiolunate ligaments, emerging through the palmar capsule of the radiocarpal joint. It was found to be a neurovascular structure surrounded by synovial tissue with vascular origins from the anterior interosseous and radial arteries and a neural origin from the anterior interosseous nerve. On entering the radiocarpal joint it attaches proximally to the interfacet prominence on the articular surface of the radius and distally to form the proximal membrane of the scapholunate interosseous ligament system. We found no anatomic evidence that this structure should be considered a ligament in a traditional mechanical sense. However, this structure may be clinically important as the vascular supply of the scapholunate interosseous ligament, as well as a sensory pathway from the scapholunate articulation.

Adult↗

PubMed1990

Wrist-joint ligament length changes in flexion and deviation of the hand: an experimental study.

A method to study ligament-length patterns in situ with roentgen-stereophotogrammetry, using strings of glued tantalum markers, was developed. The method was tested against a bone-to-bone marking method in five carpal ligaments in three specimens, whereby the hand was moved through dorsopalmar flexion and radioulnar deviation. The "glued-string" marking method was found to be superior to the bone-to-bone marking method. The length patterns obtained were found to be reproducible in the specimens and different from earlier expectations presented in the literature. The radiocapitate ligament seems to limit the displacements of the capitate in both radial and ulnar deviation, and dorsal flexion. The radiolunate ligament has the same effect for the lunate. Both the dorsal radiotriquetrum and the palmar triquetrocapitate ligaments seem to play a stabilizing role in the neutral position of the hand, whereas the radiotriquetrum ligament also has a function in palmar flexion and the triquetrocapitate ligament functions in dorsal flexion, ultimately resisting these excursions. These findings require confirmation in more extensive experiments, whereby the relationship between ligament length patterns and carpal motion axes is investigated.

Adult↗

PubMed1990

Measurement errors in roentgen-stereophotogrammetric joint-motion analysis.

In many biomechanical motion studies, kinematic parameters are estimated from position measurements on a number of landmarks. In the present investigation, dummy motion experiments are performed in order to study the error dependence of kinematic parameters on geometric factors (number of markers, isotropic vs anisotropic landmark distributions, landmark distribution size), on kinematic factors (rotation step magnitude, the presence of translational displacements, the distance of the landmarks' mean position to the rotation axis), and on anisotropically distributed measurement errors. The experimental results are compared with theoretical predictions of a previous error analysis assuming isotropic conditions for the measurement errors and for the spatial landmark distribution. In general, the experimental findings agree with the predictions of the error model. The kinematic parameters such as translations and rotations are well-determined by the model. In the helical motion description, the same applies for the finite rotation angle about and the finite shift along the helical axis. However, the direction and position of the helical axis are ill-determined. An anisotropic landmark distribution with relatively few markers located in the direction of the rotation axis will even aggravate the ill-posed nature of the finite helical axis estimation.

Biomechanical Phenomena↗

PubMed1990

Effects of data smoothing on the reconstruction of helical axis parameters in human joint kinematics.

In biomechanical joint-motion analyses, the continuous motion to be studied is often approximated by a sequence of finite displacements, and the Finite Helical Axis (FHA) or "screw axis" for each displacement is estimated from position measurements on a number of anatomical or artificial landmarks. When FHA parameters are directly determined from raw (noisy) displacement data, both the position and the direction of the FHA are ill-determined, in particular when the sequential displacement steps are small. This implies, that under certain conditions, the continuous pathways of joint motions cannot be adequately described. The purpose of the present experimental study is to investigate the applicability of smoothing (or filtering) techniques, in those cases where FHA parameters are ill-determined. Two different quintic-spline smoothing methods were used to analyze the motion data obtained with Roentgenstereophotogrammetry in two experiments. One concerning carpal motions in a wrist-joint specimen, and one relative to a kinematic laboratory model, in which the axis positions are a priori known. The smoothed and non-smoothed FHA parameter errors were compared. The influences of the number of samples and the size of the sampling interval (displacement step) were investigated, as were the effects of equidistant and nonequidistant sampling conditions and noise invariance.

Adult↗

PubMed1989

A stereophotogrammetric method for measurements of ligament structure.

A stereophotogrammetric method is presented to reconstruct the course of a curve in the three-dimensional space. This method is exclusively suitable as a non-destructive tool to determine the surface fiberstructure of ligaments, tendons and other organised collagenous structures. In addition, it is a convenient tool to measure the geometry of articular surfaces and other complicated surface shapes.

Hip Prosthesis↗

PubMed1987

Functional anatomy of the carpometacarpal joint of the thumb.

The first carpometacarpal joint is formed by the proximal joint facet of the first metacarpal and the distal joint on the trapezium. The morphologic features of these facets, together with a lax but strong joint capsule, give the thumb great mobility and play a major role in the opposition of the thumb. Based on the kinematic behavior of the joint, it was given the functional status of a ball-and-socket joint. To analyze the motion patterns of the first metacarpal with regard to the trapezium, models were proposed based on the principles of regularly curved joint surfaces. However, it has been acknowledged that irregularly curved surfaces attuned to a specifically shaped ligamentous system offer the morphologic basis for understanding mobility at the base of the thumb. The stability of the first carpometacarpal joint is not guaranteed by joint surfaces and ligaments alone because differences in mobility between the anatomic bone-ligament specimen and the joint in vivo are conspicuous. The function of muscles crossing the joint is essential. The close structural relation between the tendon of the abductor pollicis longus and the first carpometacarpal joint was observed. Five distinguishable tendons of this muscle end at different parts of the joint. The interweaving of some of the tendons with the ligamentous system undoubtedly influences the restraining and directing function of the ligamentous system.

Carpal Bones↗

PubMed1987

The carpal joint. Anatomy and function.

The carpal joint can be approached as a mechanism consisting of kinematic chains. In these chains, the proximal carpals function as intercalated segments. Intercarpal displacements are linked to one another and are based upon the mutual attuning of carpal bone geometry, joint contacts, and ligamentous interconnections.

Biomechanical Phenomena↗

PubMed1986

Accuracy of an anthropometric estimate of the muscle and bone area in a transversal cross-section of the arm.

To standardize the maximal static force (Fo) of the arm flexors, the accuracy of an anthropometric method for estimating the mid-arm cross-sectional muscle and bone area (MBA) was investigated. This was done by comparing the anthropometrically determined area (MBA.A) with the area measured by means of computerized tomography (MBA.S). In the same way, the accuracy of Heymsfield's equations (Heymsfield et al., 1982) for predicting MBA (MBA.H) from anthropometric measures was tested. MBA.A was significantly larger than MBA.S, the relative difference increasing with the thickness of the subcutaneous fat layer. This difference was attributed to a 27% underestimation of the fat layer thickness as measured with the skinfold caliper. Women being fatter than men, this caused the standardized maximal static force (Fo/MBA) to be lower in women than in men. MBA.H was 12% smaller than MBA.S. This may have been due to a difference in the way of measuring the arm circumference between the present authors and Heymsfield et al.

Adult↗

PubMed1986

The mechanism of the carpal joint.

The morphologic features of the carpal bones and their contacts play a highly significant role in the mechanism of the wrist joint. Displacements of the proximal carpal bones in both flexion and deviation of the hand take place in longitudinal articulation chains that are linked one to another. This concept is supported by the following observations: differences in curvature between the facets of the proximal carpals at the radiocarpal level suggest that simultaneous movements occur at the midcarpal level; the position of the proximal carpal bones is determined by their position with respect to both the distal carpal bones and the radius; displacements of the proximal carpal bones to the distal carpals result in swerving motions in the transverse plane in addition to dorsopalmar rotation (as a result, the volar rotated position of a proximal carpal in the volar flexed hand will differ from its position in the radial deviated hand and the positions of the proximal carpals in the dorsiflexed hand will differ from these in the ulnar deviated hand); and the three articulation chains, radial, central, and ulnar, cannot function on their own, since the linkage in the longitudinal direction is associated to a transverse linkage by the mutual joint contacts between the chains and by ligamentous interconnections.

Carpal Bones↗