PubMed Health⌕ Search

Biomedical subjects

R Putz

Publications and source records attributed to R Putz.

At least 73 records · Page 4Linked to original sources
PubMed1997

Quantitative analysis of incongruity, contact areas and cartilage thickness in the human hip joint.

Joint incongruity and cartilage thickness have been shown to determine the contact stresses and the load partitioning between the solid and fluid phases of articular cartilage. Matrix stresses, which are relevant in the development of osteoarthrosis, can, however, not be determined experimentally but must be calculated using numerical methods. The aim of the present study was to quantify the incongruity and cartilage thickness of the human hip, in order to allow for the construction of morphologically accurate finite element models. Twelve cadaveric specimens (34-86 years), two fresh and ten fixed, were investigated. The loading configuration was based on in vivo measurements of hip joint forces during midstance. The incongruity and contact areas were determined using a polyether casting technique, in the minimally and the fully loaded state. The cartilage thickness was measured at identical coordinate points with an A-mode ultrasonic system. Generally, the contact started at lower loads at the edge of the lunate surface, and the joint space increased towards its central aspects. In some specimens the contact started in the acetabular roof, leaving a joint space of up to 2 mm in the horns of the lunate surface. In others, the initial contact was observed in the anterior and posterior horns of the lunate surface with a joint space width of up to 0.75 mm in the acetabular roof. The size of the contact areas increased from about 20% of the lunate surface to 98% at higher loads. The articular cartilage thickness ranged from 0.7 to 3.6 mm, the maxima being located in the ventral aspects of the femoral head and acetabulum. These quantitative data on joint space width, contact, and cartilage thickness in the human hip joint may be used to construct and validate finite element models which are required to elucidate the mechanical factors involved in osteoarthrosis.

Adult↗
PubMed1996

Magnetic resonance chondro-crassometry (MR CCM): a method for accurate determination of articular cartilage thickness?

A method for the assessment of articular cartilage thickness based on MRI is presented and its accuracy and reproducibility tested. Six specimens of human patellae were imaged, using a fat-suppressed FLASH 3D sequence, and sectioned with a high-precision band saw. The regional distribution of articular cartilage thickness was determined from the MR images and from the anatomical sections (intervals of 0.5 mm). With image analysis 50-90% of the image points were found to lie within exactly the same thickness interval in corresponding patterns, and less than 17% deviated more than 0.5 mm. More than 85% of all pixels were reproducible with MRI after new positioning of the joint. No influence of the read-out direction and no important differences between areas of thin and thick cartilage could be detected. The authors conclude that MR chondro-crassometry can provide accurate and reproducible information on cartilage thickness.

Adult↗
PubMed1996

Determination of knee joint cartilage thickness using three-dimensional magnetic resonance chondro-crassometry (3D MR-CCM).

The objective of this article was to analyze the accuracy and precision with which the quantitative distribution of articular cartilage can be determined in the knee joint using MRI. A three-dimensional (3D) technique that accounts for the out-of-plane deviation of the interface normal in strongly curved joint surfaces (3D MR-CCM) has been developed for cartilage thickness measurements. Eight cadaveric knee-joint specimens and six volunteers were imaged using a fat-suppressed gradient-echo sequence at a resolution of 2 x 0.31 x 0.31 mm3. Cartilage volumes and topographical thickness maps were obtained and compared with those derived from anatomical sections by image analysis. The deviation of the MR volumes from those of the sections was 1-12%, the coefficient of variation after repositioning ranged from 2.9% (patella) to 8.2% (lateral tibial plateau). Between 60% and 80% of all image points could be attributed to identical thickness intervals, less than 20% deviating by more than 0.5 mm. The intraobserver and interobserver reproducibilities were very high in both the specimens and the volunteers. In the knee joint, 3D reconstructions of the cartilages, and measurements that take into account the out-of-plane deviation of the interface normals (3D MR-CCM), are required.

Adult↗
PubMed1996

Computer-aided three dimensional assessment of knee-joint cartilage with magnetic resonance imaging.

OBJECTIVE: An MRI-based technique for non-invasive assessment of the quantitative distribution of articular cartilage in the knee-joint was to be developed, and its accuracy and reproducibility tested. DESIGN: Three cadaveric specimens and one patient were studied and MRI measurements compared with anatomical sections or arthroscopy. BACKGROUND: Data on articular cartilage thickness is needed for the design of computer models, determination of cartilage material properties from arthroscopy and staging of osteoarthrosis. METHODS: The knees were imaged using strongly T2-weighted spin-echo and FISP-3D sequences. After digital subtraction and automatic segmentation, three-dimensional reconstruction of the cartilages was performed. Surface areas, volumes and the mean cartilage thickness were calculated, and the regional distribution displayed after trigonometric correction. RESULTS: The difference between MRI volumes and those obtained from the sections ranged from 4 to 21% with a reproducibility of +/-4 to +/-12% after repositioning. The thickness maps obtained with MRI were very similar to those from the sections. In the patient, a full-thickness defect demonstrated with MRI was verified by arthroscopy. CONCLUSIONS: Using the technique presented, the quantitative distribution of knee-joint cartilage may be analysed non-invasively, accurately, and in a very time-effective manner, in cadavers and in living subjects. RELEVANCE: To date there exists no accepted method for the accurate, fast and non-invasive assessment of articular cartilage thickness. Such a technique is, however, very helpful for generating computer models of diarthrodial joints, determination of cartilage material properties during arthroscopy, staging of joint disease, and objective control of chondroprotective treatment.

Journal Article↗
PubMed1996

Local muscle flaps of the second and third interosseus space for the treatment of osteomyelitis in the central metacarpal region.

Both experimental and clinical studies showed that muscle flap transposition is a reliable tool in treating chronic infections of the bone. The major advantage of local muscle flaps is the treatment with well perfused autogenous tissue without using any implants. The primary closure of the operation site and the cure of infection within four weeks allow a short immobilisation time. Nevertheless, the loss of muscle function with a possible functional and aesthetic defect in the donor site has to be accepted. The first dorsal interosseus muscle and the abductor digiti minimi muscle have been used successfully for the treatment of metacarpal osteomyelitis. Osteomyelitis in the central metacarpal bones cannot be treated with these techniques, because of their limited range. We present the muscles of the second and third interosseus space for local pedicled muscle flap transfer. The arterial network in this interosseus spaces and the vascularisation of the dorsal and palmar interosseus muscles allow to harvest muscle flaps with either proximal or distal pedicle. The loss of interosseus muscles in the second and third interosseus space is tolerable from a functional and esthetic point of view. Operative techniques are shown for the elevation of dorsal and palmar interosseus muscle flaps. Two cases of osteomyelitis in the central metacarpal bones, which were treated successfully with the new local interosseus muscle flaps, are reported.

Adult↗
PubMed1996

The scapula: principles of construction and stress.

According to current generally accepted theories, analysis of the shape of a bone provides clues to the stresses acting upon it. Although many investigations have ensured that understanding of the lower limb is relatively advance, knowledge relating to the upper limb, and particularly to the scapula, is still far from complete. We have therefore endeavoured to interpret the shape of this bone morphometrically. To this end various scapular parameters have been standardised and statistically analysed, and the results examined both from the functional and the clinical points of view. Our investigation has established that, as in the case of the long bones, the form of the scapula is dependent upon both height and sex. Assessment of the architecture of the subacromial space and its possible parameters of influence have also demonstrated that the size of this space is essentially dependent upon the height of the subject and the size of the acromial and scapulospinal angles. A short distance between the acromion and the upper edge of the glenoid cavity and a small glenoid-spinal angle can be regarded from a functional point of view as factors predisposing to the development of the impingement syndrome. We have also been able to show that certain constant structural features produce an optimal distribution of the forces acting upon the scapula. In particular, the relationship of the supporting pillars (the lateral border and the spine) of this bone to one another appears to represent the expression of an ideal adaptation to the action of those forces.

Humans↗
PubMed1996

Structure, strain and function of the transverse acetabular ligament.

To assess the morphology and function of the transverse acetabular ligament (TAL), its internal structure and insertion sites were analyzed, and its strain was determined during hip joint loading. Fifteen specimens were embedded in methyl methacrylate and cut into 500-micron sections parallel to the inlet of the acetabulum. Polarized light microscopy and contact radiography revealed important differences between the ventral and dorsal attachment of the TAL. Ventrally, the fibers insert close to the labrum, at a rather extensive site consisting of fibrous cartilage. Dorsally, the ligament arises from a wide attachment at the bony region of the posterior horn, where it is continuous with the periosteum and the joint capsule. In a second part of the study, six specimens (four fixed, two fresh) were investigated, using a testing machine to simulate hip joint loading. The strains of the TAL and of two sites of the acetabular labrum were measured with strain gauges. Loads of 10-2,800 N were applied and the degree of rotation of the femoral head was varied. At 400% body weight, the TAL encountered tensile strains of up to 3.7%, but the labrum only of up to 0.5%. The contact areas of the hip joints were determined with a polyether casting material. At 50% body weight they were found to lie in the anterior and posterior aspects of the lunate surface. These results indicate that, due to a natural incongruity, the acetabular notch is widened during loading and the TAL submitted to tension.

Acetabulum↗
PubMed1996

13 MHz high-frequency sonography of the lateral ankle joint ligaments and the tibiofibular syndesmosis in anatomic specimens.

In this study, the ligaments of the ankle joint and the tibiofibular syndesmosis were examined in formalin-fixed anatomic specimens using a 13 MHz sonographic scanner. For this purpose, 48 specimens of the ankle joint were examined, and the anterior tibiofibular, anterior talofibular, and calcaneofibular ligaments were marked by sonographically guided dye injection. The markings were checked during the subsequent dissection. The number of identifications reached 89.6% for the anterior tibiofibular and talofibular ligaments and 87% for the calcaneofibular ligament. The results show that the most frequently injured ligaments of the ankle joint can be visualized reliably by use of 13 MHz high-frequency sonography.

Ankle Joint↗
PubMed1996

[Therapy of osteomyelitis in the metacarpal region with local pedicle m. interosseus dorsalis II and III-flap-plasty. Anatomic principles and case report].

Both experimental and clinical studies showed that muscle flap transposition is a reliable method for treating chronic infections of the bone. Advantages of muscle flaps are: treatment of infection with well perfused autogenous tissue obviating the use of implants, cure of infection usually within four weeks and consequently, short immobilisation time. Disadvantages of muscle flaps are loss of muscle function with possible donor-site morbidity. The first dorsal interosseous muscle and the abductor digiti minimi muscle have been used successfully for the treatment of osteomyelitis of the metacarpals. The second and third dorsal interosseous muscle are presented for the first time. After discussing anatomy, especially vascularisation of these muscles, the operative technique is shown and a case of osteomyelitis of the third metacarpal treated by this new transposition is reported.

Adult↗
PubMed1996

[Isolated ossicle of the dens axis. Case reports and differential diagnosis].

Two patients with an incidental finding of isolated ossicles adjacent to the dens axis are presented. One case was thought to be based on an isolated part of the dens axis, possibly due to trauma; the second case could be a true ossiculum terminale. Such ossicles can be confused with acute fractures, initiating treatment that is not indicated.

Adolescent↗
PubMed1995

Morphomechanics of the humero-ulnar joint: I. Joint space width and contact areas as a function of load and flexion angle.

BACKGROUND: Previous studies have shown that the trochlear notch is deeper than necessary for an exact fit with the humerus. However, humero-ulnar joint space width and contact areas have so far not been quantified for variations in the load and angle of flexion. METHODS: Six fresh cadaveric specimens were investigated at 30 degrees, 60 degrees, 90 degrees, and 120 degrees of flexion and at loads of 25 and 500 N, simulating resisted elbow extension. The joint space width and contact were determined, using polyether casting material. RESULTS: At 25 N all joints made contact in the ventral and dorsal aspects of the articular surfaces, whereas in the depth of the trochlear notch the joint space was on average between 0.3 and 2.8 mm wide, with some variation between individuals. At 500 N the joint space width was considerably reduced and the contract areas expanded towards the depth of the notch. The size of the dorsal contact areas was significantly smaller at 30 degrees and that of the ventral ones at 120 degrees, their ventro-dorsal ratio decreasing considerably from 30 degrees to 120 degrees (p < 0.01). CONCLUSION: These results indicate that the size of the contact areas depends to a slight extent on the joint position, but that at all loads and flexion angles a bicentric contact and an important central joint space width emerge because of the concave incongruity of the joint. These data may be used for numerical calculations, analysing the effects of incongruity on the joint stress and on the functional adaptation of the subarticular tissues.

Adult↗
PubMed1995

Morphomechanics of the humero-ulnar joint: II. Concave incongruity determines the distribution of load and subchondral mineralization.

BACKGROUND: A deeper joint socket (concave incongruity) is found at most angles of flexion of the humero-ulnar joint and maintained over a wide range of physiological loading. It is, however, unclear how far this incongruity affects the distribution of load and subchondral mineralization of this joint as compared with a congruous configuration. METHODS: Two nonlinear, axisymmetrical finite element models with two cartilage layers were constructed, one congruous and one incongruous, with a joint space of realistic magnitude. The distribution of subchondral mineralization was determined by computed tomography osteoabsorptiometry in the same six specimens that were investigated in the first part of the study, and compared with the biomechanical data obtained there and the predictions of the models. RESULTS: In the congruous case, the center of the socket is highly loaded, whereas the periphery does not experience mechanical stimulation. A central bone density maximum is predicted. With concave incongruity the position of the contact areas shifts from the joint margin towards the center as the load increases, and the peak stresses are considerably lower. A bicentric ventro-dorsal distribution pattern of subchondral mineralization is predicted, and this is actually found in the six specimens. CONCLUSIONS: Concave incongruity is shown to determine load transmission and subchondral mineralization of the humero-ulnar joint. It is suggested that this shape leads to a more even distribution of stress, provides intermittent stimulation of the cartilaginous tissue, and has beneficial effects on the metabolism, nutrition, and lubrication of the articular cartilage during cyclic loading.

Absorptiometry, Photon↗
PubMed1995

Subchondral bone density in the human elbow assessed by computed tomography osteoabsorptiometry: a reflection of the loading history of the joint surfaces.

The functional adaptation of bone tissue to the mechanical stresses acting on it has been convincingly established. This association should apply as well to the subchondral bone, reflecting the long-term distribution of stress over the joint surfaces. Thirty-six specimens of the human elbow joint were investigated by computed tomography osteoabsorptiometry in order to assess the distribution of the subchondral mineralization. The distal surfaces usually were more highly mineralized than the proximal components of the joint, whereas the humeroulnar and the humeroradial parts exhibited a similar degree of mineralization. The fovea of the radial head always showed a central density maximum, and the trochlear notch usually presented a bicentric distribution pattern, with maxima beneath the ventral and dorsal regions of the articular surface. The different patterns of subchondral mineralization were shown to reflect the loading history of the overlying articular surfaces, which is determined mainly by geometrical factors. The flatter socket of the humeroradial joint leads to central load transmission, but the deeper socket of the humeroulnar joint will, by contrast, give rise to bicentric stress distribution.

Absorptiometry, Photon↗
PubMed1995

The thickness of the subchondral plate and its correlation with the thickness of the uncalcified articular cartilage in the human patella.

The regional thickness distributions of the subchondral plate and the unmineralized part of the articular cartilage were morphometrically determined in normal human patellae, and the correlation coefficient for each specimen calculated from the paired measurements. For this purpose the patellae were embedded in methyl methacrylate and cut as serial sections, which were assessed with a Vidas image-analyzing system (Kontron). The values obtained were used to reconstruct the individual and average thickness distributions and to calculate the correlation coefficients for each subject. Both the thickness of the subchondral plate and that of the cartilage revealed regular distributions which, however, followed different patterns. Central regions with maximum values from which the thickness decreased concentrically towards the periphery were found in both. However, the distribution patterns of the unmineralized cartilage and the subchondral plate could be clearly distinguished, both by the position of the maxima and by the arrangement of the isocrassids (contour lines of equal thickness). The thicknesses of the two tissues showed a correlation between 0.38 and 0.82 (mean 0.6). We attribute this to their different reactions to the type of stress acting upon them. It appears that the thickness of the subchondral plate is principally determined by stresses acting over a longer period of time with low frequency, whereas the thickness of the articular cartilage seems to be a response to intermittent dynamic stresses of a higher frequency.

Adult↗
PubMed1995

The potential of magnetic resonance imaging (MRI) for quantifying articular cartilage thickness -- a methodological study.

The thickness of patellar articular cartilage was assessed in a cadaveric human knee joint by magnetic resonance imaging. Imaging was conducted at 1.0 T, using three-dimensional gradient-echo sequences. From each of the sequences the total cartilage volume, the size of the articular surface, the mean cartilage thickness and the regional distribution of cartilage thickness were determined by image analysis. These values were then compared with those obtained from anatomical sections. The fat-suppressed FLASH sequence was found to allow the most accurate evaluation of the total volume and the regional distribution of the articular cartilage. Slight underestimation of the cartilage thickness by about 5% may be due to the fact that the calcified layer is not made visible by magnetic resonance imaging. There is, however, a very high degree of similarity between the distribution patterns obtained from the MR images and the anatomical sections. The contrast-to-noise ratios and reproducibility were also highest with the fat-suppressedFLASH sequence. This pulse sequence can therefore be recommended for experimental and clinical use.

Journal Article↗
PubMed1995

[Morphometry of the sub-acromial space and its clinical relevance].

Rupture of the rotator cuff is one of the commonest (30%) pathologic findings in elderly dissecting room subjects. Together with the degenerative tendopathy associated with increasing age, this is due to mechanical damage to the distal parts of the tendons or the soft tissues lying in the subacromial space between the acromion, coracoacromial ligament, coracoid process and humeral head. The object of this investigation was to examine the influence of the decisive metrical parameters of the subacromial space in the macerated scapula. For this purpose, defined distances and angles of 343 macerated human scapulae were measured by means of an image analysing system, and the results evaluated statistically. It was found that the size of the subacromial space depends, not only upon variations in the form of the acromion itself, but also upon the acromial and scapula-spine angles. Marked projection of the coracoid process, which is dependent upon both the angle between the long axis of the scapula and the root of the coracoid process and the coracoid angle, plays an important part in the development of the so-called subcoracoid impingement syndrome: a constriction of the subscapularis tendon between the coracoid process and the head of the humerus. A clinical assessment of the absolute size of the subacromial space should take into account the size of the body; but sex, age, and the side involved are of little significance.

Acromioclavicular Joint↗
PubMed1995

[Anatomy and pathology of tendons].

Taking into account its detailed morphology, an attempt has been made to explain a tendon's ability to transmit force between its muscular origin and skeletal insertion. This ability depends upon the aggregation and binding capacity of the molecular elements of type I collagen and is known to decrease with advancing age. The internal structure of a tendon is modified both at the muscle-tendon junction and near its attachment to bone. The very low elasticity of tendinous tissue (about 3% to 8%) is due partly to the texture (pseudo-elasticity) and partly to the molecular composition. The so-called degenerative changes in a tendon begin with deterioration of the internal vascular network and are obviously--so far as its failing capacity is concerned--both initiated and accelerated by the degree of over-loading.

Aging↗