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R Putz

Publications and source records attributed to R Putz.

At least 37 records · Page 2Linked to original sources
PubMed2001

An immunohistochemical study of the dorsal capsule of the lumbar and thoracic facet joints.

STUDY DESIGN: The molecular composition of the extracellular matrix in the dorsal capsules of lumbar and thoracic facet joints was analyzed immunohistochemically. OBJECTIVES: To determine whether the immunohistochemical profile of the lumbar joint capsule suggests a role of the capsule in limiting axial rotation of the lumbar motion segment. SUMMARY OF BACKGROUND DATA: During axial rotation of the lumbar vertebrae, the axis of rotation shifts toward the facet joints in the direction of rotation. Thus, the capsule of the opposing joint should become tensed and wrap around the inferior articular process. Previous studies suggest that wrap-around ligaments are fibrocartilaginous. However, thoracic joint capsules are largely shielded from such loading and should be purely fibrous. METHODS: Dorsal capsules were removed from lumbar and thoracic facet joints of six adult cadavers. Specimens were immunolabeled with monoclonal antibodies for collagens, chondroitin, dermatan and keratan sulfates, versican, tenascin, aggrecan and link protein. Antibody binding was detected using the Vectastain ABC 'Elite' peroxidase kit (Vector Laboratories, Inc., Burlingame, CA). RESULTS: Both lumbar and thoracic joint capsules immunolabelled for most glycosaminoglycans and for Type I, III and VI collagens. However, labeling for Type II collagen, chondroitin-6-sulfate, aggrecan, and link protein was restricted to lumbar capsules. Such labeling was constantly seen at entheses and occasionally in the midsubstance. CONCLUSIONS: The molecular composition of the lumbar joint capsule suggests that it acts as a fibrocartilaginous, 'wrap-around' ligament that withstands compression in addition to tension during torsional movements of the lumbar spine. It wraps around the inferior articular process as rotation occurs and limits further movement.

Adult↗
PubMed2001

Age-related changes in the morphology and deformational behavior of knee joint cartilage.

OBJECTIVE: Alterations of cartilage morphology and mechanical properties occur in osteoarthritis, but it is unclear whether similar changes also take place physiologically during aging, in the absence of disease. In this in vivo study, we tested the hypothesis that thinning of knee joint cartilage occurs with aging and that elderly subjects display a different amount of cartilage deformation than do young subjects. METHODS: We evaluated 30 asymptomatic subjects ages 50-78 years. Morphologic parameters for the knee cartilage (mean and maximum thickness, surface area) were computed from magnetic resonance imaging data. Results were compared with those in 95 young asymptomatic subjects ages 20-30 years. Deformation of the patellar cartilage was determined after the subjects performed 30 knee bends. RESULTS: There was a significant reduction of patellar cartilage thickness in elderly women (-12%; P < 0.05), but not in elderly men (-6%). Femoral cartilage was significantly thinner in both sexes (-21% in women, -13% in men; P < 0.01), whereas tibial cartilage thickness displayed only nonsignificant trends (-10% in women, -7% in men). Patellar cartilage deformation was -2.6% in elderly women and -2.2% in elderly men. These values were significantly lower (P < 0.05) than those in young subjects. CONCLUSION: We confirmed the hypothesis that knee cartilage becomes thinner during aging, in the absence of cartilage disease, but that the amount of reduction differs between sexes and between compartments of the knee joint. We show that under in vivo loading conditions, elderly subjects display a lower level of cartilage deformation than do healthy young subjects.

Adult↗
PubMed2001

The popliteal region: an anatomical study and a new approach to the tibial attachment of the posterior cruciate ligament.

Surgical treatment of posterior cruciate ligament injuries is gaining more and more importance. The central posterior approach according to Abbott (1945) has been considered a standard, with various complications involved owing to the local anatomic conditions. This study is intended to present a modified dorsomedial approach to the posterior capsule of the knee joint that is better adapted to the anatomic conditions. As a basis, the popliteal region was dissected in 150 knee joints, and the course of the popliteal artery with its branches as well as the bifurcation of the sciatic nerve were identified. The medial joint line served as a reference point. It has been shown that the knee joint arteries and the two sural arteries arose at relatively constant levels. At least one of the meniscofemoral ligaments was found in all of the knee joints examined; the anterior ligament was present in a slightly higher percentage than the posterior ligament. The modified dorsomedial approach to the posterior joint capsule was evaluated in 50 knee joints. Dissection was achieved by blunt division of the medial head of the gastrocnemius muscle, with careful preservation of the proximal vascular supply of that muscle. It was necessary to expose neither the popliteal artery and vein nor the tibial nerve. The tibial attachment of the posterior cruciate ligament could be exposed in every knee. The advantage of the new approach to the posterior cruciate ligament described in this study consists in the preservation of the central neurovascular bundle and the excellent exposure of the tibial attachment.

Aged↗
PubMed2001

In vivo morphometry and functional analysis of human articular cartilage with quantitative magnetic resonance imaging--from image to data, from data to theory.

Analyses of form-function relationships and disease processes in human articular cartilage necessitate in vivo assessment of cartilage morphology and deformational behavior. MR imaging and advanced digital post-processing techniques have opened novel possibilities for quantitative analysis of cartilage morphology, structure, and function in health and disease. This article reviews work on three-dimensional post-processing of MR image data of articular cartilage, summarizing studies on the accuracy and precision of quantitative analyses in human joints. It presents normative values on cartilage volume, thickness, and joint surface areas in the human knee, and describes the correlation between different joints and joint surfaces as well as their association with gender, body dimensions, and age. The article summarizes ongoing work on functional adaptation of articular cartilage to mechanical loading, analyses of in situ cartilage deformation in intact joints in vivo and in vitro, and the quantitative evaluation of cartilage tissue loss in osteoarthritis. We describe evolving techniques for assessment of the structural/biochemical composition of articular cartilage, and discuss future perspectives of quantitative cartilage imaging in the context of joint mechanics, mechano-adaptation, epidemiology, and osteoarthritis research. Specifically, we show that fat-suppressed gradient echo sequences permit valid analysis of cartilage morphology, both in healthy and severely osteoarthritic joints, as well as highly reproducible measurements (CV%=1 to 3% in the knee, and 2 to 10% in the ankle). Relatively small differences in cartilage morphology exist between both limbs of the same person (approximately 5%), but large differences between individuals (CV% approximately 20%). Men display only slightly thicker cartilage then women (approximately 10%), but significantly larger joint surface areas (approximately 25%), even when accounting for differences in body weight and height. Weight and height represent relatively poor predictors of cartilage thickness (r2 <15%), but muscle cross section areas display more promising correlations (r2 >40%). The level of physical exercise (sportive activity) does not account for interindividual differences in cartilage thickness. The thickness appears to decrease slightly in the elderly--in particular in women, even in the absence of osteoarthritic cartilage lesions. Strenuous physical exercises (e.g., knee bends) cause a 6% patellar cartilage deformation in young individuals, but significantly less deformation in elderly men and women (<3%). The time required for full recovery after exercise (fluid flow back into the matrix) is relatively long (approximately 90 min). Static in situ compression of femoropatellar cartilage with 150% body weight produces large deformations after 4 h (approximately 30% volume change), but only very little deformation during the first minutes of loading. Quantitative analyses of magnetization transfer and proton density hold promise for biochemical evaluation of articular cartilage, and are shown to be related to the deformational behavior of the cartilage. Application of these techniques to larger cohorts of patients in epidemiological and clinical studies will establish the role of quantitative cartilage imaging not only in basic research on form-function relationships of articular cartilage, but also in clinical research and management of osteoarthritis.

Cartilage, Articular↗
PubMed2001

Fibrocartilage in the transverse ligament of the human acetabulum.

Biomechanical experiments on isolated hip joints have suggested that the transverse ligament acts as a bridle for the lunate articular surface of the acetabulum during load bearing, but there are inherent limitations in such studies because the specimens are fixed artificially to testing devices and there are no modifying influences of muscle pull. Further evidence is thus needed to substantiate the theory. Here we argue that if the horns of the lunate surface are forced apart under load, the ligament would straighten and become compressed against the femoral head. It would thus be expected to share some of the features of tendons and ligaments that wrap around bony pulleys and yet previous work has suggested that the transverse ligament is purely fibrous. Transverse ligaments were removed from 8 cadavers (aged 17-39 y) and fixed in 90% methanol. Cryosections were immunolabelled with antibodies against collagens (types I, II, III, VI), glycosaminoglycans (chondroitins 4 and 6 sulphate, dermatan sulphate, keratan sulphate) and proteoglycans (aggrecan, link protein, versican, tenascin). A small sesamoid fibrocartilage was consistently present in the centre of each transverse ligament, near its inner surface at the site where it faced the femoral head. Additionally, a more prominent enthesis fibrocartilage was found at both bony attachments. All fibrocartilage regions, in at least some specimens, labelled for type II collagen, chondroitin 6 sulphate, aggrecan and link protein, molecules more typically associated with articular cartilage. The results suggest that the ligament should be classed as containing a 'moderately cartilaginous' sesamoid fibrocartilage, adapted to withstanding compression. This supports the inferences that can be drawn from previous biomechanical studies. We cannot give any quantitative estimate of the levels of compression experienced. All that can be said is that the ligament occupies an intermediate position in the spectrum of fibrocartilaginous tissues. It is more cartilaginous than some wrap-around tendons at the wrist, but less cartilaginous than certain other wrap-around ligaments, e.g. the transverse ligament of the atlas.

Acetabulum↗
PubMed2001

Levatorplasty, a new technique to treat hypernasality: anatomical investigations and preliminary clinical results.

BACKGROUND: Velopharyngoplasty is the most commonly used operative technique for the treatment of velopharyngeal insufficiency. By attaching a posterior pharyngeal flap to the velum, a nonphysiological situation is created in the upper airway. PURPOSE: The aim of this investigation was to find a new surgical approach to physiological reconstruction of the velopharyngeal sphincter. MATERIAL: Anatomical investigations were performed in four cadavers. From this study a new surgical technique was developed and called 'levatorplasty': the musculus longus capitis was taken to create a new muscular loop leading to (a) an augmentation of the posterior wall, (b) a medial shift of the lateral pharyngeal wall; and (c) stretching of the velum posteriorly. Thus, the velopharyngeal space was reduced and a physiological closure of the nasal airway space could be obtained. STUDY DESIGN: The levatorplasty was employed in nine cleft palate patients with velopharyngeal insufficiency. Pre- and postoperatively the velopharyngeal closure was evaluated by phonetic and radiological examination. RESULTS: The operation was easily performed without major complications. A concentric constriction with decrease of the velopharyngeal space was achieved and a definitive decrease of nasalance and hypernasality resulted. CONCLUSION: Long-term follow-ups have to verify whether these results will be stable. They also have to be compared with functional improvements following velopharyngoplasty or pharyngoplasty. Of special interest will be evaluation of the altered mobility of the lateral pharyngeal walls.

Adolescent↗
PubMed2000

[The anatomy and function of the pelvic floor].

PELVIC FLOOR: Anatomy of the pelvic floor seemed to be clearly. In opposite the physiology of the Levator ani and the endopelvic fascia is not yet fully understood. Especially the anatomic form of the levator plate does not conform with physiologic concepts. PELVIC STRUCTURES: Pelvic structures can be divided in three groups: the hollow organs, the endopelvic fascia and the muscles. The M. levator ani is the muscle of the pelvic diaphragm. Its parts were given different names (Fig. 1, 4) depending on their function or localization. In anatomic studies the pelvic floor is described as basin-shaped. In contrast to the anatomic results based upon the evaluation of cadavers, dynamic MRI gave different concepts: at rest the levator ani probably has the shape of a dome and differ when contract. The urogenital diaphragm is mostly a fascia and contains only fair muscular components. Therefore, many authors do not accept the term "diaphragm" and the physiologic function is still a matter of discussion. The endopelvic fascia has to fix the organs in the pelvis and forms "streets" for vascular and nervous supply. CONCLUSION: Describing anatomic structures in the common planes (transversal, sagittal, frontal) will help to understand CT- and MRI-imaging.

Aged↗
PubMed2000

Posterior radial collateral artery as the basis of the lateral forearm flap.

The lateral forearm flap is being increasingly used for covering minor-to-moderate-sized defects for which soft and thin skin is required. Within the framework of an anatomic study carried out on 28 cadaveric arms, the authors investigated the principal artery that supplies blood to this flap namely, the posterior radial collateral artery (PRCA). They found that distal to the lateral epicondyle, the PRCA lies in a constant axial line lateral to the brachioradialis muscle. The average length of the artery distal to the epicondyle is 8 cm. Distal to the epicondyle side branches of the PRCA build an arterial plexus 6 cm (+/-3.5 cm) long and 5 cm (+/-1.1 cm) wide. The posterior cutaneous antebrachii nerve lies close to the artery. This permits the harvesting of a flap that is both innervated and has adequate vascular supply.

Aged↗
PubMed2000

[Magnetic resonance imaging of the wrist--comparison of high resolution pulse sequences and different fat signal suppression techniques in cadavers].

PURPOSE: To evaluate high resolution sequences with and without fat-suppression techniques for MR imaging of the wrist. MATERIALS AND METHODS: 10 cadaver wrist specimens were imaged with 12 MR sequences (SE: 400 ms/20 ms, TSE: 3000 ms/119 ms/17 ms, fatsat (FS) TSE: 3000 ms/17 ms and 3000 ms/45 ms, STIR: 2619 ms/29 ms/160 ms, DESS 3D: 43.7 ms/9 ms/35 degrees FS and 25.4 ms/9 ms/35 degrees water excitation (WE), CISS 3D: 12.2 ms/5.9 ms/40 degrees and FLASH-sequences: 53 ms/11 ms/40 degrees FS, 23 ms/11 ms/40 degrees WE and 45 ms/11 ms/30 degrees FS) at 1.5 T. Slice thickness was 3 mm, FOV 80 x 70 mm (pixel size 0.31 x 0.31 mm). Signal intensity was measured by an ROI in bone marrow, fluid, hyaline cartilage, scapholunate (SL) ligament and triangular fibrocartilage and S/N- and C/N-ratios were calculated. Additionally, a visual evaluation was performed. RESULTS: The highest homogeneity and the least artifacts were achieved by the T1-w SE sequence. For the STIR and PD-FS TSE sequence high rankings were found for the detection of free water. The PD FS sequence had high ranking also for visualization of the SL ligament and the triangular fibrocartilage. The best sequence for the assessment of hyaline cartilage was the FLASH-FS sequence. For detailed analysis of bony structures the CISS sequence performed best. CONCLUSION: The isolated use of a PD-FS-TSE sequence enables for evaluation of all clinically relevant structures at the wrist. Dedicated questions for hyaline cartilage are answered best by the use of a FLASH 3D-FS sequence. Selective water excitation reduces acquisition time to 60%, nevertheless FS sequences are still diagnostically superior to WE sequences.

Adipose Tissue↗
PubMed1999

Fibrocartilage in the extensor tendons of the human metacarpophalangeal joints.

The extensor tendons of the fingers cross both the metacarpophalangeal (MCP) and interphalangeal joints. Previous studies have shown that where the extensor tendons replace the capsule of the proximal interphalangeal (PIP) joint, they contain a sesamoid fibrocartilage that articulates with the proximal phalanx during flexion. The fibrocartilage labels immunohistochemically for a variety of glycosaminoglycans and collagens. In the current study, we investigate the molecular composition of the extensor tendons at the level of the MCP joints. This is of particular interest because the tendon has a greater moment arm at this location (and might thus be subject to greater compression), but is separated from the joint cavity by the capsule and peritendinous tissue. Six hands were removed from elderly cadavers (39-85 years of age) and the MCP joints were fixed in 90% methanol. The extensor tendons were dissected from all fingers, cryosectioned, and immunolabelled with a panel of monoclonal and polyclonal antibodies for types I, II, III, and VI collagens, chondroitin 4 and 6 sulphates, dermatan, and keratan sulphate and aggrecan. Antibody binding was detected with the Vectastain ABC 'Elite' avidin/biotin/peroxidase kit. The extensor tendons in all the fingers had a metachromatic sesamoid fibrocartilage on their deep surface which immunolabelled for types I, III, and VI collagens, and for all glycosaminoglycans and aggrecan. Labelling for type II collagen was also seen in some fibrocartilages and was a constant feature of all index fingers. This probably relates to the greater use of that digit and the higher loads to which its tendons are subject. Chondroitin 6 sulphate and type II collagen are the most consistent markers of the fibrocartilage phenotype and most of the chondroitin 6 sulphate is probably associated with aggrecan. It is concluded that the labelling profile of the tendon fibrocartilage in the different fingers at the MCP joints is broadly similar to that at the PIP joints. Thus, the potentially greater level of compression on the extensor tendons may be counterbalanced by the lack of fusion of the tendon with the joint capsule. It is suggested that the maintenance of a similar level of fibrocartilage differentiation at two different points along the length of the extensor tendon ensures that the tensile strength is the same in the two regions and that no weak link is present.

Adult↗
PubMed1999

[Anatomical and functional aspects of the thoracic and lumbar spine].

The vertebral bodies and vertebral arches show a characteristic distribution of cortical and cancellous bone. The pedicles are loaded by uniplanar bending that is reflected by the arrangement of the Corticalis. The ligaments of the vertebral column consist of longitudinal and (with exception of the lig. longitudinal anterius) horizontal/oblique segmental ligament bundles. In combination with the anulus fibrosus, the ligaments work as a kind of gear system. They regulate the process of movements of adjacent vertebral bodies in a very precise manner and control the final phase of motion. Besides maintaining the necessary amount of pretension the intervertebral disc distributes the loads uniformly onto the adjacent vertebral bodies. The intervertebral joints are important for guided motion, by restricting the extent in specific planes and directions. Because of their position, they are able to take up the shear forces and to simultaneously restrict them in different planes. The integrity of the fascia thoracolumbalis warrants the protective function of the autochthonuos muscles.

Fascia↗
PubMed1999

[Quantitative determination of pressure distribution in the hip joint during the gait cycle].

The objective of this investigation was the experimental determination of the contact pressures in the hip joint for characteristic phases of the gait cycle. The joint forces determined in vivo with telemetric endoprosthesis by Bergmann et al. (1993) were converted into a pelvic reference system, based on kinematic gait analysis. In eight cadaveric hip joints (age 18-75 yrs.) the reaction forces were applied corresponding to four phases of the gait cycle (heel strike, mid-stance, heel off, toe off) and the pressure distribution determined with FUJI pressure sensitive film. We found maxima of 10 MPa during mid stance. The areas of highest pressure were located in the ventro-superior aspect of the acetabulum (anterior part of the acetabular roof) and in the dorso-inferior aspect of the lunate surface. The pressure distribution was relatively constant during the four phases and the maxima did not vary proportional to the applied load. The normal pressure distribution in the hip appears to be determined by the physiological incongruity of the articular surfaces and the inhomogeneous bony support of the acetabulum. During operative interventions this normal load transfer should be restored as accurately as possible.

Adolescent↗
PubMed1999

Tension and bending, but not compression alone determine the functional adaptation of subchondral bone in incongruous joints.

In the present study, we tested the hypothesis that tension and bending, rather than compression alone, determine the functional adaptation of subchondral bone in incongruous joints. We investigated whether tensile stresses in the subchondral bone of the humero-ulnar articulation are affected by the direction of muscle and joint forces, and whether the tensile stresses are large enough to cause microstructural adaptation, specifically a preferential alignment of the trabeculae and the subchondral collagen fibres. Using a previously validated finite element model of the human humero-ulnar joint, we calculated the contact pressure, the principal compressive and tensile stresses, and the strain energy density in the subchondral bone for various flexion angles. A bicentric (ventro-dorsal) pressure distribution was found in the joint at 30 degrees to 120 degrees of flexion, with contact pressures of up to between 2.5 and 3 MPa in the ventral and dorsal aspects of the ulnar joint surface, but less than 0.5 MPa in the centre. The principal tensile stress in the subchondral bone of the trochlear notch quantitatively exceeded the principal compressive stress at low flexion angles (maximum 8.2 MPa), and the distribution of subchondral strain energy density differed substantially from that of the contact stress (r=-0.72 at 30 degrees and r=+0.58 at 90 degrees of flexion). No important tensile stress was computed in the trochlea humeri. On contact radiography, we found sagittally orientated subarticular trabeculae in the notch, running tangential to the surface. Furthermore, we observed sagittally orientated split lines in the subchondral bone of the notch of 20 cadaver joints, suggesting a ventro-dorsal orientation of the collagen fibres. The trochlea humeri, on the other hand, did not show a preferential direction of the subchondral split lines, these findings confirming the predictions of tensile stresses in the model. We conclude that, due to the important contribution of tension to subchondral bone stress, the distribution of subchondral density cannot be directly employed for assessing the long term distribution of joint pressure at the cartilage surface. The magnitude of the tensional stress varies considerably with the direction of the muscle and joint forces, and it appears large enough to cause functional adaptation of the subchondral bone on a microstructural level.

Adaptation, Physiological↗
PubMed1999

In situ measurement of articular cartilage deformation in intact femoropatellar joints under static loading.

The deformational behavior of articular cartilage has been investigated in confined and unconfined compression experiments and indentation tests, but to date there exist no reliable data on the in situ deformation of the cartilage during static loading. The objective of the current study was to perform a systematic study into cartilage compression of intact human femoro-patellar joints under short- and long-term static loading with MR imaging. A non-metallic pneumatic pressure device was used to apply loads of 150% body weight to six joints within the extremity coil of an MRI scanner. The cartilage was delineated during the compression experiment with previously validated 2D and 3D fat-suppressed gradient echo sequences. We observed a mean (maximal) in situ deformation of 44% (57%) in patellar cartilage after 32 h of loading (mean contact pressure 3.6 MPa), the femoral cartilage showing a smaller amount of deformation than the patella. However, only around 7% of the final deformation (3% absolute deformation) occurred during the first minute of loading. A 43% fluid loss from the interstitial patellar matrix was recorded, the initial fluid flux being 0.217 +/- 0.083 microm/s, and a high inter-individual variability of the deformational behavior (coefficients of variation 11-38%). In conjunction with finite-element analyses, these data may be used to compute the load partitioning between the solid matrix and fluid phase, and to elucidate the etiologic factors relevant in mechanically induced osteoarthritis. They can also provide direct estimates of the mechanical strain to be encountered by cartilage transplants.

Adolescent↗
PubMed1999

[Preferential direction of collagen fibrils in the sub-chondral bone bone and the hip and shoulder joint].

We hypothesised that--due to bending and tension--there should exist a preferential direction of the collagen fibrils in the subchondral bone of the concave components of the hip and shoulder joint that results from bicentric or eccentric loading, but there should be no preferential direction in the convex joint partners. We therefore examined 25 human hip and 27 shoulder joints, these being decalcified after maceration. To analyse the preferential direction of the collagen fibrils, we used the split line method. The subchondral plate was pierced at regular intervals with needles that had been previously dipped in diluted ink. In the acetabulum, we found a predominantly transverse direction of the split lines in the ventral and dorsal horn of the lunatic surface, and these usually continued through the acetabular fossa. In the ventral part of the acetabular roof, arch-like orientations of the split lines were observed. In the glenoid cavity, a clearly preferential orientation was found in anterior-posterior direction, usually in the middle third of the articular surface. In the femoral and humeral heads, no preferential direction of the split lines was observed in any of the specimens. We interpret the split-line patterns in the acetabulum as an expression of the tensile stress that is encountered during a "spreading open" of the socket upon bicentric (ventral-dorsal) loading in the physiologically incongruous joint. In the glenoid, the relatively weak bony support in the ventral and dorsal part of the articular surface may be responsible for bending and tensile stress, particularly in view of eccentric loading during dynamic activity, and this could explain the observed anterio-posterior split line pattern. The results support the idea that the subchondral bone of concave joint partners encounters tension, leading to a preferential direction of the collagen fibrils. This can be considered as a functional adaptation of the subchondral bone on a microstructural level.

Aged↗
PubMed1999

Functional morphology of the pterygoid hamulus.

The pterygoid hamulus (PH), a structure on the under surface of the skull base which has so far hardly been described, is in a peculiar situation biomechanically. The aim of this study is to accumulate sufficient morphological data to enable a functional interpretation to be provided. A total of 93 adult skulls and 24 children's skulls have been examined, and also an additional 20 heads in which the relationship to the surrounding muscles could be investigated. Measurements were made with a sliding gauge, and sections cut from specimens embedded in methyl methacrylate were examined histologically. The hamulus is a variable structure which can, however, be allotted to one of a few basic types. As nomenclature we suggest the following terms: the base: Basis; body: Corpus, sulcus: Sulcus; neck: Collum; head: Caput of the hamulus. The average measurements are: length 7.2 mm, sagittal breadth 1.4 mm, transverse breadth 2.3 mm. The sections show that the medial cortical lamella is thicker than the lateral, and that the 2 are bound together by oblique trabeculae. The medial gradient angle of the collagen fibers is smaller than that of the lateral. A few muscles take origin from the hamulus, the tensor veli palatini turns round the neck, and a few of its fibers take origin here. The distribution of the material within the hamulus suggests that its body is subjected to greater loading in the medio-dorsal direction, but that the head is freely pulled away laterally and caudally. Its exposed position at the distal end of the upper dental arch and the formation of a bursa or sliding layer in the sulcus suggest that it may be a potential source of irritation.

Adult↗
PubMed1999

Comparison of quantitative ultrasound in the human calcaneus with mechanical failure loads of the hip and spine.

OBJECTIVE: Quantitative ultrasound of the calcaneus is used clinically for evaluating bone fracture risk, but its association with the mechanical properties at other skeletal sites is not well characterized. The objective was therefore to determine its predictive ability of the mechanical failure loads of the proximal femur and lumbar spine. METHOD: In 45 human cadavers (29 males and 16 females, aged 82.5 +/- 9.6 years), we determined the speed of sound, broadband ultrasonic attenuation (BUA) and the empirical stiffness index, using a commercial quantitative ultrasound scanner. The proximal femora and the fourth vertebral body were excised and loaded to failure in a testing machine. RESULTS: Femoral failure loads ranged from 933 to 7000 N and those of the vertebrae from 1000 to 7867 N, their correlation being 0.51 in females and -0.08 in males. Forty percent of the variability of femoral, but only 24% of the variability of the vertebral fracture loads could be predicted with calcaneal speed of sound. In the femur, a combination of speed of sound and BUA improved the prediction (r2 = 50-60%), but not in the spine. CONCLUSIONS: The study provides experimental evidence that calcaneal quantitative ultrasound is capable of predicting mechanical failure at other skeletal sites and has potential to identify patients at risk from osteoporotic fracture. The different association of quantitative ultrasound with femoral and vertebral failure may result from the influence of the cortical bone and a higher microstructure-related similarity of the calcaneus and the femur.

Aged↗