Skeletal calcification patterns of batoid, teleost, and mammalian models: Calcified cartilage versus bone matrix

This study compares the skeletal calcification pattern of batoid Raja asterias with the endochondral ossification model of mammalians Homo sapiens and teleost Xiphias gladius. Skeletal mineralization serves to stiffen the mobile elements for locomotion. Histology, histochemistry, heat deproteination, scanning electron microscopy (SEM)/EDAX analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Fourier transform infrared spectrometry (FTIR) have been applied in the study. H. sapiens and X. gladius bone specimens showed similar profiles, R. asterias calcified cartilage diverges for higher water release and more amorphous bioapatite. In endochondral ossification, fetal calcified cartilage is progressively replaced by bone matrix, while R. asterias calcified cartilage remains un-remodeled throughout the life span. Ca2+ and PO4 3- concentration in extracellular matrix is suggested to reach the critical salts precipitation point through H2 O recall from extracellular matrix into both chondroblasts or osteoblasts. Cartilage organic phase layout and incomplete mineralization allow interstitial fluids diffusion, chondrocytes survival, and growth in a calcified tissue lacking of a vascular and canalicular system. HIGHLIGHTS: Comparative physico-chemical characterization (TGA, DTG and DSC) testifies the mass loss due to water release, collagen and carbonate decomposition of the three tested matrices. R. asterias calcified cartilage water content is higher than that of H. sapiens and X. gladius, as shown by the respectively highest dehydration enthalpy values. Lower crystallinity degree of R. asterias calcified cartilage can be related to the higher amount of collagen in amorphous form than in bone matrix. These data can be discussed in terms of the mechanostat theory (Frost, 1966) or by organic/inorganic phase transformation in the course evolution from fin to limbs. Mineral analysis documented different charactersof R. asterias vs H. sapiens and X. gladius calcified matrix.

Fin systems comparative anatomy in model Batoidea Raja asterias and Torpedo marmorata: Insights and relatioships between musculo-skeletal layout, locomotion and morphology

The macroscopic and microscopic morphology of the appendicular skeleton was studied in the two species Raja asterias (order Rajiformes) and Torpedo marmorata (Order Torpediniformes), comparing the organization and structural layout of pectoral, pelvic, and tail fin systems. The shape, surface area and portance of the T. marmorata pectoral fin system (hydrodynamic lift) were conditioned by the presence of the two electric organs in the disk central part, which reduced the pectoral fin surface area, suggesting a lower efficiency of the "flapping effectors" than those of R. asterias. Otherwise, radials' rays alignment, morphology and calcification pattern showed in both species the same structural layout characterized in the fin medial zone by stiffly paired columns of calcified tiles in the perpendicular plane to the flat batoid body, then revolving and in the horizontal plane to continue as separate mono-columnar rays in the fin lateral zone with a morphology suggesting fin stiffness variance between medial/lateral zone. Pelvic fins morphology was alike in the two species, however with different calcified tiles patterns of the 1st compound radial and pterygia in respect to the fin-rays articulating perpendicularly to the latter, whose tile rows lay-out was also different from that of the pectoral fins radials. The T. marmorata tail-caudal fin showed a muscular and connective scaffold capable of a significant oscillatory forward thrust. On the contrary, the R. asterias dorsal tail fins were stiffened by a scaffold of radials-like calcified segments. Histomorphology, heat-deproteination technique and morphometry provided new data on the wing-fins structural layout which can be correlated to the mechanics of the Batoid swimming behavior and suggested a cartilage-calcification process combining interstitial cartilage growth (as that of all vertebrates anlagen) and a mineral deposition with accretion of individual centers (the tiles). The resulting layout showed scattered zones of un-mineralized matrix within the calcified mass and a less compact texture of the matrix calcified fibers suggesting a possible way of fluid diffusion throughout the mineralized tissue. These observations could explain the survival of the embedded chondrocytes in absence of a canalicular system as that of the cortical bone.

The combined cartilage growth - calcification patterns in the wing-fins of Rajidae (Chondrichthyes): A divergent model from endochondral ossification of tetrapods

The relationship between cartilage growth - mineralization patterns were studied in adult Rajidae with X-ray morphology/morphometry, undecalcified resin-embedded, heat-deproteinated histology and scanning electron microscopy. Morphometry of the wing-fins, nine central rays of the youngest and oldest specimens documented a significant decrement of radials mean length between inner, middle and outer zones, but without a regular progression along the ray. This suggests that single radial length growth is regulated in such a way to align inter-radial joints parallel to the wing metapterygia curvature. Trans-illumination and heat-deproteination techniques showed polygonal and cylindrical morphotypes of tesserae, whose aligned pattern ranged from mono-columnar, bi-columnar, and multi-columnar up to the crustal-like layout. Histology of tessellated cartilage allowed to identify of zones of the incoming mineral deposition characterized by enhanced duplication rate of chondrocytes with the formation of isogenic groups, whose morphology and topography suggested a relationship with the impending formation of the radials calcified column. The morphotype and layout of radial tesserae were related to mechanical demands (stiffening) and the size/mass of the radial cartilage body. The cartilage calcification pattern of the batoids model shares several morphological features with tetrapods' endochondral ossification, that is, (chondrocytes' high duplication rate, alignment in rows, increased volume of chondrocyte lacunae), but without the typical geometry of the metaphyseal growth plates. RESEARCH HIGHLIGHTS: 1. The wing-fins system consists of stiff radials, mobile inter-radial joints and a flat inter-radial membrane adapted to the mechanical demand of wing wave movement. 2. Growth occurs by forming a mixed calcified-uncalcified cartilage texture, developing intrinsic tensional stresses documented by morphoanatomical data.

The complex rostral morphology and the endoskeleton ossification process of two adult samples of Xiphias gladius (Xiphiidae)

The authors studied the morphology of the upper and lower jaws, vertebrae and dorsal-fin rays of the teleost fish Xiphias gladius to analyse the skeletal architecture and ossification pattern. The analogies and differences among these segments were investigated to identify a common morphogenetic denominator of the bone tissue osteogenesis and modeling. The large fat glands in the proximal upper jaw and their relationship to the underlying cartilage (absent in the lower jaw) suggested that there is a mechanism that explains rostral overgrowth in the Xiphiidae and Istiophoriidae families. Thus far, the compact structure of the distal rostrum has been interpreted as being the result of remodeling. Nonetheless, no evidence of cutting cones, scalloped outer border of osteons and sequence of bright-dark bands in polarized light was observed in this study, suggesting a primary osteon texture formed by compacting of collagen matrix and mineral deposition in the fat stroma lacunae of the bone, but without being oriented in layers of the collagen fibrils. A similar histology also characterizes the circular structures present in the other examined segments of the skeleton. The early phases of fibrillogenesis carried out by fibroblast-like cells occurred farther from the already-calcified bone surface inside the fat stroma lacunae. The fibrillar matrix was compacted and underwent mineral deposition near the previously calcified bone surface. This pattern of collagen matrix synthesis and calcification was different from that of mammalian osteoblasts, especially concerning the ability to build a lacuno-canalicular system among cells. Necrosis or apoptosis of the latter and refilling of the empty lacunae by mineral deposits might explain the anosteocytic bone formation.

Morphology of joints and patterns of cartilage calcification in the endoskeleton of the batoid Raja cf. polystigma

The skeleton of the batoid fish consists of a mixture of calcified and uncalcified cartilage with a typical layout of mineral deposition toward the outer border, leaving an uncalcified central core in most of the skeleton segments. An exception is observed in the radials, where mineral deposition is central. Joints and endoskeleton segments were studied in two adult samples of Raja cf. polystigma. Histomorphology, mineral deposition pattern, and zonal chondrocyte duplication activity were compared among several endoskeleton segments, but with particular attention to the fin rays; in the first, the uncalcified cartilage is central with an outer layer ranging from mineralized tesserae to a continuous calcified coating, whereas in the second, the uncalcified cartilage surrounds one or more central calcified columns. The diarthroses have a joint cavity closed by a fibrous capsule and the sliding surfaces rest on the base of mineralized tesserae, whereas the interradial amphiarthroses show a layer of densely packed chondrocytes between the flat, calcified discs forming the base of neighboring radials. In the endoskeleton segments, three types of tesserae are distinguished, characterizing the phases of skeletal growth and mineralization which present differences in each endoskeleton segment. The chondrocyte density between central core, subtesseral layer, and radial external cartilage did not show significant differences, while there was a significant difference in chondrocyte density between the latter zones and the type c tesserae of the pelvic girdle. The histomorphology and morphometry observed in Raja cf. polystigma suggest a model of cartilage growth associated with structural stiffening without remodeling. A key point of this model is suggested to be the incomplete mineralization of the tesseral layer and the continuous growth of cartilage, both enabling fluid diffusion through the matrix fibril network of scattered, uncalcified cartilage zones inside and between the tesserae.

The structure of cortical bone as revealed by the application of methods for the calcified matrix study

Calcination and decalcification are basic procedures useful to a morphological approach of a biological, composite material like cortical bone. The study was carried out on a whole human femur conserved in liquid (from an educational collection). Cortical fracturing and SEM observation of vascular canals surface collagen texture was used to study bone deproteination at scalar temperatures (400-1,200°C) and acid bone decalcification at crescent time intervals. Heating burned and vaporized the organic matrix with shrinkage of the bone specimens as documented by the weight loss and transverse surface morphometry. SEM showed a pattern of aligned spherulites at 400°C which maintained the collagen fibrils layout (like a mineral cast), followed by a spherulites fusion progression with the temperature increments. At 1200°C a crystalline-like structure of tightly-packed trapezohendron units. XRD analysis supported the SEM morphology displaying the complete Debey rings of hydroxyapatite and spotted Debey rings of withlockite. Surface Ca and P elution was documented after 12 hr of exposition to the acid solution by dissolution of spherulites and the whole canal surface decalcified in depth after 15 days by SEM-EDAX analysis. The periodic pattern of collagen fibrils was still evident up to 15 days of decalcification together with fine granular deposits of a not-collagenic proteic material, while after 30 days no period was observed in the decalcified fibrils. Collagen mineral cast at 400°C calcination. Complete crystalline transformation at 1200°C. Up to 15 days of decalcification fibrils period maintained.

New morphological evidence of the 'fate' of growth plate hypertrophic chondrocytes in the general context of endochondral ossification

The 'fate' of growth plate hypertrophic chondrocytes has been long debated with two opposing theories: cell apoptosis or survival with transformation into osteogenic cells. This study was carried out on the proximal tibial growth plate of rabbits using light microscopy, scanning and transmission electron microscopy. We focused particularly on the orientation of the specimens included in order to define the mineral deposition and the vascular invasion lines and obtain histological and ultrastructural images at the corresponding height of the plate. Chondrocyte morphology transformation through the maturation process (characterized by vesicles and then large cytoplasmic lacunae before condensation, fragmentation and disappearance of the nuclear chromatin) did not correspond to that observed in the 'in vitro' apoptosis models. These findings rather suggested the passage of free water from the cartilage matrix into a still live cell (swelling). The level of these changes suggested a close relationship with the mineral deposition line. Furthermore, the study provided evidence that the metaphyseal capillaries could advance inside the columns of stacked hypertrophic chondrocytes (delimited by the intercolumnar septa) without the need for calcified matrix resorption because the thin transverse septa between the stacked chondrocyte (below the mineral deposition line) were not calcified. The zonal distribution of cell types (hypertrophic chondrocytes, osteoblasts, osteoclasts and macrophages) did not reveal osteoclasts or chondroclasts at this level. Morphological and morphometric analysis recorded globular masses of an amorphous, necrotic material in a zone 0-70 μm below the vascular invasion line occasionally surrounded by a membrane (indicated as 'hypertrophic chondrocyte ghosts'). These masses and the same material not bound by a membrane were surrounded by a large number of macrophages and other blood cell precursors, suggesting this could be the cause of macrophage recall and activation. The most recent hypotheses based on genetic and lineage tracing studies stating that hypertrophic chondrocytes can survive and transform into osteoblasts and osteocytes (trans-differentiation) were not confirmed by the ultrastructural morphology or by the zonal comparative counting and distribution of cell types below the vascular invasion line.

Necrotizing fasciitis of the hand: a case report

Necrotizing Fasciitis is a rare life-threatening infection, usually polymicrobial, that frequently affects the extremities in as many as two thirds of the cases. It typically involves primarily the muscular fascia, and then spreads through muscular and subcutaneous tissues. The early diagnosis may be challenging, and appears to be crucial in the management of this condition. We report a case of a 45-year-old man, former drug abuser, diabetic, HCV+, who developed a necrotizing fasciitis of the hand following a minor trauma. Early diagnosis based on clinical, laboratory (LRINEC score) and radiological findings, together with an accurate debridement of the affected site, allowed us to limitate the amputation to the third ray only. The reconstruction with the capitate osteotomy and the coverage with the posterior interosseous flap helped us in further reduction of the functional impairment of the hand. (www.actabiomedica.it)

Intra-Pelvic Migration of Sliding Hip Screw During Osteosynthesis of Hip Fracture: A Rare Avoidable Intraoperative Complication

Introduction:

Hip fractures, which are common among old patients, are classified into two groups: intracapsular and extracapsular fractures. Extracapsular fractures can be treated with extramedullary implants [e.g. dynamic hip screw (DHS)] or intramedullary nails. Dynamic hip screw is the treatment of choice in stable pertrochanteric fractures. Intrapelvic migration of the sliding screw is a very rare complication.

Case Report:

We report a case of a 90-year old Caucasian woman who had an unusual intraoperative complication during osteosynthesis procedure for extracapsular hip fracture fixation. In fact, the sliding hip screw went deep into the pelvis during surgery. This mishap required an abdominal surgical approach by the general surgeon to remove the screw.

Conclusion:

Taking into consideration the poor quality of the bone in very old patients, we emphasize the importance of following every single step of the surgical procedure, in order to minimize the risk of this complication.

Ghrelin Increases Beta-Catenin Level through Protein Kinase A Activation and Regulates OPG Expression in Rat Primary Osteoblasts

Ghrelin, by binding growth hormone secretagogue receptor (GHS-R), promotes osteoblast proliferation but the signaling mechanism of GHS-R on these cells remains unclear. Since canonical Wnt/β-catenin pathway is critically associated with bone homeostasis, we investigated its involvement in mediating ghrelin effects in osteoblasts and in osteoblast-osteoclast cross talk. Ghrelin (10(-10)M) significantly increased β-catenin levels in rat osteoblasts (rOB). This stimulatory action on β-catenin involves a specific interaction with GHS-R1a, as it is prevented by the selective GHS-R1a antagonist, D-Lys(3)-GHRP-6 (10(-7)M). The effect of ghrelin on β-catenin involves the phosphorylation and inactivation of GSK-3β via protein kinase A (PKA). Inhibition of PKA activity reduces the facilitatory action of ghrelin on β-catenin stabilization. Ghrelin treatment of rOB significantly increases the expression of osteoprotegerin (OPG), which plays an important role in the regulation of osteoclastogenesis, and this effect is blocked by D-Lys(3)-GHRP-6. Furthermore, ghrelin reduced RANKL/OPG ratio thus contrasting osteoclastogenesis. Accordingly, conditioned media from rOB treated with ghrelin decreased the number of multinucleated TRAcP+ cells as compared with the conditioned media from untreated-control rOB. Our data suggest new roles for ghrelin in modulating bone homeostasis via a specific interaction with GHSR-1a in osteoblasts with subsequent enhancement of both β-catenin levels and OPG expression.

Pregnancy-associated osteoporosis with seven vertebral compression fractures, a case treated with strontium ranelate

This paper shows a case of pregnancy-associated osteoporosis (PAO) with seven vertebral compression fractures treated with strontium ranelate and supplementation of calcium and cholecalciferol. Clinical evaluation, laboratory and radiological results are analyzed in the case-report to demonstrate that strontium ranelate is a good option to restore quickly the value of bone mineral density in the treatment of a case of PAO.

Dietary tryptophan manipulation reveals a central role for serotonin in the anabolic response of appendicular skeleton to physical activity in rats

Several studies support a serotonin role in the physiological control of bone mass. However, whether serotonin (5-HT) is involved in bone loss due to reduced mechanical stress or unloading is unknown. We investigated the effects of reduced 5-HT tone, induced by tryptophan-free diet, in movement-restraint osteopenia induced by housing mature rats, acclimatised in single cages with a floor area of 1,500 cm(2), in smaller size single cages where their motor activity was reduced. Tryptophan-deficiency significantly worsened movement-restraint-induced bone loss in both femoral metaphysis and diaphysis (DXA analysis) but not at lumbar vertebrae and impaired the mechanical properties of the femur by significantly reducing both cortical thickness and strength strain index (pQCT analysis). Such effects resulted from an impairment of bone turnover with bone resorption exceeding bone formation. Tryptophan-supplemented diet reversed the worsening effects of tryptophan-deficiency on movement-restraint osteopenia. The improvements of both bone mass and strength were associated with an increase of serum osteocalcin and IGF-I, markers of osteoblast activity. In vitro studies in primary cultures of rat osteoblasts suggest that the anabolic action of 5-HT involves the activation of the Wnt/β-catenin pathway. Serotonin significantly increased the cytoplasmatic β-catenin protein levels by the inhibition of the enzyme glycogen synthase kinase-3β, that by phosphorylating β-catenin promotes its degradation. Our data support a role for 5-HT in the anabolic response of the appendicular skeleton to mechanical loading. We suggest that serotonin might stimulate canonical Wnt/β-catenin-dependent bone formation to occur.

Osteosynthesis and hip replacement in proximal femur fractures

Proximal femur fractures are common in elderly osteoporotic patients. The consequences of hip fractures in elderly individuals are significant in terms of years of life lost and reduction of the quality of life. The goal of the treatment is to return the patients to their pre-fracture level of quality of life and avoid complications during the surgery. To achieve this goal, surgery is usually required for the vast majority of hip fracture patients. The proximal femur fractures are classified into medial and lateral fractures; usually the former fractures are treated with hip replacement and the latter are treated with osteosynthesis. The best way to treat this type of injury is mandatory and requires an accurate pre-operative classification of the lesion, considering also the comorbidity associated with the hip fractures.

The canalicular system and the osteoblast domain in human secondary osteons

The lacunar-canalicular system in human secondary osteons was examined by two complementary techniques: light microscopy analysis of undecalcified thick sections and the SEM cortex-fractured surface technique. Unlike the earlier definitions of 'osteoblastic domain' presented as the matrix volume produced by osteoblasts in the process of osteon infilling, this study measured the domain by the length of osteoblast dendritic processes. The domain extension was defined along radial vectors advancing from the reversal line towards the central canal. According to their lengths, domains were divided into three classes: peripheral, intermediate and internal. The mean length of peripheral domains was significantly shorter than those of the intermediate and internal domains. This suggests that the infilling process is modulated by an initial preparatory phase characterised by osteoblast adhesion to the wall of the cutting cone, and a limited matrix synthesis, followed by a regular matrix volume apposition organised in concentric layers. In addition to the radial canaliculae arranged along converging vectors in planes perpendicular to the central canal, we distinguished a further class of canaliculae, the equatorial canaliculae originating from the major perimeter of the lacuna and spreading out radially in the plane of the same lacuna (therefore, perpendicularly to the radial canaliculae). The whole lacunar-canalicular network was structured as a closed system around the vascular axis of the central canal with very few canaliculae crossing the reversal line and connecting the neighbouring osteons. These anatomical observations contribute to our knowledge of lacunar-canalicular system development.

A model of osteoblast-osteocyte kinetics in the development of secondary osteons in rabbits

The kinetics of osteogenic cells within secondary osteons have been examined within a 2-D model. The linear osteoblast density of the osteons and the osteocyte lacunae density were compared with other endosteal lamellar systems of different geometries. The cell density was significantly greater in the endosteal appositional zone and was always flatter than the central osteonal canals. Fully structured osteons compared with early structuring (cutting cones) did not show any significant differences in density. The osteoblast density may remain constant because some of them leave the row and become embedded within matrix. The overall shape of the Haversian system represented a geometrical restraint and it was thought to be related to osteoblast-osteocyte transformation. To test this hypothesis of an early differentiation and recruitment of the osteoblast pool which completes the lamellar structure of the osteon, the number and density of osteoblasts and osteocyte lacunae were evaluated. In the central canal area, the mean osteoblast linear density and the osteocyte lacunae planar density were not significantly different among sub-classes (with the exclusion of the osteocyte lacunae of the 300-1000 μm(2) sub-class). The mean number of osteoblasts compared with osteocyte lacunae resulted in significantly higher numbers in the two sub-classes, no significant difference was seen in the two middle sub-classes with the larger canals, and there were significantly lower levels in the smallest central canal sub-class. The TUNEL technique was used to identify the morphological features of apoptosis within osteoblasts. It was found that apoptosis occurred during the late phase of osteon formation but not in osteocytes. This suggests a regulatory role of apoptosis in balancing the osteoblast-osteocyte equilibrium within secondary osteon development. The position of the osteocytic lacunae did not correlate with the lamellar pattern and the lacunae density in osteonal radial sectors was not significantly different. These findings support the hypothesis of an early differentiation of the osteoblast pool and the independence of the fibrillar lamellation from osteoblast-osteocyte transformation.

Cobalt, chromium and molybdenum ions kinetics in the human body: data gained from a total hip replacement with massive third body wear of the head and neuropathy by cobalt intoxication

INTRODUCTION

A patient with a total hip replacement developed optic, acoustic and peripheral neuropathy from metal ions intoxication, due to the wear products released from the prosthesis. Subsequently the kinetics of the metal ions was studied.

MATERIALS AND METHODS

Massive wear and acute intoxication allowed a study of the metal ions kinetics and of EDTA treatment.

RESULTS

Plasma and other organic fluids were saturated by each of the metal ions released from the exposed surface according to the solubility of each ion; a larger fraction of Co ions was bound within red cells, while the plasmatic fraction appeared more movable. In a patient with a prosthesis subjected to wear, the ions released are from the prosthetic and from the debris surface (spread in the body). The latter is a function of the number and size of particles.

DISCUSSION

Revision of the prosthesis from the point of view of the metal ions kinetics corresponded to a reduction of the releasing surface because of debris washed out by irrigation and tissue excision; however, the metal particles spread by lymphatic circulation continued to release ions even though the source of wear had been removed. Early diagnosis of high metal wear can be ascertained with mass spectrometry and after revision high levels of metal ions can only be reduced with repeated chelating treatment. It is preferable not to revise fractured ceramic components with a polyethylene-metal articulation.

The possible introduction of anti-osteoporosis drugs as an integrated treatment in total hip arthroplasty

The anchorage of cementless total hip arthroplasty relies on a direct bone to implant bonding. Several factors including material properties and surface treatment determine the interfacial response of the host bone to a foreign material. Another factor that must be taken into account is the bone remodeling after the prosthesis introduction. Considering this bone remodeling, in the last few years the possibility of using anti-osteoporotic drugs has been introduced as a supplementary and integrated treatment in total hip replacement.

The fibrillar organisation of the osteon and cellular aspects of its development : a morphological study using the SEM fractured cortex technique

The collagen architecture of secondary osteons was studied with scanning electron microscopy (SEM) employing the fractured cortex technique and osmic maceration. Fibrillar orientation and the change in their direction in sequential lamellae was documented where lamellar formation was ongoing, as well as in resorption pits where osteoclasts had exposed the collagen organisation of the underlying layers. Applying an adaptive stereo matching technique, the mean thickness of matrix layers removed by osteoclasts was 1.36 ± 0.45 μm. It was also documented that osteoclasts do not attack the cellular membrane of the exposed osteocytes. The mean linear osteoblast density in fractured hemicanals was assessed with SEM and no significant differences were observed comparing larger with smaller central canal osteons. These findings suggested a balance between the differentiated osteoblasts that have aligned on the surface of the cutting cone and those that are transformed into osteocytes, because the canal surface is progressively reduced as the lamellar apposition advances.

A review of the actual knowledge of the processes governing growth and development of long bones

Autoptic samples of human bones (from 8 weeks of gestation to 12 years of age) and a second group of serial, skeletal x-rays (required for pathologies not related to bone dysplasia in children from 4 months to 17 years of age) provided the material for the analysis of the physes normal growth mechanism presented in this review. Before the appearance of the ossification centers epiphyseal growth rests exclusively on chondrocytes proliferation (interstitial growth), without any detectable differentiated cellular organization. When endochondral ossification starts a defined spatial disposition of chondrocytes and a corresponding organization of the intercellular matrix is set up, so that it is possible to identify a growth vector corresponding to the columns of piled chondrocytes with direction from hypertrophic toward the proliferative cell layers. The complexity of the tubular bones growth process is well represented by the spatial arrangement of the growth vectors. In the late epiphyseal growth another mechanism is active in addition to endochondral ossification, namely, articular cartilage interstitial growth and subchondral remodelling. The knowledge of the normal mode of organization of the physis and its temporal sequence can help to better understand of the deviaton from the normal development of metaphyseal and epiphyseal dysplasias.

The incidence of hip, forearm, humeral, ankle, and vertebral fragility fractures in Italy: results from a 3-year multicenter study

Introduction

We aimed to assess the incidence and hospitalization rate of hip and "minor" fragility fractures in the Italian population.

Methods

We carried out a 3-year survey at 10 major Italian emergency departments to evaluate the hospitalization rate of hip, forearm, humeral, ankle, and vertebral fragility fractures in people 45 years or older between 2004 and 2006, both men and women. These data were compared with those recorded in the national hospitalizations database (SDO) to assess the overall incidence of fragility fractures occurring at hip and other sites, including also those events not resulting in hospital admissions.

Results

We observed 29,017 fractures across 3 years, with hospitalization rates of 93.0% for hip fractures, 36.3% for humeral fractures, 31.3% for ankle fractures, 22.6% for forearm/wrist fractures, and 27.6% for clinical vertebral fractures. According to the analyses performed with the Italian hospitalization database in year 2006, we estimated an annual incidence of 87,000 hip, 48,000 humeral, 36,000 ankle, 85,000 wrist, and 155,000 vertebral fragility fractures in people aged 45 years or older (thus resulting in almost 410,000 new fractures per year). Clinical vertebral fractures were recorded in 47,000 events per year.

Conclusions

The burden of fragility fractures in the Italian population is very high and calls for effective preventive strategies.

Morphometric analysis of the canal system of cortical bone: An experimental study in the rabbit femur carried out with standard histology and micro-CT

The osteonal pattern of cortical bone is gradually built around the intracortical vessels by the progression of the cutting cones (secondary remodelling); therefore, the central canal size can be used as index of the remodelling activity. An experimental model in the rabbit femur was used to investigate, through central canal morphometry and frequency distribution analysis, the remodelling activity, comparing the middle of the diaphysis (mid-shaft) with the extremity (distal-shaft) and at the same level sectors and layers of the cortex in transversal sections. The study documented a higher density of canals in the mid-shaft than in the distal-shaft and a higher remodelling in the distal-shaft. There were no significant differences between dorsal, ventral, medial and lateral sectors at both mid-shaft and distal-shaft levels, while the number of canals was higher in the sub-periosteal layers than in the sub-endosteal. A lower threshold of 40 microm(2) was observed in the central canal area. Sealed osteons in the midshaft were 22.43% of the total number of osteons of the central canal area between 40 and 200 microm(2) and 0.44% of those of the distal-shaft. Micro-CT allowed a 3D reconstruction of the vascular canal system, which confirmed the branched network pattern rather than the trim architecture of the traditional representation. Some aspects like the lower threshold of the central canal size and the sealed osteons documented the plasticity of the system and its capacity for adaptation to changes in the haemodynamic conditions.

An unusual form of spondyloepiphyseal dysplasia, with advanced carpal and spinal end-plate ossification mimicking COMP-mutation-like multiple epiphyseal dysplasia

We present a child with irregular ossification of tubular bone epiphyses, short bones, and spine. The radiographic evolution of bones undergoing endochondral ossification was followed from the age of 1 year 9 months to 6 years. The unusual features demonstrated in this child made classification difficult: pseudoachondroplasia was excluded because no mutations of the COMP gene were found. Considering the evolution of the radiographic appearances, the most likely diagnosis would seem to be an unusual form of spondyloepiphyseal dysplasia, mimicking some aspects of multiple epiphyseal dysplasia. Endochondral ossification was diffusely altered with a mixture of epiphyseal ossification delay associated with acceleration and early fusion. This case was a unique presentation within the family, suggesting a mutation in the affected child.

The nature of cartilage stippling in chondrodysplasia punctata: histopathological study of Conradi-Hünermann syndrome

The chondrodysplasia punctatas (CDP) are a group of genetic diseases presenting with the common hallmark of epiphyseal calcific deposits. A 21.3 week female fetus with a clinical and molecular diagnosis of X-linked dominant CDP (CDPX2 or Conradi-Hunermann syndrome) has been investigated with particular attention to the morphology of the calcific deposits (stipplings). A variable combination of normal endochondral ossification centers, calcific deposits, and a mixture of these two were observed in the lumbar spine. The calcific deposits were characterized by a growing phase, corresponding to the expansion of calcification, a steady phase, and a resorbing/remodeling phase, when calcification was progressively reduced through different biological mechanisms. The pathological mechanism of cartilage matrix calcification seemed to influence the morphology and the distribution pattern of vessels inside the epiphysis. These findings fit well with the radiographic observations of progressive regression of stippling with advancing age of the child and also give a morphological correlation.