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Spondyloenchondrodysplasia: clinical variability in three cases.

Spondyloenchondrodysplasia is a very rare skeletal dysplasia in which multiple enchondromata exist in the metaphyses of the long bones with platyspondyly. We present three patients (two of them are sibs) with spondyloenchondrodysplasia. The first patient was a 10-year-old boy, who had short stature and enchondromatous-like lesions in the metaphyses of the long bones and platyspondyly on radiography. His older sister (21-years old) had received growth hormone therapy 12 years earlier due to short stature, and her radiological findings were similar but milder than her brother. Both the sibs had normal intelligence and no calcification of the basal ganglia. The third patient was a 6-year-old boy who had short stature, mental retardation, enchondromatous-like lesions in the metaphyses of the long bones and platyspondyly. His cranial BT showed calcification of basal ganglia. The findings of the two sibs in the first family were compatible with spondyloenchondrodysplasia. The difference in clinical severity between the siblings shows the variability within the family. The third case with mental retardation and the presence of intracranial calcifications is compatible with spondyloenchondrodysplasia with basal ganglia calcification. In conclusion, we suggest that family screening and cranial imaging for the presence of intracranial calcifications should be considered in every patient with the diagnosis of spondyloenchondrodysplasia.

Adult↗

Severe Phenotype in an Indian Family With Progressive Pseudorheumatoid Arthropathy of Childhood.

Progressive pseudorheumatoid arthropathy of childhood (PPAC) is a rare autosomal recessive progressive condition that affects the cartilage of joints and bones. The symptoms of PPAC include stiffness of the joints, bony swelling of the toes and fingers, short stature, kyphosis, and muscle weakness. The radiologic manifestations are often mistaken for juvenile rheumatoid arthritis and include platyspondyly, widened metaphyses, flattened epiphyses, and large femoral heads. The disease is caused by variants in the WISP3 (also known as CCN6) gene, which encodes a member of the WNT1 inducible signaling pathway (WISP) protein subfamily, which belongs to the connective tissue growth factor (CTGF) family. We describe three affected female siblings in an Indian family with PPAC, all of whom manifest a severe phenotype of the disease. The girls all walked with a crouching gait from severe joint contractures. Radiographic findings included generalized periarticular osteopenia and widened metaphyses. The radiographs of the hands and feet showed similar changes with narrow joint spaces, widened metaphyses, and flattened epiphyses. Elbows and knees revealed gracile bones, and contractures with severe muscle atrophy. Spine films were significant for marked beaking, lumbar vertebrae anterior narrowing, irregular end plates and rotational scoliosis. X-rays of the hips revealed deformed femurs, coxa vara, and large flat epiphyses. All affected individuals were compound heterozygotes for two pathogenic variants in the WISP3/CCN6 gene, a novel nonsense variant (c.172A>T [p.Lys58*]) and a 2-base pair deletion (c.740_741delGT [p.Cys247Leufs*31]). This combination of a nonsense and frameshift variant has not previously been reported and may be the explanation for the severe clinical manifestation of PPAC in this family. Further investigation into the mechanism of the disease may provide promising therapies to modify disease progression.

WISP3↗

Spondylometaphyseal dysplasia, east-African type: a new form of early, severe SMD with rounded vertebrae.

Spondylometaphyseal dysplasias (SMD) are a heterogeneous group of bone dysplasias characterized by vertebral and metaphyseal changes of various severities. We report two unrelated patients of east African origin with a skeletal disorder consisting of 1) severe metaphyseal dysplasia of early onset, sparing hand bones, with bracket-shaped metaphyses; 2) dysplastic pelvis with irregular iliac rim; and 3) oval-shaped vertebral bodies. Contrasting with most types of SMD, the spinal dysplasia is limited to mild changes in the vertebral body shape that tend to soften with time, whereas the iliac rims have a striking lacy appearance. Except for the most common types (Kozlowski type and Schmidt type), most of the literature on SMD deals with single case reports, without longitudinal data, for which molecular definition is still lacking and classification remains unclear. These two patients could belongs to the A4 group in the classification of Maroteaux and Spranger [1991: Pediatr Radiol 2l:293-297], and illustrate the difficulties of a clinical classification of SMD.

Abnormalities, Multiple↗

Effect of 16,16-dimethyl prostaglandin E2 methyl ester on weanling rat skeleton: daily and systemic administration.

The effects of 0, 0.3, 1.0, and 3.0 mg of 16,16-dimethyl prostaglandin E2 methyl ester (Di-M-PGE2) per kilogram per day administered subcutaneously for 21 days to fluorescent-labeled weanling rats were studied, by single-photon absorptiometric and static and dynamic histomorphometric techniques, to determine possible alterations in growth and mineralized tissue mass and their mechanisms of response. Specimens of femurs, proximal tibia, and tibial shaft were analyzed. Di-M-PGE2 caused a reduction in bone elongation and a dramatic accumulation in metaphyseal trabecular hard tissue mass. At high doses, the growth cartilage exhibited reduced thickness and degenerative cell size and cell production rate. The increased metaphyseal trabecular hard tissue mass was restricted to the secondary spongiosa region and was observed at all dose levels. The metaphysis was further characterized by an increase in bone and calcified cartilage cores, a marked elevation in osteoblast and osteoclast numbers, in osteoblast-to-osteoclast ratios, and in ratios of differentiated cells to osteoprogenitor cells. These findings were consistent with the interpretations that Di-M-PGE2 depressed bone elongation by delaying the division and maturation of growth plate chondrocytes; stimulated the differentiation of osteoblasts and osteoclasts, thus generating more differentiated bone cells but suppressing their activities; and increased metaphyseal trabecular hard tissue by creating an imbalance in osteoblasts over osteoclasts and suppressing hard tissue resorption.

16,16-Dimethylprostaglandin E2↗

Comparison of osteopenic changes in cancellous bone induced by ovariectomy and/or immobilization in adult rats.

BACKGROUND: Ovariectomy (OVX) and immobilization (IMM) in rats are useful models of osteopenia, replicating some aspects of osteoporosis in humans. The purpose of this study was to compare changes in cancellous bone after OVX and/or IMM. METHODS: Differences in cancellous bone were determined at 6 and 12 weeks after OVX or IMM. Comparisons were also made when rats were ovariectomized or immobilized for 6 weeks and then immobilized (OVX/IMM) and ovariectomized (IMM/OVX), respectively, for 6 more weeks. The femurs were used to determine bone mineral content (BMC) using single photon absorptiometry (SPA) and for scanning electron microscopy (SEM). Tibias were collected for microradiography, image analysis, and histomorphometry of metaphyseal cancellous bone. RESULTS: Six and 12 weeks after OVX, there was less cancellous bone mass, compared with controls, as indicated by SPA, SEM, microradiography, image analyses, and histomorphometry. Bone was lost primarily from the central metaphyseal regions in the OVX animals, whereas the loss occurred throughout the metaphyses in the IMM animals. There were more rodlike bone spicules and fewer platelike trabeculae in the OVX and IMM groups compared with controls. Differences in the structural aspects of the cancellous bone, including differences in the types of bone struts and marrow star volumes, indicated less trabecular connectivity and greater trabecular separation in the OVX and IMM animals, compared with controls. Endochondral growth indices in the IMM groups tended to be less, whereas the OVX groups tended to be greater than controls. Cancellous bone formation rates were generally greater in the OVX groups but less in the IMM groups compared with controls. Osteoclastic resorption surfaces were substantially elevated in the IMM and OVX groups, particularly the IMM groups. Changes reflecting OVX and IMM, independently, were apparent in the OVX/IMM and IMM/OVX groups and indices of osteopenia were different from controls, including less bone mass, trabecular connectivity, and greater trabecular separation, bone turnover rates, and osteoclastic surface. CONCLUSIONS: These results demonstrate differences in the osteopenic changes that occur in cancellous bone following OVX or IMM. The changes were generally more dramatic in the IMM than in the OVX animals. When OVX and IMM were applied in combination, the osteopenic changes are particularly severe, emphasizing the importance of mechanical usage even with a deficiency of gonadal hormones.

Animals↗

Perspectives: applications of a biomechanical model of the endochondral ossification mechanism.

A biomechanical model of endochondral ossification (Frost and Jee, 1994. Anat. Rec., 240:435-446) can help to explain: (1) some differences in fracture patterns in children and adults, (2) increased fractures during the human adolescent growth spurt, (3) localization of stress fractures and pseudofractures to cortical instead of trabecular bone, (4) increased bone mass in adult-acquired and childhood obesity, (5) subchondral bone densification and osteopenia in some arthroses, (6) why and where mammals lose spongiosa with aging, (7) why, as percents of the original bone stock, metaphyseal trabecular bone losses with aging usually exceed cortical bone losses, (8) why osteochondritis dissecans and aseptic necroses of bone localize in epiphyses instead of metaphyses, (9) some features of growth plate histology in rickets and the chondrodystrophies, (10) why spontaneous fractures in osteoporotic patients affect vertebral more than metaphyseal spongiosa, (11) why osteopenias develop in most chronic, debilitating diseases, and (12) why histomorphometric values can differ in iliac bone biopsies obtained by the "vertical" Jamshidi and "horizontal" Bordier-Meunier techniques.

Adolescent↗

Microvascular pattern in the metaphysis during bone growth.

BACKGROUND: Little is known about the three-dimensional micromorphology of vessels in the growth zone of long bones, where significant vasculogenesis occurs. Therefore, we examined the microvascular pattern of the femoral metaphysis. METHODS: Six-week-old normal rats of either sex were used. We cast the femurs of 14 rats with Mercox for scanning electron microscopy (SEM), and in 10 rats we prepared tissue sections of femurs for light (LM) and transmission electron microscopy (TEM). RESULTS: In the LM, calcified cartilage was found to define cylindrical compartments beneath the last row of hypertrophied chondrocytes of the metaphyseal growth plate. These compartments ran in the bone's longitudinal axis and contained a single capillary profile. Endothelial cells of these capillaries often showed increased cytoplasmic volume and loose texture of nuclear chromatin. Cast metaphyses by SEM showed numerous parallel vascular loops with nodular protrusions 10-12 microns in diameter at their tips. The loops had ascending and descending limbs with a luminal diameter of 10-14 microns. Small projections 4-5 microns in diameter and delicate crests were sometimes found on the tip of the larger nodes. In a 100 x 100 microns area, there were 14-17 large nodes. By TEM, capillary sprouts were identified at the level beneath the last row of hypertrophied chondrocytes. These capillaries had voluminous endothelial cells rich in free ribosomes and rough endoplasmic reticulum. Endothelial cell nuclei were rounded and showed loose chromatin texture. Endothelial cells were connected by intermediate junctions and there was no basal lamina. Deeper into the metaphysis, arterioles and sinusoids were present. CONCLUSIONS: We conclude that the metaphyseal plate of the growing rat offers an optimal model to study vasculogenesis. Capillary sprouts can be readily identified, measured, and counted because they are located within a plane bordering against avascular cartilage. In addition, by using microvascular corrosion casting in SEM not only capillary sprouting per se but also different stages of neovascularization, indicated by differently sized nodular projections at the tip of vascular loops, can be studied in the growing long bone.

Animals↗

Studies on action of menaquinone-7 in regulation of bone metabolism and its preventive role of osteoporosis.

The effect of menaquinone-7 (MK-7) on bone components and bone resorbing factors induced-bone resorption using the femoral-diaphyseal and - metaphyseal tissues obtained from elderly female rats in vitro were examined. Calcium content, alkaline phosphatase activity and deoxyribonucleic acid (DNA) in the diaphyseal and metaphyseal tissues in elderly females rats were significantly decreased as compared with that of young rats, indicating that aging causes a deterioration of bone formation. The presence of MK-7 (10(-6)-10(-5) M) caused a significant prevention of reduction of biochemical components. On the other hand, the bone-resorbing factor, parathyroid hormone (1-34) (PTH; 10(-7) M) and prostaglandin E(2) (PGE(2); 10(-5) M) caused a significant decrease in calcium content in the diaphyseal and metaphyseal tissues. This decreases was completely inhibited in the presence of MK-7 (10(-7)-10(-5) M). In addition, MK-7 (10(-7)-10(-5) M) completely prevented the PTH (10(-7) M) or PGE(2) (10(-5) M) induced increases in medium glucose consumption and lactic acid production by bone tissues, Furthermore, the effect of the prolonged intake of dietary MK-7 on bone loss in ovariectomized rats was investigated. As a result, it was found that the intake of experimental diets containing the fermented soybean (natto) with supplemental MK-7 caused significant elevations of MK-7 and gamma-carboxylated osteocalcin concentration, a bio marker of bone formation, in the serum of both ovariectomized rats and normal subjects, suggesting that MK-7 may play an important role in the prevention of age-related bone loss.

Aging↗

Benefit of systemically administered rhIGF-I and rhIGF-I/IGFBP-3 on cancellous bone in ovariectomized rats.

The dose-related effects of systemically administered rhIGF-I and rhIGF-I/IGFBP-3 were monitored in the osteopenic rat skeleton at three different sites with cancellous bone: distal femoral metaphysis, epiphysis, and lumbar vertebral bodies. At the age of 16 weeks, rats were bilaterally ovariectomized (OVX) or sham operated (sham) and 8 weeks later divided into the control groups (sham OVX), and OVX groups treated with different doses of rhIGF-I or rhIGF-I/IGFBP-3 for 8 weeks. Fluorescent bone markers were given 9 and 2 days before necropsy. In addition, changes in designated bone sites as a result of ovariectomy alone were evaluated 8 and 16 weeks after surgery. High bone resorption, which dominates the postovariectomy remodeling process, resulted in a loss of cancellous bone at all measured sites. The highest trabecular bone loss was measured in the metaphyses (40%), compared with 22% in the lumbar vertebrae and 16% in the epiphyses. After 8 weeks of treatment with 7.5 mg/kg of rhIGF-I/IGFBP-3, bone formation rates were increased at all sites measured. Increased trabecular thickness was observed at the epiphyses and in the lumbar vertebral bodies. Increased bone resorption was restricted to the metaphyses of the rats that received the highest dose of rhIGF-I or rhIGF-I/IGFBP-3. Both formulations of rhIGF-I increased longitudinal bone growth similarly. This experiment demonstrates site-specific differences in cancellous bone reactions following ovariectomy. Epyphyses showed some advantages for cancellous bone histomorphometry over metaphyses and lumbar vertebral bodies. The data presented confirm the potential of rhIGF-I/IGFBP-3 complex to promote the bone formation process at various bone sites in osteoporotic rat skeleton.

Animals↗

Parathyroid hormone (hPTH 1-38) stimulates the expression of UBP41, an ubiquitin-specific protease, in bone.

Parathyroid hormone (PTH) stimulates bone formation in both animals and humans, and the expression of a number of genes has been implicated in the mediation of this effect. To discover new bone factors that initiate and support this phenomenon, we used differential display reverse transcription polymerase chain reaction (DDRT-PCR) and screened for genes, which are differentially expressed in osteoblast-enriched femoral metaphyseal primary spongiosa of young male rats after a single subcutaneous (s.c.) injection of hPTH (1-38) (8 microg/100 g). We found and cloned one full-length cDNA, which encodes a putative 348 amino acid protein. Sequence analysis of this protein demonstrates a 98, 93.7, and 82.5% identity with mouse, human, and chicken ubiquitin-specific protease UBP41, respectively. Northern blot analysis confirmed that a 3.8-4 kb UBP41 mRNA transcript was rapidly increased 1 h after acute hPTH (1-38) exposure in both metaphyseal (6- to 8-fold) and diaphyseal (3-fold) bone, but returned to control levels by 24 h after exposure. In contrast, continuous exposure to hPTH (1-38), resulted in a rapid and sustained elevation of UBP41 mRNA. PTH (1-31), which stimulates intracellular cAMP, and PTHrP (1-34) both induced UBP41 mRNA expression; whereas PTH analogs (3-34) and (7-34), that do not stimulate cAMP, had no effect on UBP41 expression. UBP41 mRNA expression was also rapidly induced 1 h after injection of PGE2, but returned to the control level by 6 to 24 h. In vitro, UBP41 mRNA is expressed in primary osteoblasts (metaphyseal and diaphyseal derived) and in the osteoblast-like cell lines UMR106, ROS17/2.8, and BALC. PTH (1-38) treatment induced UPB41 expression (3.6- to 13-fold) in both primary cultures of osteoblasts and in UMR106 cells. Further analysis in UMR 106 cells demonstrated that PGE2, forskolin and dibutyryl cAMP increased UBP41 mRNA expression 4-, 4.5-, and 2.4-fold, respectively. Tissue distribution analysis of UBP41 mRNA detected transcripts in brain, heart, skeletal muscle, kidney, liver, and testis. Together, these results demonstrate that UBP41, an ubiquitin-specific protease, is selectively upregulated in bone by the osteotropic agents PTH, PTHrP, and PGE2, possibly via the PKA/cAMP pathway. We speculate that the rapid induction of UBP41 in response to these physiological regulators contributes to the mechanism by which either the structure, activity, half-life or localization of essential proteins are modified to maintain bone homeostasis.

Animals↗

Regucalcin stimulates osteoclast-like cell formation in mouse marrow cultures.

The effect of regucalcin, a regulatory protein in intracellular signaling, on osteoclastic cell formation in mouse bone marrow culture is investigated. The bone marrow cells were cultured for 7 days in an alpha-minimal essential medium containing either vehicle or regucalcin (10(-10)-10(-8)M). Osteoclast-like cell formation was estimated by staining for tartrate-resistant acid phosphatase (TRACP), a marker enzyme of osteoclasts. The presence of regucalcin (10(-10)-10(-8)M) caused a remarkable increase in osteoclast-like multinucleated cells (MNCs). The effect of regucalcin in stimulating osteoclast-like cell formation was significantly inhibited in the presence of calcitonin (CT; 10(-9)M), 17beta-estradiol (10(-9)M), beta-cryptoxanthin (CX; 10(-6)M), or zinc sulfate (10(-4)M), which is an anti-bone resorbing factor. The effect of regucalcin on osteoclast-like cell formation was not significantly blocked in the presence of cycloheximide, an inhibitor of protein synthesis, or 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an inhibitor of transcriptional activity. The effect of parathyroid hormone (10(-7)M), 1,25-dihydroxyvitamin D(3) (10(-7)M), prostaglandin E(2) (10(-5)M), or tumor necrosis factor-alpha (10 ng/ml) in increasing osteoclast-like cell formation was significantly enhanced in the presence of regucalcin (10(-8)M). Moreover, when rat femoral-diaphyseal or -metaphyseal tissues were cultured for 48 h in the presence of regucalcin (10(-10)-10(-8)M), the diaphyseal or metaphyseal calcium content was significantly decreased in the presence of regucalcin (10(-10)-10(-8)M) in vitro. The consumption of glucose and the production of lactic acid in culture medium by the diaphyseal or metaphyseal tissues was significantly raised in the presence of regucalcin (10(-10)-10(-8)M). This study demonstrates that regucalcin directly stimulates osteoclast-like cell formation in mouse marrow culture in vitro, and that the protein stimulates bone resorption in rat femoral tissues in vitro.

Animals↗

Damage and recovery of the bone growth mechanism in young rats following 5-fluorouracil acute chemotherapy.

Chemotherapy-induced bone growth arrest and osteoporosis are significant problems in paediatric cancer patients, and yet how chemotherapy affects bone growth remains unclear. This study characterised development and resolution of damage caused by acute chemotherapy with antimetabolite 5-fluorouracil (5-FU) in young rats in the growth plate cartilage and metaphyseal bone, two important tissues responsible for bone lengthening. In metaphysis, 5-FU induced apoptosis among osteoblasts and preosteoblasts on days 1-2. In growth plate, chondrocyte apoptosis appeared on days 5-10. Interestingly, Bax was induced prior to apoptosis and Bcl-2 was upregulated during recovery. 5-FU also suppressed cell proliferation on days 1-2. While proliferation returned to normal by day 3 in metaphysis, it recovered partially on day 3, overshot on days 5-7 and normalised by day 10 in growth plate. Histologically, growth plate heights decreased by days 4-5 and returned normal by day 10. In metaphysis, primary spongiosa height was also reduced, mirroring changes in growth plate thickness. In metaphyseal secondary spongiosa, a reduced bone volume was observed on days 7-10 as there were fewer but more separated trabeculae. Starting from day 4, expression of some cartilage/bone matrix proteins and growth factors (TGF-beta1 and IGF-I) was increased. By day 14, cellular activity, histological structure and gene expression had returned normal in both tissues. Therefore, 5-FU chemotherapy affects bone growth directly by inducing apoptosis and inhibiting proliferation at growth plate cartilage and metaphyseal bone; after the acute damage, bone growth mechanism can recover, which is associated with upregulated expression of matrix proteins and growth factors.

Animals↗

Three-phase [99mTc]diphosphonate scintimetry in septic and nonseptic arthritis of the immature knee: an experimental investigation in dogs.

We compared the informative value of dynamic and static [99mTc]diphosphonate ([99mTc]DPD) scintimetry in early septic arthritis (SA) and chronic nonseptic arthritis (NSA) of the knee in puppies. SA (n = 10), induced by injection of Staphylococcus aureus into one knee, was examined after 48 h. NSA (n = 6) was induced by weekly intraarticular instillation of 1% carrageenan and examined at 2 and 12 weeks. Epiphyseal and metaphyseal count ratios (CRs) between experimental and control joint were calculated in an angiographic phase (0-20 s), a "blood pool" phase (20-256 s), and a bone uptake phase (2 hs). Control dogs (n = 4) had a CR of 1.0 in all regions and phases, the coefficients of variation being 0.06 and 0.03 in dynamic and static phases, respectively. In NSA, all scintimetric phases showed decreased metaphyseal uptake and largely unchanged epiphyseal uptake. Generally, SA exhibited vastly increased angiographic uptake in all regions and increased epiphyseal blood pool uptake, whereas delayed epiphyseal uptake varied and delayed metaphyseal uptake tended to decrease. Two septic joints had generalized reduction in dynamic uptake, probably owing to increased intraarticular pressure; in one of these, dynamic uptake in the distal femoral epiphysis (FE) was totally absent, suggesting temporary circulatory arrest during the dynamic scanning procedure. The use of regional dynamic and static [99mTc]DPD scintimetry increased the pathophysiologic and diagnostic value of joint scintigraphy, especially with respect to the early detection of SA and its avascular complications.

Animals↗

Skeletal unloading induces biphasic changes in insulin-like growth factor-I mRNA levels and osteoblast activity.

To determine the local mechanisms involved in the effects of skeletal unloading on bone formation, we studied the temporal pattern of mRNA levels for insulin-like growth factor-I (IGF-I), IGF-I receptor type I (IGF-IR), and transforming growth factor beta receptor type II (TGF-betaRII) in relation to osteoblast phenotypic markers and osteoblast activity in hindlimb suspended rats. Skeletal unloading decreased bone volume and the mineralizing and osteoblastic surfaces at 4, 7, and 14 days in the tibial metaphysis, whereas the mineral appositional rate returned to normal at 14 days of suspension. RT-PCR analysis showed that skeletal unloading decreased type 1 collagen (Col 1) and osteocalcin (OC) mRNA levels in metaphyseal bone at days 4 and 7, and the levels returned to normal at 14 days of suspension. Unloading also decreased mRNA levels for IGF-I, IGF-IR, and TGF-betaRII at 4-7 days in the metaphyseal bone. However, IGF-I and IGF-IR levels rose above normal at 14 days of suspension. The biphasic changes in IGF-I mRNA levels were strongly correlated with Col 1 and OC mRNA levels. The associated biphasic pattern of IGF-I/IGF-IR expression, osteoblast markers, and osteoblast activity strongly suggests an important role for IGF-I signaling in the local effect of skeletal unloading on metaphyseal bone formation.

Animals↗

The periphysis and its effect on the metaphysis. II. Application to rickets and other abnormalities.

The metaphyseal collar due to the periphysis is lost (in 98% of 49 subjects) as an early sign of rickets and returns with recovery. The term "pseudophysis" refers to that unossified metaphyseal osteoid and cartilage as in rickets. The collar is intact in metaphyseal chondrodysplasias (a helpful sign in differential diagnosis from rickets), is shortened in achondroplasia, and frequently is spared in osteomyelitis, luetic bone disease, and Caffey infantile cortical hyperostosis. The periphyseal bone bark is thinned, but often apparent, in rickets, and is not thinned in cases of tyrosinosis and phenylketonuria.

Bone Diseases, Developmental↗

Spontaneous rickets in the wild arctic fox Alopex lagopus.

Normal and rachitic, skeletally immature arctic foxes (Alopex lagopus) were subjected to physical examination, roentgenographic studies, and in some cases histologic studies. The involved animals had active rickets coupled with antecedent normal diaphyseal bone formation. Evaluation of all the long bones showed highly variable manifestations of the disease, which undoubtedly reflect different rates of physeal endochondral transformation and metaphyseal remodeling. Histologic examination showed distinct patterns of widening of the physes and variable osteodystrophy in the trabecular and cortical bone of the metaphyses and epiphyseal ossification centers. These aforementioned factors certainly would necessitate different regional calcium needs and, therefore, different regional responses to the most rapid deficiency. The physes involved in the most rapid growth rates of this period showed the most widening of the growth plate, and the most dystrophic changes in the metaphysis. Skeletal injuries, including metaphyseal fractures and slow-down of longitudinal growth (particularly in the ulna) were also evident. Because of apparent dietary differences in the affected and normal fox kits, this juvenile-onset disease was presumed due to calcium-deficient intake following weaning. To the best of our knowledge this is the first report of spontaneously occurring rickets in a wild animal in its nautral habitat. There are several possible mechanisms for the variable widening of the physis and the loss of bone mineralization in these fox kits: calcium-deficient diet, binding of calcium in the bowel by high phosphorus intake, secondary hyperparathyroidism, and vitamin A toxicity.

Alaska↗

Skeletal metastasis: the effect on the immature skeleton.

The unique opportunity to study the entire appendicular skeleton of a child who died from metastatic angiosarcoma allowed detailed assessment of radiographically evident involvement. Virtually every portion of the appendicular skeleton had evidence of metastatic disease. However, the extent of involvement was extremely variable, especially when contralateral regions were assessed. The most likely region of metastasis, the metaphysis, is normally a fenestrated cortex of woven bone in the young child, rather than a well demarcated cortex formed by osteon (lamellar) bone, as it is in the adult. The pattern of destruction is such that less extensive areas may be involved before becoming radiographically evident, and trabecular bone involvement may be evident even without cortical damage. The metaphyseal metastatic spread supports the concept of arterial hematogenous dissemination, comparable to osteomyelitis in the child. Pathologic metaphyseal fractures involved both proximal humeri; the fracture also extended along a portion of the metaphyseal-physeal interface in one humerus. In one distal femur the physis readily separated from the metaphysis; this was a non-displaced type 1 growth mechanism injury.

Bone Neoplasms↗

Congenital bowing of the long bones. A review and phenotype analysis of 13 undiagnosed cases.

Phenotype analysis of 13 patients with congenital bowing of long bones and otherwise undiagnosable conditions allowed sorting into three major groups. Patients in group 1 had normal bone texture; bowing was confined to the femora, the long bones were relatively thin, there were no epiphyseal or metaphyseal abnormalities, and associated malformations or CNS abnormalities were common. Patients in group 2 had osteopenia; bowing was more generalized, the long bones were relatively thick, there were metaphyseal ossification abnormalities. Two brothers belonged to a third group with normal bone texture, relatively thick bones, bowing of the upper and lower limbs, and metaphyseal abnormalities. The subdivision of patients with congenital bowing of the long bones in these groups may be biologically significant. The occurrence of malformations only in group 1 is remarkable. Osteopenia, as found in patients of group 2, may be an important pathogenetic factor not present in patients of groups 1 and 3. Known causes of congenital bowing of long bones are tabulated.

Bone Diseases, Developmental↗