From Matrix Vesicles to Miniature Rocks: Evolution of Calcium Deposits in Calf Costochondral Junctions

Objective Initial stages of cartilage matrix calcification depend on the activity of matrix vesicles. The purpose of the study was to describe how calcified matrix vesicles join into larger structures, to present their up-to-date undescribed 3-dimensional image, and to observe how calcified matrix relates to chondrocyte lacunae. Design Calcified cartilage was obtained from the zone of provisional calcification of calf costochondral junctions, then enzymatically isolated and studied by microtomography, scanning electron microscopy, atomic force microscopy and X-ray diffraction, and Fourier transform infrared spectroscopy. Results Hyaluronidase digestion released packets of granules surrounded by the cartilage matrix. Further digestion, with collagenase and trypsin, removed matrix and exposed granules with dimensions within 50 to 150 nm range, which we consider as equivalent of calcified matrix vesicles. Granules joined into larger groups with dimensions of 0.5 to 2 μm, which we call globular units. Certain matrix vesicles appeared well connected but contained globular units that had spaces filled with electron lucent material, presumably matrix or chondrocyte remnants. Globular units were organized into massive structures taking the shape of oval plates. Comparison of these plates with lacunae containing isogenous groups of chondrocytes from proliferative zone of costochondral junction suggests that the cells from a single lacuna were responsible for the formation of one plate. The plates were connected with each other and extended over provisional calcification zone. Conclusions The outcome showed how particular calcified matrix vesicles associate into globular units, which organize into massive structures assuming the shape of oval plates and eventually cover large areas of cartilage matrix.

Hypervitaminoses, Hypovitaminoses, Fluorosis, and Lead Poisoning

Chapter 116 discusses hypervitaminoses, including hypervitaminosis A and D, and hypovitaminoses, particularly scurvy and its effects on the musculoskeletal system. Fluoride and lead poisoning are also discussed. The pathophysiology of these diseases and imaging findings are delineated. The main imaging findings of hypervitaminosis A are wavy metaphyseal periostitis in children and enthesopathy in adults. Metastatic calcification is seen with hypervitaminosis D. In scurvy, there is a dense line of the physis, at the zone of provisional calcification, and a lucent metaphyseal band, with possible periosteal elevation caused by subperiosteal hemorrhage. In fluorosis, there is increased bone density and periostitis. In lead poisoning, there are dense metaphyseal bands.

Is surgery always indicated in rachitic coronal knee deformities? Our experience in 198 knees

Introduction: Defective mineralization of osteoid matrix prior to physeal closure causes rickets. Poor calcification of the cartilage matrix in the zone of provisional calcification causes flattened skull, rachitic rosary, bowed legs, coxa vara and brittle bones. The recent literature has seen an increase in the incidence of the disease in both developing and developed nations. We evaluated behaviour of lower limb deformities due to nutritional rickets in 117 patients. Materials and methods: A prospective study was conducted from January 2009 to December 2011 for clinical and radiological evaluation of knee deformities in nutritional rickets. A total of 117 patients with 198 coronal plane knee deformities between 2 years and 12 years age of rickets were enrolled in this study. Results: In our study, there were 65 genu varum and 133 genu valgum deformities. Seven genu varum (10.7%) and 37 genu valgum (28%) deformities were regarded as failure. Fifty eight genu varum got corrected completely obtaining an average of 5° of valgum in an average of 6.3 months. The average rate of spontaneous correction was 1.9° a month. Ninety six valgum got corrected obtaining an average of 4.7 valgum in an average of 13.3 months. The average rate of spontaneous correction was 0.92° a month. Conclusion: Most of the rachitic deformities get corrected with age. Genu varum is having better chances and a faster rate of correction as compared with genu valgum. Early surgery may be indicated in late presenting cases. We believe varum above 4 years and 18° of valgum above 9 years usually do not correct and may require surgical intervention.

Skeletal Manifestations of Scurvy: A Case Report from Dubai

Introduction. Nutritional deficiencies are rarely reported in developed countries. We report a child of Pakistani origin brought up in Dubai who developed skeletal manifestations of scurvy due to peculiar dietary habits.Case Presentation. A 4.5 year old boy presented with pain and swelling of multiple joints for three months and inability to walk for two months. Dietary history was significant for exclusive meat intake for the preceding two years. On examination the child’s height and weight were below the 5th percentile for his age. He was pale and tachycardic. There was significant swelling and tenderness over the wrist, knee and ankle joints, along with painful restriction of motion. Basic blood workup was unremarkable except for anemia. However, X-rays showed delayed bone age, severe osteopenia of the long bones, epiphyseal separation, cortical thinning and dense zone of provisional calcification, suggesting a radiological diagnosis of scurvy. The child was started on vitamin C replacement therapy. Over the following two months, the pain and swelling substantially reduced and the child became able to walk. Repeat X-rays showed improvement in the bony abnormalities.Conclusion. Although scurvy is not a very commonly encountered entity in the modern era, inappropriate dietary intake can lead to skeletal abnormalities which may be confused with rickets. A high index of suspicion is thus required for prompt diagnosis of scurvy in patients with bone and joint symptoms.

Sequential Serum Aluminum and Urine Aluminum: Creatinine Ratio and Tissue Aluminum Loading in Infants With Fractures/Rickets

Aluminum toxicity is associated with the development of bone disorders, including fractures, osteopenia, and osteomalacia. Fifty-one infants with a mean (± SEM) birth weight of 1007 ± 34 g, gestational age of 28.5 ± 0.3 weeks, and serial radiographic documentation at 3, 6, 9, and 12 months for the presence (n = 16) or absence (n = 35) of fractures and/or rickets were studied at the same intervals to determine the serial changes in serum aluminum concentrations and urine aluminum-creatinine ratios. Autopsy bone samples were used to determine the presence of tissue aluminum. Serum aluminum concentrations from 46 infants were stable and similar between groups, with mean values between 15 and 22 µg/L. Urine aluminum-creatinine (micrograms per milligram) ratios from 14 infants were higher in infants with fractures and/or rickets (0.26 ± 0.06 vs 0.12 ± 0.04) at onset, and rate of decrease in aluminum-cratinine ratio was faster in infants without fractures and/or rickets. All but three infants were tolerating complete enteral feeding at all sampling points. One infant who received aluminum-containing antacid had marked increase in serum aluminum to 83 µg/L while urine aluminum-creatinine ratio increased from 0.09 to a peak of 8.53. Vertebrae from three infants at autopsy (full enteral feeding was tolerated for 37 and 41 days in two infants, respectively) showed aluminum deposition in the zone of provisional calcification and along the newly formed trabecula. It is concluded that in enterally fed very low birth weight infants, serum aluminum levels and urine aluminum-creatinine ratios were similar in infants with and without fractures and/or rickets, presumably in part from modulation of aluminum absorption. However, aluminum absorption can be increased as indicated by increased serum and urine aluminum concentrations from aluminum antacid therapy. Bone accumulation of aluminum is possible with currently used enteral and parenteral nutrients, but the critical level of tissue aluminum loading associated with development of fractures and/or rickets remains to be determined.

Light microscopic localization of labile calcium in hypertrophied chondrocytes of long bone with alizarin red S.

A method which localizes labile 5% ethylene glycol-bis-(beta-amino-ethyl ether)N-N'-tetraacetic acid-removable calcium in spherules within hypertrophied chondrocytes and in pericellular matrix using alizarin red S (ARS) is described. Fresh blocks of epiphyseal cartilage approximately 1 mm thick were immersed into 0.5-2% ARS solution containing 7% mounted on glass slides in 7% sucrose or in glycerol-gelatin. The stained tissue blocks were also dehydrated in acetone, cleared in xylene and mounted in Preservaslide. The ARS precipitated ionic calcium as red Ca-ARS salt which was birefringent in polarizing microscope, stable in water at pH 4-9 and in nonpolar organic solvent but soluble in polar solvents, especially in dimethyl sulfoxide. In contrast, ARS-stained insoluble calcium phosphate was stable even in dimethyl sulfoxide. Calcium in the hypertrophied chondrocytes, therefore, was thought to be present in a readily ionizable state instead of as insoluble calcium phosphate. Since addition of 7% sucrose retained as well as improved ARS localization of cellular calcium, the calcium was believed to be present in an osmotically sensitive, membrane-bound cytoplasmic compartment. The ARS-positive labile calcium in spherules which develop in the hypertrophied chondrocytes as well as in the pericellular matrix at the zone of provisional calcification suggested a preparatory stage in the process of cartilage calcification.