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Calcium localization in normal rachitic, and D3-treated chicken epiphyseal chondrocytes utilizing potassium pyroantimonate-osmium tetroxide.

Normal, rachitic, and vitamin D3-replete chicken growth plates were studied utilizing the potassium pyroantimonate-osmium tetroxide procedure. A marked membrane and mitochondrial calcium was revealed in all specimens in the maturing and early hypertrophic zones which disappeared as heavy matrix mineralization began. The most significant difference shown in the specimens was in the marked intracellular lipid content of chondrocytes in all zones of the rachitic and D3-replete growth plates. There was negligible lipid present in normal specimens. It is suggested that as most of the mechanisms postulated as necessary for calcification are present in rachitic chicks, perhaps the increased intracellular lipid pool results from the formation of abnormal lipids for insertion into the plasma membrane and thus prevents normal calcium transport. Chains of intracellular vesicles were also visualized in maturing and hypertrophic chondrocytes. These were more often seen in rachitic growth plates and in increased numbers in the early D3-replete specimens. The etiology is unknown at the present time.

Animals↗

Blood vessels in epiphyseal cartilage of human fetal femoral bone: a scanning electron microscopic study of corrosion casts.

Formation of intrachondral vessels (cartilage canals) in the proximal femoral epiphysis was studied in 13- to 22-week-old human fetuses using a corrosion casting technique and scanning electron microscopy. Several successive morphological stages of angiogenesis occurring inside the hyaline cartilage were distinguished. The process of cartilage vascularization starts with the formation of hairpin loops sent off from the perichondrial vascular network into the adjacent cartilage. A capillary glomerulus is then formed at the leading end, and the entire vascular unit grows in length, assuming a mushroom-like shape. Its further elongation is accompanied by a backward expansion of the capillary network which surrounds a pair of main vessels (arteriole and venule) like a manchette. The subsequent branching of such primary vascular units proceeds according to the same morphological patterns. The resulting tree-like vascular formations become interconnected via their lateral branches. This study clearly supports the invasion theory of cartilage canal formation.

Blood Vessels↗

Immunhistochemical demonstration of different collagen types in the normal epiphyseal plate and in benign and malignant tumors of bone and cartilage.

Several benign and malignant tumors of bone and cartilage were examined by means of type-specific collagen antibodies in connection with indirect immunofluorescence technique in order to determine wether there is a positive correlation between cell morphology and gene expression as refered to the synthesis of tissue- or cell-specific collagen. In general benign bone and cartilage tumors show the collagen type corresponding to the original maternal tissue. In malignant osteogenic tumors a strong positive correlation was found between morphologic differentiation of osteosarcoma cells and tissue specific collagen synthesarcomas. Unrelated to the grade of differentiation and the type of malignant tumor, collagen type III could be demonstrated in all tumors investigated, occurring rather from vascular stroma than from the tumor cell itself.

Bone Neoplasms↗

Totally absorbable fixation in the treatment of fractures of the distal femoral epiphyses. A prospective clinical study.

Nine adolescent patients with a femoral fracture involving the physeal plate were treated by using self-reinforced absorbable polyglycolide (SR-PGA) and poly-L-lactide (SR-PLLA) screws with a follow-up for an average of 2 years and 2 months. During the follow-up all but one of the femurs became skeletally mature. In two of nine patients a clinically significant growth disturbance occurred. The average length difference of the femurs was -5 mm (ranging from +8 mm(-)-41 mm). One valgus deformity was noted. In four patients a lengthening and in four patients a shortening of the operated femur were registered at the end of follow-up. Open reduction and fixation with absorbable screws seem to be suitable for the fixation of distal femoral fractures in adolescents.

Adolescent↗

Intramedullary wiring for tibial shaft fractures in children before epiphyseal closure. Indications and technique--experience of 36 patients.

Between 1958 and 1987 36 children underwent intramedullary wiring for tibial shaft fractures. Of these, 29 presented with combined tibial and fibular fractures, and 7 showed isolated tibial shaft fractures. Fractures were simple in 22 and compound in 14 patients. Mean patient age was 13 years (4-16 years). Only bending fractures with and without splinters were wired. The wiring technique and the protocol for postoperative care are reviewed. Mean immobilization time in long-leg casts was 12 weeks; intramedullary wires were removed after a mean interval of 17.7 weeks. Patients were selected for intramedullary wiring because of compound fractures of variable severity (14 patients), brain injuries with associated fractures (1), relative separation of the fracture ends with the fibula intact (2), severe dislocation or expected instability following closed reduction (9), and secondary dislocation or unsatisfactory alignment on skeletal traction (9). Complications included infections of 2nd degree compound fractures (2 patients), transitory peroneal palsy (2) and delayed union (2). Non-union and damage related to immobilization were not seen. A total of 19 patients were available for follow-up. Mean follow-up time was 9 years. Posttreatment lateral displacement was found to be irreversible except in infants but had no functional relevance. Malalignment showed a tendency towards spontaneous correction, which decreased with increasing age. Correction surgery proved to be unnecessary. Differential longitudinal growth was not consistently evaluable because of the heterogeneity of the material; reported data on this parameter from the literature were equally inconclusive.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Bone strength measurements at the proximal tibia. Penetration tests and epiphyseal compressive strength.

Three penetration tests were obtained from corresponding locations at each condyle of 19 proximal tibiae. The patterns of condylar cancellous bone strength varied little between knees. The medial condyle was the strongest with an average medial to lateral strength ratio of 1.9, and in most knees the medial condyle was strongest centrally while the lateral condyle was strongest posteriorly. The penetration strength at 5 successive 2 mm levels beneath the resected subchondral surface also showed a constant pattern of variation. Bone strength decreased significantly at first except at the posterolateral site, then tended to level off. The reduction of strength was most pronounced in the centre of the condyles. The penetration tests were good predictors of the static compressive strength of the proximal tibia. Correlation coefficients of approximately 0.90 were obtained indicating statistically highly significant correlations (p less than or equal to 0.00001). The tests were carried out with equipment developed for in vivo measurements of cancellous bone strength during total knee replacement. The findings confirm the close relationship of these investigations to conventional compression tests.

Aged↗

Energy dispersive X-ray elemental analysis of isolated epiphyseal growth plate chondrocyte fragments.

Isolated cells of matrix fragments of freeze fractured and freeze dried growth plate from the four species was analyzed by EDX. Cells were removed from the tissue by stereoscopic microdissection using an SEM and mounted on thin film supports on TEM grids: this approach eliminated specimen X-ray background and reduced instrumental and support background levels to insignificant proportions. Chondrocyte and matrix fragments were dissected and analyzed. Cell Ca reaches EDX detectable levels in hypertrophic cells close to the mineralization front. At all stages of maturation, the cells exhibit high P; however, matrix Ca levels are elevated before P. This data suggests that the early cartilage matrix is accumulating Ca and that the cells' role in this process may be to elevate the matrix Ca and P concentration. All cells showed clear S peaks although these are reduced in late hypertrophic cells. With mineralization, matrix S levels fall, indicating a loss of sulfated proteoglycans. Matrix before mineralization contains more K than would be expected from data of previous studies. It is suggested that while this K may be bound to fixed anionic sites in the matrix, reported values for cartilage lymph and extracellular fluid should be reviewed.

Animals↗