Diaphyseal Shaft Research Articles

Architecture of Implanted Bone Matrix Gelatin Influences Heterotopic Calcification and New Bone Formation

Heterotopic bone formation in skeletal muscle induced by compacted demineralized bone matrix gelatin (BMG) was studied histologically and biochemically. BMG was obtained by dehydrating diaphyseal shafts of femora and tibiae of 4-week-old male Sprague-Dawley rats, cutting the bone into chips, and demineralizing and extracting the chips with various solutions. The BMG was treated with 4 M guanidine-HCl, and compacted BMG was prepared by centrifugation. The compacted BMG was implanted into the rectus abdominis muscle of 5-week-old male Sprague-Dawley rats. The resulting specimens were examined histologically, and their alkaline phosphatase activity and the calcium content of the tissues were measured 3, 5, 7, 10, and 15 days after implantation. The BMG (separated BMG) with 75- to 500-microns particle sizes were implanted into control rats. The results showed that calcification, alkaline phosphatase activity, and bone formation were suppressed by implantation of the compacted BMG and that scarcely any vascularization occurred. Calcification, vascularization, and alkaline phosphatase activity were related and were indispensable for bone formation. In the control group, bone formation was observed at sites of high activity of alkaline phosphatase and well-developed vascularization. These results suggested that compacting of BMG suppressed vascularization, decreased calcification, and consequently reduced the induction of bone formation.

Knee ligament injuries combined with ipsilateral tibial and femoral diaphyseal fractures: The “floating knee”

The incidence of rupture of the knee ligaments was retrospectively studied in 47 patients with ipsilateral fractures of the femoral and tibial diaphyseal shaft. Fifteen patients proved to have an instability of the knee at the time of follow up. Disruption of the knee ligaments had not been recognised initially. At the time of initial treatment, injury of the knee ligaments had been diagnosed in only three cases. After stabilisation of both fractures in these cases, the knee ligaments had been repaired; at re-examination these patients had no complaints and their knees were perfectly stable. In view of the high incidence of missed cases, the possibility of disruption of the knee ligaments should be considered in all patients with fractures of both the femoral and tibial shaft. Meticulous examination of the knee at the time of injury is strongly advocated.

Effect of Bupivacaine on Muscle Tissues and New Bone Formation Induced by Demineralized Bone Matrix Gelatin

Heterotopic bone formation induced by demineralized bone matrix gelatin (BMG) in bupivacaine-HCl-treated skeletal muscle was examined histologically. BMG was obtained by dehydrating diaphyseal shafts of femora and tibiae of male, 4-week-old Sprague-Dawley (SD) rats, cutting it into chips, and demineralizing and extracting the chips with various solutions. The BMG was implanted into the rectus abdominis muscle of male, 5-week-old SD rats, bupivacaine-HCl was injected at the same site, and the resulting plaques of tissues were examined histologically on days 5, 10, 15 and 20 after BMG implantation. Heterotopic bone formation occurred in all animals. The bupivacaine-treated group had more degenerated and injured muscle fibers, and more osteocytes than the control group. Electron microscopy showed that the basement membrane of muscle fibers was discontinuous and that many mononucleated cells resembling activated satellite cells were present on day 5. Many fibroblasts, undifferentiated mesenchymal cells and myogenic cells were seen in the area around the BMG. In new bones there were few osteocytes on day 10, but their numbers were increased on days 15 and 20 after implantation, especially in the bupivacaine-treated group. The population of osteocytes that increased rapidly may have included mononucleated cells similar to activated satellite cells.

Induction of endochondral bone by demineralized bone matrix from diabetic rats.

In this investigation we examined the osteoinductive potential of demineralized bone matrix derived from chronically diabetic (streptozotocin-induced) rats. Long-Evans rats (28-31 days) were made diabetic with a single injection of streptozotocin (65 mg/kg) and provided food and water ad lib for 2 months. Diaphyseal shafts of femurs and tibias removed from the diabetic rats and their sibling controls were dehydrated, pulverized, sieved to 74-420 micron particles, and demineralized. Matrix was then bioassayed for its ability to induce endochondral bone on day 11 following subcutaneous implantation over the thorax of Long-Evans rats. The resulting plaques of tissue were subjected to histological analysis, determination of alkaline phosphatase activity, and calcium content. Bone matrix derived from diabetic animals proved to be a significantly better inducer of endochondral bone than did control matrix.

An in vitro assay of bone development using fetal long bones of mice: morphological studies.

The purpose of this study was to examine the morphological changes in an in vitro system in which the two elements of bone modelling, formation and resorption, could be studied simultaneously. Pregnant mice were killed on days 15, 16 and 17 of gestation, the fetuses were removed and the radii and ulnae dissected free of soft tissue. The bones were cultured for 6 days in media (BGJ) supplemented with 20% fetal calf serum and 150 micrograms/ml vitamin C. Growth and mineralization were estimated by measuring the total length of the bone, and diaphysis, and by light and transmission electron microscopy (TEM). The results of this study indicate that there is a continuous measurable increase in the total length of fetal mouse long bones over the 6 days of culture. These bones show a continuous growth of periosteal bone, with mesenchymal tissue penetrating into the diaphyseal shaft, and development of bone marrow like tissue. TEM examination showed differentiation of mesenchymal cells to osteoblasts, formation of new bone matrix and bone mineralization similar to that found in developmentally matched controls. In the cartilagenous epiphyses, however, many hydroxyapatite crystals were not associated with matrix vesicles. In addition, some of the chondrocytes of the hypertrophic zone appeared to be dedifferentiating into mesenchymal cells with osteoblast-like features. In spite of the lack of osteoclasts in the 15- and 16-day explants, osteoclasts appeared in the diaphysis after 2 and 4 days in culture. Our results suggest that this system can serve as a good model for the study of bone formation and resorption as they occur, simultaneously, during bone modelling.(ABSTRACT TRUNCATED AT 250 WORDS)

Fractures of the Tibia Treated by Flexible External Fixation

Thirty-four patients with fractures of the tibial diaphyseal shaft were treated by flexible anterior half-frame external fixation. The average time to union in the frame was 12 weeks for a simple closed tibial fracture and 26 weeks for a complex open tibial fracture. Complications included malalignment and loss of initial reduction. Most of the complications could have been avoided if special attention had been paid to technical details of reduction of the fracture and insertion of the pins.

Distraction Epiphysiolysis as a Method of Limb Lengthening

Distraction epiphysiolysis as a means of lengthening bone has been studied in sheep tibiae by histologic, histochemical and microradiographic and electron microscopic methods. The tibiae have been studied 1, 2, 3 and 4 weeks and 2, 4, 6 and 12 months after the induction of this procedure. Distraction epiphysiolysis occurs in the following stages: development of a fracture along a line dividing the maturing from the hypertrophic chondrocytes, with the formation of a hematoma between the fracture surfaces; downward displacement of the metaphyseal cartilaginous fragment and gradual resorption of the hematoma, which is replaced by fibrous tissue; elongation of the fibrous tissue; with the formation of collagen bundles oriented parallel to the tensile force of distraction; calcification and ossification of these bundles, with the formation of longitudinal and parallel bone trabeculae; development of periosteal bone, which becomes a new diaphyseal shaft. The results show that distraction epiphysiolysis actually lengthens the bone segments; bone structure is completely restored, without serious changes occurring in the soft tissues. Restoration of endochondral ossification in the epiphysis tends to be unpredictable, however, so that the procedure is reliable only in subjects that have almost reached skeletal maturity.

Calcium deficiency, pregnancy, and lactation in rats. Some effects on blood chemistry and the skeleton.

The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.

A functional analysis of fusion of the tibia and fibula in the rat and mouse.

The distal diaphyseal shafts of the rat tibia and fibula fuse postnatally, a process initiated by the seventh day with the formation of secondary cartilage that is subsequently replaced by endochondral ossification. The histological appearance of this fusion process is described. A homologous process occurs postnatally in the mouse. An analysis of some of the pertinent recent developmental, comparative and paleontological data indicated that extrinsic, biomechanical factors probably played a significant causal role in tibia-fibula fusions. The production of secondary cartilage is evoked by extrinsic forces, and these fusions were analyzed within the present concepts of intrinsic and extrinisic factors in skeletogenesis. It was concluded that the fusions currently reported fit well within the hypothesis of the functional matrix and that, such fusions between skeletal tissues are secondary, compensatory and mechanically obligatory responses to the prior demands of functionally related nonskeletal tissues and organs.

The ultrastructure of the organic matrix of calcified cartilage and bone in embryonic mouse radii

It was found that in embryonic mouse radii the organic matrix of both calcified cartilage and bone is surrounded by a border of moderate electron density. The chemical composition of this structure is still unknown although we found proof that the border does not contain an appreciable amount of Thorotrast-stainable mucopolysaccharides. Where bone formation has just begun small islands of calcification can be found. The organic matrix of these islands contains Thorotrast-stainable mucopolysaccharides. Collagen fibrils, however, are absent. Only later on, when the islands become confluent, the fibrils between them become part of the bone matrix. In a certain phase of development the diaphyseal shaft of a radius consists of an inner layer of calcified cartilage and an outer, thicker one of bone tissue.