[Osteoclastic resorption of trabeculae in osteoporotic femoral head: a scanning electron microscopic study]

Osteoclastic resorption was studied by scanning electron microscopy on the trabeculae of femoral heads collected from 7 cases of aged women at an average age of 72.4 years, who underwent endoprosthetic replacement for intracapsular fracture of femoral neck. Femoral head trabeculae from 3 young adults killed in traffic accident served as control. The trabeculae of the femoral head formed round or roundish arch structure. The columnar trabeculae of the femoral head in the aged women showed overt osteoclastic resorption, manifesting thinning, tapering and perforation. The icicle-like trabeculae then became rounded, lost height and eventually turned into a small tubercle. As a result, the inter-trabecular space enlarged markedly. Under high magnification, on the trabeculae could be discerned oval, narrow oval or spindle-shaped Howship lacunae, which were various in size, depth and content, but all revealed punch-out edge. Around the lacunae the collagen fibril lamella normally covering the quiscient bone surface became resorbed sooner or later. During bone resorption, the inorganic component of the bone matrix were first dissolved and resorbed leaving behind rough and irregular collagen fibrils; nevertheless, the collagen might be degraded and resorbed first with residual inorganic crystals and irregular bone nodules. Then emerged in the Howship lacunae and surrounding area newly formed collagen fibrils and bone tissue, signifying reversal and new bone formation phases following the the bone resorption phase. In the aged women, however, this phenomenon was rather infrequently encountered, thereby leaving the bone turnover always in a negative balance state.

[Osteogenic potential of rabbit dermal fibroblasts cultured in vitro: a histochemical and scanning electron microscopic study]

Split-thickness rabbit skin was processed into small chips that were cultured in vitro and subjected to inverted phase contrast microscopic and scanning electron microscopic observation. The fibroblasts swam out of the skin chips and they increased in number rapidly and became confluenced. The cells exhibited squamous configuration, possessing arboreal bifurcations and forming multi-layer structure. The fibroblasts then excreted numerous minute granules, heaping up on and around the cells. Henceforth emerged on the cell surface fine needle-like crystals, that agglomerated with the granules to form nodules. The fibroblasts orientated themselves in a radiating pattern around the large nodules. Neighbouring nodules could be linked up into trabecular structure. Histochemical study of both the nodules and the trabecular structure with specific new bone labeller (Tetracycline and Alizarin red S) revealed positive reaction, denoting that the nodules and the trabecular structure produced by the fibroblasts were bone tissues. These results pointed out clearly to the osteogenic potential of the dermal fibroblasts.

Arch structure of trabeculae of the upper femoral end and its biomechanical significance in hip fractures

We studied ultrastructurally the cancellous bone tissues of the upper femoral ends, collected from 12 patients undergoing endoprosthesis replacement for fractures of the femoral neck and from 7 fresh cadavers. The bone tissues were composed of meshwork of trabeculae, that constituted tier upon tier of anisotropic arch structures of different diameters and sizes. The arch structures of the cancellous bone tissues in the femoral heads assumed round or roundish configurations, whereas those of the femoral head-neck junctions revealed oval outlines and those of the femoral necks showed narrow oval profiles. The fine structures of the trabeculae in the femoral head could be divided into superficial zone, central zone, and transitional zone. Under weight-bearing, the central zone suited to sustain the load, while the superficial zone could produce elastic deformation lest fracture of the trabecaulae should ensue. The long axes of the oval arch structures of the femoral head-neck junction and the narrow oval arch structures of the femoral neck coincided with those of the femoral neck, thereby facilitating weight-bearing under physiological conditions. However, external violence in the form of either adduction or abduction force would act in a horizontal direction on the long axes of the oval and narrow oval arches so as to produce subcapital or transverse fracture of the femur in the aged.

[Changes in contents of aluminium, calcium and phosphorus contents of local bone after implantation of alumina endoprosthesis]

Thirty rabbits were divided equally into 5 groups randomly. A hole, 6mm in diameter and 2mm deep, was bored on both ilia of the thirty animals. Two cubes of alumina were implanted into the hole on one side of each animal, while the hole on the opposite side served as control. Six rabbits each were sacrificed on 10, 20, 40, 60 and 90 days after operation. Calcium, phosphorus and aluminium contents of bone tissues in and around both holes were determined by Inductively Coupled Plasma-Atomic Emission Spectrometry. The results show that the aluminium content of the bone tissues on the implanted side in each group was higher than that of the control with statistically significant difference in the 10-, 40- and 60-day groups (P < 0.05). This means that the implantation definitely releases aluminium into the bone tissues. On the contrary, calcium and phosphorus contents were significantly lower in the bone tissues on the implanted side than in the control side in the 10- and 20-day groups (P < 0.05-0.001). It implies that the aluminium released from the implant in the early stage can interfere with the metabolism of calcium and phosphorus and thus delay the mineralization of the bone tissues.

Effects of osteogenesis on dermal fibroblasts cultured in vitro

Fibroblast were harvested from in vitro culture of split-thickness skin of New Zealand rabbit. Some opaque bone nodules were found in the culture flasks when the fibroblasts underwent subculture for 8 days. After a 37-day subculture of fibroblasts, some of the nodules might enlarge extend and form trabecular-like or flake-like structures. The above-mentioned structures revealed golden-yellow fluorescence under the blueviolet light fluorescence microscope when the specimens were labeled with tetracycline intravitally, denoting that they were newly formed bone tissues. Both calcium salt and collagen stainings for these structures showed positive reaction, fully reflecting the calcium and collagen composition. Osteogenesis caused by dermal fibroblast cultured in vitro was thus verified.

Origin of bone hyperplasia in osteoarthritic femoral head. Tetracycline labelling and scanning electron microscopic study

Total hip replacement was carried out in 7 patients with advanced osteoarthritis of the hip joint. The patients were given tetracycline orally before operation to label the newly formed bone tissues. The excised femoral heads were processed into undecalcified sections, which were subjected to both fluorescence microscopic and scanning electron microscopic (SEM) observation. Band-shaped golden fluorescence was detected along the trabeculae, reflecting newly formed bone tissues by the cambium layer of the periosteum. In the intertrabecular space, reticular and spherical golden fluorescence was detected, implying newly formed bone tissues by the marrow stromal cells. Under SEM, both reticular and spherical new bone tissues were discovered in the inter-trabecular space as mentioned above. There were two forms of reticular new bone tissues, a diffuse form and a tape-shaped new bone tissues. The diffuse bone tissues grew and expanded and eventually studded the inter-trabecular space. The tape shaped tissues, which were first deposited on the trabecular arch surface, increased in amount and then woven into thin and dense tapes of the reticulum. These tapes contacted in an end-to-end fashion, and appeared to shuttle back and forth through the trabecular arches, forming new secondary arch structures. The spherical new bone tissues were deposited on the surface of the trabecular arch structures and gradually packed the intertrabecular space. These new bone tissues were contributed to hyperplasia in the osteoarthritic femoral head.

[Trabecular arch structure of the upper end of femur and its biomechanical significance in hip fractures: a scanning electron microscopic study]

Scanning electron microscopic study was carried out in cancellous bone tissues of the femoral heads of 19 specimens. The reticular cancellous bone tissues comprised columns and flakes of trabeculae. The arch structure of the cancellous bone in the femoral head assumed round or roundish configuration, the arch structure of the femoral head-neck junction revealed oval outline, while the arch structure of the femoral neck showed narrow oval profile. The fine structure of the trabeculae in the femoral head could be divided into three zones: superficial zone central zone and transitional zone. Under weight-bearing, the central zone suited to sustain the load, while the superficial zone could produce elastic deformation lest fracture should ensue. These structural characteristics endowed the femoral head cancellous bone tissues the capability to bear weight and to absorb the impulsive load. The arch structure of the femoral head-neck junction and the femoral neck facilitates weight-bearing under physiological condition. However, external violence in the form of either adduction or abduction force, would act in a horizontal direction on the long axis of the oval and narrow oval arches. Under such circumstances, the arch structures would lose their mechanical advantage, and thus subcapital or transcervical fracture of femur might take place in aged people suffering from osteoporosis.

[Origin of bone hyperplasia in osteoarthritic femoral head: a scanning electron microscopic study]

Total hip replacement was carried out in 7 Patients suffering from osteoarthritis of the hip joint. They were given tetracycline preoperatively to label the newly formed bone tissues. The excised femoral heads were processed into undecalcified specimens, which were subjected to fluorescence microscopic and scanning electron microscopic studies. Narrow ribbon-shaped golden fluorescence could be observed along the trabeculae, reflecting newly formed bone by the cambium layer of the periosteum, while in the intertrabecular space both reticular and particulate and ball-shaped fluorescence could be detected, implying newly deposited bone by the marrow stromal cells. Under scanning electron microscope, the reticular new bone produced the new secondary trabeculae. The particulate and ball-shaped new bone tissues were deposited on the surface of the trabecular periosteum and filled up the inter-trabecular space. All these new bone tissues accounted for the bone hyperplasia or the osteoarthritic femoral head.

Local changes in aluminium, calcium and phosphorus content of bone caused by alumina implant

Thirty rabbits were divided equally into 5 groups randomly. A hole, 6 mm in diameter and 2 mm deep, was bored on each iliac crest. Two pieces of alumina were implanted into the hole of one side, while the opposite side served as control. These rabbits were killed on 10, 20, 40, 60 and 90 days after operation. Calcium, phosphorus and aluminium contents of iliac bone on both sides were determined by Inductively Coupled Plasma--Atomic Emission Spectrometry. The results showed that the aluminium content of the implanted side in each group was higher than that of the control and difference was significant in 10, 40 and 60 day groups (P < 0.05). This shows that the implant releases aluminium into the bone. Moreover, the calcium and phosphorus contents were significantly lower on the implanted side than on the control side in 10 and 20 day groups (P < 0.05-0.001). Apparently, the aluminium released from the implant in the early stage can interfere with the local calcium and phosphorus metabolism and delay the mineralization of the bone.

[Relation of ultrastructural changes of articular cartilage and the arthroscopic classification in osteoarthritic knee]

This paper reported the ultrastructural changes found in the diseased articular cartilages of 43 osteoarthritic knee joints, which were assessed according to the "Arthroscopic classification of the articular cartilage". The electron microscopic findings and the arthroscopic classification of the articular lesions were correlated. The lesioned articular cartilage revealed two categories of pathological changes. 1. The changes on the part of the articular chondrocytes comprised (1) The nucleus showed pyknosis and karyorrhexis. (2) The cytoplasm exhibited fat droplets, glycogen granules, and/or microfilaments. Lysosomes also emerged frequently. The mitochondria swelled and the rough-surfaced endoplasmic reticulum dilated and became vesiculated. At the same time there was detachment of cell processes or of the cytoplasmic membrane. The chondrocyte underwent necrosis, contracted and eventually disintegrated into lipid debris. These changes increased in extent and degree with the lesion and the severity went parallel with the sequence of the "Arthroscopic stage classification". 2. The changes on the part of the matrix included appearance of electron-dense lipid debris and numerous, coarse and banded collagen fibrils. They resided both in the pericellular matrix and in the general matrix. Sometimes fibroblast-like cells made their appearance in the matrix. These cells also revealed degenerative changes. All these changes went parallel with the sequence of the "Arthroscopic grade classification".

[Histochemical study on effect of radix Salviae miltiorrhizae on growth of isolated cells from embryonic chicken frontal bone cultured in vitro]

12-day embryonic chicken frontal bone digested with trypsin to prepare the suspension of isolated bone cells. 3 x 10(6) cells were harvested altogether. The cells were divided equally into five parts. Then the Eagle medium and 0.1%, 0.2%, 0.4% and 0.8% Radix Salviae Miltiorrhizae in Eagle medium were added respectively and cultured in 5% CO2 incubator. It was observed under the inverted microscope every day. At the 26th day of culture, the cells were studied. The specimens were stained with H. E., Alcian Blue-Sirius Red, Alizarin Red S staining and alkaline phosphatase-acid phosphatase reaction for comparison. It was found that the maturation of the osteoblast-like cells could be accelerated by Radix Salviae Miltiorrhizae. Secretion of the collagenous substance, positive alkaline phosphatase reaction and deposition of mineral on the collagenous substance, forming bone nodules were found to be enhanced. But unduly high concentration of Radix Salviae Miltiorrhizae could lead to inhibition of osteoblast-like cell growth. The optimal concentration of Radix Salviae Miltiorrhizae was 0.2% in culture medium.

[Scanning electron microscopic study of subchondral bone tissues in osteoarthritic femoral head]

In total hip replacement for 12 aged women with advanced osteoarthritis of the hip joint, three types of lesioned articular cartilage with various degrees of severity and ivory bone were obtained together with their subchondral bone tissues. These specimens were processed and studied under scanning electron microscope and were compared with sex and age-matched non-osteoarthritic femoral head articular cartilage specimens. In osteoarthritic femoral heads, with deepening of the articular lesion, the articular cartilage gradually became thinned out and eventually lost. The subchondral bone plate became markedly thickened in most of the specimens. The epiphyseal trabeculae were also thickened and turned rough so that the meshwork pattern gradually disappeared. The thickened trabeculae finally fused into a large piece of dense bone tissues without microfracture. These changes could be accounted for by the increased stress imposed on the subchondral bone tissues as a result of incompetence of the diseased articular cartilage. Consequently, the changes on the part of subchondral bone tissues of the osteoarthritic femoral heads were the sequent, rather than the cause, of the articular lesions.

Scanning electron microscopic study of subchondral bone tissues in osteoarthritic femoral head

During total hip replacement for 12 cases of advanced osteoarthritis of the hip joint in aged women, three types of diseased or abnormal articular cartilage with different degrees of severity (white articular cartilage, white and hyperplastic articular cartilage, and yellowish articular cartilage) and ivory bone were obtained together with their subchondral bone tissues. These specimens were processed and studied under scanning electron microscope and were compared with sex- and age-matched non-osteoarthritic femoral head articular cartilage specimens. The following findings were observed: 1. In non-osteoarthritic femoral head, the subchondral bone plate was quite thin. The bone plate connected on its deep surface with the lattice-work of trabeculae of the epiphyseal region. The trabeculae were fine and smooth and some revealed round or spindle-shaped callus resulted from microfracture. 2. In osteoarthritic femoral heads, with increased the severity of the articular lesion, the articular cartilage gradually became thinned out and eventually lost. The subchondral bone plate was markedly thickened. The epiphyseal trabeculae were also thickened and turned rough so that the lattice-work pattern gradually disappeared. The thickened trabeculae finally fused into a large piece of dense bone tissue. No microfracture was detected. These changes were attributable to the increased stress imposed on the subchondral bone tissues as a result of defective articular cartilage. Consequently, the changes on the part of the subchondral bone tissues of the osteoarthritic femoral heads were the sequent, rather than the cause, of the articular lesions.

[Subchondral bone tissues in osteoarthritis of knee joint: a tetracycline labelling study]

The patients with late osteoarthritis of the knee joint were given oral tetracycline to label the newly formed bone tissues before they were subjected to high tibial osteotomies or knee replacements. During the operation, the sclerotic subchondral bone tissue of the tibia and/or femur were procured. The bone specimens were processed into undecalcified sections and studied under fluorescence microscope. Apart from the autofluorescence of the trabeculae, strips of golden green labelled fluorescence of high intensity were noted along their peripheries, indicating that there were formatting and deposition of new bone along the periphery of the trabeculae. These new bone tissues were produced by the osteoblasts abutting the trabecular periphery. In the fatty tissues of the marrow interstices between the trabeculae, scattered dots and small flakes of golden green labelled fluorescence emerged at first. Then the labelled-fluorescent dots and flakes agglomerated into large pieces of more intense fluorescence with concomitant decrease in fatty tissues. Eventually, these large pieces of labelled fluorescence fused with those of the trabeculae and there was a further decrease in fatty tissues. These findings suggested that the formation and deposition of new bone tissues in the marrow interstices proceeded according to above three stages. The new bone tissues were produced by marrow stromal cells. The two kinds of new bone tissues increased the bone mass and rendered sclerotic changes in upper end of the tibia and lower end of the femur in osteoarthritis of knee joint.

Ultrastructural investigation of granulation tissues on the osteoarthritic femoral head. A scanning electron microscopic and transmission electron microscopic study

From the femoral heads of nine cases of advanced osteoarthritis of hip joint, three categories of granulation tissues with different colors (bright red, dark-red and white granulation tissues) and texture were obtained. After processing, the specimens were observed under scanning electron microscope and transmission electron microscope. With transformation of the granulation tissues from bright red to white, the collagen fibers therein contained gradually changed from fine to thick ones. Nevertheless, the cellular components in these three types of granulation tissues always possessed the characteristics of both fibroblasts and chondrocytes, i.e., fibroblastic configuration with pericellular Type I collagen fibrils bearing 64 nm periodicity; and chondrocytic scallop-shaped cytoplasmic membrane with intracytoplasmic fat droplets and glycogen granules and pericellular Type II collagen fibrils. All these indicated that in osteoarthritis of hip joints, the granulation tissues of the femoral heads transformed eventually into fibrocartilage, irrespective of their color and texture.

Ultrastructural study of hip joint osteoarthritis. Scanning electron microscopic study of articular cartilage of femoral head

The surface structure of four different articular cartilages of the femoral head was studied with scanning electron microscope in 12 cases of hip joint osteoarthritis. These articular cartilages were mink white, yellow, dusky red and hyperplastic and thickened. The osteoarthritic articular cartilage surface was uneven with puckerings of various height, width and orientation. The puckerings were covered with fibril network. The fibrils were exposed collagen fibrils and of different diameters. Wider fiber bundles without orientation were found on the fibril network. On the surface of the hyperplastic articular cartilage observed were many deep and oval spaces left behind after breakdown of the lacunae of cells in the clusters of articular chondrocytes. In the spaces, remnants of articular chondrocytes were seen.

Electron radioautographic study of experimental fracture healing

The mitotic activities of various cellular components of callus tissues in different periods after tibial fracture of rat were studied with 3H-thymidine labeling and electron radioautographic method. Silver grains were accumulated over the nuclear areas of mesenchymal cells, monocytes, macrophages, endothelial cells of capillaries, fibroblasts, chondroblasts and chondrocytes, as a result of incorporation of the labelling material during their mitosis. Although osteoblasts and osteocytes could not undergo mitosis, they also revealed silver grains over nuclear areas because of their derivation from the mesenchymal cells or osteogenic cells.

Radioautographic findings in osteoarthritic femoral head

During total hip replacement for 8 patients with hip joint osteoarthritis specimens of femoral articular cartilages of 3 types of involvement were taken, i.e. the "normal" articular cartilage, the fissured and wrinkled articular cartilage, and the yellow or dusky red, markedly thickened, and roughened articular cartilage. Radioautographical studies with 3H-Thymidine labelling showed the clusters of articular chondrocyte, degeneration, death and vanishing of the chondrocytes with empty lacunae left; and mitosis and proliferation of the chondrocytes, as evidenced by silver granules in the nuclear area. In the articular cartilages of three types of involvement, the percentages of degenerated, dead and vanished chondrocytes represented by empty lacunae, of non-mitotic chondrocytes without silver granule and of chondrocytes undergoing mitosis with silver granules, were 19.9, 38.3 and 41.8; 9.1, 48.9 and 42; 5.3, 35.0 and 59.7 respectively. A large number of empty lacunae appeared in the "normal" articular cartilage, signifying aging of the cartilage. Chondrocytes bearing silver granules appeared not only in the "normal" articular cartilage but also largely in the severe osteoarthritic cartilage and served as a compensatory manifestation of both aging and osteoarthritis.

Effect of intra-articular fracture on articular chondrocytes. A transmission electron microscopic study

Intra-articular fractures involving the subchondral bone were produced surgically in both left and right medial femoral condyles of twenty rabbits. The edges of the fractures on the left side were well approximated, while those on the right side maintained with a gap of 2 mm. Transmission electron microscopic study of the nearby articular cartilages conducted 1, 2, 3, 4 and 5 months after the fracture revealed the following results: 1) The neighbouring articular chondrocytes tended once to assume the configuration of fibroblasts; 2) Those remote from the fracture showed both degeneration and hyperplasia to form clones; 3) Even after the intra-articular fractures were well-healed, degeneration and hyperplasia of the articular chondrocytes nearby the fracture would persist for some time.

The treatment of primary vertebral tumors by radical resection and prosthetic vertebral replacement

The basic principles for the treatment of primary vertebral tumors include radical resection of the tumor, insertion of a prosthetic vertebral body, and bone grafting within and around the prosthetic vertebral body. Since 1970, the authors have treated 12 cases with this procedure. In order to improve the vertebral prosthesis, 94 dried adult vertebral column specimens were studied. The anterior cortex of each vertebral body was thicker than the posterior cortex. The thickness of the anterior cortex of the dorsolumbar vertebral bodies progressively increases from the proximal to caudal vertebra. The lower lumbar vertebrae are therefore almost twice as thick as the upper dorsal vertebrae. The cortices of the vertebral bodies, especially the anterior cortex, serve as a strut against the pressure of the prosthesis. Four types of prostheses were used. The Type 1 prosthesis failed to take into account the anatomic features of the dorsolumbar vertebral bodies in cross section. Types 2, 3, and 4 are modified versions with specific indications for their use.