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PubMed1979

The effects of dynamic loading on intracalcaneal wood implants and on the tissues surrounding them.

The dorsal parts of the calcanei of rabbits were resected and replaced with similarly-shaped implants made of ash wood. In each case the Achilles tendon was reinserted into the projecting part of the implant so as to subject the latter to the dynamic loads generated by use of the limb. The implants were removed from some of the animals after 5 weeks and from the others after 14 weeks. They were evaluated by preparing undecalcified microtome sections and ground sections which were examined by light microscopy and microradiography. Some of the animals underwent vital staining so as to produce polychromatic sequential labelling of the calcaneal specimens. In the area of insertion of the Achilles tendon soft tissue grew into the larger pores of the wood and, in some cases, differentiated into cartilage. Every implant remained stably anchored in the calcaneus. In every animal the intracalcaneal part of the implant became surrounded by new bone which was in direct contact with the surface of the implant and which also formed in the pores of the wood, even all rabbits loaded the operated foot. The formation of new bone in and around the implants demonstrates the basic feasibility of using ash wood as an isoelastic implant material in bone.

Achilles Tendon↗
PubMed1984

Osseous penetration rate into implants pretreated with bone cement.

The titanium bone growth chamber consists of two titanium disks held together by two screws. At the level of the intersection between the disks, a 1 mm wide canal penetrates the implant. After implantation, in e.g. the rabbit, tibial metaphysis bone and vessels will grow through this canal, the contents of which are collected four weeks after surgery. Microradiography and a computer-based analysis give a numerical representation of the amount of newly formed bone in the canal. When the bone ingrowth into two identical titanium implants, one inserted in the left and the other in the right tibia, was compared, only small and insignificant differences were found in the same animal. However, when one animal was compared to another, greater differences in the bone-forming capacity were found, in spite of the fact that the rabbits were controlled with respect to race, age and sex. The osseous penetration rate into titanium canals was compared to the bone ingrowth in equally sized pipes of polymerized acrylic cement which had been inserted in the titanium chamber. In these cases there was significantly less bone formed in the cement pipes compared to the titanium controls. Poor biocompatibility of the cement compared to titanium is suggested to be one factor responsible for the reduced bone formation in the cement environment. This may be one reason for the fibrous tissue capsule generally seen around cemented implants.

Animals↗
PubMed1978

Gross vascularization of experimentally induced transplanted tumors of the central and peripheral nervous system.

Subcutaneously and intracerebrally transplanted neurinomas as well as intracerebrally grafted gliomas, both derived from primary tumors with resorptive carcinogens were investigated after injection of micropaque by conventional histologic methods and by postmortem X-ray analysis. Growth pattern and vasculature were similar in subcutaneously and intracerebrally transplanted malignant neurinomas. The most common feature was a parallel arrangement of vessels as shown by microradiography and vessel free zones. In intracerebrally grafted glioma, the growth of tumors was confined to or starting from the ventricular system. Sinusoidal vessels, capillary proliferations and proliferation of vessel wall were found. The outstanding feature was the occurrence of extravascular contrast deposits, thus indicating the vulnerability of tumor vessels and frequency of hemorrhages into these tumors.

Animals↗
PubMed1989

An experimental investigation in the dog into the mode of osseous integration of total joint implants.

An uncemented scaled down version of the Mueller SLS femoral component was inserted into 30 dogs. The material (Protasul 100), geometry, and finish were identical to those designed for clinical use. Half of the prostheses inserted were fitted out with a modular collar to improve stability. Initial stability was achieved through press fit which was made possible by the special modification of the surface area and external configuration of the prosthesis. The function of the prosthesis was assessed through clinical assessment and force plate gait analysis. This was correlated with the degree of osseous integration which was evaluated on the basis of regular radiological examinations, and at post mortem by microradiography of the serially sectioned undecalcified femurs, and histological examination of selected sections under regular and ultraviolet light. The animals were sacrificed at 4, 8, and 12 months. Force plate gait analysis revealed that all animals walked with a normal gait by the 4th post-operative month. Evaluation revealed that 29/30 femoral prostheses became successfully integrated. The prostheses without the collar were less stable and most achieved stability only by incorporation of the distal tip of the prostheses in bone and the remainder in dense fibrous tissue. The prostheses with the collar were stable and achieved without fail full bony integration. The stability was provided by appositional growth of bone which came into direct contact with the implant over the proximal 1/3 and the distal 1/3 without an intervening fibrous membrane. Despite failure of full integration of the collarless prostheses clinically and by force plate analyses the two groups were indistinguishable.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Age and disease-related changes in the mineral of bone.

Bone mineralization changes with age and disease. The distribution of mineral particles in a given bone (mineralization profile) has been studied using density fractionation as well as microradiography and electron backscattering imaging. The biological determinant of mineralization is the rate of turnover. During rapid growth and periods of high remodeling, mineralization is shifted towards lower mineral density (hypomineralization). During aging and periods of low remodeling, mineralization is shifted towards higher mineral densities (hypermineralization). Chemicals can also influence the mineralization profile of bone. Fluoride induces hypermineralization by stabilizing the apatite lattice and reducing bone mineral solubility, whereas strontium induces hypomineralization by loosening the apatite lattice and increasing bone mineral solubility. Drugs such as bisphosphonates induce hypermineralization by inhibiting resorption and acting as crystal poison. Finally, mineralization can be impaired by defects as in rickets and osteomalacia or made excessive by continuous accretion of mineral without resorption as in osteopetrosis.

Absorptiometry, Photon↗
PubMed1978

Lead-loaded ion-exchange resin bead as a calcergen.

Several heavy metals have direct calcifying effects in connective tissues; most notable among them is lead (Pb), whether administered topically (1) or systemically with local injury (2). The mechanisms of metal-induced soft tissue calcification have been studied by injecting salts of known in vitro calcifying potential into subcutaneous connective tissue (3); of the metals used, only lead and holmium produced an early accumulation of minerals on collagen in vivo. Lead is also claimed to accelerate bone healing in the rabbit leg with no toxic effects (4). Lead-loaded ion-exchange resin beads, implanted into surgically prepared subcutaneous pouches in rats, rapidly induced subcutaneous calcification which has been studied by microradiography and electron-probe microanalysis.

Animals↗
PubMed1982

A technique for cutting slices from femoral heads and other awkwardly shaped bones.

For cutting thin, parallel slices from round and other awkwardly shaped bones, we have developed an useful aid by modifying the Microslice II cutting saw primarily designed for geological or metallurgical purposes. To ensure a good grip of the bone, the specimen is embedded in a bolus of wax in a cylindrical container and is advanced along the container by a screw plunger toward the cutting blade of the machine. It is thus possible to cut even from awkwardly shaped bones 2-30 mm thick parallel slices suitable for decalcified or undecalcified histological sections and also for radiodensitometry or quantitative microradiography.

Bone and Bones↗
PubMed1975

Electrical modification of disuse osteoporosis.

Localized electrical stimulation of the immobilized hind limb of young rabbits resulted in dramatically more bone in the tuber calcis (heel bone) compared to the severe loss of bone (osteoporosis) seen in unstimulated, immobilized controls. Detailed histological evaluation using microradiography and fluorescence and polarization microscopy showed that the increase was probably due to an overall inhibition of surface cortical bone loss )endosteal resorption) and an increase in the quantity of the new immature bone. There was also evidence of increased osteonal resorption in the stimulated animals.

Animals↗
PubMed1988

Ultrasonic measurement of immobilization-induced osteopenia: an experimental study in sheep.

An animal model was used to examine the use of noninvasive transmission ultrasound to measure changes in bone mass which occur following disuse. Unilateral achilles tenectomy was performed on the left leg of eight adult sheep. Following a 12-week period of nonweight bearing, presacrifice transmission ultrasound measurements were taken across the calcanei of the intact and the experimental limbs and compared with those values taken postoperatively. Following specimen harvest, cross-sectional areas of the bones were quantified by microradiography and stereology, and compared with the in vivo ultrasound measurements. There was an average of 8.6% less total bone area, and 18.0% less trabecular volume fraction in the experimental nonweight-bearing limbs as compared with control intact calcanei. The difference in bone mass was associated with a 9.0% decrease in the velocity of sound from the postoperative to the presacrifice ultrasound measurements taken from the experimental calcanei, and a 2.3% increase in the control calcanei. The velocity of sound was found by the Student's t test to be a highly reliable discriminator between the experimental and control limbs.

Animals↗
PubMed1985

[Quantitative determination of the effect of induced alternating currents on the integration of autologous spongiosa transplants].

In a right-left experiment on the ulna of beagles, the authors investigate the influence of induced alternating current on the number of healed-in autologeous spongiosa grafts taken from the same side of the body. At first an atrophic pseudarthrosis is produced in both ulnae of twenty animals by bone resection and electrocoagulation over six months. Following to spongiosa transplantation and plate osteosynthesis, the ulnae are stimulated during eight weeks with a sinusoidal current of 38 cps and an electromagnetically induced alternating-current voltage of 600 mV on an average. The blindfold evaluation of the X-ray picture is performed by four experts and shows significantly better results in the stimulated side. By variance analysis of the results of electronic planimetry of serial layers in the region of transplantation represented by microradiography, it is demonstrated that the greater bone density of the stimulated grafts compared to the control grafts is statistically significant. It has to be considered that these results refer strictly to the electric data and treatment times applied by the authors. Particularly the results are not valid for the unique application of electromagnetic fields without alternating-current component.

Animals↗
PubMed2004

[New bone formation by extracorporeal shock waves. Dependence of induction on energy flux density].

BACKGROUND: The purpose of this study was to test the hypothesis that shock waves can induce new bone formation even without cortical fractures and periosteal detachment as suggested in the literature. METHODS: Extracorporeal shock waves with energy flux densities between 0 mJ/mm(2) (sham treatment) and 1.2 mJ/mm(2) were applied in vivo to the distal femoral region of rabbits (1500 pulses at 1 Hz frequency each). Oxytetracycline was injected on days 5-9 and the animals were sacrificed on day 10. Sections of both femora of all animals were investigated with broadband fluorescence microscopy and contact microradiography for new periosteal and endosteal bone, periosteal detachment, cortical fractures, and trabecular bone with callus. RESULTS: Shock waves with energy flux densities of 0.9 mJ/mm(2) and 1.2 mJ/mm(2) resulted in new periosteal bone formation in the presence of cortical fractures and periosteal detachment. After application of shock waves with energy flux density of 0.5 mJ/mm(2), clearly detectable signs of new periosteal bone formation were observed without cortical fractures or periosteal detachment. CONCLUSIONS: The results of this study challenge the current view in the literature that the creation of cortical fractures and periosteal detachment are prerequisites for new bone formation mediated by extracorporeal shock waves.

Animals↗
PubMed1998

[Bone regeneration stimulated by bone substitute materials].

Prompted by severe problems in autogeneic and allogeneic bone transplantation, intensive efforts were made to find sufficient substitutes. A main demand on these materials, especially in healing of osseous defects, is to achieve results comparable to those of auto- or allografts. These must be related to their biomechanical and particularly to their biological properties, i.e. the ability to form new bone, osseous integration and physiological remodeling. Within different trials in the tibiae of sheep we investigated bone substitutes like hydroxyapatite ceramics (HA) or partially demineralized bone matrix (pDBM) and compared them to the gold standards of autogeneic and allogeneic bone transplantation. Therefore we used two different models: the drill hole model with small size defects of 6 mm in diameter and the shaft defect model as a true-to-life defect with a 5 cm large diaphyseal defect. Evaluation was done by X-rays, histology, microradiography, fluorescent microscopy and morphometry of the small size defects. HA showed only small effects on new bone formation and works merely as an osteoconductor. However, excellent new bone formation was regularly achieved by pDBM in the small defects, whereas it was limited in the large size defects. But considering their mechanism of action, it is possible to bridge large bone defects by pDBM.

Bone Demineralization, Pathologic↗
PubMed2003

The mineralization of bone tissue: a forgotten dimension in osteoporosis research.

Osteoporosis treatment should not only prevent the loss of bone tissue, not interfere with apatite and avoid bone mineral changes at the crystal level, but should also increase the mechanical resistance of bone and thus protect the skeleton against new fractures. Mineral substance is crystallized as nonstoichiometric carbonated apatite ionic crystals of small size and extended specific surface. Consequently, they have a very large interface with extracellular fluids, and numerous interactions between ions from the extracellular fluid and ions constituting apatite crystals are thus possible. It is generally agreed that bone strength depends on the bone matrix volume and the microarchitectural distribution of this volume, while the degree of mineralization of bone tissue is almost never mentioned as a determinant of bone strength. We now have evidence that the degree of mineralization of bone tissue strongly influences not only the mechanical resistance of bones but also the bone mineral density. In adult bone, our model is based on the impact of changes in the bone remodeling rate on the degree of mineralization of bone tissue. The purpose of this paper is to report the main results concerning the interactions of strontium (Sr) with bone mineral in animals and in osteoporotic women treated with strontium ranelate (SR). These studies aimed to evaluate using X-ray microanalysis, X-ray diffraction and computerized quantitative contact microradiography: (1) the relative calcium and Sr bone content, (2) the distribution of Sr in compact and cancellous bone, (3) the dose dependence of the deposition of Sr in bone, (4) the interactions between Sr and mineral at the crystal level (in monkeys), (5) the influence of Sr on the mean degree of mineralization of bone tissue and on the distribution of the degree of mineralization of bone tissue, and (6) the bone clearance of Sr over short periods of time (6 and 10 weeks) after cessation of SR administration (monkeys treated for 13 and 52 weeks, respectively). In monkeys killed at the end of exposure (13 or 52 weeks), Sr was taken up in a dose-dependent manner into compact and cancellous bone, with a higher content in new bone than in old bone. The Sr content greatly decreased (about 2-fold) in animals killed 6 or 10 weeks after the end of treatment but this affected new bone almost exclusively. After SR treatment, there were no significant changes in crystal characteristics. Easily exchangeable in bone mineral, Sr was slightly linked to crystals by ionic substitution (generally 1 calcium ion substituted by 1 Sr ion in each unit cell). The degree of bone mineralization was not significantly different in the various groups of monkeys. Thus, at the end of long-term SR treatment and after a period of withdrawal, Sr was taken up in a dose-dependent manner into new bone without alteration of the degree of bone mineralization and with no major modification of bone mineral at the crystal level. In postmenopausal osteoporotic women treated with SR (0.5, 1 and 2 g/day) for 2 years, Sr was dose-dependently deposited into new bone without changes in the degree of mineralization of bone tissue. These findings could reflect dose-dependent stimulation of bone formation and are of potential value for the use of SR in the treatment of osteoporosis. In conclusion, the different studies performed on bone samples from monkeys and humans treated with various doses of SR showed that Sr was heterogeneously distributed between new and old bone but in a dose-dependent manner without alteration of the crystal characteristics and the degree of mineralization of bone tissue, even after long-term administration of often high doses of SR (the highest therapeutic dose used in humans is 4-fold lower than the lowest experimental dose administered to monkeys). This emphasizes the value, as antiosteoporotic treatment, of SR, which is safe at the bone mineral level.

Animals↗
PubMed1999

The effect of vitamin K and D supplementation on ovariectomy-induced bone loss.

This study was designed to assess the effect of vitamin K and D supplementation on ovariectomy-induced bone loss. Female Sprague-Dawley rats aged 8-9 months were ovariectomized (OVX) or sham operated and divided into five experimental groups: (1) ovariectomy (OVX), (2) OVX plus vitamin K supplementation, (3) OVX plus vitamin D supplementation, (4) OVX plus vitamin K and vitamin D supplementation, and (5) sham operation. The trabecular bone area was estimated by bone histomorphometry by microradiography and histological examination. Bone loss in OVX plus vitamin K and vitamin D group was significantly reduced at both 7 and 14 weeks compared with the OVX group. No significant bone loss in OVX plus vitamin K or OVX plus vitamin D groups was found. A similar effect of vitamin K and D supplementation on ovariectomy-induced bone loss was recognized in histological examination. Our findings indicate that vitamins K and D may have a synergistic effect on reducing bone loss. This is valuable information for the treatment of bone loss in postmenopausal women with osteoporosis.

Animals↗
PubMed2002

Distraction osteogenesis by Ilizarov and unilateral external fixators in a canine model.

We studied distraction osteogenesis in canine experimental model using two types of external fixators, Ilizarov (n=6) or AO unilateral (n=9) external fixator. Distraction started 1 week after surgery (2 x 0.5 mm/day) and lasted for 3 weeks. Specimens were harvested from weeks 7 through 12. The outcome was assessed by X-ray, histology, histomorphometry and microradiography. Bone regeneration as observed by X-rays was satisfactory and similar in both groups. Both endochondral ossification and intramembranous ossification were found simultaneously in both groups. In both groups, bone formation parameters were significantly higher in the area of consolidating bone. No differences in histomorphometric parameters existed between the groups. In the study period, the bone formation was enhanced and prevailed in the distraction area. This study demonstrated the utility of the canine experimental model for the study of distraction osteogenesis.

Animals↗
PubMed2005

The dimensional accuracy for preparation of the femoral cavity in HIP arthroplasty. A comparison between manual- and robot-assisted implantation of hip endoprosthesis stems in cadaver femurs.

INTRODUCTION: The aim of the study was to determine the precision of the preparation of the femoral cavity in cementless hip arthroplasty. We compared the bone-prosthesis interface after manual- and robot-assisted implantation of the stems. MATERIAL AND METHODS: After plastination the specimens were cut to slices of 2.5 mm and documented by microradiography. The interface between prosthesis and bone was measured digitally with a specially designed software. RESULTS: The manually implanted prostheses showed an average full-contact area of 60% and an average area of gaps of 40% with an average height of 0.8 mm. The robot-assisted implanted stems had a significantly higher bone-prosthesis interface area of 93% and gap areas of less than 0.2 mm depth. Destructions of the spongeous bone were seen with the manually implanted stems but not after robot-assisted implantations. There was one stem fracture during the manual preparation of a stem. Microradiographic examination showed microfractures in the region of the lesser trochanter in two femora after robot-assisted implantation CONCLUSION: The robot-assisted technique highly increased the fitting area at the bone-prosthesis interface. The main reason for the fractures might be the absence of a robot done marker for the ideal implantation height with the applied type of prosthesis.

Arthroplasty, Replacement, Hip↗
PubMed2006

The femoral head expandable peg: improved periimplant bone properties following expansion in a cadaveric model.

PURPOSE: The femoral head expandable peg offers a new concept of bone-device purchase treating proximal femur fractures. We describe the expansion influence on both the periimplant bone properties and the intraosseous pressure. METHODS: A 10 x 8 mm cannulated peg consisting of a stainless steel oval-shaped transversely sectioned rod was tested on 13 femoral heads retrieved from patients with subcapital fracture treated by hemiarthroplasty. Normal saline solution was used to expand the diameter of its membrane from 7.8 to 10.5 mm, resulting in abutment of the distal peg to the compacted cancellous bone of the femoral head. The intraosseous pressure was monitored using a 1.4 mm drill-hole. RESULTS: Dual-energy X-ray absorptiometry and microradiography demonstrated increased periimplant bone density following peg expansion, without significant increase in the intraosseous pressure. CONCLUSION: The new implant afforded improved periimplant bone density, less trabecular damage and preservation of bone stock, all contributing to reliable biomechanical support and potentially decreasing the high complication rate following screw fixation in osteoporotic femora. Further studies are needed in order to establish clinical safety and efficacy.

Absorptiometry, Photon↗
PubMed2005

Two unusual stab injuries to the neck: homicide or self-infliction?

A 31-year-old woman was found dead by her daughter, lying in the living room which showed a large pool of blood, secondary droplets and stains from arterial blood spatter, dropping and contact. This bloody scene and two puncture wounds at the anterior aspect of the neck, one of them transecting the left common carotid artery leading to exsanguination, arose suspicion of homicide. However, the wound morphology including notches and a parallel skin incision as well as microradiography demonstrated that the two puncture wounds had been produced by glass. At the scene, a broken wine glass with two dagger-like tips had been standing on a table in front of a sofa where the woman had been sitting, and she most likely sustained the injury when she suddenly moved her head downwards, thus moving into the protruding tips. This self-inflicted accident demonstrates that inspection of the scene and synthesis of autopsy and scene findings can be crucial for a successful medico-legal reconstruction. The mechanism of producing the accidental injury is very extraordinary, in that the woman actively moved into a shattered wine glass instead of falling into an intact architectural glass surface.

Accidents, Home↗