Subcapital fracture of the hip following an intertrochanteric fracture. A case report and literature review

A 42-year-old alcoholic man who had a normal femoral head histologically incurred a subcapital fracture four months after surgical treatment of an intertrochanteric fracture of the same hip. Subcapital fracture of the hip following intertrochanteric fracture is an unusual occurrence, with possibly as few as 11 cases documented in the literature. Affected persons are usually elderly females with severe osteoporosis. Though unusual, the fracture is obvious and not difficult to treat.

Charged beads: generation of bone and giant cells

Based on reports of electrically induced bone formation and findings that some materials used to promote bone ingrowth are stimulatory in bead form, the osteogenic potential of beads with different surface charges was examined. In this preliminary study, three types of Sephadex beads were injected into chick femora: type I, DEAE beads, positively charged; type II, CM beads, negatively charged; type III, G-25, uncharged. Beads were injected into the femoral midshaft, and after 3 days, 4 days, and 1 week, birds were sacrificed and femora were processed for histology. Type I beads: at 3 days, were surrounded by multinucleated giant cells; by 4 days, patches of bead-associated new bone were present along with giant cells; after 1 week, occasional bead-associated multinucleated cells were seen, but now most beads were surrounded by new intramedullary bone, forming an extensive bead-bone lattice. With bead types II and III, bead-associated new bone was seen at 3 days and 4 days only when beads lodged near the endosteum or in the metaphysis. At 7 days, no bone was seen with either of these two bead types. The response to the type I beads may be likened to a remodeling phenomenon with large numbers of giant cells at 3 days, new bone and giant cells at 4 days, and evidence only of bone formation at 7 days.

The effect of low dietary calcium and calcium supplementation on calcium metabolism and bone in the immature, growing rat

The data presented here were obtained from a series of experiments designed to determine 1) whether normal growth and bone development could be maintained in young, growing rats (3-9 weeks of age) on a diet containing 0.1% Ca, and 2) whether Ca presented in a bolus would be utilized as effectively as the same amount of Ca distributed throughout the diet. Weanling female rats were raised to 9 weeks of age on diets containing 0.4% P and either 0.5% or 0.1% Ca. One group of animals on the 0.1% Ca diet was given oral supplements of CaCO3 twice each day to supply the same amount of Ca consumed by age-matched animals on the 0.5% Ca diet. We found that animals consuming diet containing 0.1% Ca grew at the same rate as animals receiving 0.5% Ca, or 0.1% Ca + supplement for up to 9 weeks of age when the experiment was terminated. Measurement of femur length indicated that long bone length was the same for all animals. However, the 0.1% Ca group exhibited mild hypocalcemia (9.1 mg/dl vs 10.4 for controls), a 2.6-fold elevation in immunoreactive parathyroid hormone, and an increase of similar magnitude in circulating levels of 1,25-dihydroxyvitamin D. Bones from the 0.1% Ca group contained less than half as much Ca as bones from the 0.5% Ca group, and exhibited significant decreases in mid-shaft diaphyseal thickness, % trabecular volume of the distal metaphysis and breaking strength (torsion testing). These results suggest that while a diet containing 0.1% Ca is able to maintain normal growth, bone mineralization is compromised.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional alterations in long bone produced by internal fixation devices. Part I. 85Sr clearance

We examined the effect of rigid plate application on the radiostrontium clearance of the intact canine femur at 6 months. We examined each of the component surgical steps. We calculated the clearance both for the whole bone and for each of the five transverse sections of the whole bone. Screw application, but not drilling, increased the clearance in the segment about the screw holes. Plate application produced an increase in the segment beneath the plate as well as around the screws and in the whole bone. These changes are accomplished not only by an absolute increase in clearance to the middle three segments, but by a relative diminution in clearance by the most proximal and distal segments. The histomorphometric changes in long bones following rigid plating may be accompanied by regional increases in bone blood flow.

Regional alterations in long bone 85Sr clearance produced by internal fixation devices. Part II. Histomorphometry

The effects of each of the surgical stages involved in compression plating on the development of cortical thinning and porosity were assessed in the intact midshaft, stress-shielded femoral segments of adult mongrel dogs 6 months postoperatively. The data were evaluated in terms of a postsurgical tetracycline-based measure of remodeling and terminal 85Sr clearance (SrC) values for the plated segments of bone. Drilling had no effect on any parameter. Screw application was associated with minimal cortical thinning (p less than 0.05), while plate fixation clearly promoted thinning (p less than 0.01) and porosity (p less than 0.05). The percentage of labeled osteons, a measure of remodeling activity, increased only after plate fixation (p less than 0.05), and the labeling patterns suggested that most osteons had formed during the first 4 postsurgical months. That none of these changes were correlated with the 6-month SrC values suggests that the development of plate-induced osteopenia involves disparate histomorphometric time constants, rather than lack of any association.

Pull-out strengths of bone screws at various sites about the pelvis--a preliminary study

The pull-out strength of both cortical and cancellous screws from bone at various sites about cadaveric pelves was examined. No significant differences were seen between cortical or cancellous screws at similar sites with the possible exception of the sacroiliac joint. Pull-out strengths were best correlated to the depth of bone at a particular screw hole. For practical purposes, the strongest sites are in the thick buttress of bone along the iliopubic column.

Radiostrontium clearance and bone formation in response to simulated internal screw fixation

Changes in radiostrontium clearance (SrC) and bone formation (tetracycline labeling) were observed in the femurs of skeletally mature dogs following the various operative steps involved in bone screw fixation. Drilling, but not periosteal stripping, produced a small but statistically significant increase in SrC and endosteal bone formation in the distal third of the bone. Strontium clearance values equivalent to those produced by drilling alone were recorded after screw fixation at low or high torque (5 versus 20 inch pounds), as well as by the insertion of loosely fitting stainless steel implants. Bone formation (equals the percentage tetracycline-labeled trabecular bone surfaces) was increased by 30% when SrC values exceeded 3.5 ml/100 g bone/min, and the relationship was linear when SrC values ranged between 1.0 and 7.0 ml/100 g bone/min. The changes in SrC and bone formation one-week after bone screw application are primarily those associated with a response to local trauma caused by drilling.

Bone maturation and quality of bone material in rats flown on the space shuttle 'Spacelab-3 Mission'

The maturation profiles of calcium, phosphorus, magnesium and hydroxyproline in the femoral trabecular and cortical bone and in the thoracic vertebrae from male rats flown on the 7-day 'Spacelab-3 Mission' were measured by density gradient analysis. In rats exposed to a spaceflight environment, profiles of the matrix and mineral moieties were shifted toward both the lower (vertebrae) and higher density fractions (femurs and vertebrae), patterns indicating a decrease in bone growth/turnover. X-Ray diffraction of vertebrae indicated that spaceflight is associated with a decrease in apatite crystal size/perfection.

Bone deficit in ovariectomized rats. Functional contribution of the marrow stromal cell population and the effect of oral dihydrotachysterol treatment

This study investigates the proliferative and osteogenic role of marrow stromal/osteoprogenitor cells in the development of the cortical bone deficit in ovariectomized (OVX) female rats. In vitro, clonal growth of marrow stromal cells from OVX rats was significantly impaired (vs. sham-operated controls). Yet in vivo, cells from sham-operated and OVX rats had equal osteogenic potential in several in vivo experimental situations, such as in intraperitoneally implanted millipore diffusion chambers and in intramuscular implants of marrow plus osteoinductive bone matrix (composite grafts). Long-term (6 mo) dihydrotachysterol (DHT) treatment of OVX rats enhanced their in vitro proliferative potential and clonal growth, as well as their osteogenic expression in composite grafts. The observation that the in vivo osteogenic performance of OVX rat marrow stromal cells was normal at extraosseous sites suggests that the mechanisms leading to osteopenia may involve an abnormality in cell-matrix interactions.

The changes in quality of mandibular bone mineral in otherwise totally immobilized rhesus monkeys

The status of bone mineral and osteocalcin in the young adult Rhesus monkey mandible was assessed following a 14-day period of postcranial immobilization, and after 7- and 28-day recovery periods. Specimens of cortical bone taken from the compact bone at the inferior border of the jaws were ground in liquid nitrogen and sieved to a particular size below 20 micron. The bone powder was then fractionated in a bromoform-toluene density gradient to determine its mineralization profile (Ca, P, CO3, and osteocalcin), and X-ray diffraction was used to determine apatite crystal size in some fractions. There was no change in the chemistry of the mandibular bone from the immobilized animals. However, the mineralization profile in that group showed a significant shift toward the higher density fractions, indicating the presence of a greater than normal content of mature well-mineralized bone. While this trend was accentuated in the jaws following a 7-day postimmobilization recovery period, partial recovery of the normal profile was observed after a 28-day recovery period. The osteocalcin profile shifted like the mineralization profile during the immobilization and recovery periods. X-ray diffraction analyses showed that the shift in the mineralization profile during the immobilization period was associated with a decrease in apatite crystal size.

Effect of rotopositioning on the growth and maturation of mandibular bone in immobilized rhesus monkeys

As part of an ongoing effort to mimic the hypokinesia and hypogravity of spaceflight, the effects of 14 d immobilization and rotopositioning on mandibular bone osteon growth (= radial rate of closure) was assessed in 12 juvenile Rhesus monkeys by tetracycline labeling. The monkeys had been restrained in a supine position and rotated 908 every 30 min through a full 3608 arc for 14 d. Osteon growth was also assessed after the immobilized/rotopositioned animals had been permitted to recover in metabolism cages for periods of 28 and 56 d. The closure rates of osteons in the cortex of the inferior border of the mandible were not abnormal during immobilization/rotopositioning or during recovery. The regression line plots yielded slopes of: Controls = 0.946-1.000; Immobilized/Rotopositioned = 1.045; 28 d Recovery = 0.833; 56 d Recovery = 0.829. Microradiographs indicated a normal distribution of osteons of different mineral density: lowly (28%), moderately (53%), and highly mineralized (18%). Bone porosity values also remain within the normal range (18.3 6 4.1%). These results suggested that 14 d immobilization/rotopositioning did not effect abnormal changes in the rates of bone formation and mineralization in the mandibular cortex of the juvenile Rhesus monkey.

Fracture healing perspectives

This paper reviews the sequence of histomorphologic changes that occur in and around a fracture site, and discusses recent concepts about the roles of the cells and bone matrical moieties in promoting specific cell transformations during the phases of callus tissue formation and consolidation of the bony cortex. Current knowledge about the roles of autocrine, paracrine, and endocrine polypeptide growth and transforming factors lends new perspectives about this classic problem in bone physiology.

In vitro evaluation of circadian patterns of bone collagen formation

The circadian patterns of bone collagen formation were studied in vitro to ascertain whether the biorhythmic profiles previously measured in vivo reflect true differences in collagen synthesis. Alteration of amino acid pool sizes did not negate the circadian-stage differences in bone collagen production. Evaluations of proline uptake and transport, as well as collagenous protein turnover, demonstrated that the intracellular assembly and secretion of bone collagenous protein during the dark span is truly decreased relative to that during the light period. It was further affirmed that PTH is essential for maintenance of the normal circadian collagen synthesis rhythms.

Effect of an adrenocorticotropin analogue, ACTH 1-17, on DNA synthesis in murine metaphyseal bone

The effects of injections of a synthetic adrenocorticotropin (ACTH 1-17, Synchrodyn) on the rate of DNA labeling in the metaphyseal bone of CD2F1 mice were tested on a chronopharmacological dosing schedule. Groups of mice that had been conditioned to a 12-hr light/12-hr dark schedule were injected at one of six different timepoints, 4 hr apart, during a single 24-hr span with either a low (0.02 I.U./kg) or a high (20 I.U./kg) dose of ACTH 1-17. Control groups received injections of a placebo at corresponding timepoints. Subgroups of mice were injected with [3H]thymidine ([3H]Tdr) to follow the changes in DNA labeling in the proximal tibial metaphysis at 15 min and 2, 4, 8, 12 and 24 hr after ACTH 1-17 or placebo treatment. All mice were injected with the isotope 30 min before killing, except for those killed 15 min after Rx administration where the isotope had been injected 14 min before killing. The data were analyzed both by analysis of variance and by the cosinor method, the latter of which tests the fit of a 24-hr cosine curve to the data. The effect of ACTH 1-17 on the target cell population was dependent not only upon the dose but upon the time of administration. Both doses exerted time-dependent action, ranging from stimulation to inhibition of DNA labeling. Inhibition was noted when the ACTH 1-17 was administered at 2 hr after the beginning of the daily dark span when nocturnal animals become active. When administered at this circadian stage, the larger dose in particular was associated with an inhibition of DNA labeling lasting for 24 hr. The inhibitory effect was much shorter when the same dose was injected 4 hr earlier. Moreover, the large ACTH 1-17 dose had a stimulatory effect lasting for 24 hr when it was administered 2 hr after the onset of the daily light span, with a much shorter stimulation following administration of the large dose at 6 hr after the beginning of the daily dark span. A circadian stage-dependent stimulation or inhibition of DNA labeling at 2 or 14 hr after light onset, respectively, was thus complemented by an initial inhibition followed by stimulation and vice versa at 10 and 18 hr after light onset respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of fixation devices on radiostrontium clearance in the intact canine femur

Femoral metaphyseal/diaphyseal blood flow was studied by 85Sr clearance in unfractured segments of dog femurs following compression plating and various control procedures (drilling with and without application of screws). The animals were tested as early as seven days and as late as two months after surgery. The only statistically significant change in strontium clearance (SrC) was an increase produced by the application of stainless-steel bone screws, with or without plates. The presence or absence of compression had no consistent effect on changes in the rate of SrC. During the period of study, no changes in bone mineralization, haversian porosity, or cortical bone thickness accompanied the SrC alterations.

3-D femoral stress analysis using CT scans and p-version FEM

The potential of the finite element method as a computational aid for making objective clinical decisions has not yet been exploited due to the unreliability of the results obtained. The main reasons for this may be attributed to the poor quality of the finite elements available in the conventional softwares, improper modeling of the three dimensional problem, and errors introduced by incorrect representation of geometry and material properties. Herein, we report an attempt to derive a three-dimensional finite element model for the adult human femur which permits reliable representation of the local stress patterns. The geometry was obtained by serial computed tomography scans. The mechanical properties were based on laboratory tests and information available in the literature. The analysis is performed with a new generation software. Preliminary results suggest that the scheme could be automated and used for in vivo analysis.

Adrenal/parathyroid regulation of DNA, collagen and protein synthesis in rat epiphysial cartilage and bone

Young, growing rats which had been chronically (2 weeks) adrenalectomized or parathyroidectomized were used to define the roles of the adrenal and parathyroid glands on the maintenance of normal circadian rhythms of DNA, collagen and non-collagen protein synthesis in the skeleton. The animals were conditioned to food being available ad libitum and to 12 h light: 12 h darkness (lights on from 08.00 to 20.00 h). The pace of DNA, collagen and non-collagen protein synthesis in different regions of the tibia (tibial growth cartilage, metaphysial bone and diaphysial bone) was measured by the in-vivo incorporation of tritiated thymidine (1 h) and radioactive proline (48 h). In intact rats there were no regional differences in the phasing of the circadian profiles; peak DNA and non-collagen protein synthesis occurred at the onset of the dark period while peak collagen synthesis occurred during the middle of the period of light. Adrenalectomy selectively abolished the regional DNA synthesis rhythms without altering the phases of the serum Ca and phosphorus (P) rhythms, which peak at mid-day and at the onset of darkness respectively. Parathyroidectomy abolished the regional rhythms for collagen and non-collagen protein synthesis and serum Ca rhythms, without altering the phase of the serum P and corticosterone rhythms. Dietary Ca-lactate supplements, which raised serum Ca levels towards normal in parathyroidectomized rats, were able to correct serum corticosterone values but did not normalize bone collagen and non-collagen protein synthesis values. These data indicate that the adrenal rhythm governs the proliferative activities of bone and cartilage cells, and that parathyroid hormone is essential to maintain normal collagen and non-collagen protein synthesis rhythms.

Mineralization in rat metaphyseal bone exhibits a circadian stage dependency

Density gradient fractionation analysis of rat metaphyseal bone was used to delineate the biorhythmic changes in bone matrix mineralization. Seventy-two 4-week-old rats were entrained to 12-hr light, 12-hr dark cycles (light, 0800-2000 hr; darkness, 2000-0800 hr) for 4 weeks. All animals were fed ad lib. on Purina laboratory rat chow and tap water. Groups of 10-12 rats were killed by cervical dislocation at 4-hr intervals during a 24-hr period, and the tibias were then biopsied and frozen in liquid N2. Metaphyseal bone was fractionated via bromoformtoluene density gradients into specific gravity fractions ranging from 1.7 to 2.8. Density gradient fractions were analyzed for concentrations of calcium and inorganic phosphorus. Chronograms indicated that the accumulation of both calcium and inorganic phosphorus into the newly forming/least-dense mineral moieties of bone (1.3-1.7 sp grav) showed a single peak in the biorhythm of the rat. A statistically significant circadian rhythm of mineralization was detected for calcium (P less than 0.001) and inorganic phosphorus (P less than 0.039), with peaks during the environmental dark span. These results suggest that the physiological phasing of bone mineralization in the light-dark synchronized rat, is similar to that previously noted for cartilage mineralization and is antiphasal to the midday peak in bone collagen synthesis.

Intestinal microflora as potential modifiers of sensitizer activity in vivo

Treatment of mice (some bearing Lewis Lung tumors), with penicillin (PEN) at 500 mg/l drinking water for one week prior to treatment with misonidazole (MIS), resulted in: the elimination of their anaerobic cecal flora; a decrease in MIS-induced neurotoxicity; an increase in pharmacological exposure to MIS; a decrease in MIS chemopotentiation; a probable increase in MIS radiosensitization; an increase in MIS induced hypothermia. Assuming no chemical interaction between PEN and MIS, these observations indicate that the intestinal microflora can influence the activity of MIS in vivo. Therefore their influence should be considered in all sensitizer-related studies in vivo. The observed reduction in the neurotoxic but not the radiosensitizing potential of MIS following PEN treatment indicates a therapeutic benefit.

From bone lining cell to osteocyte--an SEM study

We describe the SEM appearance of the rat endosteal bone lining cell ( BLC ) population, and the sequence of morphological changes of these cells as they self-incorporate into unmineralized bone matrix (osteoid), establish intercellular connections, and construct lacunae. The osteoblast/nascent osteocyte series was progressively unsheathed by gentle digestion of the osteoid with 0.25% collagenase. The osteoblasts which leave the polygonally packed BLC compartment rapidly develop numerous complexly branched processes that contact the processes elaborated by previous generations of maturing and mature osteocytes. As osteoblasts mature and approach the mineralization front, they appear to lose processes. The mature cells begin to form osteocyte lacunae by depositing an asymmetric perimeter of woven collagen fibrils, such that as the cells roof-over, the lacunae appear as pocketlike constructions. The collagen fibrils on the perilacunar matrix are oriented in a tangential or circular pattern, while those in the more distal matrix are arranged in a parallel pattern. With the completion of a lacuna, its wall appears to mineralize quickly, for lacunae could be recognized only when they are forming.

The effects of spaceflight on the mineralization of rat incisor dentin

The lower incisors of Male Wistar rats flown for 18.5 days on the Soviet Cosmos-1129 Biosatellite were sectioned and chemically analyzed with an electron microprobe in order to determine whether there were specific effects of spaceflight on dentin formation/mineralization. Control tissues were obtained from rats housed under identical conditions in a land-based mock-up of the Biosatellite. The profiles of calcium (Ca), phosphorus (P), and sulfur (S) concentrations in dentin were measured in continuous traverses (1.0 micron intervals) from the pulp to the dentinoenamel junction. The incisor dentin formed during spaceflight had higher than normal (at 1G) concentrations of Ca (+ 10-15%) and P (+ 20-30%), particularly in the temporally youngest tissues within 80 micron of the pulp which had been least affected by secondary mineralization. The S-concentration profiles tended to decrease with tissue age. Fourier analysis (to determine the growth rhythms) revealed abnormal distributional patterns of S in the recently formed dentin from the Flight rats. The sulfur fluctuations in Flight animals alone periodically peaked above the irregular background fluctuations. These observations indicate that spaceflight has measureable effects on dentinogenesis, and they may also bear on the problem of the regulatory role of proteoglycans in mineralization and in the maturation of mineral and matrix moieties in skeletal tissue.

Salter innominate osteotomy. The effect of blood supply to the roof of the acetabulum

Quantitative studies of blood flow (hydrogen washout technique) and bone mineralization rate (tetracycline labeling) were performed in the ilium of 23 immature dogs before and after Salter innominate osteotomy. The vascular anatomy, blood flow rate, and mineralization rate (appositional bone growth) on the roof of the acetabulum were disturbed after operation. Radiographic healing and normal patterns of circulation to the ilium were partially restored within two weeks and completely restored after six weeks. The data suggest that a single iliac osteotomy is without long-term consequence to the viability of acetabular bone.

Growth and maturation of mandibular bone in otherwise totally immobilized rhesus monkeys

The effects of 14 days of total postcranial body immobilization (in plaster casts) on the mineralization rate and on the maturation of matrix and mineral moieties in the rhesus jaw were studied by tetracycline labeling and by density gradient methods, respectively. Immobilization did not alter the rates of periosteal and endosteal mineralization in the dense cortical bone from the lingular region of the jaw, but it did impair mineralization in osteonal bone. Osteons that continued to show radial closure did so at a normal rate. In the more trabecular cortex (premolar region) in young monkeys (3-6 kg body weight), immobilization impaired bone mineralization, as shown by lower ratios of calcium and inorganic phosphorus to hydroxyproline (Ca/HO-Pr;Pi/HO-Pr), and it reduced the rate at which the newly formed bone and mineral moieties matured. In older monkeys (6-10 kg body weight) immobilization did not alter Ca/HO-Pr and Pi/HO-Pr ratios or impair tissue maturation. These changes tended to normalize within 7 to 14 days after decasting.