Callus Volume Research Articles

Closed head experimental traumatic brain injury increases size and bone volume of callus in mice with concomitant tibial fracture.

Concomitant traumatic brain injury (TBI) and long bone fracture are commonly observed in multitrauma and polytrauma. Despite clinical observations of enhanced bone healing in patients with TBI, the relationship between TBI and fracture healing remains poorly understood, with clinical data limited by the presence of several confounding variables. Here we developed a novel trauma model featuring closed-skull weight-drop TBI and concomitant tibial fracture in order to investigate the effect of TBI on fracture healing. Male mice were assigned into Fracture + Sham TBI (FX) or Fracture + TBI (MULTI) groups and sacrificed at 21 and 35 days post-injury for analysis of healing fractures by micro computed tomography (μCT) and histomorphometry. μCT analysis revealed calluses from MULTI mice had a greater bone and total tissue volume, and displayed higher mean polar moment of inertia when compared to calluses from FX mice at 21 days post-injury. Histomorphometric results demonstrated an increased amount of trabecular bone in MULTI calluses at 21 days post-injury. These findings indicate that closed head TBI results in calluses that are larger in size and have an increased bone volume, which is consistent with the notion that TBI induces the formation of a more robust callus.

A biomechanical, micro-computertomographic and histological analysis of the influence of diclofenac and prednisolone on fracture healing in vivo.

BackgroundNon-steroidal anti-inflammatory drugs (NSAIDs) have long been suspected of negatively affecting fracture healing, although numerous disputes still exist and little data are available regarding diclofenac. Glucocorticoids interfere in this process over a similar and even broader mechanism of action. As many previously conducted studies evaluated either morphological changes or biomechanical properties of treated bones, the conjunction of both structural measures is completely missing. Therefore, it was our aim to evaluate the effects of diclofenac and prednisolone on the fracture callus biomechanically, morphologically and by 3-dimensional (3D) microstructural analysis.MethodsFemura of diclofenac-, prednisolone- or placebo-treated rats were pinned and a closed transverse fracture was generated. After 21 days, biomechanics, micro-CT (μCT) and histology were examined.ResultsThe diclofenac group showed significantly impaired fracture healing compared with the control group by biomechanics and μCT (e.g. stiffness: 57.31 ± 31.11 N/mm vs. 122.44 ± 81.16 N/mm, p = 0.030; callus volume: 47.05 ± 15.67 mm3 vs. 67.19 ± 14.90 mm3, p = 0.037, trabecular thickness: 0.0937 mm ± 0.003 vs. 0.0983 mm ± 0.003, p = 0.023), as confirmed by histology. Biomechanics of the prednisolone group showed obviously lower absolute values than the control group. These alterations were confirmed in conjunction with μCT and histology.ConclusionsThe inhibiting effects of both substances were not only mediated by absolute parameters (e.g. breaking load, BV), but we have shown, for the first time, that additional changes occurred in the microstructural bony network. Especially in patients at risk for delayed bone healing (arteriosclerosis, diabetes mellitus, smoking), the administration of these drugs should be weighed carefully.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-016-1241-2) contains supplementary material, which is available to authorized users.

Establishment of Embryogenic Cultures and Efficient Plant Regeneration System from Explants of Forced Softwood Shoots of Teak (Tectona grandis L.)

The present study highlights an efficient plant regeneration system in teak (Tectona grandis L.) using forced softwood shoots as an initial plant material. Forced softwood shoots of teak were cut to prepare shoot tip, nodal and internodal explants and cultured on Murashige and Skoog (MS) medium + NAA (1, 3, 6, 10, and 15 µmol ⋅ L−1) or TDZ (0.001, 0.01, 0.1, 1, 4, 8, 10, 12 µmol ⋅ L−1) for callus induction. Such calluses were further grown on the same levels of TDZ or 0.4, 1, 4, 8, 10 µmol ⋅ L−1 BA + 1 µmol ⋅ L−1 IBA or GA3. Callus induction was the highest with 4.55 cm3 callus volume and 5.75 g dry weight at 0.1 µmol ⋅ L−1 TDZ from shoot tips after 35 days. Embryogenic calluses were then shifted to 6, 8 or 12 µmol ⋅ L−1 TDZ + 2 µmol ⋅ L−1 BA or IBA along with 5 mmol ⋅ L−1 ascorbic acid (AA) for shoot regeneration from embryogenic cultures. The highest embryogenesis (100%) with 36.4 globular and 5.5 heart-shaped embryo-like structures was obtained at 8 µmol ⋅ L−1 TDZ + 2 µmol ⋅ L−1 BA after 63 days. Such cultures when further maintained on the same medium up to 150 days resulted in 100% shoot regeneration with 16.4 mean shoots. Shoots were elongated up to 50 mm on agar medium + 8 µmol ⋅ L−1 BA + 1 µmol ⋅ L−1 GA3. An efficient rooting response (70%) was achieved having 4.50 mean number and 49.10 mm root length at 8 µmol ⋅ L−1 IBA + 8 µmol ⋅ L−1 NAA + 0.1% activated charcoal after 36 days. Rooted shoots were acclimatized in glasshouse, achieving 56.6% plantlet survival.

Does cefuroxime alter fracture healing in vivo? A micro-computertomographic, biomechanical, and histomorphometric evaluation using a rat fracture model.

Cefuroxime is widely used for antibiotic prophylaxis in orthopedic surgery. However, a recent study indicated a dose-dependent reduction in osteoblast function in vitro. Nevertheless, cell culture might not sufficiently imitate the complex process of bone remodeling. As data concerning possible in vivo interactions of cefuroxime on fracture healing are completely missing, we investigated the following hypothesis: Does Cefuroxime impair bone healing in vivo? Therefore, 34 male Wistar rats were randomised to cefuroxime-treated or control groups, a Kirschner wire was inserted into right femora and closed transverse fractures were produced. Twenty-one days later, the structural properties of the fracture callus in the early fracture healing phase were evaluated via a combination of micro-CT (μCT), biomechanics and histology. µCT demonstrated similar values in the cefuroxime and control group (e.g., callus volume: 67.19 ± 14.90 mm3 vs. 55.35 ± 6.74 mm3 , p = 0.12; density: 635.48 ± 14.81 mg HA/cm3 vs. 647.87 ± 13.01 mg HA/cm3 , p = 0.16). Biomechanically, similar values were again determined between the groups, in terms of both maximum load (77.65 ± 41.82 vs. 78.54 ± 20.52, p = 0.95) and stiffness (122.44 ± 81.16 vs. 123.74 ± 60.08, p = 0.97). Histological findings were consistent with the radiographic results. Thus, no relevant differences between the cefuroxime and control groups could be found and the reported negative effects on osteoblasts in vitro were not confirmed in vivo by using standard concentrations of cefuroxime. In conclusion, cefuroxime can reasonably be recommended in a clinical setting as an antibiotic therapy when fracture healing is involved. However, supraphysiological doses were not evaluated, which may be present when cefuroxime is used as an additive to bone cement and released over time. Therefore, future studies should evaluate the in vivo effects of prolonged high cefuroxime doses on implant incorporation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2282-2291, 2017.

Does Anticoagulant Medication Alter Fracture-Healing? A Morphological and Biomechanical Evaluation of the Possible Effects of Rivaroxaban and Enoxaparin Using a Rat Closed Fracture Model.

Low molecular weight heparin (LMWH) is routinely used to prevent thromboembolism in orthopaedic surgery, especially in the treatment of fractures or after joint-replacement. Impairment of fracture-healing due to increased bone-desorption, delayed remodelling and lower calcification caused by direct osteoclast stimulation is a well-known side effect of unfractioned heparin. However, the effect of LMWH is unclear and controversial. Recent studies strongly suggest impairment of bone-healing in-vitro and in animal models, characterized by a significant decrease in volume and quality of new-formed callus. Since October 2008, Rivaroxaban (Xarelto) is available for prophylactic use in elective knee- and hip-arthroplasty. Recently, some evidence has been found indicating an in vitro dose independent reduction of osteoblast function after Rivaroxaban treatment. In this study, the possible influence of Rivaroxaban and Enoxaparin on bone-healing in vivo was studied using a standardized, closed rodent fracture-model. 70 male Wistar-rats were randomized to Rivaroxaban, Enoxaparin or control groups. After pinning the right femur, a closed, transverse fracture was produced. 21 days later, the animals were sacrificed and both femora harvested. Analysis was done by biomechanical testing (three-point bending) and micro CT. Both investigated substances showed histomorphometric alterations of the newly formed callus assessed by micro CT analysis. In detail the bone (callus) volume was enhanced (sign. for Rivaroxaban) and the density reduced. The bone mineral content was enhanced accordingly (sign. for Rivaroxaban). Trabecular thickness was reduced (sign. for Rivaroxaban). Furthermore, both drugs showed significant enlarged bone (callus) surface and degree of anisotropy. In contrast, the biomechanical properties of the treated bones were equal to controls. To summarize, the morphological alterations of the fracture-callus did not result in functionally relevant deficits.

Local pamidronate influences fracture healing in a rodent femur fracture model: an experimental study.

BackgroundBisphosphonates are a main component in the therapy of osteoporosis and other bone resorptive diseases. Previous studies have shown a positive effect of systemically applied bisphosphonates on fracture healing. Nevertheless high doses are related to side effects like osteonecrosis of the jaw, nephrotoxis and gastrointestinal symptoms. In this study we investigated the effect of locally applied pamidronate on fracture healing.MethodsIn a rodent model a simple femur fracture was set in female Wistar rats. We performed intramedullary fixation of the fracture and placed a collagen matrix around the fracture area. One group was treated with pamidronate, the other group with placebo via the matrix.To investigate the volume and quality of the callus we used micro-CT (μCT) and histology after 14 and 28 days.ResultsOur results show a positive influence of local applied pamidronate on callus volume. After 14 days an insignificant increase of callus volume in the treated animals was seen. 28 days after trauma the increase of callus volume in the treatment group was significantly higher in comparison to the control group. Osteonecrosis was not seen.ConclusionsLocally applied bisphosphonates increase the callus volume in fracture healing.

Dynamic Stabilization with Active Locking Plates Delivers Faster, Stronger, and More Symmetric Fracture-Healing.

Axial dynamization of fractures can promote healing, and overly stiff fixation can suppress healing. A novel technology, termed active plating, provides controlled axial dynamization by the elastic suspension of locking holes within the plate. This prospective, controlled animal study evaluated the effect of active plates on fracture-healing in an established ovine osteotomy model. We hypothesized that symmetric axial dynamization with active plates stimulates circumferential callus and delivers faster and stronger healing relative to standard locking plates. Twelve sheep were randomly assigned to receive a standard locking plate or an active locking plate for stabilization of a 3-mm tibial osteotomy gap. The only difference between plates was that locking holes of active plates were elastically suspended, allowing up to 1.5 mm of axial motion at the fracture. Fracture-healing was analyzed weekly on radiographs. After sacrifice at nine weeks postoperatively, callus volume and distribution were assessed by computed tomography. Finally, to determine their strength, healed tibiae and contralateral tibiae were tested in torsion until failure. At each follow-up, the active locking plate group had more callus (p < 0.001) than the standard locking plate group. At postoperative week 6, all active locking plate group specimens had bridging callus at the three visible cortices. In standard locking plate group specimens, only 50% of these cortices had bridged. Computed tomography demonstrated that all active locking plate group specimens and one of the six standard locking plate group specimens had developed circumferential callus. Torsion tests after plate removal demonstrated that active locking plate group specimens recovered 81% of their native strength and were 399% stronger than standard locking plate group specimens (p < 0.001), which had recovered only 17% of their native strength. All active locking plate group specimens failed by spiral fracture outside the callus zone, but standard locking plate group specimens fractured through the osteotomy gap. Symmetric axial dynamization with active locking plates stimulates circumferential callus and yields faster and stronger healing than standard locking plates. The stimulatory effect of controlled motion on fracture-healing by active locking plates has the potential to reduce healing complications and to shorten the time to return to function.

An artificial intelligence approach for modeling volume and fresh weight of callus – A case study of cumin (Cuminum cyminum L.)

Cumin (Cuminum cyminum Linn.) is valued for its aroma and its medicinal and therapeutic properties. A supervised feedforward artificial neural network (ANN) trained with back propagation algorithms, was applied to predict fresh weight and volume of Cuminum cyminum L. calli. Pearson correlation coefficient was used to evaluate input/output dependency of the eleven input parameters. Area, feret diameter, minor axis length, perimeter and weighted density parameters were chosen as input variables. Different training algorithms, transfer functions, number of hidden nodes and training iteration were studied to find out the optimum ANN structure. The network with conjugate gradient fletcher-reeves (CGF) algorithm, tangent sigmoid transfer function, 17 hidden nodes and 2000 training epochs was selected as the final ANN model. The final model was able to predict the fresh weight and volume of calli more precisely relative to multiple linear models. The results were confirmed by R2≥0.89, R(i)≥0.94 and T value ≥0.86. The results for both volume and fresh weight values showed that almost 90% of data had an acceptable absolute error of ±5%.

Automated measurement of fracture callus in radiographs using portable software.

The development of software applications that assist the radiographic evaluation of fracture healing could advance clinical diagnosis and expedite the identification of effective treatment strategies. A radiographic feature regularly used as an outcome measure for basic and clinical fracture healing research is new bone growth, or fracture callus. In this study, we developed OrthoRead, a portable software application that uses image-processing algorithms to detect and measure fracture callus in plain radiographs. OrthoRead utilizes an optimal boundary tracking algorithm to semi-automatically segment the cortical surface, and a novel iterative thresholding selection algorithm to then automatically segment the fracture callus. The software was validated in three steps. First, algorithm accuracy and sensitivity were analyzed using surrogate models with known callus size. Second, the callus area of distal femur fractures measured using OrthoRead was compared to callus area manually outlined by orthopaedic surgeons. Third, the callus area of ovine tibial fractures was measured using OrthoRead and compared to callus volume measured from micro-CT. The software had less than a 5% error in measuring surrogate callus, and was insensitive to changes in image resolution, image rotation, and the size of the analyzed region of interest. Strong positive correlations existed between OrthoRead and clinicians (R(2) = 0.98), and between 2D callus area and 3D callus volume (R(2) = 0.70). The average run time for OrthoRead was 3 s when using a 2.7 GHz processor. By being accurate, fast, and robust, OrthoRead can support prospective and retrospective clinical studies investigating implant efficacy, and can assist research on fracture healing mechanobiology. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1224-1233, 2016.

Effect of Pulsed Wave Low-Level Laser Therapy on Tibial Complete Osteotomy Model of Fracture Healing With an Intramedullary Fixation.

Background:Fractures pose a major worldwide challenge to public health, causing tremendous disability for the society and families. According to recent studies, many in vivo and in vitro experiments have shown the positive effects of PW LLLT on osseous tissue.Objectives:The aim of this study was to evaluate the outcome of infrared pulsed wave low-level laser therapy (PW LLLT) on the fracture healing process in a complete tibial osteotomy in a rat model, which was stabilized by an intramedullary pin.Materials and Methods:This experimental study was conducted at Shahid Beheshti University of Medical Sciences in Tehran, Iran. We performed complete tibial osteotomies in the right tibias for the population of 15 female rats. The rats were divided randomly into three different groups: I) Control rats with untreated bone defects; II) Rats irradiated by a 0.972 J/cm2 PW LLLT; and III) Rats irradiated by a 1.5 J/cm2 PW LLLT. The right tibias were collected six weeks following the surgery and a three-point bending test was performed to gather results. Immediately after biomechanical examination, the fractured bones were prepared for histological examinations. Slides were examined using stereological method.Results:PW LLLT significantly caused an increase in maximum force (N) of biomechanical repair properties for osteotomized tibias in the first and second laser groups (30.0 ± 15.9 and 32.4 ± 13.8 respectively) compared to the control group (8.6 ± 4.5) LSD test, P = 0.019, P = 0.011 respectively). There was a significant increase in the osteoblast count of the first and second laser groups (0.53 ± 0.06, 0.41 ± 0.06 respectively) compared to control group (0.31 ± 0.04) (LSD test, P = 0001, P = 0.007 respectively).Conclusions:This study confirmed the efficacy of PW LLLT on biomechanical strength, trabecular bone volume, callus volume, and osteoblast number of repairing callus in a complete tibial osteotomy animal model at a relatively late stage of the bone healing process.

The effect of semaphorin 3A on fracture healing in osteoporotic rats

BackgroundsSemaphorin 3A (Sema3A) was demonstrated to exert an osteoprotective effect by both inhibiting osteoclastic bone resorption and promoting osteoblastic bone formation. The effect of Sema3A on fracture healing of osteoporotic rats was investigated in this study. MethodsTwelve weeks after bilateral ovariectomy, all animals underwent unilateral transverse osteotomy on the proximal tibiae, and were then randomly divided into two groups. Rats received vehicle (control) or weekly local injection of Sema3A (500μg/kg) into the injury site (group Sema3A) after fracture surgery until sacrifice at 4 and 8weeks. Specimens were harvested and examined by radiography, iDXA, histology, micro-CT, and three-point bending test. ResultsCompared to control, Sema3A treatment significantly increased bone mineral density, percent bone volume and biomechanical strength of the callus at 4 and 8weeks post-fracture. At 8weeks after fracture, the bone volume of callus showed no difference between groups, while the average cross-sectional area of callus in the control group was 43.8% higher than that of Sema3A group. Histological images showed increased callus formation at 4weeks post-fracture and better callus ossification in the Sema3A group, while callus remodeling in the control group seemed to be delayed and not well bridged. ConclusionsResults in this study indicated that Sema3A treatment increased callus volume and density at 4weeks post-fracture, and induced promoted callus ossification and remodeling at 8weeks post-fracture compared to control.

Individual and combined effects of noise-like whole-body vibration and parathyroid hormone treatment on bone defect repair in ovariectomized mice.

The effectiveness of intermittent administration of parathyroid hormone and exposure to whole-body vibration on osteoporotic fracture healing has been previously investigated, but data on their concurrent use are lacking. Thus, we evaluated the effects of intermittent administration of parathyroid hormone, whole-body vibration, and their combination on bone repair in osteoporotic mice. Noise-like whole-body vibration with a broad frequency range was used instead of conventional sine-wave whole-body vibration at a specific frequency. Mice were ovariectomized at 9 weeks of age and subjected to drill-hole surgery in the right tibial diaphysis at 11 weeks. The animals were divided into four groups (n = 12 each): a control group, and groups treated with intermittent administration of parathyroid hormone, noise-like whole-body vibration, and both. From postoperative day 2, the groups treated with intermittent administration of parathyroid hormone and groups treated with both intermittent administration of parathyroid hormone and noise-like whole-body vibration were subcutaneously administered parathyroid hormone at a dose of 30 µg/kg/day. The groups treated with noise-like whole-body vibration and groups treated with both intermittent administration of parathyroid hormone and noise-like whole-body vibration were exposed to noise-like whole-body vibration at a root mean squared acceleration of 0.3g and frequency components of 45-100 Hz for 20 min/day. Following 18 days of interventions, the right tibiae were harvested, and the regenerated bone was analyzed by micro-computed tomography and nanoindentation testing. Compared with the control group, callus volume fraction was 40% higher in groups treated with intermittent administration of parathyroid hormone and 73% higher in groups treated with both intermittent administration of parathyroid hormone and noise-like whole-body vibration, and callus thickness was 35% wider in groups treated with both intermittent administration of parathyroid hormone and noise-like whole-body vibration. Indentation modulus was 46% higher in groups treated with noise-like whole-body vibration and 43% higher in groups treated with both intermittent administration of parathyroid hormone and noise-like whole-body vibration, and hardness was 31% higher in groups treated with both intermittent administration of parathyroid hormone and noise-like whole-body vibration compared with the control group. There was no interaction between the two treatments for both structure and mechanical indexes. The main effects of intermittent administration of parathyroid hormone and noise-like whole-body vibration on bone repair included increased bone formation and enhanced mechanical function of regenerated bone, respectively. The combined treatment resulted in further regeneration of bone with high indentation modulus and hardness, suggesting the therapeutic potential of the combined use of noise-like whole-body vibration and intermittent administration of parathyroid hormone for enhancing osteoporotic bone healing.

Osteogenic progenitors in bone marrow aspirates have clinical potential for tibial non-unions healing in diabetic patients

There is a significantly higher incidence of delayed unions, non-unions, and increased healing time in diabetic patients compared with non-diabetic patients. Studies suggest that diabetics suffer from deficiencies of pancreatic stem/progenitor cells, and a clinically relevant question arises concerning the availability and functionality of progenitor cells obtained from bone marrow of diabetics for applications in bone repair. We have evaluated the cellularity and frequency of osteogenic mesenchymal stem cells (MSCs) in bone marrow from 54 diabetic patients (12 with type 1 and 42 with type 2) with tibial non-unions. These patients were treated with bone marrow MSCs (BM-MSCs) delivered in an autologous bone marrow concentrate (BMC). Clinical outcomes and marrow cellularity were compared to 54 non-diabetic, matched patients with tibial non-unions also treated with BMC. After adjusting for age and sex, no differences were identified with respect to bone marrow cellularity and MSC number among the diabetic and non-diabetic groups and both groups received approximately the same number of MSCs on average. BMC treatment promoted non-union healing in 41 diabetic patients (76%) and 49 non-diabetic patients (91%), but the non-diabetic patients healed more quickly and produced a larger volume of callus. We recommend that diabetic patients be treated with an increased number of progenitor cells by increasing the bone marrow aspiration volume. We also anticipate a need to extend the time of casting and non-weight bearing for diabetic patients as compared with non-diabetic patients.

Deficiency of inducible and endothelial nitric oxide synthase results in diminished bone formation and delayed union and nonunion development

BackgroundBetween 5% and 10% of all fractures fail to heal adequately resulting in nonunion of the fracture fragments. This can significantly decrease a patient's quality of life and create associated psychosocial and socio-economic problems.Nitric oxide (NO) and nitric oxide synthases (NOS) have been found to be involved in fracture healing, but until now it is not known if disturbances in these mechanisms play a role in nonunion and delayed union development. In this study, we explored the role of endothelial and inducible NOS deficiency in a delayed union model in mice. Materials and methodsA 0.45mm femur osteotomy with periosteal cauterization followed by plate-screw osteosynthesis was performed in the left leg of 20–24week old wild type, Nos2−/− and Nos3−/− mice. Contralateral unfractured legs were used as a control. Callus volume was measured using micro-computed tomography (μCT) after 28 and 42days of fracture healing. Immuno histochemical myeloperoxidase (MPO) staining was performed on paraffin embedded sections to assess neutrophil influx in callus tissue and surrounding proximal and distal marrow cavities of the femur. After 7 and 28days of fracture healing, femurs were collected for amino acid and RNA analysis to study arginine-NO metabolism. ResultsWith μCT, delayed union was observed in wild type animals, whereas in both Nos2−/− and Nos3−/− mice nonunion development was evident. Both knock-out strains also showed a significantly increased influx of MPO when compared with wild type mice. Concentrations of amino acids and expression of enzymes related to the arginine-NO metabolism were aberrant in NOS deficient mice when compared to contralateral control femurs and wild type samples. Discussion and conclusionIn the present study we show for the first time that the absence of nitric oxide synthases results in a disturbed arginine-NO metabolism and inadequate fracture healing with the transition of delayed union into a nonunion in mice after a femur osteotomy. Based on these data we suggest that the arginine-NO metabolism may play a role in the prevention of delayed unions and nonunions.

Systemic Treatment with Strontium Ranelate Does Not Influence the Healing of Femoral Mid-shaft Defects in Rats.

Strontium ranelate (SrR) has both bone anabolic and anti-resorption properties and has therefore the potential to increase the healing of bone defects. The aim of the present study was to investigate the effect of systemic treatment with SrR during the healing of cortical bone defects in rats. In addition, the vertebral bodies were examined in order to elucidate the effect of short-term treatment with SrR on intact trabecular bone. Sixty 16-week-old female Wistar rats were randomized into four groups. A cylindrical defect was drilled through the anterior cortex of the mid-femoral diaphysis in both hind limbs. Two of the groups were treated with SrR (900 mg/kg b.w.) mixed into the food and two groups served as controls. The animals were euthanized after either 3 or 8 weeks of treatment. Healing of the defects was analyzed with µCT, mechanical testing, and stereology. Treatment with SrR resulted in increased thickness of the defects after 3 weeks of treatment, whereas no effect on bone volume fraction (BV/TV), mechanical properties (maximum strength and maximum stiffness), periosteal callus volume, or osteoclast-covered bone surfaces (Oc.S/BS) after either 3 or 8 weeks of treatment was found. Furthermore, SrR increased the bone material density (ρ) of the vertebral bodies, and tended to increase BV/TV after 8 weeks of treatment (p = 0.087). The mechanical properties of the vertebral bodies were not influenced by SrR treatment. In conclusion, 3 weeks of treatment with SrR increased the thickness of the healing mid-femoral cortical bone defects in rats, but did not influence BV/TV, mechanical properties, periosteal callus volume, or Oc.S/BS after either 3 or 8 weeks. Furthermore, SrR had no effect on the microstructure and mechanical properties of the vertebral bodies.

Effect of osteoporosis medications on fracture healing.

Antiosteoporotic medications are often used to concurrently treat a patient's fragility fractures and underlying osteoporosis. This review evaluates the existing literature from animal and clinical models to determine these drugs' effects on fracture healing. The data suggest that these medications may enhance bone healing, yet more thorough prospective studies are warranted. Pharmacologic agents that influence bone remodeling are an essential component of osteoporosis management. Because many patients are first diagnosed with osteoporosis when presenting with a fragility fracture, it is critical to understand how osteoporotic medications influence fracture healing. Vitamin D and its analogs are essential for the mineralization of the callus and may also play a role in callus formation and remodeling that enhances biomechanical strength. In animal models, antiresorptive medications, including bisphosphonates, denosumab, calcitonin, estrogen, and raloxifene, do not impede endochondral fracture healing but may delay repair due to impaired remodeling. Although bisphosphonates and denosumab delay callus remodeling, they increase callus volume and result in unaltered biomechanical properties. Calcitonin increases cartilage formation and callus maturation, resulting in improved biomechanical properties. Parathyroid hormone, an anabolic agent, has demonstrated promise in animal models, resulting in accelerated healing with increased callus volume and density, more rapid remodeling to mature bone, and improved biomechanical properties. Clinical data with parathyroid hormone have demonstrated enhanced healing in distal radius and pelvic fractures as well as postoperatively following spine surgery. Strontium ranelate, which may have both antiresorptive and anabolic properties, affects fracture healing differently in normal and osteoporotic bone. While there is no effect in normal bone, in osteoporotic bone, strontium ranelate increases callus bone formation, maturity, and mineralization; forms greater and denser trabeculae; and improves biomechanical properties. Further clinical studies with these medications are needed to fully understand their effects on fracture healing in order to simultaneously treat fragility fractures and underlying osteoporosis.

Genetic modification of Rosa pinna (Clerodendrum philippinum Schauer) with gai mutant gene for improved plant architecture

Rosa pinna ( Clerodendrum philippinum Schaue r), is a shrub with attractive and fragrant flowers. However, the tall and spread architecture and high leaf to flower ratio hinder its use as an ornamental plant. Hence, changing the level of acceptance of C. philippinum by incorporating a dwarfing gene to the plant is considered useful. A study was conducted to find a suitable regeneration medium and ultimately to modify the plant architecture through transformation of the gibberellic acid inhibitor (gai) mutant dwarfing gene by particle bombardment. Effects of different concentrations of thidiazuron (TDZ:Nphenyl N’ 1,2,3-thidiazol-5-yl urea) on callus initiation and regeneration of shoots and the effects of micro career flying distance in gene transformation of C. philippinum were investigated. The regenerated shoots were first cultured on hormone free MS medium and transferred to a MS medium with 0.5 mg/L in dole butyric acid for rooting after four weeks. The shortest duration for callus initiation, the largest callus volume (28 days after establishment) and the highest number of shoots (75 days after establishment) were observed in 1.5 mg/L TDZ in the MS medium. Results of transferring the gai mutant gene to in vitro leaves of C. philippinum revealed that both the shortest time duration and the highest plant regeneration were at 9 cm micro-carrier flying distance. Leaf tissues of regenerated plants, which carry the gai mutant gene, positively responded for the beta-glucuronidase (GUS) assay. The regenerated shoots were rooted and successfully acclimatized. Tropical Agricultural Research Vol. 25 (1): 27-37 (2013)

Impaired Fracture Healing Caused by Deficiency of the Immunoreceptor Adaptor Protein DAP12.

Osteoclasts play an important role in bone metabolism, but their exact role in fracture healing remains unclear. DAP12 is an immunoadaptor protein with associated immunoreceptors on myeloid lineage cells, including osteoclasts. Its deficiency causes osteopetrosis due to suppression of osteoclast development and activation. In this report, we assessed the impact of DAP12 on the fracture healing process using C57BL/6 (B6) and DAP12–/– mice. Healing was evaluated using radiography, micro-CT, histology, immunohistochemistry and real-time RT-PCR. Radiography showed lower callus volume and lower callus radiolucency in DAP12–/– mice during later stages. Micro-CT images and quantitative structural analysis indicated that DAP12–/– mice developed calluses of dense trabecular structures and experienced deteriorated cortical shell formation on the surface. Histologically, DAP12–/– mice showed less cartilaginous resorption and woven bone formation. In addition, prominent cortical shell formation was much less in DAP12–/– mice. Immunohistochemistry revealed lower invasion of F4/80 positive monocytes and macrophages into the fracture hematoma in DAP12–/– mice. The expression levels of Col1a1, Col2a1 and Col10a1 in DAP12–/– mice increased and subsequently became higher than those in B6 mice. There was a decrease in the gene expression of Tnf during the early stages in DAP12–/– mice. Our results indicate that DAP12 deficiency impairs fracture healing, suggesting a significant role of DAP12 in the initial inflammatory response, bone remodeling and regeneration.

Local application of a proteasome inhibitor enhances fracture healing in rats.

The ubiquitin/proteasome system plays an important role in regulating the activity of osteoblast precursor cells. Proteasome inhibitors (PSIs) have been shown to stimulate the differentiation of osteoblast precursor cells and to promote bone formation. This raises the possibility that PSIs might be useful for enhancing fracture healing. In this study, we examined the effect of the local administration of PSI on fracture repair in rats. The effects of treatment on the healing of a fractured femur were assessed based on radiographs, micro-computed tomography (μCT) analysis, biomechanical testing, and histological analysis. PSI enhanced osteogenic differentiation in bone marrow- and periosteum-derived mesenchymal progenitor cells in vitro. Moreover, the local administration of PSI in vivo promoted fracture healing in rats, as demonstrated by an increased fracture callus volume in radiographs at 2 weeks post-fracture, and improved radiographic scores. By week 4, PSI treatment had enhanced biomechanical strength and mineral density in the callus as assessed using bending tests, and μCT, respectively. Histological sections demonstrated that PSI treatment accelerated endochondral ossification during the early stages of fracture repair. Although further investigations are necessary to assess its clinical use, the local administration of PSIs might be a novel, and effective therapeutic approach for fracture repair.

In Vivo Mechanical Characterization of the Distraction Callus During Bone Consolidation.

Understanding the evolution of callus mechanical properties over time provides insights in the mechanobiology of fracture healing and tissue differentiation, can be used to validate numerical models, and informs clinical practice. Bone transport experiments were performed in sheep, in which a distractor type Ilizarov was implanted. The forces through the fixator evolution were measured and the callus stiffness was estimated from these forces. Computerized tomography images were taken and bone volume of the callus at different stages was obtained. The results showed that the maximum bone tissue production rate (0.146 cm³/day) was achieved 20 days after the end of the distraction phase. 50 days after the end of the distraction phase, the callus was ossified completely and had its maximum volume, 6-10 cm³ In addition, 80-90% of the load sustained by the operated limb was recovered and the callus stiffness increased exponentially until 5.4-11.4 kN/mm, still below 10% of the healthy level of callus stiffness. The effects of the bony bridging of the callus and the time of the fixator removal on callus force, stiffness and volume were analyzed. These outcomes allowed relating quantifiable biological aspects (callus volume and tissue production rate) with mechanical parameters (callus force and stiffness) using data from the same experiment.