首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
    
Due to the annular gap between intramedullary (IM) nails and the endosteal surface, high interfragmentary movement can occur under loading. This could prolong the healing time, particularly for thin IM nails that are often used for unreamed IM nailing. The aims of our study were to determine the influence of the nail diameter on the healing time of human tibial shaft fractures and to investigate whether the healing time could be shortened by increasing the stiffness of the implant material. Therefore, a corroborated numerical model for simulating the fracture healing process in humans was used to simulate the healing process of human tibial fractures treated with IM nails. The calculated healing time (up to 71 weeks) was longest for transverse fractures treated with thin IM nails made of titanium. That the healing time was disproportionately long depended on the nail diameter, and could be greatly reduced by using a thicker nail or using steel instead of titanium. To avoid a prolonged healing time, the nail should be thick, and the annular gap should be as narrow as possible. Alternatively, using steel instead of titanium may also help to avoid a prolonged healing time.  相似文献   

2.
    
ObjectiveTo compare the biomechanical behaviors of the spatial bridge locking fixator (SBLF), single locking plate (SP), and double locking plate (DP) for AO/OTA 32‐A3.2 fractures using finite element analysis and biomechanical tests.MethodsAxial loading of 700 N was conducted on the AO/OTA 32‐A3.2 model via finite element analysis. The von Mises stress and the interfragmentary movement (IFM) were comparatively analyzed in the three configurations above. On the mechanical tester, axial and torsional loading of 30 synthetic femurs (five specimens of each configuration for each test at random) was performed, and the interfragmentary movement, torsion angle, stiffness, and ultimate load were recorded and analyzed.ResultsThe finite element analysis (FEA) results showed that the von Mises stress of the spatial bridge locking fixator (SBLF) was lower than that of the single locking plate (SP) and higher than that of the double locking plate (DP). At 700 N, the axial IFMs were 0.15–0.38 mm (SBLF), 0.03–0.84 mm (SP), and 0.02–0.07 mm (DP). The biomechanical experiment indicated that the axial interfragmentary movements (IFMs) were 0.44 ± 0.23 mm (SBLF), 1.02 ± 0.40 mm (SP), and 0.07 ± 0.07 mm (DP) (p < 0.001). The axial IFM of the SBLF group had the highest probability (79.26%) of falling within the ideal range (0.2–0.8 mm), and the SP and DP groups had probabilities of 27.10% and 3.14%, respectively. The axial stiffness in the SBLF group (1586 ± 130 N/mm) was significantly lower than that in the DP group (10,264 ± 2671 N/mm) (p < 0.001) but greater than that in the SP group (725 ± 178 N/mm) (p = 0.396). The range of axial loads to ultimate failure was 3385–4527 N (SBLF), 3377–4664 N (SP), and 3780–4804 N (DP). The shear motion of the fracture end was 0.35 ± 0.14 mm (SBLF), 0.16 ± 0.10 mm (SP), and 0.08 ± 0.04 mm (DP) (p < 0.001). The torsional stiffness was 1.68 ± 0.14 Nm/degree (SBLF), 2.32 ± 0.29 Nm/degree (SP) (SBLF&SP, p < 0.001), and 3.53 ± 0.73 Nm/degree (DP) (SBLF&DP, p < 0.001).ConclusionsThe SBLF structure may exhibit a better biomechanical performance compared with the SP and DP in providing the best quantity and more symmetrical interfragmentary movement for AO/OTA 32‐A3.2 fractures.  相似文献   

3.
    
When using locked plating for bone fracture fixation, screw loosening is reported as one of the most frequent complications and is commonly attributed to an incorrect choice of screw configuration. Choosing a patient‐optimized screw configuration is not straightforward as there are many interdependent variables that affect device performance. The aim of the study was to evaluate the influence that locking screw configuration has on loosening risk and how this is influenced by bone quality. This study uses finite element models that incorporate cortical bone heterogeneity, orthotropy, and geometrical nonlinearity to examine the effect of screw configuration on variables associated with loosening and interfragmentary motion. Strain levels within the bone were used as indicators of regions that may undergo loosening. The study found that, in healthy bone under axial loading, the most important variables influencing strain levels within the bone were the size of the bridging span (working length) and the plate rigidity. Unlike healthy bone, osteoporotic bone was found to be particularly sensitive to the spacing of the screws within the plate. Using two empty screw holes between the screws closest to the fracture was found to reduce the strain levels at the first screw by 49% in osteoporotic bone (compared to only 2.4% in healthy bone). The study also found that under torsional loading the total number of screws used was the most important variable with a 59% reduction in the strain around the screws closest to the fracture when using six rather than four screws in osteoporotic bone. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1856–1864, 2016.  相似文献   

4.
    
Compact bone makes up approximately 80% of the human skeleton by mass; but there are little data available on the effects of increased bone turnover on compact bone mechanical and material properties. This study addresses this question by measuring intracortical remodeling, resorption cavity number, and porosity in an ovariectomized (OVX) sheep model, and measures changes in biomechanical properties. Thirty‐eight sheep were divided into two groups. Group 1 were controls (n = 19), and Group 2 were ovariectomized (OVX; n = 19). Fluorochrome dyes were administered intravenously to both groups at five time points over 12 months post‐OVX to label sites of bone turnover. At 12 months post‐OVX all animals were euthanized. Samples were harvested from the left metatarsal and were analyzed for intracortical bone turnover at five time points, the number of resorption cavities, and the level of intracortical porosity. The effects of these parameters on bone biomechanical properties were then measured. Bone turnover was increased in the OVX group at 6, 9, and 12 months (p < 0.05). Resorption was also higher in the OVX group at 12 months (p < 0.05). Furthermore, porosity was significantly increased in the OVX group at 12 months (p < 0.05). Stiffness and yield strength were reduced in the OVX group compared to controls (p = 0.05). Ultimate compressive strength and work to fracture did not differ between groups. These findings provide new insights into the mechanisms and effects of increased bone turnover on bone material and microstructural properties. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:303–309, 2009  相似文献   

5.
    
The aim of this review was to summarize the advantages and pitfalls of the available osteoporotic animal models of bone healing. A thorough literature search was performed in MEDLINE via OVID and EMBASE to identify animal studies investigating the effect of experimental osteoporosis on bone healing and bone regeneration. The osteotomy model in the proximal tibia is the most popular osseous defect model to study the bone healing process in osteoporotic-like conditions, although other well-characterized models, such as the post-extraction model, might be taken into consideration by future studies. The regenerative potential of osteoporotic bone and its response to biomaterials/regenerative techniques has not been clarified yet, and the critical size defect model might be an appropriate tool to serve this purpose. Since an ideal animal model for simulating osteoporosis does not exist, the type of bone remodeling, the animal lifespan, the age of peak bone mass, and the economic and ethical implications should be considered in our selection process. Furthermore, the influence of animal species, sex, age, and strain on the outcome measurement should be taken into account. In order to make future studies meaningful, standardized international guidelines for osteoporotic animal models of bone healing need to be set up.  相似文献   

6.
    
Although mechanical loading is known to influence trabecular bone adaptation, the role of specific loading parameters requires further investigation. Previous studies demonstrated that the number of loading cycles and loading duration modulate the adaptive response of trabecular bone in a rabbit model of applied loading. In the current study, we investigated the influence of load magnitude on the adaptive response of trabecular bone using the rabbit model. Cyclic compressive loads, producing peak pressures of either 0.5 or 1.0 MPa, were applied daily (5 days/week) at 1 Hz and 50 cycles/day for 4 weeks post‐operatively to the trabecular bone on the lateral side of the distal right femur, while the left side served as an nonloaded control. The adaptive response was characterized by microcomputed tomography and histomorphometry. Bone volume fraction, bone mineral content, tissue mineral density, and mineral apposition rate (MAR) increased in loaded limbs compared to the contralateral control limbs. No load magnitude dependent difference was observed, which may reflect the critical role of loading compared to the operated, nonloaded contralateral limb. The increased MAR suggests that loading stimulated new bone formation rather than just maintaining bone volume. The absence of a dose‐dependent response of trabecular bone observed in this study suggests that a range of load magnitudes should be examined for biophysical therapies aimed at augmenting current treatments to enhance long‐term fixation of orthopedic devices. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 930–934, 2013  相似文献   

7.
    
Compact bone makes up approximately 80% of the human skeletal mass. This study examines the effect of estrogen deficiency on compact bone turnover and associated geometrical structural adaptation over a 31‐month period in a large animal model. Twenty‐seven skeletally mature sheep were divided into control (n = 16) and ovariectomy group (OVX, n = 11). Animals were administered five different fluorochrome dyes to label intracortical bone turnover, and sacrificed at 31 months. Compact bone samples were analyzed for cortical geometry, intracortical turnover at five time points, resorption cavities, porosity, and compressive strength. Intracortical bone turnover was significantly increased in OVX, which demonstrated seasonal variation. Cross‐sectional area in OVX was significantly greater than control and was associated with an increased section modulus. Intracortical porosity was significantly increased in OVX, however, there was no significant difference in ultimate compressive strength between the groups. Our results demonstrate increased intracortical bone turnover, resportion spaces, and porosity in OVX, without adversely affecting compressive strength. Our results also support the hypothesis of geometrical adaptation of compact bone in response to estrogen deficiency. These results suggest an early structural compensatory response in compact bone, despite increased intracortical turnover. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:248–251, 2010  相似文献   

8.
    
We compared the effect of a sclerostin antibody to that of a clinically relevant dose of parathyroid hormone (PTH) in a rat model for metaphyseal bone healing. Screws of steel or poly methyl methacrylate (PMMA) were inserted bilaterally into the proximal tibia of young male rats. During 4 weeks the animals then received injections of either phosphate buffered saline (control), sclerostin antibody (25 mg/kg, twice weekly) or PTH (5 µg/kg, daily). The healing response around the screws was then assessed by mechanical testing and X‐ray microtomography (µCT). To distinguish between effects on healing and general effects on the skeleton, other untraumatized bone sites and serum biomarkers were also assessed. After 4 weeks of treatment, PTH yielded a 48% increase in screw pull‐out force compared to control (p = 0.03), while the antibody had no significant effect. In contrast, the antibody increased femoral cortical and vertebral strength where PTH had no significant effect. µCT showed only slight changes that were statistically significant for the antibody mainly at cortical sites. The results suggest that a relatively low dose of PTH stimulates metaphyseal repair (screw fixation) specifically, whereas the sclerostin antibody has wide‐spread effects, mainly on cortical bone, with less influence on metaphyseal healing. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:471–476, 2014.  相似文献   

9.
    
Fracture healing can be enhanced by load bearing, but the specific components of the mechanical environment which can augment or accelerate the process remain unknown. The ability of low‐magnitude, high‐frequency mechanical signals, anabolic in bone tissue, are evaluated here for their ability to influence fracture healing. The potential for short duration (17 min), extremely low‐magnitude (25 µm), high‐frequency (30 Hz) interfragmentary displacements to enhance fracture healing was evaluated in a mid‐diaphyseal, 3‐mm osteotomy of the sheep tibia. In a pilot study of proof of concept and clinical relevance, healing in osteotomies stabilized with rigid external fixation (Control: n = 4), were compared to the healing status of osteotomies with the same stiffness of fixation, but supplemented with daily mechanical loading (Experimental: n = 4). These 25‐µm displacements, induced by a ferroactive shape‐memory alloy (“smart” material) incorporated into the body of the external fixator, were less than 1% of the 3‐mm fracture gap, and less than 6% of the 0.45‐mm displacement measured at the site during ambulation (p < 0.001). At 10‐weeks post‐op, the callus in the Experimental group was 3.6‐fold stiffer (p < 0.03), 2.5‐fold stronger (p = 0.05), and 29% larger (p < 0.01) than Controls. Bone mineral content was 52% greater in the Experimental group (p < 0.02), with a 2.6‐fold increase in bone mineral content (BMC) in the region of the periosteum (p < 0.001). These data reinforce the critical role of mechanical factors in the enhancement of fracture healing, and emphasize that the signals need not be large to be influential and potentially clinically advantageous to the restoration of function. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 922–930, 2009  相似文献   

10.
  相似文献   

11.
    
In clinical and experimental studies an acceleration of fracture healing and increased callus formation induced by low‐intensity pulsed ultrasound (LIPUS) has been demonstrated. The exact molecular mechanisms of ultrasound treatment are still unclear. In this study ultrasound transmitted cytoskeletal and growth rate changes of SAOS‐2 cells were examined. Osteoblast‐like cell lines (SAOS‐2) were treated using low‐intensity pulsed ultrasound. Cytoskeletal changes were analyzed using rhodamine phalloidine for f‐actin staining and indirect immunofluorescence techniques with different monoclonal antibodies against several tubulin modifications. To examine changes of cell number after ultrasound treatment cell counts were done. Significant changes in cytoskeleton structure were detected compared to controls, including an enhancement of stress fiber formation combined with a loss of cell migration after ultrasound application. We further observed that sonication altered the proportion of the more stable microtubules to the more labile microtubule subclass. The labile tyrosinated microtubules appeared highly enhanced, whereas the amount of the more stable acetylated microtubules was remarkably diminished. All these observations were quantified by fluorometric measurements. The centrosomal γ‐tubulin was frequently scattered throughout the cell's cytoplasm, giving rise to additional polyglu‐positive microtubular asters, which induced multipolar spindles, leading either to aneuploid mini‐or giant cells. Moreover, a significant increase of cell number was noticed in the sonicated group. These experiments demonstrate that ultrasound treatment increases cell number and leads to significant changes of the cytoskeletal structure and composition in vitro. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:286–294, 2009  相似文献   

12.
    
Current diagnostic modalities, such as radiographs or computed tomography, exhibit limited ability to predict the outcome of bone fracture healing. Failed fracture healing after orthopaedic surgical treatments are typically treated by secondary surgery; however, the negative correlation of time between primary and secondary surgeries with resultant health outcome and medical cost accumulation drives the need for improved diagnostic tools. This study describes the simultaneous use of multiple (n = 5) implantable flexible substrate wireless microelectromechanical (fsBioMEMS) sensors adhered to an intramedullary nail (IMN) to quantify the biomechanical environment along the length of fracture fixation hardware during simulated healing in ex vivo ovine tibiae. This study further describes the development of an antenna array for interrogation of five fsBioMEMS sensors simultaneously, and quantifies the ability of these sensors to transmit signal through overlaying soft tissues. The ex vivo data indicated significant differences associated with sensor location on the IMN (p < 0.01) and fracture state (p < 0.01). These data indicate that the fsBioMEMS sensor can serve as a tool to diagnose the current state of fracture healing, and further supports the use of the fsBioMEMS as a means to predict fracture healing due to the known existence of latency between changes in fracture site material properties and radiographic changes. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1873–1880, 2019  相似文献   

13.
    
Substance P (SP) has been shown in vitro to stimulate both formation and resorption of bone. This seemingly contradictory observation could be explained by in vivo variations in skeletal loading and rate of bone turnover, features which may be explored during different phases of fracture healing. In 50 SD rats, the right tibia was fractured and fixed with an intramedullary pin in straight alignment and in anterior angulation resulting in a convex and concave side under different load. Fracture repair was assessed by radiography, histology, and semi‐quantitative immunohistochemistry of SP nerve fiber occurrence at days 7, 21, 35, 56, and 84 post‐fracture. During regeneration, days 7–35, abundant SP‐nerve ingrowth was observed in the fracture callus reaching a side‐symmetrical peak at day 21 in straight fractures. In angulated fractures, the SP peak was also observed at day 21 on the concave loaded side, but not until day 35 on the convex unloaded side. Each SP‐peak coincided with cortical bridging. During remodeling, days 35–84, a side‐symmetrical disappearance of SP‐positive fibers was seen in straight fractures. The same pattern was seen on the concave loaded side of angulated fractures. However, on the convex unloaded side, where resorption now took place, SP‐fibers remained until the end of the experiment. Our study suggests that neuronal SP during bone regeneration has a stimulatory role on bone formation, while during remodeling increased SP fiber density in unloaded areas may be related to bone resorption. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1643–1650, 2010  相似文献   

14.
    
Neuromuscular electrical stimulation (NMES) could simulate physiological muscle functions known to be associated with the normal bone healing process. The object of the present study was to evaluate the effect of NMES on fracture healing, using an animal model. Thirty rabbits received unilateral, transverse, mid-tibial, 3-mm gapped osteotomies that were stabilized with double-bar external fixators. The femoral vein was ligated to induce venous stasis. From the fourth post-operative day, the study group was treated with 1 h daily of NMES for four weeks, while the control group was treated without NMES. For NMES, two surface electrodes were used: one above the patellar tendon and another around the lateral thigh. Callus area and mineral content at the osteotomy gap were measured, biweekly, using computerized tomographic examinations. Biomechanical properties of healing were evaluated with a torsion test, eight weeks after the index operation. Osteotomies treated with NMES exhibited 31% (p=0.01) higher mineral content and 27% (p=0.009) larger callus area than control osteotomies at eight weeks. The maximum torque, torsional stiffness, angular displacement at maximum torque, and energy required to failure of specimens in the study group were 62% (p=0.006), 29% (p=0.03), 34.6% (p=0.008), and 124% (p<0.0001) higher, respectively, than those in the control group at eight weeks. The results of the present study demonstrated that the use of NMES can enhance callus development and mineralization, with the consequent improvement in biomechanical properties of the healing bone.  相似文献   

15.
    
Calcium phosphate cements (CPCs) are widely used for bone‐defect treatment. Current developments comprise the fabrication of porous scaffolds by three‐dimensional plotting and doting using biologically active substances, such as strontium. Strontium is known to increase osteoblast activity and simultaneously to decrease osteoclast resorption. This study investigated the short‐ and long‐term in vivo performances of strontium(II)‐doted CPC (SrCPC) scaffolds compared to non‐doted CPC scaffolds after implantation in unloaded or load‐bearing trabecular bone defects in sheep. After 6 weeks, both CPC and SrCPC scaffolds exhibited good biocompatibility and osseointegration. Fluorochrome labeling revealed that both scaffolds were penetrated by newly formed bone already after 4 weeks. Neither strontium doting nor mechanical loading significantly influenced early bone formation. In contrast, after 6 months, bone formation was significantly enhanced in SrCPC compared to CPC scaffolds. Energy dispersive X‐ray analysis demonstrated the release of strontium from the SrCPC into the bone. Strontium addition did not significantly influence material resorption or osteoclast formation. Mechanical loading significantly stimulated bone formation in both CPC and SrCPC scaffolds after 6 months without impairing scaffold integrity. The most bone was found in SrCPC scaffolds under load‐bearing conditions. Concluding, these results demonstrate that strontium doting and mechanical loading additively stimulated bone formation in CPC scaffolds and that the scaffolds exhibited mechanical stability under moderate load, implying good clinical suitability. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:106–117, 2018.  相似文献   

16.
Osteoblasts are derived from mesenchymal stem cells (MSCs), which initiate and regulate bone formation. New strategies for osteoporosis treatments have aimed to control the fate of MSCs. While functional disuse decreases MSC growth and osteogenic potentials, mechanical signals enhance MSC quantity and bias their differentiation toward osteoblastogenesis. Through a non-invasive dynamic hydraulic stimulation (DHS), we have found that DHS can mitigate trabecular bone loss in a functional disuse model via rat hindlimb suspension (HLS). To further elucidate the downstream cellular effect of DHS and its potential mechanism underlying the bone quality enhancement, a longitudinal in vivo study was designed to evaluate the MSC populations in response to DHS over 3, 7, 14, and 21 days. Five-month old female Sprague Dawley rats were divided into three groups for each time point: age-matched control, HLS, and HLS+DHS. DHS was delivered to the right mid-tibiae with a daily “10 min on-5 min off-10 min on” loading regime for five days/week. At each sacrifice time point, bone marrow MSCs of the stimulated and control tibiae were isolated through specific cell surface markers and quantified by flow cytometry analysis. A strong time-dependent manner of bone marrow MSC induction was observed in response to DHS, which peaked on day 14. After 21 days, this effect of DHS was diminished. This study indicates that the MSC pool is positively influenced by the mechanical signals driven by DHS. Coinciding with our previous findings of mitigation of disuse bone loss, DHS induced changes in MSC number may bias the differentiation of the MSC population towards osteoblastogenesis, thereby promoting bone formation under disuse conditions. This study provides insights into the mechanism of time-sensitive MSC induction in response to mechanical loading, and for the optimal design of osteoporosis treatments.  相似文献   

17.
    
This study evaluates the ability of a Glass Reinforced Hydroxyapatite Composite (GRHC), in a new microporous pellet formulation with autologous bone marrow concentrate (BMC), to enhance bone regeneration and new bone formation. Ninety non‐critical sized bone defects were created in the femurs of nine Merino breed sheep and randomly left unfilled (group A), filled with GRHC pellets alone (group B) or filled with GRHC pellets combined with BMC (group C). The sheep were sacrificed at 3 weeks (three sheep), 6 weeks (three sheep) and 12 weeks (three sheep) and histological analysis (Light Microscopy‐LM), scanning electron microscopy (SEM) and histomorphometric analysis (HM) were performed. At 3, 6, and 12 weeks, HM revealed an average percentage of new bone of 48, 72, 83%; 25, 73, 80%, and 16, 38, 78% for Groups C, B and A respectively (significantly different only at 3 weeks p < 0.05). LM and SEM evaluation revealed earlier formation of well‐organized mature lamellar bone in Group C. This study demonstrates that the addition of a bone marrow concentrate to a glass reinforced hydroxyapatite composite in a pellet formulation promotes early bone healing. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1176–1182, 2017.
  相似文献   

18.
    
Connexin43 (Cx43) plays an important role in osteoblastic differentiation in vitro, and bone formation in vivo. Mice with osteoblast/osteocyte‐specific loss of Cx43 display decreased gap junctional intercellular communication (GJIC), bone density, and cortical thickness. To determine the role of Cx43 in fracture healing, a closed femur fracture was induced in Osteocalcin‐Cre+; Cx43flox/flox (Cx43cKO) and Cre‐; Cx43flox/flox (WT) mice. We tested the hypothesis that loss of Cx43 results in decreased bone formation and impaired healing following fracture. Here, we show that osteoblast and osteocyte‐specific deletion of Cx43 results in decreased bone formation, bone remodeling, and mechanical properties during fracture healing. Cx43cKO mice display decreased bone volume, total volume, and fewer TRAP+ osteoclasts. Furthermore, loss of Cx43 in mature osteoblasts and osteocytes results in a significant decrease in torsional rigidity between 21 and 35 days post‐fracture, compared to WT mice. These studies identify a novel role for the gap junction protein Cx43 during fracture healing, suggesting that loss of Cx43 can result in both decreased bone formation and bone resorption. Therefore, enhancing Cx43 expression or GJIC may provide a novel means to enhance bone formation during fracture healing. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:147–154, 2012  相似文献   

19.
    
Beyond its classical role in regulation of erythropoiesis, erythropoietin (EPO) has been shown to exert protective and regenerative actions in a variety of non‐hematopoietic tissues. However, little is known about potential actions in bone regeneration. To analyze fracture healing in mice, a femoral 0.25 mm osteotomy gap was stabilized with a pin‐clip technique. Animals were treated with 500 U EPO/kg bw per day or with vehicle only. After 2 and 5 weeks, fracture healing was analyzed biomechanically, radiologically and histologically. Expression of PCNA and NFκB was examined by Western blot analysis. Vascularization was analyzed by immunohistochemical staining of PECAM‐1. Circulating endothelial progenitor cells were measured by flow‐cytometry. Herein, we demonstrate that EPO‐treatment significantly accelerates bone healing in mice. This is indicated by a significantly greater biomechanical stiffness and a higher radiological density of the periosteal callus at 2 and 5 weeks after fracture and stabilization. Histological analysis demonstrated significantly more bone and less cartilage and fibrous tissue in the periosteal callus. Endosteal vascularization was significantly increased in EPO‐treated animals when compared to controls. The number of circulating endothelial progenitor cells was significantly greater in EPO‐treated animals. The herein shown acceleration of healing by EPO may represent a promising novel treatment strategy for fractures with delayed healing and non‐union formation. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:165–172, 2011  相似文献   

20.
To evaluate the effects of electrical stimulation on the mechanical properties of healing skin, 20 Hanford mini-pigs weighing 10–15 kg with trochanteric pressure ulcers were subjected to electrical stimulation. Examination of the biomechanical properties of the skin and changes in wound area and volume was done on previously wounded and healing pigskin subject to AC or DC electrical stimulation. The behavior of normal pigskin was compared to (1) denervated controls, (2) denervated AC-stimulated skin, and (3) denervated DC-stimulated skin. A denervated limb trochanteric pressure sore model developed in house permitted the use of a 6.5-mm percutaneous cancellous screw for wound formation and a 3-cm-diameter spring compression indentor to create reproducible and uniformly controlled grade 3 or higher tissue ulcers in the monoplegic hind limbs. Denervation was accomplished by right unilateral extradural rhizotomies from L2 to S1 nerve roots. Electrodes were placed 1 cm distal and proximal to the wound periphery, and wounds were stimulated 2 h/day, 5 days/week for 30 days. Dumbbell-shaped skin specimens with a length to width ratio of 3:1 were uniaxially loaded in tension until failure at an extension rate of 150 mm/min. The stiffness values for skin samples oriented parallel to the current flow were reduced by nearly half the values obtained for normal controls. Statistical differences (P <. 05) were found for stress, Young modulus, and stiffness when compared to normal skin. Samples oriented in the perpendicular direction were comparable to normal skin (P= NS). Both AC- and DC-stimulated wounds showed (1) a reduced healing time when compared to controls, and (2) that electrical stimulation may orient new collagen formation in a pattern similar to normal skin, even in the absence of neural influences.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号