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1.
BACKGROUND: Osteopenia is one factor that may influence the decision about the type of implant fixation to use in total hip arthroplasty. However, clinical studies generally do not associate the outcome of an arthroplasty with the degree of osteopenia. The mechanical integrity of the cement fixation of an implant may be affected by the relative degree of osteopenia, which could account for some of the variable long-term results after total hip arthroplasty performed with cement. The purpose of this study was to determine the effects of bone porosity, trabecular orientation, cement pressure, and cement penetration depth on fracture toughness at the bone-cement interface. METHODS: Trabecular bone from the proximal part of bovine femora was used with a single brand of commercial acrylic bone cement to form compact-tension interface specimens representing a range of bone porosities, orientations, and cement pressures within a clinically achievable range. All specimens were loaded to failure with use of a servohydraulic testing machine, and fracture toughness at the interface was calculated. After testing, images of a representative sample of specimens were made with use of computed tomography to measure the penetration depth of the cement into the bone. RESULTS: Significant correlations were found between fracture toughness and bone porosity, trabecular orientation, and cement pressure, with bone porosity having the strongest effect (p < 0.000015). Examination of the computed tomographic images also showed a significant correlation between fracture toughness and maximum cement penetration depth (p < 0.033), as well as significant partial correlations between maximum and mean penetration depth and bone porosity (p < 0.0037 and p < 0.0028). CONCLUSION: The fracture resistance of the bone-cement interface is greatly improved when the ability of the cement to flow into the intertrabecular spaces is enhanced.  相似文献   

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Wang Y  Yan F  Song DC  Qu YL  Yang GF  Shi ZW  Gu WG  Song YB  Li DB  Wang CL 《中华外科杂志》2008,46(6):431-433
目的 评价骨水泥振动器对提高骨水泥-骨界面微嵌合强度的效果及临床意义.方法 取新鲜成猪股骨100根,随机分成6组;力学测试组:抗拉力实验组(A1)与对照组(A2)和抗压力实验组(B1)与对照组(B2)模型每组各20个;影像学测试组:实验组(C1)与对照组(C2)模型各10个.对模型进行力学及影像学检测,比较实验组与对照组骨水泥-骨界面的微嵌合强度.结果 力学及影像学测定显示实验组骨水泥-骨界面微嵌合强度均高于对照组,二者比较差异具有显著统计学意义(P<0.01).结论 骨水泥振动器能显著提高骨水泥-骨界面微嵌合强度,对于减少人工假体远期无菌性松动具有一定的意义.  相似文献   

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Summary The generation of osteoclasts in cultures of cat bone marrow was completely inhibited for 4 weeks with 10−6M hydrocortisone (HC) and partially inhibited with 10−7 to 10−9M in a dose-dependent fashion. This effect was completely reversible when cultures were exposed for only 2 weeks to 10−9 or 10−8M HC. However, cultures in which higher concentrations (10−7 to 10−5M) were maintained for the same period did not show complete recovery in terms of numbers of osteoclasts and number of nuclei per cell after withdrawal of HC, suggesting that precursor cells of osteoclasts were also damaged by HC. To study the effects of HC on osteoclasts already present in the cultures, 10−6M was added to 4-week-old untreated cultures. The number of osteoclasts decreased rapidly and a gross morphological response was also apparent (rounding of the cells leading to detachment from the substratum and inhibition of cell fusion), indicating that the generation as well as the survival of osteoclasts in vitro are sensitive to HC. The morphological changes observed under optical and electron microscopy correspond to those of the reported inactive form of osteoclasts, and suggest that their function may also be altered by HC.  相似文献   

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增加载荷分享的动力内固定对椎体骨量和骨结构的影响   总被引:2,自引:0,他引:2  
目的分析比较动力椎弓根螺钉内固定与相对坚强内固定对固定区椎体骨密度和骨结构的影响,探讨增加载荷分享的意义。方法24只山羊随机分为四组,每组6只。对照组:仅行脊柱椎旁肌剥离;单纯植骨融合组:切除L3后部结构,行后外侧植骨融合;坚强固定融合组:在脊柱不稳模型上行相对坚强内固定及后外侧植骨融合;动力固定融合组:在脊柱不稳模型上行动力椎弓根螺钉内固定及后外侧植骨融合。术后24周处死动物,取腰椎标本。采用定量计算机断层扫描法(QCT)测定腰椎标本固定区椎体松质骨的骨密度。在普通显微镜下观察固定区椎体骨小梁结构;并行骨形态计量学分析,计算骨小梁体积比、平均骨小梁间距、平均骨小梁厚度和骨矿化沉积速度。结果与对照组比较,坚强固定融合组的骨密度明显下降(P< 0.01);而动力固定融合组与对照组比较差异无显著性。与对照组和单纯植骨融合组比较, 坚强固定融合组的骨小梁体积比、平均骨小梁厚度和骨矿化沉积速度均明显下降(P< 0.01),平均骨小梁间距明显增加(P< 0.05);而动力固定融合组与对照组比较各项参数的差异无显著性。光镜下可观察到坚强固定融合组固定区椎体有骨质疏松改变。结论坚强内固定对固定区椎体有应力遮挡效应;而动力椎弓根螺钉固定器能增加载荷分享,有效缓解应力遮挡效应。  相似文献   

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Purpose

To evaluate the effect of vertebroplasty with a bone filler device compared with balloon kyphoplasty.

Methods

A total of 222 patients underwent operations from January 2008 to October 2012. One-level fractures numbered 169 (86.7 %) cases and two-level fractures numbered 26 (13.3 %). A total of 221 vertebral levels were analyzed consequently. Vertebral height, compression ratio, and segmental Cobb’s angle were measured in preoperative and postoperative lateral X-rays.

Results

The compression ratio was the most influential parameter among three variables. Adjusted postoperative compression ratio was not significantly different between two operation groups. Bone cement leakage rates did not differ (p < 0.05). Bone cement distribution was spongy type in the majority of the vertebroplasty with bone filler device (94.5 %), but only in 42.0 % of the kyphoplasty. High bone densitometry readings and long period from diagnosis to operation were significant risk factors for bone cement leakage.

Conclusions

Vertebroplasty with a bone filler device could achieve equivalent compression reduction and bone cement leakage rate, as well as greater sponge-type bone cement distribution, which were advantages over balloon kyphoplasty.  相似文献   

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卵巢切除对大鼠皮质骨结构和力学性能的影响   总被引:9,自引:0,他引:9       下载免费PDF全文
目的:研究卵巢切除大鼠皮质骨的几何学改变和力学性能改变,探讨雌激素缺乏时皮质骨改变的发生机理。方法:选雌性SD大鼠56只,分为Sham组和OVX组,动物分别在4、12、20和28周时处死7只,取其胫骨备用。左侧于近3/5和远2/5交界部切断,在电镜下摄片,计测截面总面积、皮质骨面积、骨外径周长、骨髓腔面积和骨内径周长。右侧以近3/5与远2/5交界点为加载点进行三点弯曲力学实验。结果:Sham组术后4周至28周胫骨截面总面积和骨外径周长逐渐增加。(P<0.005),而髓腔面积和内径周长变化不明显。OVX组截面总面积和外径周长也有逐渐增加趋势。但差异无显性。而内径周长和髓腔面积都明显增加,在相同时期显大于Sham组(P<0.005),而皮质骨面积却与Sham组差异无显性。三点弯曲试验结果表明,从4-28周实验对照两组抗弯强度和刚度均逐渐增加,但两组间差异无显性。在各时期骨组织材料力学性能也无显性差异。结论:卵巢切除对皮质骨的影响主要表现在使骨髓控扩大,对骨外膜的影响较小,在短期内皮质骨的力学性能无明显影响。  相似文献   

13.
Hadeishi H  Suzuki A  Yasui N  Satou Y 《Neurosurgery》2003,52(4):867-70; discussion 870-1
OBJECTIVE: During cranial base surgery, use of a high-speed drill for osteotomy has become common. We performed anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette, and we report the advantages and clinical applications of this method. DESCRIPTION OF INSTRUMENTATION: The ultrasonic surgical equipment comprises a power supply unit, footswitch, and handpiece (weight, 110 g; diameter, 20 mm; length, 140 mm from tip to angled section). The handpiece tip is 2 mm wide, and the amplitude of longitudinal vibration can be varied from 120 to 365 microm at an ultrasonic frequency of 25 kHz. Cool-controlled irrigation fluid emerges near the tip, through the sheath. EXPERIENCE AND RESULTS: We performed anterior clinoidectomy in eight cases of paraclinoid aneurysm and opening of the internal auditory canal in six cases of acoustic neuroma without damage to the dura mater or nearby structures such as brain tissue, blood vessels, and cranial nerves. In addition, no damage to the facial nerve or labyrinthine organ resulted from heat or vibration caused by the ultrasonic bone curette. CONCLUSION: Ultrasonic bone curettage represents safe instrumentation for performance of anterior clinoidectomy and opening of the internal auditory canal without damage to surrounding structures. This technique allows surgeons to perform procedures on deep areas without incurring psychomotor stress.  相似文献   

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Introduction

The ultrasonic BoneScalpel is a tissue-specific device that allows the surgeon to make precise osteotomies while protecting collateral or adjacent soft tissue structures. The device is comprised of a blunt ultrasonic blade that oscillates at over 22,500 cycles/s with an imperceptible microscopic amplitude. The recurring impacts pulverize the noncompliant crystalline structure resulting in a precise cut. The more compliant adjacent soft tissue is not affected by the ultrasonic oscillation. The purpose of this study is to report the experience and safety of using this ultrasonic osteotome device in a variety of spine surgeries.

Methods

Data were retrospectively collected from medical charts and surgical reports for each surgery in which the ultrasonic scalpel was used to perform any type of osteotomy (facetectomy, laminotomy, laminectomy, en bloc resection, Smith Petersen osteotomy, pedicle subtraction osteotomy, etc.). The majority of patients had spinal stenosis, degenerative or adolescent scoliosis, pseudoarthrosis, adjacent segment degeneration, and spondylolisthesis et al. Intra-operative complications were also recorded.

Results

A total of 128 consecutive patients (73 female, 55 male) beginning with our first case experience were included in this study. The mean age of the patients was 58 years (range 12–85 years). Eighty patients (62.5 %) had previous spine surgery and/or spinal deformity. The ultrasonic scalpel was used at all levels of the spine and the average levels operated on each patient were 5. The mean operation time (skin to skin) was 4.3 h and the mean blood loss was 425.4 ml. In all cases, the ultrasonic scalpel was used to create the needed osteotomies to facilitate the surgical procedure without any percussion on the spinal column or injury to the underlying nerves. There was a noticeable absence of bleeding from the cut end of the bone consistent with the ultrasonic application. There were 11 instances of dural injuries (8.6 %) and two of which were directly associated with the use of ultrasonic device. In no procedure was the use of the ultrasonic scalpel abandoned for use of another instrument due to difficulty in using the device or failure to achieve the desired osteotomy.

Conclusions

Overall, the ultrasonic scalpel was safe and performed as desired when used as a bone cutting device to facilitate osteotomies in a variety of spine surgeries. However, caution should be taken to avoid potential thermal injury and dural tear. If used properly, this device may decrease the risk of soft tissue injury associated with the use of high speed burrs and oscillating saws during spine surgery.  相似文献   

15.
Measurements of ultrasonic velocity and specific differential attenuation (SDA) were obtained on 24 bovine trabecular bone specimens from the femoral condyles. The measurements were obtained using two pairs of ultrasonic transducers, one with a low nominal center frequency (500 kHz) and the other pair with a high nominal center frequency (1 MHz). The ultrasonic velocity and specific differential attenuation associated with the bone samples were determined both with and without marrow, i.e., replacing the marrow with water in the pores of the trabecular bone. Significant increases (2.1% and 2.9%) in the velocity of ultrasound were observed after removal of the marrow, for the low and high frequency transducer pairs, respectively. In contrast, significant decreases (−6.5% and −8.8%) in SDA were observed after removal of the marrow, for the low and high frequency transducer pairs, respectively. The bone densities (BD) of the samples were also determined using single photon absorptiometry (SPA). Correlations between ultrasonic parameters and bone densities for samples both with and without marrow were found to be similar. For example, for the 1 MHz transducer pair, the correlation between BD and velocity was r=0.86 with marrow, and r=0.89 without marrow. This study also compared the results obtained using a contact (no water bath) technique and an insertion (with a water bath) technique of ultrasonic measurements. For the high frequency transducer pair, the correlation coefficients between the two methods were r=0.99 and r=0.93, for the velocity and specific differential attenuation, respectively. Similar results were found for the low frequency transducer pair as well. In addition, approximately equal correlations between BD and ultrasonic velocity and SDA were also found, indicating that contact and insertion measurements provide essentially equivalent information.  相似文献   

16.
Thousands of blood pressure measurements are done daily without the patients' disrobing. This study was therefore undertaken to determine the validity of such measurements, especially those taken when the patient's armsleeve has been rolled up onto the proximal aspect of the arm. An inflatable constricting device was applied to the proximal aspect of the arm and a standard sphygmomanometer was applied distal to the inflatable cuff. The constricting cuff was inflated to 0, 20, 40, 60, 80, and 100 mm Hg in random sequence, and the blood pressure was recorded at each level. Statistically significant elevations in the mean systolic blood pressure were detected at proximal constricting pressures of 80 mm Hg (P less than .01) and 100 mm Hg (P less than .001), and in the mean diastolic blood pressure at 20 mm Hg (P less than .005). However, the magnitude of the elevations was small: 3.9, 4.4, and 2.5 mm Hg, respectively. We conclude that though a proximal constricting device may induce statistically significant alterations in blood pressure measurements these alterations are small and not likely to affect treatment decisions.  相似文献   

17.
Rosette strain gauges were attached to the cranial and caudal aspects of the proximal half of the radius in eight skeletally mature female sheep; The sheep's radius has a slight cranially convex curvature. During walking it was deformed so that the cranial surface was subjected to tension aligned along the bone's lon axis, and the caudal surface to compression similarly aligned. The compressive strain on the caudal aspect of the bone was consistently larger (X 1-9) than the tensile strain on the cranial aspect. The thickness of the cortex did not reflect this difference but in younger animals the process of osteonal remodelling seemed further advanced in the cortex which was customarily subject to the larger deformation. The relevance of these findings is discussed in relation to the technique of internal fixation and to our understanding of the basis of the mechanical adaptability of bone.  相似文献   

18.
目的 比较不同膳食结构对去卵巢大鼠(OVX)骨量和骨结构的影响。方法 30只去卵巢大鼠随机分为3组,分别以基础、高脂和黄豆饲料喂养3个月。每周称体重一次,结算各组大鼠每天的摄食量。3个月后,采血测血清血脂水平、血钙、血磷和雌二醇;双能X线骨密度仪测定实验前、后大鼠全身、脊柱和股骨骨密度;取一侧股骨制备脱钙骨切片,进行骨形态学观察和骨计量学测定。结果 1、各组大鼠每天食物摄入量、血钙和血磷无统计学差异。2、黄豆饲料组大鼠体重最小(P<0.05);血清E2水平最高(P<0.05);全身、股骨和脊柱BMD均最高(P<0.05);骨小梁数量最多、骨小梁面积和厚度均最大(P<0.05)。而高脂饲料组大鼠体重最大(P<0.05);TG和LDL水平最高,HDL最低 (P<0.05);全身、股骨和脊柱BMD均最低(P<0.05),高脂饲料与基础饲料相比,骨小梁数量无差异,但骨小梁面积和厚度较大(P<0.05)。结论 从绝经后骨质疏松预防角度来说,富含黄豆的饮食较高脂饮食是一种较好的膳食结构;后者可能加速了女性的骨丢失。  相似文献   

19.
Low-level laser therapy (LLLT) is increasingly being used in the regeneration of soft tissue. In the regeneration of hard tissue, it has already been shown that the biomodulation effect of lasers repairs bones more quickly. We studied the activity in bone cells after LLLT close to the site of the bone injury. The femurs of 48 rats were perforated (24 in the irradiated group and 24 in the control group) and the irradiated group was treated with a GaAlAs laser of 660 nm, 10J/cm2 of radiant exposure on the 2nd, 4th, 6th and 8th days after surgery (DAS). We carried out histomorphometry analysis of the bone. We found that activity was higher in the irradiated group than in the control group: (a) bone volume at5 DAS (p=0.035); (b) osteoblast surface at 15 DAS (p=0.0002); (c) mineral apposition rate at 15 and 25 DAS (p=0.0008 and 0.006); (d) osteoclast surface at 5 DAS and 25 DAS (p=0.049 and p=0.0028); and (e) eroded surface (p=0.0032). We concluded that LLLT increases the activity in bone cells (resorption and formation) around the site of the repair without changing the bone structure.  相似文献   

20.
Adla DN  Kitsis C  Miles AW 《Injury》2005,36(1):65-70
The compressive forces generated by the AO/ASIF 3.0 mm cannulated cancellous and 2.0 mm cortical screws, Mini-Acutrak and Herbert/Whipple small bone cannulated screws were measured in the laboratory with the use of simulated cancellous bone and a load cell washer as a means of quantifying their fixation capabilities. The Herbert/Whipple screw and the Mini-Acutrak screw were found to have nearly identical compression capabilities and provided more compression than the cortical screw. The AO/ASIF cannulated screw when used with a support screw demonstrated a compressive capacity twice that of the 2.0 mm cortical screw and higher than the headless Mini-Acutrak and Herbert/Whipple screws. The Mini-Acutrak screw produced about 70% of compression of the cancellous screw in spite of having a diameter almost half that of the cancellous screw. The Herbert/Whipple screw in spite of its larger size compared to the Mini-Acutrak produced almost the same amount of compression.  相似文献   

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