Micro-mechanical damage of trabecular bone–cement interface under selected loading conditions: a finite element study

In this study, two micro finite element models of trabecular bone–cement interface developed from high resolution computed tomography (CT) images were loaded under compression and validated using the in situ experimental data. The models were then used under tension and shear to examine the load transfer between the bone and cement and the micro damage development at the bone–cement interface. In addition, one models was further modified to investigate the effect of cement penetration on the bone–cement interfacial behaviour. The simulated results show that the load transfer at the bone–cement interface occurred mainly in the bone cement partially interdigitated region, while the fully interdigitated region seemed to contribute little to the mechanical response. Consequently, cement penetration beyond a certain value would seem to be ineffective in improving the mechanical strength of trabecular bone–cement interface. Under tension and shear loading conditions, more cement failures were found in denser bones, while the cement damage is generally low under compression.     

Continuous measurements of water tensions in the xylem of trees based on the elastic properties of wood

According to the cohesion theory for the ascent of water in vascular plants, significant tensions should develop in the water columns of transpiring trees. These tensions cause small but detectable changes in the diameter of the xylem as a consequence of adhesive forces between water molecules and the inner xylem walls. The diurnal time course of tension in the water columns in the xylem of the trunk of mature Scots pine (Pinus sylvestris L.) was measured during the summer of 1995 by means of a displacement transducer mounted on a rigid steel frame. The apparent elastic modulus of Scots pine wood in the radial direction (E  ^′ _r ) was determined in the laboratory and then used to estimate tensions from the measured displacement. Laboratory measurements on logs indicated that only the sapwood contributed to dimensional changes of the xylem. Corrections for thermal expansion of the system were included. Water tensions fell by 0.19 MPa over the course of the day, when needle water potentials fell by 0.50 MPa. Such data are consistent with the cohesion theory, and with the view that the hydraulic resistances to flow in above- and below-ground plant parts are of similar magnitude. Received: 23 November 1996 / Accepted: 11 February 1997     

微波高温灭活及自体髂骨异体骨粒复合骨水泥修复 治疗长骨骨巨细胞瘤骨缺损

目的:探讨微波高温灭活及自体髂骨、异体骨粒复合骨水泥修复骨巨细胞瘤病灶刮除后骨缺损的临床应用效果。方法:应用原位分离插入式微波天线高温灭活技术,自体髂骨、异体骨粒复合骨水泥修复21例长骨骨巨细胞瘤术后骨缺损,从手术技术、肿瘤复发情况、肢体关节功能等方面全面综合评价此方法临床应用效果。结果:21例患者均获得骨性愈合,无骨折及内固定断裂发生,2例复发,复发率9.8%;肢体关节功能优18例(85.7%)、良3例(14.3%)、中差0例。结论:微波高温能彻底杀灭肿瘤组织降低复发率,自体髂骨保证与近关节软骨下骨愈合,异体骨粒复合骨水泥能良好充填残余瘤腔、且具有良好的生物力学性能,以防发生关节软骨面塌陷。     

微波高温灭活及自体髂骨异体骨粒复合骨水泥修复治疗长骨骨巨细胞瘤骨缺损

目的：探讨微波高温灭活及自体髂骨、异体骨粒复合骨水泥修复骨巨细胞瘤病灶刮除后骨缺损的临床应用效果。方法：应用原位分离插入式微波天线高温灭活技术,自体髂骨、异体骨粒复合骨水泥修复21例长骨骨巨细胞瘤术后骨缺损,从手术技术、肿瘤复发情况、肢体关节功能等方面全面综合评价此方法临床应用效果。结果：21例患者均获得骨性愈合,无骨折及内固定断裂发生,2例复发,复发率9.8%;肢体关节功能优18例（85.7%）、良3例（14.3%）、中差0例。结论：微波高温能彻底杀灭肿瘤组织降低复发率,自体髂骨保证与近关节软骨下骨愈合,异体骨粒复合骨水泥能良好充填残余瘤腔、且具有良好的生物力学性能,以防发生关节软骨面塌陷。     

髓内钉固定联合骨水泥填充治疗四肢骨干转移癌伴病理性骨折的临床研究

目的:研究髓内钉固定联合骨水泥填充治疗四肢骨干转移癌伴病理性骨折的临床疗效。方法:选取2009年1月到2014年1月我院收治的四肢骨干转移癌伴病理性骨折患者90例,所有患者均给予髓内钉固定联合骨水泥填充进行治疗。应用视觉模拟评分法(VAS)评定术前、术后患者的疼痛情况,应用Enneking评分来评价患者的肢体功能,应用Kanofsky评分法评价患者的生活质量。结果:所有患者均成功随访,随访时间为10-48个月,平均随访时间为(33.8±2.5)个月。所有患者围手术期均无感染或者其他并发症。术后VAS评分、Enneking评分以及Kanofsky评分均显著优于手术前,比较差异具有统计学意义(P0.05);Enneking评分显示,32例优,34例良,22例中,2例差,优良率为73.3%。结论:髓内钉固定联合骨水泥填充治疗四肢骨干转移癌伴病理性骨折疗效确切,能显著改善肢体功能,减轻患者疼痛,提高患者的生活质量。     

网袋强化椎体成形术与经皮后凸椎体成形术在胸腰段骨质疏松压缩骨折中的短期疗效比较

摘要 目的：研究和比较使用网袋强化椎体成形术与经皮后凸椎体成形术在胸腰段骨质疏松压缩骨折中的短期疗效和安全性。方法：对2018年1月至2021年1月3年内,诊断为脊柱骨质疏松性骨折且行手术治疗的共计95例患者进行回顾性分析。根据实施手术方式的不同,将纳入的95例患者分为网袋组和PKP组。其中行网袋强化椎体成形术41例（网袋组）,行经皮后凸椎体成形术54例（PKP组）。统计和比较两组患者在术后的3天,3月的VAS评分及ODI评分。并对患者的影像学指标进行详细比较,包括患椎的前后缘及中线高度,cobb角,及骨水泥的分布以及骨水泥渗漏率。结果：在术后3天及3月时,两组患者的VAS评分和ODI评分较前均有显著改善(P<0.05),但两组间并无显著差异(P>0.05)。在术后3天及3月时,两组患者的患椎前后缘、中线高度及cobb角较前均有显著改善(P<0.05),但两组间并无显著差异(P>0.05)。网袋组在术后的骨水泥单侧分布率、渗漏率均优于对照组(P<0.05)。两组均未出现严重并发症(P>0.05)。结论：在胸腰椎骨质疏松性压缩骨折的治疗中,与常规的经皮椎体后凸成形术相比,网袋强化椎体成形术在手术疗效及撑开效果中无明显差异,但骨水泥渗漏率显著降低,能够有效的提高手术的安全性,在临床中可以进一步推广。     

An approximate model for cancellous bone screw fixation

This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.     

Finite element assessment of block-augmented total knee arthroplasty

Loosening and migration of tibial prostheses have been identified as causes of early total knee replacement (TKR) failure. The problem is made more complex when defects occur in the proximal tibia compromising fixation and alignment. Clinical studies using metal augments have shown these to be an alternative to other means of defect treatment. Finite element (FE) analysis can be used to identify regions that may be prone to loosening and migration. In the current work, 3D FE models of TKR uncontained type-2 defects treated with block augments have been constructed and analysed. It has been shown that a metal augment is the most suitable. The use of bone cement (PMMA) to fill proximal defects is not considered suitable as stresses carried by the cement block exceed those of the fatigue limit of bone cement. It has been shown that the stresses in the proximal cancellous bone of block-augmented models are significantly below levels likely to cause damage due to overloading. Furthermore, the use of stem extensions has been shown to reduce the cancellous bone stresses in the proximal region thus increasing the likelihood of bone resorption. Given this, it is recommended that stem extensions are not required unless necessary to mitigate some other problem.     

Absence of cross-linking via trans-glutaminase in barnacle cement and redefinition of the cement

Balanomorphan barnacles attach their calcareous bases to a variety of substrata, including others of the same species, through secretion of an underwater adhesive, commonly referred to as cement. In this multi-functional process of underwater attachment, curing of the adhesive is crucial for the formation of a secure attachment. To date, there has been no direct evidence presented to suggest the involvement of cross-linking or polymerization in the cement curing process, despite the emergence of this hypothesis in the recent literature. A recently proposed mechanism for cement curing involves glutamyl-lysine cross-linking via the action of trans-glutaminase. However, in the opinion of the author, inadequate attention may have been paid to sample collection during the study and the conditions used in the analysis may not be adequate to support the conclusions of the paper. Indeed, further investigation, the results of which are presented here, did not provide any evidence to support adhesive curing via glutamyl-lysine cross-linking. Therefore, the hypothesis that the process of cement curing is similar to the clotting system of barnacle hemolymph is not compatible with the data reported so far. In order to allay any potential confusion, a new definition of the barnacle cement is proposed.