股骨骨折术后1 年随访骨愈合模型的有限元分析

目的：对股骨骨折髓内钉术后1 年骨愈合模型快速建模，通过有限元分析研究对比术前术后模型，通过术前判定内固定取 出后骨折断端是否断裂。方法：运用Mimics、Geomagic Studio、Abaqus等软件采用快速个体化建模方法对股骨骨折髓内钉术后1 年内固定取出术前后的多层螺旋CT 数据进行快速建立模型，术前模型模拟剥除钢板后进行有限元分析，施加人体单腿站立时的 静力载荷和约束，并将分析结果与术后模型进行对比，观察米塞斯应力分布情况、最大值及其所处部位。结果：按照材料属性进行 区别显示米赛斯应力的最大值及最小值，在不同应力载荷下，手术前后各类型材料的米赛斯应力最大值及最小值部位相同，各类 型材料中，最大值均没有位于骨折断端，不同方法的最大应力值部位相近，均在股骨中远端1/4 交界处，手术前后应力分布基本相 同。结论：采用个体化建模方法可以对骨折内固定取出前的骨愈合模型进行运算分析，快速预判术后是否导致骨折断端断裂。     

髓内钉及其骨折内固定的力学研究

“Ｖ”形和梅花形髓内钉是常用的长管骨骨折髓内固定材料。目前临床上梅花形髓内钉有代替“Ｖ”形髓内钉的趋势,本文从力学角度对其进行研究包括、．髓内钉及其髓内固定骨折模型弯曲试验显示,梅花形髓内钉抗弯强度和承受载荷系数均大于“Ｖ”形髓内钉;２．抗弯截面惯性矩研究显示,新型双冠形髓机钉优于梅花形髓内钉优于“Ｖ”形髓内钉;３．髓内钉设计成双冠形截面将大大改进其力学原理。     

弹性髓内钉与接骨板内固定治疗儿童股骨干骨折的临床疗效对比研究

摘要 目的：对比弹性髓内钉与接骨板内固定治疗儿童股骨干骨折的临床疗效。方法：本研究为回顾性研究,选取我院于2018年3月~2019年8月期间收治的儿童股骨干骨折患者98例,根据固定方式的不同将患儿分为A组（n=50,接骨板内固定治疗）和B组（n=48,弹性髓内钉治疗）,观察两组优良率、术前/术后相关指标及并发症发生情况。结果：B组的优良率高于A组（P<0.05）。B组手术时间、切口长度短于A组,术中出血量少于A组（P<0.05）。B组骨折愈合时间、住院时间、手术至内固定拆除时间、取出内固定手术时间短于A组（P<0.05）。两组患儿并发症发生率对比,差异无统计学意义（P>0.05）。结论：相对于接骨板内固定治疗,弹性髓内钉治疗儿童股骨干骨折,疗效更好,可有效改善术中、术后指标,且不增加并发症的发生率。     

单端固定式下颌骨修复体的应力分析

目的：针对包括一侧髁状突的下颌骨缺损,通过有限元应力分析,了解单端固定式下颌骨修复体在功能运动时的受力与变形规律,以期寻求更加合理的修复体的设计和固定方式。方法：建立下颌骨断端和修复体的简易三维模型,模拟咀嚼运动,施加垂直方向载荷,进行有限元法应力分析,计算出该模型各组成部分的应力分布和受力变形。结果：在该模型加载时,延伸板基部和近断端处上部的螺钉颈部是应力集中的部位,近断端处下部的螺钉颈部和修复体的远端舌侧为形变最大的部位。结论：单端固定式下颌骨修复体在加载时,延伸板的基部和靠近断端的固定螺钉是应力集中的部位,修复体远离固定的一侧是变形最大的部位,提示我们应将延伸板形态设计为尽可能加宽,并应增加下颌骨下缘处的固定,使修复体与下颌骨断端受力更加合理,变形也尽可能缩小。     

顺行髓内钉、逆行髓内钉及锁定加压钢板内固定治疗股骨远端骨折的对比研究

摘要目的：探讨顺行髓内钉、逆行髓内钉及锁定加压钢板内固定3种方法治疗股骨远端骨折患者的疗效。方法：对2011年1月至2012年12月间我院收治的101例股骨远端骨折进行临床随机分组手术,分别在手术中使用顺行髓内钉、逆行髓内钉以及锁定加压钢板内固定。对三组患者手术时间、术中出血量以及切口长度等一般情况进行比较分析,同时采用Harris评分系统对三组患者术后恢复情况进行分析比较。结果：经过手术治疗后,逆行髓内钉组Harris评分显著高于其他两组（P〈0．05）。另外,逆行髓内钉组手术过程短、出血量少、手术切口小,上述指标与其他两组比较均有统计学意义（P〈0．05）。结论：股骨远端骨折行逆行髓内钉治疗的疗效优于顺行髓内钉以及锁定加压钢板内固定,具有手术时间短、术中出血少、切口小等优点,能够有效提高术后膝关节功能的恢复,值得临床推广使用。     

闭合复位空心钉内固定对第五掌骨颈骨折的治疗观察

目的分析闭合复位空心钉内固定对第五掌骨颈骨折的治疗价值。方法随机抽取我院近年来收治的第五掌骨颈骨折患者45例,采取闭合复位空心钉内固定治疗,观察患者术后关节功能恢复情况。结果 45例患者术后伤口均Ⅰ期愈合,术后无感染、断钉等并发症发生。术后患侧颈干角较术前明显降低(P0.05),与健侧颈干角相比无明显差异(P0.05);术后掌指关节活动度较术前明显增加(P0.05),与健侧掌指关节活动度相比无统计学意义(P0.05)。结论闭合复位空心钉内固定治疗第五掌骨颈骨折效果显著,可快速恢复手部功能。     

双层滑动型接骨板的生物力不分析与临床应用

临床实践证明双层滑动型接骨板治疗四肢长骨骨折是疗效较好的内固定方法。本文从生物力学角度对24具湿润新鲜尸体股骨进行力学试验。测定了骨折固定部位的应力、应变、位移的分布，证明了这种固定方法是符合生物力学原理的，从载荷、应力、位移等一系列曲线表明它的松动、移位，钉板断裂很少发生，它能促进新骨生长和加速骨折愈合。     

MIPO技术结合锁定加压钢板、顺行交锁髓内钉及锁定加压钢板治疗肱骨干中段骨折疗效的对比研究

摘要 目的：探讨微创经皮钢板内固定（MIPO）技术结合锁定加压钢板、顺行交锁髓内钉、锁定加压钢板治疗肱骨干中段骨折的疗效。方法：选择2016年2月至2019年2月我院收治的126例肱骨干中段骨折患者，采用随机数字表法将其分为三组，MIPO组（42例）采用MIPO技术结合锁定加压钢板固定治疗，髓内钉组（42例）采用顺行交锁髓内钉固定治疗，钢板组（42例）采用锁定加压钢板固定治疗。所有患者术后随访12个月，比较三组手术时间、术中出血量、术后住院时间、骨折愈合时间、术前和术后第12个月美国加州大学肩关节评分系统（UCLA）评分、Mayo肘关节功能评分（MEPS）、欧洲五维健康量表(EQ-5D)评分以及并发症发生率。结果：MIPO组和髓内钉组的术中出血量与术后住院时间均少于钢板组（P＜0.05），MIPO组和髓内钉组之间无统计学差异（P＞0.05）。MIPO组、钢板组骨折愈合时间短于髓内钉组（P＜0.05），MIPO组、钢板组之间无统计学差异（P＞0.05）。MIPO组、钢板组术后第12个月UCLA评分均高于髓内钉组（P＜0.05），MIPO组、钢板组之间无统计学差异，第12个月MEPS无差异（P＞0.05）。术后第12个月MIPO组、钢板组EQ-5D评分高于髓内钉组（P＜0.05），MIPO组、钢板组之间无统计学差异（P＞0.05）。三组桡神经损伤、肩峰损伤发生率相比较，差异有统计学意义（P＜0.05），桡神经损伤以钢板组发生率最高，肩峰损伤以髓内钉组发生率最高。结论：MIPO技术结合锁定加压钢板具有微创、术后恢复快、对肩关节功能及生活质量的影响较小、术后并发症较少的优势，是肱骨干中段骨折较为理想的治疗方式。     

单端固定式下颌骨修复体的应力分析

目的:针对包括一侧髁状突的下颌骨缺损,通过有限元应力分析,了解单端固定式下颌骨修复体在功能运动时的受力与变形规律,以期寻求更加合理的修复体的设计和固定方式。方法:建立下颌骨断端和修复体的简易三维模型,模拟咀嚼运动,施加垂直方向载荷,进行有限元法应力分析,计算出该模型各组成部分的应力分布和受力变形。结果:在该模型加载时,延伸板基部和近断端处上部的螺钉颈部是应力集中的部位,近断端处下部的螺钉颈部和修复体的远端舌侧为形变最大的部位。结论:单端固定式下颌骨修复体在加载时,延伸板的基部和靠近断端的固定螺钉是应力集中的部位,修复体远离固定的一侧是变形最大的部位,提示我们应将延伸板形态设计为尽可能加宽,并应增加下颌骨下缘处的固定,使修复体与下颌骨断端受力更加合理,变形也尽可能缩小。     

髓内固定对老年股骨转子间骨折患者关节功能的影响

摘要 目的：研究髓内固定对老年股骨转子间骨折患者关节功能的影响。方法：选取2016年9月~2019年9月我院收治的股骨转子间骨折的老年患者80例为研究对象,采用随机数字表法将其分为两组,每组各40例。对照组患者采用Gamma钉进行治疗,观察组患者采用股骨近端防旋髓内钉固定治疗。比较两组患者的围术期相关指标、骨折愈合时间、Harris评分、临床治疗效果及并发症的发生情况。结果：观察组患者的手术时间、切口长度、术中出血量、术后引流量、住院时间及骨折愈合时间均显著少于或短于对照组(P＜0.05)。术前,两组患者的Harris评分比较无统计学差异(P＞0.05);术后6个月及术后12个月,两组患者的Harris评分均较术前显著升高,且观察组显著高于对照组(P＜0.05)。观察组患者的治疗优良率为92.50 %,显著高于对照组(75.00 %,P＜0.05)。两组患者深静脉血栓、感染、褥疮、固定松动、股骨头坏死及严重疼痛的发生率比较无统计学差异(P＞0.05)。结论：股骨近端防旋髓内钉固定治疗老年股骨转子间骨折效果明显优于Gamma钉治疗,可有效缩短骨折愈合时间,提高髋关节功能。     

Rigidity and stress analyses of external fracture fixation devices—A theoretical approach

The rigidity and stresses in external fracture fixation devices were studied by means of the finite element method. Different geometries and material parameters were simulated using a beam element model. Axial, bending and torsional loads were applied through the bone ends and the displacement obtained at the fracture sites was used to calculate the fracture fixation stiffness. The key parameters which increased fixation rigidity were identified. High pin stresses were predicted under certain application conditions. Possible clinical implications for the use of such apparatus are discussed in the light of bone fracture healing. The present results are expected to have a significant impact on future design modifications and clinical applications of this popular instrument in orthopedic surgery and traumatology.     

In vivo gait analysis in a mouse femur fracture model

Although the mouse has become a preferred species for molecular studies on fracture healing, gait analysis after fracture fixation and during bone healing has not yet been performed in mice. Herein, we introduce a novel technique for gait analysis in mice and report the change of motion pattern after fracture and fixation. A standardized femur fracture was stabilized by a common pin. The non-fractured tibia was additionally marked with a pin, allowing continuous analysis of the tibio-femoral angle by digital video-radiography. Dynamic gait analysis was performed at day fourteen after surgery in a radio-opaque running wheel. Fracture fixation resulted in a significantly reduced range and maximum of the tibio-femoral angle compared to non-fractured controls. This was associated with a significantly reduced stride length. Because stride frequency was slightly increased and, thus, stride time diminished, stride velocity was not significantly reduced compared to controls. Thus, our study demonstrates distinct alterations of the gait of mice at 2 weeks after femur fracture and stabilization. Our results support the need of gait analysis in fracture healing studies to assess the animals’ well-being.     

A new technique for internal fixation of femoral fractures in mice: impact of stability on fracture healing

Mouse models are of increasing interest to study the molecular aspects of fracture healing. Because biomechanical factors greatly influence the healing process, stable fixation of the fracture is of interest also in mouse models. Unlike in large animals, however, there is a lack of mouse models which provide stable osteosynthesis. The purpose of this study was therefore to develop a technique for a more stable fixation of femoral fractures in mice and to analyze the impact of stability on the process of fracture healing. The new technique introduced herein includes an intramedullary pin and an extramedullary metallic clip. Ex vivo biomechanical analysis revealed a significantly higher implant stiffness of our pin-clip technique when compared with previously described intramedullary fixation techniques. In vivo, we studied the course of healing after the more stable fixation with our pin-clip technique and compared the results with that observed after unstable fixation with the pin-clip technique after cutting the clip. After 2 and 5 weeks of fracture healing radiological analysis demonstrated that the more stable fixation with the pin-clip technique results in a significantly higher union rate compared to the unstable fixation. Torsional stiffness at 5 weeks was almost 3-fold of that measured after unstable fixation. Histomorphological analysis further showed that fractures stabilized with the pin-clip technique healed with a smaller periosteal callus area, an increased fraction of bone and a reduced amount of fibrous tissue. Of interest, the pin-clip fixation showed reliable union after 5 weeks, whereas the unstable pin fixation did not regularly achieve adequate fracture healing. In conclusion, we introduce a novel, easily applicable internal osteosynthesis technique in mice, which provides rotational stability after femoral fracture fixation. We further show that a more stable osteosynthesis significantly improves the process of fracture healing also in mice.     

Organic Gallium Treatment Improves Osteoporotic Fracture Healing Through Affecting the OPG/RANKL Ratio and Expression of Serum Inflammatory Cytokines in Ovariectomized Rats

This study aimed to investigate the impact of organic gallium (OG) on osteoporotic fracture healing in ovariectomized female Sprague-Dawley rats, as well as study the mechanisms of OG on osteoporotic fracture healing. Forty-five female Sprague-Dawley rats were divided into three groups: sham operation group (Sxas control group), ovariectomized group (Ovx), and Ovx treated with OG group (Ovx + OG). Rat femoral fractures were studied using a standardized fracture-healing model utilizing bone fixation with an intramedullary pin. Six weeks later, analyses of micro-CT, histomorphometric, RNA extraction, RT-qPCR, and serum were performed following sacrifice of all mice. In comparison with Ovx group, OG can significantly increase bone volume (BV), tissue volume (TV), BV/TV radio, bone strength, callus bony area, and as similar to BMP-2 expression. OG treatment elevated OPG messenger RNA (mRNA) and inhibited RANKL mRNA, and showed an effect on OPG/RANKL ratio. OG treatment can inhibit the expression of TNF-α and IL-6. In conclusion, current study results indicate that organic OG can positively affect the OPG/RANKL ratio and inhibit the expression of serum inflammatory cytokines; thus, it can improve osteoporotic fracture healing.     

Development of a locking femur nail for mice

We herein report on a novel locking intramedullary nail system in a murine closed femur fracture model. The nail system consists of a modified 24-gauge injection needle and a 0.1-mm-diameter tungsten guide wire. Rotation stability was accomplished by flattening the proximal and distal end of the needle. Torsional mechanical testing of the implants in osteotomized cadaveric femora revealed a superiority of the locking nail (3.9+/-1.0 degrees rotation at a torque of 0.9 Nmm, n=10) compared to the unmodified injection needle (conventional nail; 52.4+/-3.2 degrees, n=10, p<0.05). None of the implants, however, achieved the rotation stability of unfractured femora (0.3+/-0.5 degrees, n=10). In a second step, we tested the feasibility of the in vivo application of the locking nail to stabilize a closed femoral midshaft fracture in C57BL/6 mice. Of interest, none of the 10 animals showed a dislocation of the locking nail over a 5-week period, while 3 of 4 animals with conventional nail fracture stabilization showed a significant pin dislocation within the first 3 days (p<0.05). Mechanical testing after 5-weeks stabilization with the locking nail revealed an appropriate bone healing with a torque at failure of 71.6+/-3.4% and a peak rotation before failure of 68.4+/-5.3% relative to the unfractured contralateral femur. With the advantage that closed fractures can be fixed with rotation stability, the herein introduced model may represent an ideal tool to study bone healing in transgenic and knockout mice.     

Bone remodelling analysis of a bovine femur for a veterinary implant design

The response of bovine bone to the presence of an implant is analysed with the aim of simulating bone remodelling in a developing model of a polymeric intramedullary interlocking nail for veterinary use. A 3-D finite element model of the femur diaphysis is built based on computed tomography images and using a CAD-based modelling pipeline. The bone remodelling process after the surgery is analysed and compared with the healthy bone. The remodelling law assumes that bone adapts to the mechanical environment. For the analyses a consistent set of loads is determined for the bovine walk cycle. The remodelling results reproduce the morphologic features of bone and provide evidence of the difference on the bone behaviour when comparing metallic and polymeric nails. Our findings indicate that an intramedullary polymeric nail has the advantage over the metallic one of improving long-term bone healing and possibly avoiding the need of the implant removal.     

Numerical analysis of an osseointegrated prosthesis fixation with reduced bone failure risk and periprosthetic bone loss

Currently available implants for direct attachment of prosthesis to the skeletal system after transfemoral amputation (OPRA system, Integrum AB, Sweden and ISP Endo/Exo prosthesis, ESKA Implants AG, Germany) show many advantages over the conventional socket fixation. However, restraining biomechanical issues such as considerable bone loss around the stem and peri-prosthetic bone fractures are present. To overcome these limiting issues a new concept of the direct intramedullary fixation was developed. We hypothesize that the new design will reduce the peri-prosthetic bone failure risk and adverse bone remodeling by restoring the natural load transfer in the femur. Generic CT-based finite element models of an intact femur and amputated bones implanted with 3 analyzed implants were created and loaded with a normal walking and a forward fall load. The strain adaptive bone remodeling theory was used to predict long-term bone changes around the implants and the periprosthetic bone failure risk was evaluated by the von Mises stress criterion. The results show that the new design provides close to physiological distribution of stresses in the bone and lower bone failure risk for the normal walking as compared to the OPRA and the ISP implants. The bone remodeling simulations did not reveal any overall bone loss around the new design, as opposed to the OPRA and the ISP implants, which induce considerable bone loss in the distal end of the femur. This positive outcome shows that the presented concept has a potential to considerably improve safety of the rehabilitation with the direct fixation implants.     

Experimental and probabilistic analysis of distal femoral periprosthetic fracture: a comparison of locking plate and intramedullary nail fixation. Part B: probabilistic investigation

The following is Part B of a two-part study. Part A evaluated, biomechanically, intramedullary (IM) nails versus locking plates for fixation of an extra-articular, metaphyseal wedge fracture in synthetic osteoporotic bone. Part B of this study introduces deterministic finite element (FE) models of each construct type in synthetic osteoporotic bone and investigates the probability of periprosthetic fracture of the locking plate compared with the retrograde IM nail using Monte Carlo simulation. Deterministic FE models of the fractured femur implanted with IM nail and locking plate, respectively, were developed and validated using experimental data presented in Part A of this study. The models were validated by comparing the load-displacement curve of the experimental data with the load-displacement curve of the FE simulation with a root-mean square error of less than 3?mm. The validated FE models were then modified by defining the cortical and cancellous bone modulus of elasticity as uncertain variables that could be assumed to vary randomly. Monte Carlo simulation was used to evaluate the probability of fracture (POF) of each fixation. The POF represents the cumulative probability that the predicted shear stresses in the cortical bone will exceed the expected shear strength of the cortical bone. This investigation provides information regarding the significance of post-operative damage accumulation on the POF of the implanted bones when the two fixations are used. The probabilistic analysis found the locking plate fixation to have a higher POF than the IM nail fixation under the applied loading conditions (locking plate 21.8% versus IM nail 0.019%).     

A 3D computational simulation of fracture callus formation: influence of the stiffness of the external fixator

The stiffness of the external fixation highly influences the fracture healing pattern. In this work we study this aspect by means of a finite element model of a simple transverse mid-diaphyseal fracture of an ovine metatarsus fixed with a bilateral external fixator. In order to simulate the regenerative process, a previously developed mechanobiological model of bone fracture healing was implemented in three dimensions. This model is able to simulate tissue differentiation, bone regeneration, and callus growth. A physiological load of 500 N was applied and three different stiffnesses of the external fixator were simulated (2300, 1725, and 1150 N/mm). The interfragmentary strain and load sharing mechanism between bone and the external fixator were compared to those recorded in previous experimental works. The effects of the stiffness on the callus shape and tissue distributions in the fracture site were also analyzed. We predicted that a lower stiffness of the fixator delays fracture healing and causes a larger callus, in correspondence to well-documented clinical observations.     

Biomechanical assessment and clinical analysis of different intramedullary nailing systems for oblique fractures

The aim of this study is to evaluate the fracture union or non-union for a specific patient that presented oblique fractures in tibia and fibula, using a mechanistic-based bone healing model. Normally, this kind of fractures can be treated through an intramedullary nail using two possible configurations that depends on the mechanical stabilisation: static and dynamic. Both cases are simulated under different fracture geometries in order to understand the effect of the mechanical stabilisation on the fracture healing outcome. The results of both simulations are in good agreement with previous clinical experience. From the results, it is demonstrated that the dynamization of the fracture improves healing in comparison with a static or rigid fixation of the fracture. This work shows the versatility and potential of a mechanistic-based bone healing model to predict the final outcome (union, non-union, delayed union) of realistic 3D fractures where even more than one bone is involved.