空心钉在股骨颈中构型的生物力学研究

目的通过生物力学实验探讨空心钉固定股骨颈骨折时,3枚螺钉的构型对固定强度和稳定性的影响。方法选取25～70岁尸体股骨8对,左右股骨随机分成两组。倾角50°截骨,3枚空心钉分别呈正三角和倒三角构型固定股骨颈骨折。生物力学实验机对股骨-螺钉复合体进行线性递增的加载,同时测量股骨头的位移和沿截骨面的剪切位移。结果倒三角形构型的空心固定组较正三角形组具有更高的极限负荷和抗剪切能力,差异有统计学意义（P〈0.05）。结论对于无后部皮质粉碎的股骨颈骨折,采用倒三角构型的空心钉固定,较正三角构型固定在体外的生物力学上具有更高的固定强度和稳定性。     

I.CO.S.螺钉治疗股骨颈骨折的生物力学研究

目的 探讨I.CO.S.(ideal compression screw)螺钉在治疗股骨颈骨折中的生物力学作用,为临床选择此类螺钉治疗股骨颈骨折提供理论依据.方法 取甲醛固定成年(45～60岁)尸体股骨标本48个,选骨密度及股骨颈长度相似的标本30个,制备股骨颈头下型骨折模型,随机分为I.CO.S.螺钉组(实验组)和普通空心加压螺钉组(对照组),实验组根据植钉数量及位置不同又分为A(水平位2枚)、B(垂直位2枚)、C(倒三角位3枚)3个亚组,对照组分为D(水平位2枚)、E(垂直位2枚)、F(倒三角位3枚)3个亚组,每亚组5个标本.以速率1.2 mm/min线性载荷0～600 N分级加载,测定各组载荷下股骨卜段应变值、股骨头水平位移和垂直位移,并进行屈服力学性能测试.结果 在生物力学稳定性方面:A、B、C组水平位移和屈服载荷均较D、E、F组好(p<0.05),A、D组应变、水平位移和屈服载荷均较B、E组好(P<0.05),而C、F组间以及A、C组间应变、水平位移、垂直位移、屈服位移和屈服载荷差异均无统计学意义(P>0.05).结论 I.CO.S.螺钉固定股骨颈骨折稳定可靠,且2枚I.CO.S.螺钉水平位固定有较高的生物力学稳定性,可为临床应用提供力学依据.     

InterTan钉板系统与空心钉固定Pauwels Ⅲ型股骨颈骨折的有限元分析

目的 用有限元分析的方法研究InterTan钉板系统与3枚互相平行的空心钉固定PauwelsⅢ型股骨颈骨折的生物力学特点. 方法选取1名男性健康志愿者,28岁,体质量为75 kg,通过16排螺旋CT扫描,取右侧近端股骨数据作为样本.通过逆向工程软件分别重建PauwelsⅢ型股骨颈骨折三维可视化模型、InterTan钉板系统固定模型及3枚互相平行空心钉固定模型,并于Ansys软件中建立2种内固定模型的三维有限元模型,予以轴向700 N应力,研究不同内固定的von Mises应力分布和位移分布、股骨的yon Mises应力分布和位移分布,并比较内固定和股骨模型的应力峰值和位移峰值. 结果 内固定物的应力主要集中于骨折线附近,其中InterTan钉板系统钉板系统固定模型的应力峰值(65.7 MPa)低于空心钉固定模型(116.4 MPa)；骨端的应力分布集中于股骨近端内侧,InterTan钉板系统固定模型的应力峰值(13.2 MPa)小于空心钉固定模型(27.6 MPa).lnterTan钉板系统固定模型中,内固定物位移方向为垂直向下,内固定物和骨端的位移峰值分别为0.84和0.76 mm;空心钉固定模型中,位移方向沿着股骨颈方向,内固定物和骨端的位移峰值分别为1.49和1.61 mm. 结论 使用InterTan钉板系统固定PauwelsⅢ型股骨颈骨折时,应力分布均匀,固定稳定性优于3枚互相平行空心钉固定.InterTan钉板系统固定时,位移方向垂直向下,髋内翻是需要预防的并发症；后者位移方向沿着股骨颈向外侧,股骨颈短缩为需要预防的并发症.     

利用有限元探究内固定治疗股骨颈骨折的生物力学研究

目的:利用有限元分析研究不同内固定治疗Pauwels Ⅲ型股骨颈骨折的生物力学特点。方法:选取1名健康受试者的股骨CT数据进行三维重建,骨折造模,装配动力髋螺钉、锁定加压钢板、三枚空心钉、四枚空心钉和髓内钉,建立有限元模型,在股骨头顶端轴向加载1400 N应力。研究不同内固定的应力分布和位移分布、股骨的应力分布和位移分布,并比较内固定和股骨模型的应力峰值和位移峰值。结果:股骨和内固定应力较大区域均分布于股骨颈及股骨干部位,且在骨折线附近均出现应力增大的现象;内固定位移分布主要集中于股骨头内螺钉尖端位置,股骨位移集中于股骨头顶端,应力加载位置。四枚空心钉的应力最小,峰值为135.3 MPa;锁定加压钢板的应力最大,峰值为405.9 MPa,但锁定加压钢板的位移12.3 mm为最小峰值;三枚空心钉的位移18.8 mm为最大峰值;三枚空心钉固定时,股骨受力最小,应力峰值为36.8 MPa,但股骨位移最大,峰值为19.3 mm;锁定加压钢板固定时,股骨受力104.6 MPa为最大应力峰值而位移12.6mm为最小位移峰值。结论:锁定加压钢板在固定股骨颈骨折时稳定性最高,但股骨和内固定承受更大的压力和剪切力;动力髋螺钉固定短期内促进骨折愈合较有优势,但长期固定时髓内钉固定更佳。     

股骨颈膨胀式带锁加压钉的研制及生物力学评价

目的 探讨股骨颈骨折内固定的方法，评价HZS型股骨颈膨胀式带锁加压钉(interlocking expanding compressive screw,IECS)的生物力学性能。方法 根据股骨颈骨折特殊的生物力学特性，设计制作由主钉、股骨头分叉钉、分叉钉推进螺帽、加压螺帽匀力垫、加压螺帽、斜向锁钉和主钉尾帽构成的股骨颈膨胀式带锁加压钉，以单枚双头加压螺钉(dynamic compressive screw,DCS)、双头加压子母螺钉(twin compressive screur，2CS)和三枚空心加压螺钉(three cannulated screws,3CS)作对照组进行生物力学实验。结果 IECS固定的股骨颈骨折在位移、轴向和水平剪切刚度、扭转强度和刚度、极限载荷等生物力学性能均明显优越于DCS、2CS和3CS。结论 IECS能有效对抗骨折断端间的分离、扭转、剪切、张应力和压应力。结构轻巧，操作简便，安全可靠。     

老年人股骨颈骨折内固定治疗的研究进展

内固定治疗老年人股骨颈骨折,尤其空心钉的应用,较髋关节置换具有微创、经济、操作简便的优势,成为近年来骨科临床研究的热点.空心钉的构型问题仍存在争议,大多数临床医生认为3枚空心钉平行置入的倒三角构型固定方法在生物力学及临床效果方面优于正三角构型,而非平行的强斜置钉技术能使螺钉分担更多体重,减少术后并发症,更适用于老年骨质疏松患者.内固定治疗股骨颈骨折术后骨不连、股骨颈短缩等难题仍是国内外学者关注的焦点.如何把握内固定手术的适应证,了解并发症的相关因素,预防并发症的发生有待进一步探索.     

三枚双头空心加压钉(DECS)治疗股骨颈骨折的生物力学研究与临床应用

目的：探讨治疗体骨颈骨折采用三枚双头空心加压钉的生物力学原理和临床应用，方法：采用8具尸股骨股骨颈骨折用三枚双头空心加压钉固定，并比较三种不同器械的生物力特性。结果：生物力学试验和临床应用表明，该术式不仅使股骨颈在抗压，抗弯和导等生物力学性能上特别优越，而且使骨折断端嵌插紧密，能加速骨折愈合，应力遮挡少，病人能早期下床活动和减少并发症，结论：三枚双头空心加压螺纹外内固定比其它内固定更具有生物力学优势，是一种理想的内固定术式。     

新构型空心钉固定股骨颈骨折的有限元分析

目的对3枚空心钉"轴心加压+侧方支撑"新构型固定股骨颈骨折的生物力学特性进行三维有限元分析,为临床应用提供理论依据。方法选取1名健康成年男性志愿者,采用股骨CT扫描数据建立三维模型后模拟PauwelsⅡ型股骨颈骨折,分别采用正三角形、倒三角形、"轴心加压+侧方支撑"构型空心钉进行固定,在不同负荷下对空心钉应力分布及峰值、股骨位移分布及峰值、股骨颈骨折头侧端应力分布及峰值进行分析。结果各组上方空心钉应力大于下方空心钉,应力大多集中于螺纹与螺杆交界处并向两端呈减小趋势,螺钉尾部应力局部又有所增大。各组股骨位移最大处为股骨头负重处,从上向下位移递减。正三角形组股骨颈骨折头侧端应力高度集中,位于下方偏前处,而倒三角形组与新构型组断端应力相对较均匀分散于股骨颈下半部分。1倍体重负荷下正三角形组空心钉应力峰值(150 MPa)、股骨位移峰值(0.69 mm)、股骨颈骨折头侧端应力峰值(51 MPa)最高,倒三角形组次之(分别为93 MPa、0.65 mm、22 MPa),新构型组最小(分别为77 MPa、0.58 mm、18 MPa)。随着负荷增加,各组空心钉应力峰值、股骨位移峰值、股骨颈骨折头侧端应力峰值相应增加,但新构型组始终最小。结论 "轴心加压+侧方支撑"新构型固定的空心钉较三角形排列的空心钉承受应力和位移较小,且骨折端应力较小,整体稳定性较好。     

空心钉和骨圆针固定治疗股骨转子间骨折的力学随机对照试验

目的:通过与4枚斯氏针固定比较,利用生物力学方法评价多枚空心钉固定股骨转子骨折的适应证和可靠性。方法:使用Sawbone股骨模型,模拟EvansⅢA型骨折,分别用2种多枚空心钉方法(矩外空心钉和矩内空心钉法)及多枚骨圆针固定,在CSS-11101力学实验机上进行载荷试验,取300 N载荷下股骨头垂直位移和张口位移数值,比较3种方法的轴向刚度。通过扭转实验比较3种固定方法的抗扭转能力。结果:3种固定方法在轴向刚度方面差异有统计学意义(P<0.05),而抗扭转能力方面差异无统计学意义(P>0.05)。结论:矩外空心钉固定力学性能相似于4枚骨圆针,而矩内空心钉固定弱于4枚骨圆针。应用多枚空心钉固定应选择稳定型股骨转子间骨折。     

预防股骨颈骨折空心钉内固定术后股骨颈短缩空心螺纹钉优化选择的有限元分析

目的：运用有限元分析法比较采用不同数量全螺纹空心钉在不同置钉位置内固定治疗Pauwels Ⅱ型股骨颈骨折,预防术后颈短缩的生物力学特性。方法：选取健康老年女性志愿者1名,年龄55岁,体重70 kg,身高165 cm。采用CT扫描,获取右侧股骨数据,在三维建模软件分别建立PauwelsⅡ型股骨颈骨折模型、全螺纹空心钉和半螺纹空心钉模型。按全螺纹空心钉数量和置入呈倒三角分布位置分为8组骨折内固定模型：3枚半螺纹钉组、1枚前上方全螺纹钉加2枚半螺纹钉组,1枚后上方全螺纹钉加2枚半螺纹钉组,1枚下方全螺纹钉加2枚半螺纹钉组,1枚前上方半螺纹钉加2枚全螺纹钉组,1枚后上方半螺纹钉加2枚全螺纹钉组,1枚下方半螺纹钉加2枚全螺纹钉组,3枚全螺纹钉组。在有限元分析软件中分别加载同样载荷,比较分析各组的内固定物的应力分布及应力峰值、股骨近端应力分布及应力峰值、骨折断端切面的应力分布及应力峰值、内固定物位移峰值,并比较术后股骨颈长度。结果：各组的内固定应力主要集中于骨折线处,且均位于下方螺钉的底部,应力峰值分别为239.71、213.44、199.37、230.82、201.63、215.72、185.6...     

How to choose the suitable FNS specification in young patients with femoral neck fracture: A finite element analysis

BackgroundConsensus regarding the optimal approach for the treatment of femoral neck fractures remains lacking. A new internal fixation femoral neck system (FNS) was developed and used in clinical practice. We aimed to investigate the biomechanical outcomes of different types of FNS in the treatment of unstable femoral neck fractures.MethodIn this study, we constructed three different types of unstable femoral neck fractures of Pauwels classification with angles of 50°, 60°, and 70°. We set up four test groups, namely, the one-hole plated FNS group, two-hole plated FNS group, inverted cannulated screw group and triangle cannulated screw group. Under 2100 N axial loads, displacements and the von Mises stress of the femur and internal fixation components were measured for each fracture group.ResultsWhen the Pauwels angle was 50°or 60°, the one-hole locking plated FNS was as superior as the two-hole plated FNS in terms of femur and internal fixation displacement, and the inverted cannulated screw had slightly better stability than the triangular cannulated screw. However, when the angle increases to 70°, the two-hole locking plate has the minimum displacement, followed by the triangular cannulated screw and inverted cannulated screw, which is the worst displacement for the single-hole locking plate. Regardless of the angle, the two sets of FNS have higher internal fixation stress than the two sets of cannulated screws, which is approximately 1.6-3.0 times that of the cannulated screw group.ConclusionFrom the perspective of biomechanics, we suggest that when the angle of the fracture line is less than 60°, both single-hole locking plated or double-hole locking plated FNS can be used to treat unstable femoral neck fractures. However, when the angle of the fracture line is greater than 70°, we recommend using a double-hole locking plated FNS. This result needs further verification in further clinical studies.     

Finite element analysis of the effect of cannulated screw placement and drilling frequency on femoral neck fracture fixation

BackgroundPositioning of the implanted cannulated screw is paramount for stable femoral neck fracture fixation. To avoid overdrilling, the aim of this study is to determine the optimum configuration of three cannulated screws employed in femoral neck fracture fixation.MethodsUsing a CT scan from a 28 year old healthy male, several models of femoral neck fracture fixation were developed using finite element analysis. After drilling small holes (in either fixed or random patterns) for screw insertion, the mechanical stresses on the screws were compared for three fracture types.ResultsThe inverted isosceles triangle was found to be the best screw configuration. Using finite element analysis, the upper limit of drilling frequency and the maximum stress on the screws for 30°, 50°, and 70° drilling were 14, 16, and 19 times and 46.1 MPa, 61.9 MPa, and 51.0 MPa, respectively. The upper limit of drilling frequency and the maximum stress on the screws for subcapital type, transcervical type, and basicervical type were 14, 16, and 40 times and 24.7 MPa, 61.9 MPa, and 113.5 MPa, respectively.ConclusionsResults of this study had supported the use of the inverted isosceles triangle as the best screw configuration for femoral neck fracture fixation. Screw position, Pauwels angle, and drilling frequency can all affect the mechanical strength of femoral neck fracture fixation.     

髋前侧小切口植骨及内固定治疗中老年股骨颈骨折

目的探讨髋前侧小切口自体髂骨植骨及空心钉内固定治疗中老年移位型股骨颈骨折的疗效是否优于单纯空心钉内固定术。方法回顾分析2006年1月一2011年5月在我院治疗并获得随访的49例中老年移位型股骨颈骨折的临床资料,其中26例行单纯空心钉内固定术（对照组）,23例行髋前侧小切口自体髂骨植骨及空心钉内固定术（植骨组）,比较2组围术期情况和疗效。结果与对照组相比,植骨组手术时间长[（53．5±12．7）minVS．（40．4±9．7）min,t=4．084,P=0．000],术中出血量多[（66．1±22．7）mlvs．（46．4±13．8）ml,t=-3．719,P=0．000],术后住院时间无统计学差异[（7．1±2．9）dV8．（6．2±3．6）d,t=-0．955,P=0．344],但术后骨折愈合率高[100．0％（23／23）VS．76．9％（20／26）,P=0．016],股骨头缺血性坏死率低[8．7％（2／23）VS．34．6％（9／26）,X2=4．710,P=0．030]。49例随访12～48个月,平均25个月。根据髋关节功能Harris评分标准,植骨组术后评分显著高于对照组[（85．7±4．3）分vs．（79．1±6．2）分,t=-4．274,P=0．000]。结论髋前侧小切口自体髂骨植骨及空心钉内固定治疗中老年移位型股骨颈骨折,骨折愈合率高,股骨头缺血性坏死率较低,对中老年股骨颈骨折治疗具有积极意义。     

Biomechanical properties of off-axis screw in Pauwels III femoral neck fracture fixation: Bicortical screw construct is superior to unicortical screw construct

ObjectivesThe purpose of this study is to determine the biomechanical properties of the bicortical off-axis screw fixation for stabilizing of Pauwels III femoral neck fractures compared with other fixation methods.MethodsEighteen synthetic femurs (Sawbones Pacific Research Laboratories, Vashon, WA) were divided into three groups. The osteotomy was made vertically to mimic the Pauwels type III femoral neck fracture. Group A (n = 6) was fixed with traditional inverted triangle cannulated screws. Group B (n = 6) was fixed with a unicortical off-axis screw and two parallel cannulated screws. Group C (n = 6) was fixed with a bicortical off-axis screw and two parallel cannulated screws. Each group was tested with a nondestructive axial compression test at a 7° of valgus followed with 1000 cycles of cyclic loading test from 100 N to 1000 N. Finally, a destructive axial compression test was applied until catastrophic failure.ResultsThe average axial stiffness from group A to group C was 856.5, 934, and 1340 N/mm, respectively. The average ultimate failure load from group A to group C was 2612.7, 2508.8, and 3706 N, respectively. Group C exhibited significantly greater axial stiffness and a higher ultimate failure load than the other two groups (P < 0.05). Regarding the interfragmental displacement, the values from group A to group C were 0.41, 0.83, 0.36, respectively, and group B exhibited significantly larger fracture gap formation after the cyclic loading test.ConclusionsThe results of this biomechanical study show statistically significant increases in axial stiffness and ultimate failure load for the off-axis screw placed in bicortical fashion. Once the off-axis screw was positioned unicortically, the largest fracture diastasis was observed as compared to the other two methods.     

空心钉联合同种异体腓骨内固定治疗中青年股骨颈骨折临床初步观察

目的探讨空心钉联合同种异体腓骨内固定治疗中青年股骨颈骨折的初步疗效。方法采用同种异体腓骨植入股骨头前外侧,并以两枚AO空心钉固定治疗中青年股骨颈骨折。结果经临床应用40例40个髋关节,初步随访24～84个月,平均48．5个月,15例出现坏死症状,5例晚期塌陷,塌陷率12．5％,3例塌陷进展行全髋关节置换,髋关节Harris功能评分,优良率92．5％。结论空心钉联合同种异体腓骨内固定治疗中青年股骨颈骨折具有以下优点：（1）促进股骨颈骨折愈合预防骨不连及股骨颈短缩;（2）增加股骨头负重区软骨下骨的机械支撑,分散传导局部应力,提供有效的头内稳定性,利于坏死修复,尽早预防股骨头坏死后塌陷或塌陷进展;（3）增加固定稳定性,可早期下地活动。该手术方法简单、疗效可靠,尤其适用于中青年股骨颈移位或粉碎性骨质缺损骨折。     

Effect of integrity of the posterior cortex in displaced femoral neck fractures on outcome after surgical fixation in young adults

Aim

To assess whether disruption of the posterior cortex of intracapsular femoral fractures leads to an increased incidence of complications following closed reduction and internal fixation by multiple cannulated screws in young adults.

Methods

A total of 146 consecutive adult patients with 146 femoral neck fractures were treated by closed reduction and internal fixation with parallel cannulated screw in inverted triangle or diamond configurations. All enrolled patients were divided into three groups: those with a non-displaced femoral neck fracture (Garden types I or II), those with a displaced femoral neck fracture (Garden types III or IV) but no posterior cortex disruption and those with a displaced femoral neck fracture (Garden types III or IV) and a disrupted posterior cortex.

Results

Based on an average follow-up of 4.76 years (range, 2-6 years), displaced femoral neck fractures with a disrupted posterior cortex demonstrated an increased risk for avascular necrosis of the femoral head, shortening, redisplacement and conversion of prosthetic replacement as compared with those fractures without posterior cortex disruption (p = 0.002, 0.016, 0.001 and <0.0001, respectively).

Conclusions

As compared with a femoral neck fracture with an intact posterior cortex, a displaced femoral neck fracture with a disrupted posterior cortex increases the risk for avascular necrosis, redisplacement and shortening and raises the likelihood that prosthetic replacement will be needed. Orthopaedic surgeons should be aware of this prognostic factor.     

股骨干骨折合并同侧股骨颈骨折治疗的临床观察

目的：探讨股骨干合并同侧股骨颈骨折的治疗特点和不同固定方法的疗效。方法：股骨干骨折合并同侧股骨颈骨折27例,男22例,女5例;年龄14～65岁,平均35岁。动力髋螺钉（DHS）固定3例,加压钢板加空心加压螺钉固定12例,重建钉固定8例,顺行髓内钉加空心加压螺钉固定4例。13例固定术前用克氏针临时固定股骨颈骨折。结果：术后随访36～75个月,平均44个月。25例股骨颈骨折平均愈合时间4.5个月,2例股骨颈骨折不愈合。27例股骨干均愈合,平均愈合时间6个月。未用克氏针临时固定股骨颈骨折14例中,2例出现股骨颈不愈合,3例轻度髋内翻畸形。结论：股骨干合并同侧股骨颈骨折有许多固定方法可供选择,加压钢板加空心加压螺钉固定简便易用,在实施固定术前用克氏针临时固定股骨颈骨折可避免股骨颈骨折再移位和损伤。     

Screw positions in femoral neck fractures: Comparison of two different screw positions in cadavers

To evaluate the influence of different screw positions on the stability of fixation in femoral neck fractures, 30 cadaveric proximal femora were osteotomized and fixed with 2 cannulated screws. The proximal screw was placed either with a posterior cortical support in the femoral neck or centrally, supported only by cancellous bone. The distal screw rested on the femoral calcar. The specimens were tested in bending, using the force at 2 and 5 mm deflection at the osteotomy site and at fracture, as an expression of the stability of fixation. The test sequences were recorded on a x-y plotter and on videotape. Bone density measurements were made at the femoral neck, Ward's triangle, and the trochanter region.

Our findings indicate that a posterior position with cortical support for the proximal screw, compared to a central screw position with only cancellous bone support, increases the stability of femoral neck fractures.     

空心钉不同排列方式对股骨颈骨折术后疗效的影响

目的比较两种空心钉不同排列方式对老年股骨颈骨折术后疗效的影响。方法 2010年2月至2012年1月我科治疗老年股骨颈骨折142例,其中行空心加压螺钉固定87例,分别使用两种不同排列方式的空心钉,A组行经矩立体交叉排列方式,共45例,男17例,女28例,平均年龄(73.66±8.01)岁;B组行AO三角形排列方式,共42例,其中男13例,女29例;平均年龄(75.16±8.52)岁。分别记录并比较两组患者术中出血量、手术时间、C型臂照射时间、住院时间;此外,术后1年对两组患者患侧髋关节活动功能及股骨颈短缩情况进行随访并比较。结果两组比较,年龄、性别、合并症、美国麻醉医师协会(American society of anesthesiologists,ASA)评分、骨折类型、骨密度差异无统计学意义(P0.05);对术中情况进行比较,发现两组患者麻醉方式、出血量、手术时间及C型臂透视时间均差异无统计学意义(P0.05);术后1年随访,A组(经矩立体交叉排列方式)中,3例随访期间死亡,39例骨折愈合,2例骨折不愈合,3例失效,1例股骨头缺血坏死,其中14例发生股骨颈短缩,Harris髋关节功能评分平均(85.13±10.30)分;B组(三角形排列方式)中,2例死亡,39例骨折愈合,1例骨折不愈合,1例失效,没有股骨头缺血坏死的病例,23例发生股骨颈短缩,Harris髋关节功能评分平均(78.44±14.17)分。两组相比,B组(三角形排列方式)较A组(经矩立体交叉排列方式)更容易发生股骨颈短缩(P0.01),同时Harris评分较A组小,说明患肢功能较差(P0.01)。结论三角形排列方式治疗老年股骨颈骨折较经矩立体交叉排列方式更容易发生股骨颈短缩,髋关节功能也较差。