两种内固定治疗青壮年不稳定型股骨颈骨折的有限元分析

目的 分析有限元模型下3枚空心钉固定和3枚空心钉联合1/3管型内侧支撑钢板固定治疗青壮年不稳定型股骨颈骨折的生物力学性能。方法 对1名28岁志愿者的股骨CT数据进行三维重建，建立PauwelsⅢ型股骨颈骨折内固定的有限元模型，比较3枚空心钉和3枚空心钉联合1/3管型内侧支撑钢板的应力分布、应力峰值，以及股骨的位移分布、位移峰值。结果 (1) 2种内固定的应力均分布于股骨颈骨折断端周围，应力峰值：3枚空心钉模型为40.98 MPa,联合1/3管型内侧支撑钢板模型的空心钉、钢板及配套螺钉分别为28.92、22.58、51.13 MPa。(2) 2种内固定的股骨最大位移均集中于股骨头顶端，股骨位移峰值：3枚空心钉模型为0.93 mm,联合1/3管型内侧支撑钢板模型为0.68 mm。结论 与3枚空心钉固定相比，有限元模型下3枚空心钉联合1/3管型内侧支撑钢板治疗青壮年不稳定型股骨颈骨折的力学传导性更好，内固定及骨折端稳定性更高。     

不同内固定方式固定Pauwels Ⅲ型股骨颈骨折模型的有限元分析

[目的]Pauwels Ⅲ型股骨颈骨折,骨折线相对垂直,骨不连发生率高,本研究即骨折以有限元分析的方法分析5种内固定方式固定Pauwels Ⅲ型股骨颈骨折的生物力学特点,从而为此类骨折治疗理念提供参考。[方法]根据Pauwels Ⅲ型骨折类型建立股骨颈骨折有限元模型,同时建立5种内固定模型,分别为:a:2枚拉力螺钉模型;b:3枚"倒品字"形排列拉力螺钉模型;c:3枚"倒品字"型排列全螺纹空心螺钉;d:股骨颈锁定钢板的内固定模型;e:InterTan钉板系统固定模型。并于Ansys软件中建立5种内固定的三维有限元模型,研究不同内固定的von Mises应力分布及位移分布、股骨的von Mises应力分布及位移分布,并比较股骨及内固定模型应力峰值、位移峰值,分析骨折固定后生物力学稳定性。[结果]骨折端应力峰值大小分别为:a:10.58 MPa;b:12.51 MPa;c:17.13 MPa:d:5.14 MPa;e:1.62 MPa。内固定的应力峰值分别为a:210.91 MPa;b:116.49 MPa;c:62.56MPa:d:142.49 MPa;e:65.72 MPa。所有模型的位移均集中于股骨头处,其峰值为:a:1.17 mm;b:1.11 mm;c:0.72 mm;d:0.99 mm;e:0.76 mm。[结论]钉板系统对骨折端的力学稳定性维持优于螺钉系统,且能有效预防股骨颈短缩,为Pauwels Ⅲ型股骨颈骨折推荐的内固定方式。     

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。     

PauwelsⅡ、Ⅲ型股骨颈骨折的内固定治疗进展北大核心CSCD

股骨颈骨折约占髋部骨折的50%[1],老年人较多,大多是低能量损伤所致,随着社会现代化的进展,股骨颈骨折的发生率日趋上升,且年龄逐步年轻化。股骨颈骨折后的生物力学环境影响骨折愈合及预后。Pauwels分型[2]是首个基于生物力学提出的股骨颈骨折分型,直观地描述了骨折的稳定性,Pauwels角越大,垂直剪切力就越大,骨折就越不稳定,术后并发症发生率也就越大,对治疗方式、内固定的选择有较强的指导意义。该分型根据Pauwels角(股骨颈骨折线与双侧髂前上棘连线的夹角)将股骨颈骨折分为3型,<30°为Ⅰ型,30°~50°为Ⅱ型,>50°为Ⅲ型。PauwelsⅠ型最为稳定,大多主张保守治疗。年龄<65岁的青壮年,骨质坚硬,多为高能量损伤所致,骨折移位较为严重,以PauwelsⅡ、Ⅲ型居多,并发症多,预后差,目前公认的治疗是内固定手术,但内固定方法的选择尚未形成统一意见。本文就青壮年PauwelsⅡ、Ⅲ型股骨颈骨折的内固定治疗现状作一综述,以帮助临床医生根据患者的病情选择适合的内固定治疗方法。     

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。     

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.     

加压空心钉不同部位治疗股骨颈骨折的生物力学研究

目的通过对加压空心钉内固定不同部位的生物力学研究,得出各种相关的生物力学数据,以得出更加稳定的内固定植入方法,在生物力学方面为临床治疗提供理论依据。方法将股骨模型按人体股骨颈骨折时常见的pauwels70°角用电锯截断,模拟常见的内收型股骨颈基底骨折,分别按正三角（向前分散排列、向前平行排列）,倒三角（向前分散排列、向前平行排列）不同的固定结构做成股骨颈骨折复位固定模型,在微机控制电子万能试验机上施加一定载荷,测出模型在水平和垂直方向的位移,同时在股骨颈内外侧贴应变片,在应变力综合测试仪上测出内、外侧的应变,根据公式计算出断面张开角。结果3枚空心加压螺钉采用上2枚,下1枚的向前分散倒三角形结构时,无论在载荷下水平位移、垂直位移、内外侧应力及断面张开角,还是在股骨颈骨折牢固固定方面,生物力学相关数据均显示最好。结论3枚加压空心钉呈倒三角向前分散结构的内固定方式最稳定。     

切开复位空心螺钉加内侧支撑钢板固定治疗Pauwels Ⅲ型股骨颈骨折的三年随访结果报道

目的探讨切开复位空心螺钉加内侧支撑钢板固定Pauwels Ⅲ型股骨颈骨折的疗效及并发症发生情况。方法回顾性分析2015年1月至2018年10月期间新疆维吾尔自治区中医医院创伤骨科收治的8例新鲜Pauwels Ⅲ型股骨颈骨折患者资料。男7例, 女1例;年龄(47.7±14.0)岁;Pauwels角为50°～70°者6例, >70°者2例。所有患者骨折闭合复位均不理想, 行改良Smith-Petersen入路切开复位空心螺钉加内侧支撑钢板固定。记录患者术后1个月、6个月、1年、3年随访时的骨折愈合情况、髋关节Harris评分及并发症发生情况等。结果术后1个月:8例患者均获随访, 髋关节Harris评分为(38.4±3.6)分;并发症:股骨颈短缩7例, 切口脂肪液化1例。术后6个月:7例患者获随访, 髋关节Harris评分为(70.6±2.8)分;1例患者解剖位愈合, 4例患者短缩愈合, 2例患者短缩延迟愈合。与术后1个月相比, 股骨颈短缩、中空螺钉退钉、支撑钢板内螺钉松动程度均增加。术后1年:7例患者获随访, 髋关节Harris评分为(85.5±4.4)分;与术后6个月相比, 骨折愈...     

4枚与3枚空心钉固定Pauwels Ⅲ型股骨颈骨折比较

[目的]比较4枚与3枚空心钉内固定PauwelsⅢ型股骨颈骨折的临床效果.[方法]2014年1月-2018年11月,70例Pauwels Ⅲ型股骨颈骨折患者纳入本研究,采用抽签法将患者随机分为两组.其中,35例采用4枚空心钉内固定(四钉组),35例采用3枚空心钉内固定(三钉组),比较两组患者围手术期情况、随访结果和影像...     

双螺钉系统与3枚空心加压螺钉治疗股骨颈骨折的比较研究

目的:比较双螺钉系统与3枚空心加压螺钉内固定治疗股骨颈骨折的疗效。方法:对2007年1月至2009年6月收治的67例股骨颈骨折患者的临床资料进行回顾性分析,男38例,女29例;年龄31～71岁,平均50.6岁;左侧41例,右侧26例。根据不同内固定方式分为两组,双螺钉系统组(A组)30例,男19例,女11例;空心加压螺钉组(B组)37例,男19例,女18例。按Pauwells角分型:Pauwells角≥50°空心加压螺钉组22例,双螺钉系统组16例;Pauwells角<50°空心加压螺钉组15例,双螺钉系统组14例。比较两组患者的住院时间、手术时间、术中出血量、下地时间、切口感染、术后并发症、骨折复位质量、内固定置入满意率、骨折不愈合发生率、股骨头缺血性坏死率、内固定失效率、髋关节功能评分(Harris评分)。结果:67例患者术后均获得随访,时间30～59个月,平均42个月。从围手术期指标分析,两组患者在住院时间、术中出血量、下地时间、切口感染、术后内科并发症等方面差异无统计学意义(P>0.05),手术时间双螺钉系统组为(31.1±9.7)min;空心加压螺钉组为(40.4±12.7)min,差异有统计学意义(P<0.05)。从术后评估及中远期并发症分析:在内固定置入满意率、骨折复位质量、骨折不愈合发生率、股骨头缺血性坏死率等方面差异无统计学意义(P>0.05);而在内固定失效率上,Pauwells≥50°的病例,双螺钉系统组未出现退钉、断钉、螺钉切割股骨头等失效病例,而空心加压螺钉组有2例出现退钉,2例出现螺钉切割股骨头,2例螺钉未完全进入股骨头,两组比较差异有统计学意义(P<0.05);在Pauwells<50°的病例,双螺钉系统组出现1例螺钉松动的失效病例,空心加压螺钉组有1例出现螺钉切割,两组比较差异无统计学意义(P>0.05),其中螺钉松动、退钉及切割股骨头的患者年龄都大于65岁。术后6、30个月两组Harris评分差异无统计学意义(P>0.05)。结论:双螺钉系统内固定术治疗股骨颈骨折具有创伤小、操作简便、固定确实等优点。与传统的3枚空心加压螺钉固定比较,双螺钉系统组具有更少的手术时间,更少的内固定失败率,更高的患髋功能评分。特别对于Pauwells角≥50°的股骨颈骨折的患者有良好的疗效。     

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.     

Titanium alloy cannulated screws and biodegrade ceramic nails for treatment of femoral neck fractures: A finite element analysis

BackgroundOur previous studies have demonstrated the mechanical effect of sclerosis around screw paths on the healing of femoral neck fractures (FNF) after internal fixation. Furthermore, we discussed the possibility of using bioceramic nails (BNs) to prevent sclerosis. However, all these studies were conducted under static conditions as the patient was standing on one leg, while the effect of the stress generated during movement is unknown. The purpose of this study was to evaluate the stress and displacement under dynamic stress loading conditions.MethodsTwo types of internal fixation, namely cannulated screws and bioceramic nails, were utilized in conjunction with various finite element models of the femur. These models included the femoral neck fracture healing model, the femoral neck fracture model, and the sclerosis around screws model. The resulting stress and displacement were analyzed by applying the contact forces associated with the most demanding activities during gait, including walking, standing, and knee bending. The present study establishes a comprehensive framework for investigating the biomechanical properties of internal fixation devices in the context of femoral fractures.ResultsThe stress at the top of the femoral head in the sclerotic model was increased by roughly 15 MPa during the knee bend and walking phases and by about 30 MPa during the standing phase compared to the healing model. The area of high stress at the top of the femoral head was increased during the sclerotic model's walking and standing phases. Additionally, the stress distribution throughout the dynamic gait cycle was comparable before and after the removal of internal fixations following the healing of the FNF. The overall stress distribution of the entire fractured femoral model was lower and more evenly distributed in all combinations of internal fixation. Furthermore, the internal fixation stress concentration was lower when more BNs were used. In the fractured model with three cannulated screws (CSs), however, the majority of the stress was concentrated around the ends of the fractures.The maximal stress in the healing model with one CS and two BNs was the highest at all stages of gait over three combinations of internal fixation, and the stress was mainly carried by CS.ConclusionsThe presence of sclerosis around screw paths increases the risk of femoral head necrosis. Removal of CS has little effect on the mechanics of the femur after healing of the FNF. BNs have several advantages over conventional CSs after FNF. Replacing all internal fixations with BNs after the healing of FNF may solve the problem of sclerosis formation around CSs to improve bone reconstruction owing to their bioactivity.     

A sliding hip screw augmented with 2 screws is biomechanically similar to an inverted triad of cannulated screws in repair of a Pauwels type-III fracture

ObjectivePauwels III femoral neck fractures are highly unstable. These fractures are commonly treated with three cannulated screws or sliding hip screw (SHS) implants, however high rates of non-union persist. A hybrid SHS construct has recently been proposed. The objective of the study was to compare this construct to the familiar inverted triad of cannulated screws and to a single SHS.MethodsFourth generation biomechanical femur analogs were used to create a highly repeatable injury model. The hybrid SHS construct contained a SHS with two superior cannulated screws in an inverted triangle configuration. Eight samples for each construct were biomechanically evaluated and the results compared using ANOVA (p < 0.05).ResultsThe cannulated triad and hybrid SHS provided similar stiffness and fracture gap motion. The single SHS exhibited significantly lower stiffness and larger fracture plane diastasis than either the inverted triangle of cannulated screws or hybrid SHS (p < 0.05). None of the constructs exhibited catastrophic failure during cyclic loading nor under loading up to 2.5 times body weight.ConclusionsThe single SHS provided the least stable fracture fixation, while the inverted triad and hybrid SHS constructs were mechanically similar. The fracture repair simulated here illustrates how these repairs have the potential to return near pre-fracture strength in ideal conditions with young, healthy bone. However; in clinical situations where comminution impairs load transfer through the cortices the hybrid SHS may be the most favorable option.     

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.     

A biomechanical study of simulated femoral neck fracture fixation by cannulated screws: effects of placement angle and number of screws

The angle of placement of hip screws to fix femoral neck fractures is still a controversial subject, and it must be addressed. In the study reported here, we compared the relative stiffness of fixation of simulated Pauwels type III femoral neck fractures fixed with either 2 or 3 cannulated screws implanted at 135 degrees, 145 degrees, and 150 degrees. Each femur was fixed with 2 or 3 cannulated screws and tested under axial loading and anteroposterior (AP) bending. Then each femur was fatigued to 1000 cycles and tested to failure. Fourteen femurs were tested. Results showed that axial stiffness values were not statistically different at different angles. AP bending stiffness of the high-angle (150 degrees) construct was significantly higher than that of either of the other 2 constructs (for 2 screws only). Two-screw fixation appears to be adequate; adding a third screw may not be necessary.     

国人前路齿突螺钉置入安全角度与齿突容纳能力的影像学分析

目的以CT三维重建资料为基础,对3种不同标志方法引导的前路齿突螺钉置入的安全角度及可靠性进行分析,并评估国人齿突的容纳能力。方法应用影像归档和通信系统(PACS)对选取的141例国人颈椎CT三维重建资料中的齿突图像进行测量分析,其中男96例,女45例。分别以寰椎前结节、枢椎椎体下终板、C3椎体前缘切线为标志,测量不同标志线下前路齿突螺钉置钉的安全角度范围、最佳置钉角度与最佳置钉长度,并对男性与女性的最佳置钉长度进行比较分析。进一步测量齿突基底部最窄矢状内径与外径、基底部最窄冠状内径与外径,分析国人齿突是否能够容纳2枚直径为3.5 mm的皮质骨螺钉,并分别对男性与女性齿突基底部径线长度及齿突的螺钉容纳能力进行比较。结果以寰椎前结节、枢椎椎体下终板、C3椎体前缘切线作标志线置钉的安全角度范围分别为22.82°~30.37°、55.55°~63.08°、13.83°~21.42°;最佳置钉角度分别为27.09°±2.98°、58.85°±4.43°、18.09°±5.09°;最佳置钉长度为(38.35±2.93)mm,其中男性为(39.04±2.89)mm,女性为(36.89±2.46)mm,两者比较差异有统计学意义(P0.05)。齿突基底部最窄冠状内径、外径分别为(6.21±1.01)mm、(8.87±1.04)mm,最窄矢状内径、外径分别为(7.16±1.13)mm、(10.34±0.98)mm,男性与女性齿突基底部矢状、冠状径线相比较,差异均有统计学意义(P0.05)。141例资料中,有65例(46%)齿突冠状面能够容纳2枚直径为3.5 mm的皮质骨螺钉,其中男50例,女15例,两者比较差异有统计学意义(P0.05);在齿突基底部的矢状径线上,有128例(91%)能够容纳2枚直径为3.5 mm的皮质骨螺钉,其中男92例,女36例,两者比较差异有统计学意义(P0.05)。结论以寰椎前结节、枢椎椎体下终板及C3椎体前缘切线做标志线,前路齿突置钉的安全角度范围分别为22.38°~30.43°、55.52°~63.54°、13.38°~21.53°。齿突的矢状径有容纳2枚螺钉的更大空间,为国人前路齿突交叉置钉提供了可能。     

寰枕关节后路经关节螺钉固定钉道参数的测定

目的 明确后路寰枕关节经关节螺钉固定的技术参数;探讨枕颈部经关节螺钉内固定技术的临床意义。方法 30例含完整寰枕关节干燥骨性标本,直视下行后路寰枕关节经关节克氏针植入后行X线摄片,在X线胶片上测量寰枕关节经关节螺钉固定的钉道角度和钉道长度。结果 寰枕关节经关节螺钉固定的钉道理想角度为:螺钉方向在矢状面的上倾角为 53. 3°±3. 4°,在冠状面的内倾角为 20. 0°±2. 6°。钉道长度为: (29. 28±2. 46)mm。结论 寰枕关节后路经关节螺钉植入存在一定的方向性和钉道长度问题,结合后路C1, 2经关节螺钉内固定后可视为能满足当前临床需要的一种相对理想的枕颈融合内固定术式。     

Biomechanical comparison of four different fixation methods in the management of Pauwels type III femoral neck fractures: Is there a clear winner?

BackgroundCannulated screws augmented with the medial buttress plate could confer greater biomechanical stability and higher union rates than the screw fixation alone for treating young patients with Pauwels type III femoral neck fractures (FNFs). No study has evaluated the effects of distal bicortical screw fixation and biomechanical properties of buttress plate augmentation under simultaneous vertical and rotational forces, physiologically acting on the hip joint. This study aimed to compare the biomechanical properties of four methods of three cannulated screw fixation under the combined axial and torsional loading in a synthetic femur model of type III FNF.MethodsTwenty-four third-generation composite femora were divided into four groups (6 femora in each group) based on the screw fixation configuration: inverted triangle configuration (Group A),  Pauwels' configuration (Group B), inverted triangle configuration combined with medial buttress plate using distal unicortical (Group C), and distal bicortical screw placement (Group D). A Pauwels type III FNF was simulated on the sawbones. Each model was subjected to the combined axial and torsional cyclic loading and subsequently tested to failure.ResultSignificant differences were determined in axial stiffness (AS) among the four groups (p = 0.024), whereas there was no significant difference in torsional stiffness (p = 0.147). The mean AS was higher in group D (639.5 ± 86.2 N/mm) than in group A (430.6 ± 94.8 N/mm), group B (426.2 ± 41.9 N/mm), and group C (451.2 ± 156.7 N/mm). Failure forces (FFs) were significantly different among four groups (p = 0.007), while there was no considerable difference in failure moment values (p = 0.555). The mean FF was significantly higher in group D (1307.1 ± 96.4 N) than in group A  (1076.9 ± 371.2 N) and group B (1075.5 ± 348.3 N) (p = 0.014 and p = 0.018, respectively). There was no significant difference in the mean FF between groups D and C.ConclusionRegardless of the medial plate use, multiple cannulated systems could provide similar biomechanical results regarding torsional stiffness and failure moments. Bicortical placement of the most distal screw in medial buttress plate application could improve axial stability but not significantly affect the rotational stability of the inverted triangle screw fixation system in managing type III FNFs.     

经骶骨纵向固定腰骶滑脱的解剖学研究

目的　对骶骨进行形态学测量 ,研究后路空心钉经骶骨纵向固定腰骶部的安全性。方法　对 2 0例干燥骶骨标本进行CT扫描 ,并进行多平面重建 (MPR)分析 ,测量S1水平骶骨侧块中心的长、宽及面积 ,确定该固定方法的空心钉钉道的长度、安全方向和范围。结果　 2 0例骶骨标本中 ,该固定方法的最窄部分位于S1神经孔水平 ,其几何中心的平均长度为 (37.31± 4 .2 1)mm(2 9～ 4 6 .7mm) ,平均宽度为 (2 1.2 9± 3.5 7)mm(16 .3～ 2 7.4mm) ,平均面积为 (6 .31± 1.2 3)cm2 。通过测量和分析 ,空心钉在矢状面和冠状面的平均最小角度分别为 2 6 .2 9°(2 4 .1°～ 31.3°)和 4 3.6 5°(2 6 .0°～ 5 4 .5°) ,空心钉的平均长度为 85 .2 8mm。结论　相关解剖学数据表明 ,只要进钉的方向及角度正确 ,空心钉经骶骨纵向固定的通道位于骶骨内。术前行CT检查或三维重建 ,制定个体化固定方案 ,该方法可安全地应用于临床。