个性化3D打印多孔钛合金加强块重建重度髋臼骨缺损的生物相容性和生物力学研究

[目的]评价巴马小型猪髋臼骨缺损模型个性化3D打印多孔钛合金加强块多孔内骨长入情况和生物力学性能。[方法]在巴马小型猪建立髋臼缺损模型,制备个性化3D打印多孔钛合金加强块置于缺损处。扫描电子显微镜测量多孔钛合金加强块多孔涂层内部结构参数(孔隙率、孔径和梁径),CT扫描三维重建测量个性化加强块置入术后的匹配率;力学试验机测量加强块的刚度、抗压强度和弹性模量以及加强块置入术后的生物力学;Micro-CT检查评价加强块多孔涂层内的骨长入和骨整合。[结果]钛合金加强块内部结构参数,总孔隙率为(55.48±0.61)%,孔径(319.23±25.05)μm,梁径(240.10±23.50)μm;力学性能参数:刚度为(21 464.60±1 091.69)N/mm,抗压强度为(231.10±11.77)MPa,弹性模量为(5.35±0.23)GPa。加强块置入术后的匹配度为:(91.40±2.83)%。Micro-CT扫描结果显示个性化3D打印多孔钛合金加强块的多孔涂层内有骨小梁长入;个性化3D打印多孔钛合金加强块置入术后即刻和12周最大抗剪切强度载荷值分别为(929.46±295.99)N和(1 521.93±98.38)N(P=0.030)。[结论]本研究中设计的个性化3D打印多孔钛合金加强块具有良好的骨组织生物相容性和生物力学性能。     

个性化3D打印多孔钛合金加强块重建重度髋臼骨缺损的有限元分析

目的 建立个性化3D打印多孔钛合金加强块重建重度髋臼骨缺损有限元模型,分析个性化3D打印多孔钛合金加强块、螺钉以及骨的生物力学和临床应用安全性。方法 利用1例Paprosky ⅢA型髋臼骨缺损病人的骨盆CT数据建立完整的个性化3D打印多孔钛合金加强块重建重度髋臼骨缺损有限元模型,模拟1倍体重（单足站立）、4倍体重（步行）和6倍体重（慢跑）加载负荷下分析加强块、螺钉以及骨的应力分布。结果 个性化3D打印多孔钛合金加强块的最大应力分布为10.130 MPa（1倍体重）、40.706 MPa（4倍体重）和61.213 MPa（6倍体重）,固定加强块的螺钉最大应力分布为12.424 MPa（1倍体重）、50.250 MPa（4倍体重）和75.860 MPa（6倍体重）,骨面应力分布最大应力分布为10.439 MPa（1倍体重）、42.627 MPa（4倍体重）和64.554 MPa（6倍体重）。结论 有限元模拟术后即刻完全负重站立时所有部件的应力分布均小于其屈服强度,不会发生失效;但是于步行和慢跑加载负荷下,与加强块和螺钉接触骨面的部分区域松质骨会发生失效。因此从有限元分析角度考虑,病人术后即刻可以进行完全负重站立康复锻炼,但是不能进行完全负重的步行或慢跑康复运动。     

应用钛板修复髋臼大面积骨缺损的生物力学研究

[目的]比较应用钛板修复髋臼不同面积骨缺损与初次全髋关节置换术时髋臼周围生物力学变化及初始稳定性的研究。[方法]选取12具30~50岁男性尸体骨盆。随机分成四组,每组3具,于髋臼负重区人工制造出占整个髋臼50%、60%、70%的三种混合型骨缺损(AAOSⅢ型),作为骨缺损组;应用钛板+植骨+骨水泥+高分子聚氯乙烯杯固定,对三种程度的骨缺损进行髋臼重建;无骨缺损组行单侧骨水泥型假体髋关节置换术。试验模拟人体单足直立位,在CSS-44020型生物力学试验机上进行。应用双页型压敏纸测定各标本在轴向加载,持续加压下,髋臼顶负重区在不同程度骨缺损应用钛板修补与正常初次髋关节置换的应力变化情况。[结果](1)载荷200 N时,骨缺损组50%,60%,70%和无骨缺损组平均应力分别为267.628 6 N;268.635 2 N;270.691 4 N,266.463 8N。经方差分析,F=0.715,P>0.05,按α=0.05水准,各组应力值无明显差异;(2)以钛板重建髋臼严重骨缺损,臼顶负重区的应力变化规律相同。在50%骨缺损组,载荷200 N,400 N,600 N受到应力分别为267.628 6 N,507.831 4 N,693.177 1 N。[结论](1)在同一载荷下,应用钛板重建修复50%~70%髋臼缺损组间与初次髋关节置换组髋臼应力变化无明显差异。随加载负荷的增加,臼顶负重区压应力随之增加。在生物力学方面未出现应力集中及假体不稳等现象;(2)钛板具有良好的生物相容性和力学性能,强度高,可根据髋臼缺损修剪,使其完全贴附于缺损臼壁,金属网孔能够刺激并且允许新生骨组织长入形成"锚固效应",使金属网架和髋臼壁合为一整体,既增加髋臼抗压强度,又降低金属网架的断裂和疲劳的可能性。     

双梯度羟基磷灰石涂层复合转化生长因子的研究

目的　探讨双梯度羟基磷灰石涂层假体材料的生物学特性 ;检测转化生长因子对羟基磷灰石 (HA)涂层与骨界面之间生物连接的影响。方法　将钛合金植入体 (Ti)、带羟基磷灰石涂层的钛合金植入体 (HaTi)和TGF β复合涂层植入体 (TGFHaTi)植入犬股骨 ,术后 3、6、16周分别处死 3组动物 ,通过组织切片、计算机图像分析、顶出试验、扫描电镜等方法进行观察。结果　早期骨 假体界面骨性结合率比较 :Ti 相似文献   

改良髋臼后壁解剖万向覆压型固定钢板在髋臼后壁骨折中应用

目的比较改良髋臼后壁解剖万向覆压型固定钢板内固定与普通重建钢板内固定治疗髋臼后壁骨折的疗效。方法将42例髋臼后壁骨折患者分别行改良髋臼后壁解剖万向覆压型钢板内固定术(万向组,20例)与重建钢板内固定术(重建组,22例)。结果患者均获得随访,时间12～24个月。与万向组比较,重建组手术出血量多、手术时间与住院时间长,差异均有统计学意义(P 0. 05)。术后髋关节功能:重建组优14例,良5例,可2例,差1例;万向组优16例,良3例,可1例;两组疗效比较差异有统计学意义(P 0. 05)。结论改良髋臼后壁解剖万向覆压型钢板治疗髋臼后壁骨折术中螺钉固定方便、牢固,术后功能恢复好,术后并发症少,可作为髋臼后壁骨折手术治疗的选择方式。     

人工关节非骨水泥固定方法的生物力学分析

目的　为人工关节生物固定方法的改进提供一些理论及实验依据。方法　通过推出试验 (Push out)方法对BMP2复合多孔金属表面植入体、多孔金属表面植入体、喷涂HA的PCA植入体、羟基磷灰石涂层植入体在填入骨 -假体交界面后界面的结合强度进行检测 ,并对获得的数据进行统计学分析。结果　BMP对界面结合强度有增强作用 ,在植入的早期尤其显著。结论　对植入体表面进行多孔处理并复合HA对中期促进骨与植入体结合效果显著 ,在假体制造工艺中HA涂层的制备对假体的生物固定效果有较大的影响     

髋臼后壁骨折3种内固定方式的有限元分析

目的通过有限元分析比较3种内固定方式治疗髋臼后壁骨折的生物力学性能,评估不同内固定方式的稳定性。方法建立包括骨盆主要韧带及股骨上1/3的骨盆三维有限元模型,模拟骨折面积50%的髋臼后壁骨折,髋臼后壁骨折采用后柱钢板+空心钉(空心钉组)、后柱钢板+弹簧板(弹簧板组)、后柱钢板+弹簧板+空心钉(弹簧板+空心钉组)内固定,统一用后柱钢板压住骨折块。加载不同负荷模拟站立、前屈、侧弯三种运动状态,比较分析3组骨盆各部件与内固定物的应力分布及垂直位移。结果骨盆模型生物力学传递途径与既往研究高度一致,表明模型的可靠性与内固定治疗的有效性。相同载荷下空心钉组骨盆和内固定物的应力最大。空心钉组骨折区域的最大应力、垂直位移、内固定物与骨折区域应力差值均大于弹簧板组与弹簧板+空心钉组,而弹簧板+空心钉组最小。结论上述3种内固定方式治疗髋臼后壁骨折均能取得良好的生物力学稳定性,但后柱钢板+弹簧板+空心钉内固定能改善整体的应力分布,降低再骨折和内固定断裂的风险,同时能促进骨折愈合,表现出更好的生物力学相容性。     

应用非骨水泥髋臼或金属髋臼支架行髋关节翻修术的临床研究

目的 评估非骨水泥髋臼及金属髋臼支架加植骨修复髋臼骨缺损的效果.方法 我院自2001年9月至2008年9月应用髋臼翻修支架行髋关节翻修术22例(24髋).其中Lima非骨水泥人工翻修髋臼2例(2髋),Kerboull 支架2例(2髋),GAP 髋臼翻修支架18例(20髋).男性6例(6髋),女性16例(18髋).平均年龄62岁(34～79岁).感染性松动2例(2髋),无菌松动20例(22髋).平均随访时间48个月(18～84个月),对其进行临床和影像学评估.Harris评分术前平均为56分(44～75分).结果 末次随访时22例患者Harris评分平均为89分(78～94分).优良率为95.5%(21/22).三种髋臼翻修支架的外展角满意,髋臼旋转中心基本得到了重建.髋臼翻修支架及其聚氯乙烯臼无明显移位,假体周围无透亮线,髋臼植骨愈合良好.结论 应用非骨水泥髋臼或髋臼支架修复髋臼侧巨大骨缺损,重建了髋臼正常旋转中心、提供了翻修假体的初期稳定性、避免了所植骨在血管化时期的过度机械负重,是翻修髋臼巨大骨缺损的可靠方法.     

钛网结合重建钢板内固定治疗髋臼后壁粉碎性骨折

目的探讨钛网结合重建钢板内固定治疗髋臼后壁粉碎性骨折的临床疗效。方法采用钛网结合重建钢板内固定治疗18例髋臼后壁粉碎性骨折。结果 18例均获随访6～24个月,平均12个月。骨折复位质量根据Matta影像学评定标准评估:优14例,良3例,差1例。髋关节功能根据改良d’Aubigne-Postel标准进行评定:优14例,良2例,差2例。结论该术式可有效复位、固定每一块碎骨片,恢复髋臼关节面的平整,降低并发症发生率。     

联体解剖型钛板在髋臼后壁粉碎性骨折中的应用

目的探讨联体解剖型钛板内固定治疗髋臼后壁粉碎性骨折的临床疗效。方法自2013-05—2014-09采用联体解剖型钛板内固定治疗21例髋臼后壁粉碎性骨折(联体解剖板组),与自2010-01—2013-04采用重建钢板治疗的32例髋臼后壁粉碎性骨折的临床资料(重建板组)进行比较。结果联体解剖板组均获平均9.8(6~12)个月随访,本组手术时间(60±12.5)min,术中出血量(150±37.5)ml。末次随访髋关节功能按改良Merle d'Aubingne-Postel评分优良率85.7%。重建板组均获平均11.4(8~17)个月随访,本组手术时间(103±25.5)min,出血量(260±95.5)ml,髋关节功能按改良Merle d'Aubingne-Postel评分优良率84.4%。联体解剖板组手术时间(t=2.970,P0.05)、术中出血量(t=5.847,P0.05)均少于重建板,差异有统计学意义。2组治疗效果的优良率比较差异无统计学意义(P0.05)。结论采用联体解剖板固定治疗髋臼后壁粉碎性骨折能够获得与重建板相同的临床效果,且其手术时间、术中出血量较少,手术操作难度较低。     

Titanium Alloy Gamma Nail versus Biodegradable Magnesium Alloy Bionic Gamma Nail for Treating Intertrochanteric Fractures: A Finite Element Analysis

ObjectiveTo using finite element analysis to investigate the effects of the traditional titanium alloy Gamma nail and a biodegradable magnesium alloy bionic Gamma nail for treating intertrochanteric fractures.MethodsComputed tomography images of an adult male volunteer of appropriate age and in good physical condition were used to establish a three‐dimensional model of the proximal femur. Then, a model of a type 31A1 intertrochanteric fracture of the proximal femur was established, and the traditional titanium alloy Gamma nails and biodegradable magnesium alloy bionic Gamma nails were used for fixation, respectively. The von Mises stress, the maximum principal stress, and the minimum principal stress were calculated to evaluate the effect of bone ingrowth on stress distribution of the proximal femur after fixation.ResultsIn the intact model, the maximum stress was 5.8 MPa, the minimum stress was −11.7 MPa, and the von Mises stress was 11.4 MPa. The maximum principal stress distribution of the cancellous bone in the intact model appears in a position consistent with the growth direction of the principal and secondary tensile zones. After traditional Gamma nail healing, the maximum stress was 32 MPa, the minimum stress was −23.5 MPa, and the von Mises stress was 31.3 MPa. The stress concentration was quite obvious compared with the intact model. It was assumed that the nail would biodegrade completely within 12 months postoperatively. The maximum stress was 18.7 MPa, the minimum stress was −12.6 MPa, and the von Mises stress was 14.0 MPa. For the minimum principal stress, the region of minimum stress value less than −10 MPa was significantly improved compared with the traditional titanium alloy Gamma nail models. Meanwhile, the stress distribution of the bionic Gamma nail model in the proximal femur was closer to that of the intact bone, which significantly reduced the stress concentration of the implant.ConclusionThe biodegradable magnesium alloy bionic Gamma nail implant can improve the stress distribution of fractured bone close to that of intact bone while reducing the risk of postoperative complications associated with traditional internal fixation techniques, and it has promising clinical value in the future.     

骨盆定制假体的设计及有限元分析

目的:介绍骨盆定制假体的设计,利用有限元分析方法评价骨盆肿瘤定制假体在3种不同工况下的生物力学性能。方法:利用CAD软件设计1例骨盆肿瘤患者重建所需的钛合金材质假体,用有限元法分析检查和评估该定制假体在静态和缓慢步态工况下的强度和刚度值。结果:有限元分析结果表明,3种工况下骨盆的最大Von Mises应力分别为39.0、202.8、42.4 MPa;最大位移分别为0.199、0.766、0.847 mm。假体中的最大Von Mises应力分别为62.3、318、468 MPa。骨盆和假体中的最大Von Mises应力都远低于相应材料的屈服强度。结论:该研究可以根据患者情况对定制假体的形状和尺寸做精确设计,通过有限元法强度计算可以降低骨骼应力水平和骨折风险,延长假体的使用寿命,保证了患者术后正常步态下的安全性和稳定性。     

髋臼骨折不同内固定方式的生物力学稳定性研究

目的:探讨3种不同的内固定方式固定髋臼双柱骨折的生物力学稳定性。方法 :16个髋关节标本随机分为4组,其中1组完整髋臼作为正常对照组,其余3组模拟双柱骨折后,分别按下列方法内固定:前柱螺钉加后柱钢板(SP),前柱钢板加后柱螺钉(PS),后柱双钢板(PP)。通过连续垂直加载,记录骨折的位移程度和髋臼的接触特性。结果:在载荷800 N时,SP、PS和PP 3组髋臼平均纵向位移位分别为(1.92±0.81)、(2.09±1.13)、(3.44±0.75)mm,SP与PP组比较差异有统计学意义(P=0.033)。SP、PS和PP 3组髋臼平均横向位移位分别为(0.63±0.33)、(0.77±0.45)、(1.44±0.56)mm,SP组与PS组相比较差异有统计学意义(P=0.047)。800 N载荷压力下,在髋臼负重区,与正常对照组相比,SP、PS和PP组分别接触面积增加了6%、9%和27%,其中PP组与正常对照组差异存在统计学意义(P=0.027);在髋臼负重区,与正常对照组相比,SP、PS和PP组平均应力分别增加了4%、29%和39%,其中PP组与正常对照组差异存在统计学意义(P=0.003)。结论:在生物力学的稳定性和接触性方面,前柱螺钉加后柱钢板有较大优势。     

电阻片应变法在测量三翼臼固定后骨盆应力变化中的应用

目的应用电阻片应变法测量骨盆髋臼骨缺损模型三翼臼固定后髋臼上方的应力值。方法成年男性尸体骨盆标本4只，无髋关节骨质缺损或畸形。于臼顶处造成节段性骨缺损，缺损面积约为髋臼面积的20％。根据三翼臼扩展角度不同分为0、36、45和60°4个实验组，并设立无缺损、无翼假体骨盆为对照组。在4只骨盆标本上各布置7组电阻应变花，1、2和3号位置为骨盆外侧与臼杯3个翼对应的髋臼上方，4号位置为骨盆外侧髋臼与骶髂关节连线近端，5、6和7号位置于骨盆内侧髋臼与骶髂关节连线由外下向内上方均匀分布。模拟单腿站立时髋关节负重情况，进行150、300、450、600、750和900N分级加载，收集各组各级加载和卸载时应变片应变信息。结果测试点最大等效应力为6．93MPa，最小等效应力为1．08MPa。结论骨盆髋臼骨缺损三翼臼固定后，在宿主骨没有引发高应力区，为翼间移植骨的生长提供了力学环境下的数据。     

人工股骨头置换术中置入不同直径假体球头的有限元分析

目的 :针对老年股骨颈骨折行人工股骨头置换术中,借助三维有限元分析的方法 ,探讨置入不同直径的假体球头后的髋关节生物力学变化,观察对髋关节应力分布变化,以便选择出合适的假体球头尺寸。方法:利用薄层CT资料及人工股骨头假体相关参数建立装配有不同假体球头直径的人工股骨头置换术后髋关节有限元模型(M0:术前模型;M1:球头直径=原股骨头直径;M2:球头直径=原股骨头直径+1 mm;M3:球头直径=原股骨头直径-1 mm;M4:球头直径=原股骨头直径-2 mm),并加载关节合力及相关肌肉的负荷,模拟人缓慢行走时单足站立状态,分析不同直径假体植入后髋臼周围骨质及软骨的应力分布及变化。结果:(1)M1～M4中骨盆均出现了不同程度的应力集中,M3的骨盆Von Mises应力峰值为44.8 MPa,与术前最为接近,增量约13.4%,且M3的骨盆位移在术后4组模型中最小,为1.40 mm;其次是M1,应力峰值为47.3 MPa,增量约19.7%,骨盆位移为1.59 mm。(2)在髋臼区域,M3的Von Mises应力峰值为23.3 MPa,与术前最为接近,增量约6.3%,其次是M1,应力峰值为24.0 MPa,增量约8.1%。(3)髋臼软骨上,M1与M3的应力分布同术前相似,且M3的Von Mises应力峰值为18.5 MPa,与术前最为接近;其次是M1,应力峰值为22.5 MPa。(4)M1～M4均在人工股骨头的外上象限出现不同程度的应力集中,而在其下方表现为应力遮挡;其中M3的Von Mises应力分布较其余模型更为均匀,其峰值70.8 MPa为各组中最低,其次为M1(80.7 MPa)。结论:在行人工股骨头置换术时,建议优先使用比原股骨头直径小1 mm的假体球头,其次是与原股骨头直径相等的假体球头,来获得与置换术前的髋关节最接近的自然力学特性,降低因尺寸差异导致的并发症风险。     

A novel anatomical self-locking plate fixation for both-column acetabular fractures

PurposeTo compare the stability of the posterior anatomic self-locking plate (PASP) with two types of popular reconstruction plate fixation, i.e. double reconstruction plate (DRP) and cross reconstruction plate (CRP), and to explore the influence of sitting and turning right/left on implants.MethodsPASP, DRP and CRP were assembled on a finite element model of both-column fractures of the left acetabulum. A load of 600 N and a torque of 8 N·m were loaded on the S1 vertebral body to detect the change of stress and displacement when sitting and turning right/left.ResultsThe peak stress and displacement of the three kinds of fixation methods under all loading conditions were CRP > DRP > PASP. The peak stress and displacement of PASP are 313.5 MPa and 1.15 mm respectively when turning right; and the minimal was 234.0 Mpa and 0.619 mm when turning left.ConclusionPASP can provide higher stability than DRP and CRP for both-column acetabular fractures. The rational movement after posterior DRP and PASP fixation for acetabular fracture is to turn to the ipsilateral side, which can avoid implant failure.     

一种新型植骨重建钛网的三维有限元研究

目的研究新型植骨重建钛网的生物力学特点及其避免术后沉陷的有效性。方法设计并研制了一种新型的植骨重建钛网,以现有钛网为研究对照,建立使用2种钛网的椎体次全切除植骨重建手术的三维有限元模型,施加载荷,模拟术后颈椎活动,分别在屈曲、侧屈及扭转3种工况下施加73．6N的预载荷,观察钛网、钢板以及相邻椎体终板的应力分布。结果在3种不同工况条件下,使用新型植骨重建钛网较使用现有钛网可使钢板承受应力减低1．48—3．95MPa（23．5％～41．3％）,钛网承受应力增加0．61～1．13MPa（12．2％～22．2％）,相邻椎体下终板承受应力降低0．41～1．43MPa（27．7％～44．9％）,相邻椎体上终板承受应力降低0．91～1．42MPa（28．0％-38．6％）。结论颈前路椎体次全切除减压术中使用新型钛网进行植骨重建可一定程度上增加手术节段稳定性,降低术后钛网沉陷的可能性。     

Anatomical quadrilateral plate for acetabulum fractures involving quadrilateral surface: A review

IntroductionThe management of acetabulum fractures in osteoporotic elderly, as well as comminuted fractures in younger patients is likely to be difficult. These fractures need specific fixation techniques especially when the quadrilateral plate is involved. Standard implants may not be able to adequately support the fixation, so newer pre-shaped fixation plates have been proposed with some of these already in use. The concept of anatomic plates has come up for many fracture locations for providing a better buttress effect to the comminuted fragments. There has been a need to look for an anatomic buttress plates being developed for acetabulum fractures involving the quadrilateral surface.Materials and methodsThe literature has been reviewed to find the various newer designs that have been used for buttressing the quadrilateral surface in comminuted acetabular fractures. An attempt has been made to study their design characteristics and clinical outcomes. The review also includes the analysis of Anatomic Quadrilateral plate (AQP) used in fixation of acetabulum fracture involving quadrilateral surface in a series of 33 patients.ResultsThere has been few anatomical plates developed for the stabilization of acetabular quadrilateral surface fractures. Some of these plates have been successfully used in management of acetabular fractures primarily in young patients. Issues however remain in their application and outcomes in osteoporotic fractures of the acetabulum, as these plates support the pelvic brim fragments either from superior or medial surface. The newer development i.e. ‘Anatomical Quadrilateral Plate’ is optimized to counter the displacement forces due to its positioning on the pelvic brim rather than its superior or medial surface. Other special features include the possibility of longer screws across bone due to oblique position of holes, the typical location of a locking hole on the plate beam which permits dual cortical compression fixation either by using a bigger screw or a specially designed screw in screw construct across the supra-acetabular corridor. The option of using hybrid fixation of both locking and unlocked screws in AQP allows proper stress distribution on the underlying bone, aiding both primary as well as secondary stability. The minimum of one year post surgery outcome of patients having acetabular fixation using this Anatomic quadrilateral plate has been analyzed in 33 patients. Twenty three of these were aged more than 50 years and 28 out of total 33 were males. Associated injuries included Ipsilateral lower limb injury in 2 patients and distal radius fracture in 5 patients. The fracture pattern included ‘Anterior column posterior hemi-transverse’ in 10 patients,’ Associated Both Column’ injury in 9 and ‘T type’ acetabular fractures in 8 patients. Isolated ‘Anterior column’ was fractured in 6 patients. The surgical approach was ‘Anterior Intra-pelvic’ (AIP) in 23 patients and ‘Modified Ileo-femoral’ in other 10 patients. One patient had additional K L approach. Among the implants, the AQP plate was used without its pubic arm in 6 patients. The post-operative x rays showed anatomical reduction in 28 patients, while other 5 had gaps and/or steps up to 2 mm size. In subsequent car, one of these patients needed hip arthroplasty for problem arising due to collapse in fixation within six months. EQ 5D 5L telephonic score was used to know the outcome at minimum of one year follow up in 33 patients. As per this score, only 3 patients had an issue with mobility, with only one having problem in self-care activity. Six patients complained of minor limitations in carrying out their usual activities and only one patient had anxiety affecting him. In their self-assessment of overall health status, 22 patients marked it 100, 7 made it 90, 3 as 80 and 1 had marked it as 70 in a score range of 0–100. Considering the predominant elderly profile in this series of patients, the acetabular reconstruction using ‘Anatomic quadrilateral plate’ has shown encouraging results.ConclusionFor stabilization of acetabular fractures involving quadrilateral surface area and pelvic brim, various new implants have been used. The Anatomic quadrilateral plate due to its anatomical shape, the various options in fracture fixation is best optimized for management of comminuted acetabulum fractures especially in poor quality bones. It has been successful in achieving good outcome in elderly group of patients having these complex injuries.     

Anatomical quadrilateral plate for acetabulum fractures involving quadrilateral surface: A review

IntroductionThe management of acetabulum fractures in osteoporotic elderly, as well as comminuted fractures in younger patients is likely to be difficult. These fractures need specific fixation techniques especially when the quadrilateral plate is involved. Standard implants may not be able to adequately support the fixation, so newer pre-shaped fixation plates have been proposed with some of these already in use. The concept of anatomic plates has come up for many fracture locations for providing a better buttress effect to the comminuted fragments. There has been a need to look for an anatomic buttress plates being developed for acetabulum fractures involving the quadrilateral surface.Materials and methodsThe literature has been reviewed to find the various newer designs that have been used for buttressing the quadrilateral surface in comminuted acetabular fractures. An attempt has been made to study their design characteristics and clinical outcomes. The review also includes the analysis of Anatomic Quadrilateral plate (AQP) used in fixation of acetabulum fracture involving quadrilateral surface in a series of 33 patients.ResultsThere has been few anatomical plates developed for the stabilization of acetabular quadrilateral surface fractures. Some of these plates have been successfully used in management of acetabular fractures primarily in young patients. Issues however remain in their application and outcomes in osteoporotic fractures of the acetabulum, as these plates support the pelvic brim fragments either from superior or medial surface. The newer development i.e. ‘Anatomical Quadrilateral Plate’ is optimized to counter the displacement forces due to its positioning on the pelvic brim rather than its superior or medial surface. Other special features include the possibility of longer screws across bone due to oblique position of holes, the typical location of a locking hole on the plate beam which permits dual cortical compression fixation either by using a bigger screw or a specially designed screw in screw construct across the supra-acetabular corridor. The option of using hybrid fixation of both locking and unlocked screws in AQP allows proper stress distribution on the underlying bone, aiding both primary as well as secondary stability. The minimum of one year post surgery outcome of patients having acetabular fixation using this Anatomic quadrilateral plate has been analyzed in 33 patients. Twenty three of these were aged more than 50 years and 28 out of total 33 were males. Associated injuries included Ipsilateral lower limb injury in 2 patients and distal radius fracture in 5 patients. The fracture pattern included ‘Anterior column posterior hemi-transverse’ in 10 patients,’ Associated Both Column’ injury in 9 and ‘T type’ acetabular fractures in 8 patients. Isolated ‘Anterior column’ was fractured in 6 patients. The surgical approach was ‘Anterior Intra-pelvic’ (AIP) in 23 patients and ‘Modified Ileo-femoral’ in other 10 patients. One patient had additional K L approach. Among the implants, the AQP plate was used without its pubic arm in 6 patients. The post-operative x rays showed anatomical reduction in 28 patients, while other 5 had gaps and/or steps up to 2 mm size. In subsequent car, one of these patients needed hip arthroplasty for problem arising due to collapse in fixation within six months. EQ 5D 5L telephonic score was used to know the outcome at minimum of one year follow up in 33 patients. As per this score, only 3 patients had an issue with mobility, with only one having problem in self-care activity. Six patients complained of minor limitations in carrying out their usual activities and only one patient had anxiety affecting him. In their self-assessment of overall health status, 22 patients marked it 100, 7 made it 90, 3 as 80 and 1 had marked it as 70 in a score range of 0–100. Considering the predominant elderly profile in this series of patients, the acetabular reconstruction using ‘Anatomic quadrilateral plate’ has shown encouraging results.ConclusionFor stabilization of acetabular fractures involving quadrilateral surface area and pelvic brim, various new implants have been used. The Anatomic quadrilateral plate due to its anatomical shape, the various options in fracture fixation is best optimized for management of comminuted acetabulum fractures especially in poor quality bones. It has been successful in achieving good outcome in elderly group of patients having these complex injuries.     

A quantitative in vitro assessment of fit and screw fixation on the stability of a cementless hemispherical acetabular component

This investigation quantifies in vitro the effect of component fit, as well as the effect of adjuvant screw fixation, on the initial stability of cementless hemispherical titanium acetabular total hip arthroplasty components and assesses apposition of the acetabular components to bone. Six, fresh human hemipelvi (3 matched pairs) were harvested at autopsy. Titanium alloy acetabular components with a porous surface of commercially pure titanium fiber mesh (Harris Galante Porous acetabular components, Zimmer, Warsaw, IN) were used for implantation. Initially, each acetabulum was underreamed to achieve a 2 mm press-fit with the acetabular component. Pressuresensitive film had been placed along the dome and medial wall at the bone-implant interface to assess the completeness of seating. After the implant was impacted into the acetabular cavity, relative motion between the implant and bone was measured during simulated single leg stance. Adjuvant fixation of the implant was then obtained with the insertion of four 6.5 mm cancellous screws. High-contrast roentgenograms of the specimens in multiple views were obtained after initial cup insertion and again after screw insertion. The stability of each implant under load was measured with four, three, two, one, and no screws in place. Further reaming of the bone was done to create a 1 mm press-fit. The sequence was then repeated. Further reaming was done to create an exact-fit and the sequence was repeated again. Under these conditions, 1 mm press-fit with or without screws provided the optimum combination of fit and stability. With the 2 mm press-fit, incomplete seating of the implant was found in every case, resulting in gaps between the dome of the implant and the bone. This reduced the area of the porous surface in contact with bone, and resulted in an increase in micromotion with the dome of the implant. The addition of supplemental screws did not significantly enhance stability of the implant under press-fit conditions. Exact-fit reaming with the use of two, three, or four screws yielded acetabular component stability at the dome equal to 1 mm press-fit, but at the rim the acetabular component was less stable than 1 mm press-fit. The optimum combination might be a press-fit introduction of the acetabular component, and the advantage of screws must be weighed against possible particulate debris and vascular damage.