寰椎椎板钩联合枢椎椎弓根螺钉内固定的力学稳定性评价

目的 评价寰椎椎板钩联合枢椎椎弓根螺钉内固定的生物力学稳定性.方法 取6具新鲜尸体颈椎标本置于1.5 N·m载荷下,测量C_(1-2)节段的三维运动范围(ROM).标本按随机顺序,依次行完整状态(完整状态组)、不稳状态(齿状突周围韧带切除,为不稳状态组)、经寰枢关节间隙螺钉联合Gallic内固定(固定A组)、寰椎椎板钩联合枢椎椎弓根螺钉内固定(固定B组)、寰枢椎椎弓根螺钉内固定(固定C组)5种状态下的三维ROM值测量.比较各组标本的屈伸、侧屈、旋转ROM值.结果 完整状态组、不稳状态组、固定A、B、C组的平均屈伸ROM值分别为17.78°、30.69°、2.25°、2.93°、2.73°,组间比较差异有统计学意义(F=216.69,P=0.000);平均侧屈ROM值分别为9.56°、17.18°、1.91°、2.30°、2.05°,组间比较差异有统计学意义(F=122.75,P=0.000);平均旋转ROM值分别为44.19°、57.30°、1.22°、2.88°、2.07°,组间比较差异有统计学意义(F=154.54,P=0.000).固定A、B、C组较完整状态组和不稳状态组各个方向的ROM值均明显减少,差异均有统计学意义(P<0.05),但固定A、B、C组之间符个方向的ROM值比较差异均无统计学意义(P>0.05).结论 寰椎椎板钩联合枢椎椎弓根螺钉内固定可提供与经寰枢关节间隙螺钉联合Gallic内固定和寰枢椎椎弓根螺钉内固定相当的力学稳定性.在以上两种方法无法实施时,可作为一种安全的替代.     

后路枕骨髁螺钉内固定系统的生物力学研究

目的 :通过对后路枕骨髁螺钉内固定系统治疗枕颈部不稳的生物力学研究,为其临床应用提供理论依据。方法:选取6具年龄32~55岁,身高155~180cm的颈椎尸体标本,不做手术处理建立正常模型,切断标本的寰椎横韧带、齿状突尖韧带、翼状韧带,制作枕颈不稳模型,枕骨髁螺钉的置钉固定建立枕骨髁螺钉内固定模型,分别给予三个模型枕骨1.5N·m的屈伸、侧弯、旋转力矩,测量标本C0~C1与C0~C2的前屈后伸、侧弯、旋转的运动范围(range of motion,ROM),分析比较正常模型、失稳模型及内固定模型的运动范围改变,评价枕骨髁螺钉内固定系统的生物力学有效性。结果:在C0~C1节段上,正常模型的前屈、后伸、侧弯、旋转活动度分别为:14.13°±0.71°、7.60°±0.43°、3.77°±0.27°、5.42°±0.44°,失稳模型的活动度分别为23.57°±2.26°、11.96°±1.44°、5.21°±0.29°、7.13°±0.67°,枕骨髁螺钉内固定模型的活动度分别为7.53°±0.77°、3.79°±0.64°、2.56°±0.34°、0.89°±0.31°;而在C0~C2节段上,正常模型的前屈、后伸、侧弯、旋转活动度分别为:19.72°±0.71°、17.62°±0.97°、7.55°±0.51°、51.46°±3.11°,失稳模型的活动度分别为30.57°±2.32°、23.85°±0.91°、9.37°±0.55°、68.91°±6.25°,枕骨髁螺钉内固定模型的活动度分别为11.30°±0.66°、9.19°±0.63°、5.12°±0.59°、7.39°±0.76°。失稳模型的活动度大于正常模型,正常模型的活动度大于固定模型。结论:枕骨髁螺钉内固定系统能有效减少枕颈部的前屈、后伸、侧弯、旋转的运动范围,充分证明了该固定技术具有可靠的生物力学稳定性。     

寰椎椎弓根螺钉联合经寰枢关节螺钉内固定稳定性的生物力学研究

【摘要】 目的：评估寰椎椎弓根螺钉联合经寰枢关节螺钉固定技术的力学稳定性。方法：选取成人颈椎新鲜标本6具,解剖剔除肌肉制备上颈椎完整模型（完整组）,用生物力学测试及计算机视觉分析软件测量在1.5Nm力矩下前屈后伸、左右侧弯和左右旋转时C1-C2的活动度（ROM）;破坏寰椎前弓和侧块制备不稳模型（失稳组）,再次测量相同力矩下各运动方向C1-C2的ROM活动度。随后暴露寰枢椎置钉点,根据先后顺序置入寰椎椎弓根螺钉+枢椎椎弓根螺钉固定（C1P+C2P组）、单纯经寰枢关节螺钉固定（TA组）、寰椎椎弓根螺钉+经寰枢关节螺钉固定（C1P+TA组）,依次分别测量相同力矩下各运动方向C1-C2的ROM,比较各组C1-C2 ROM的差异。结果：失稳组相较于完整组在六个方向上有更大的ROM,两组所有方向上的ROM均有显著性差异（P<0.05）;C1P+C2P组、C1P+TA组、TA组与失稳组比较,所有方向上的ROM均有显著性减少（P<0.05）,三组间比较,前屈、后伸、左旋转和右旋转方向上的ROM存在统计学差异（P<0.05）,C1P+TA组相似文献   

Solis椎间融合器治疗Ⅱ型Hangman骨折的生物力学评价

目的:比较Solis椎间融合器、椎间植骨及椎间植骨+钢板内固定治疗Ⅱ型Hangman骨折的生物力学稳定性,为临床应用Solis椎间融合器治疗Hangman骨折提供理论依据.方法:6具成人新鲜冷冻颈椎标本,每具依次制作成以下5种状态组,即正常对照组(A组)、Ⅱ型Hangman骨折模型组(B组)、Solis椎间融合器置人组(C组)、单纯椎间植骨组(D组)、椎间植骨+钢板内固定组(E组).按以上顺序应用脊柱三维运动试验机和三维激光扫描仪测试每一状态下C2/3节段的三维运动范嗣(ROM).结果:与A组比较,B组前屈、后伸、旋转及侧弯ROM均显著增大(P<0.05);C组旋转ROM显著增大(P<0.05),其他方向无显著性差异(P>0.05);D组前屈、后伸及旋转ROM显著增大(P<0.05).侧弯方向无显著性差异:E组旋转ROM显著增大(P<0.05),其他方向无显著性差异(P>0.05).与B组比较,C组、E组均在前屈、后伸和侧弯方向及D组在后伸、侧弯方向ROM显著变小(P<0.05),C、D、E组旋转及D组前屈ROM与B组比较无显著性差异.C、D及E组相互比较,C组后伸ROM显著小于D组(P<0.05),其他方向与D组比较无显著性差异;C组前屈ROM显著大于E组(P<0.05),其他方向与E组比较无显著性差异;D组前屈、后伸及侧弯ROM均显著大于E组(P<0.05),旋转方向与E组比较无显著性差异.结论:在Ⅱ型Hangman骨折的治疗中,Soils椎间融合器有助于恢复前屈、后伸及侧弯方向上的稳定性,但在旋转方向上不能恢复稳定性,术后需辅以外固定,以确保融合;其稳定作用弱于钢板内固定,但优于单纯植骨.     

新型蝶形枕颈内固定系统固定的生物力学稳定性研究

目的 :评价新型蝶形枕颈内固定系统固定的生物力学稳定性。方法 :选取6具新鲜冰冻人体枕颈部标本,年龄为20~35岁,男3具,女3具。每具标本解剖截取其C6以上的部位,保留枕骨粗隆以下的颅骨骨性结构及其与颈椎相连的韧带部分,仔细剔除附着于颅脊交界区骨性结构周围的肌肉组织,完整地保留该区域的各种韧带与关节囊,制作为正常模型(N组),用Motion Analysis三维运动测试机测量C0~C3节段的屈伸、侧屈及旋转三维运动范围(ROM);然后离断寰枢椎间横韧带,制成寰枢椎的失稳模型(UN组),测量C0~C3节段的屈伸、侧屈及旋转三维ROM;再将每具标本进行新型蝶形枕颈系统固定,蝶形枕骨板先后依次以11枚螺钉固定(A组)、以7枚螺钉固定(B组)及以3枚螺钉固定(C组),最后每具标本进行SUMMIT系统固定(D组),每种固定后测量C0~C3节段的屈伸、侧屈及旋转三维ROM。对蝶形枕骨板不同的固定方式与寰枢正常模型、失稳模型及SUMMIT系统固定进行组间比较,比较A、B、C、D组内固定方式中枕颈部的屈伸、侧屈及旋转三维稳定性。结果:在6种不同工况下,A、B、C、D组固定方式稳定性均优于正常组及失稳组,组间比较有统计学差异(P0.05)。在前屈、后伸、左右侧屈方向上的比较,A、B、C、D四种内固定方式组间无统计学差异(P0.05)。而在左右旋转方向上,A、B、C、D四种不同固定方式组间比较有统计学差异,其中B、C、D三种内固定方式间的比较无统计学差异(P0.05),而A组与B、C、D三组间的比较均有统计学差异(P0.05)。结论:新型蝶形枕颈内固定系统固定与SUMMIT内固定系统固定一样能提供有效的力学固定强度,其中以11枚螺钉固定的新型蝶形枕颈内固定系统固定在旋转稳定性上更优。     

下腰椎不同固定方式的生物力学对比研究

目的 观察下腰椎不同固定方式对腰椎稳定性的影响.方法 新鲜成人尸体下腰椎标本6具,测定L4/5节段屈伸、左右侧屈、左右旋转6个方向ROM和刚度值的变化,按5组顺序依次测试:A组(正常下腰椎标本组);B组(单侧椎板关节突螺钉固定+椎间单枚Cage);C组(单侧椎弓根螺钉固定+椎间单枚Cage);D组(单侧椎弓根螺钉联合对侧椎板关节突螺钉固定+椎间单枚Cage);E组(双侧椎弓根螺钉固定+椎间单枚Cage).结果 与A组比较,B组各运动状态ROM有减少,而刚度明显增加,差异有统计学意义(P＜0.05);与B组比较,C组各运动方向ROM与刚度,差异无统计学意义(P＞0.05);与C组比较,D组各运动状态ROM有减少,而刚度增加,差异有统计学意义(P＜0.05);与E组比较,D组各运动方向ROM与刚度,差异无统计学意义(P＞0.05);与E组比较,C组各运动状态ROM有增加,而刚度减少,差异有统计学意义(P＜0.05).结论 单侧椎板关节突螺钉固定并椎间融合器植骨方法提供了一定的稳定性,而单侧椎弓根螺钉联合对侧椎板关节突螺钉固定并椎间融合器植骨具有与双侧椎弓根螺钉固定相同的稳定性,临床上可根据病例的具体情况,如身高体质量指数、病变类型及病变节段稳定程度选择性地应用上述两种固定融合方法.     

前路单节段融合内固定治疗伴椎弓根断裂的Denis B型胸腰椎爆裂骨折生物力学研究

目的探讨前路单节段融合内固定治疗伴椎弓根断裂的Denis B型胸腰椎爆裂骨折后的脊椎生物力学稳定性。方法取6具新鲜成人尸体胸腰椎标本(T11~L3)作为正常组(A组),采用椎体切除法依次建立L1Denis B型爆裂骨折模型并行前路单节段融合内固定,分别为椎弓根完整组(B组)、单侧椎弓根切断组(C组)和双侧椎弓根切断组(D组)。通过脊柱三维运动机依次测定各组在8.0 N·m纯力偶矩下屈伸、左右侧弯及左右旋转活动度(range of motion,ROM)。结果 B、C、D组T12、L1脊柱运动单元前屈、后伸、左右侧弯ROM均显著低于A组(P0.05),D组显著高于B、C组(P0.05),B、C组间差异无统计学意义(P0.05);B、C组左右旋转ROM均显著低于A、D组(P0.05),B、C组间及A、D组间比较差异无统计学意义(P0.05)。各组间L1、L2脊柱运动单元前屈、后伸、左右侧弯、左右旋转ROM比较,差异均无统计学意义(P0.05)。结论前路单节段融合内固定治疗Denis B型胸腰椎爆裂骨折伴一侧椎弓根断裂时,在屈伸、侧弯及旋转方向能提供足够初始生物力学稳定性,而伴双侧椎弓根断裂时生物力学稳定性差。     

脊柱坚强内固定与动态内固定对邻近节段影响比较的生物力学研究

目的研究经椎弓根坚强固定与弹性固定脊柱节段对邻近节段三维运动范围的影响。方法把24例小牛L1~S2脊柱标本随机分成4组:A组为坚强固定组(对照组),B组为固定旋转及屈伸,但不限制侧弯(简称侧弯组);C组为固定旋转及侧弯,但不限制屈伸(简称屈伸组);D组为固定侧弯及屈伸,但是不限制旋转(简称旋转组)。固定L3~5节段,在2.0N.m载荷下进行三维运动测试,分析各组条件下邻近节段(L2、3)在前屈后伸、侧弯及旋转上的运动范围变化。结果侧弯组与坚强固定组的邻近标本节段活动范围(ROM)比较,前屈后伸、旋转活动范围差异无统计学意义(P>0.05),侧弯活动范围差异有统计学意义(P<0.01);屈伸组与坚强固定组的邻近标本节段活动范围(ROM)比较,旋转侧弯活动范围差异无统计学意义(P>0.05),但屈伸活动范围则差异有统计学意义(P<0.05);旋转组与坚强固定组的邻近标本节段活动范围(ROM)比较,旋转侧弯及屈伸活动范围差异无统计学意义(P>0.05)。结论脊柱的坚强固定及放开旋转的脊柱固定,均会导致应力的集中,不利于应力的分散;而放开侧弯及屈伸的脊柱固定则均有利于应力的分散,应力分散方向与放开的脊柱固定方向相一致。     

下颈椎前路椎弓根螺钉内固定在三柱损伤模型中初始稳定性的生物力学研究

目的:比较下颈椎前路椎弓根螺钉内固定(ATPS)和3种传统颈椎内固定技术在下颈椎3柱损伤模型中的初始稳定性,为其临床应用提供力学依据。方法:采集6具人颈椎标本并测定各原始标本(原始标本组)的三维运动范围,制成三柱损伤模型,模拟钛网植骨后依次行ATPS、前路钢板固定(AP)、前路钢板+侧块螺钉固定(AP+LMS)、后路椎弓根螺钉内固定(PTPS),测量4种内固定技术下的三维运动范围,将结果标准化并进行相互比较。结果:ATPS组屈伸、侧弯、轴向旋转运动范围标准化数值分别为(77.17±4.75)%、(82.00±2.61)%、(83.17±2.23)%,均明显小于原始标本组的100%、100%、100%(P0.05)。AP组屈伸、侧弯、轴向旋转运动范围标准化数值分别为(119.67±7.42)%、(116.33±7.53)%、(112.67±5.99)%,均明显大于原始标本组(P0.05)。AP组屈伸、侧弯、轴向旋转运动范围标准化数值均明显大于ATPS组(P0.05)。PTPS组屈伸、侧弯运动范围标准化数值与ATPS组相比差异均无统计学意义(P0.05);其轴向旋转运动范围标准化数值为(86.83±2.48)%,明显大于ATPS组(P=0.009)。AP+LMS组屈伸运动范围标准化数值为(68.50±2.43)%,小于ATPS组(P=0.003);其侧弯、轴向旋转运动范围标准化数值与ATPS组相比差异均无统计学意义(P0.05)。结论:ATPS可在下颈椎三柱损伤模型中提供足够的初始稳定性,其在生物力学性能方面优于AP、PTPS,和AP+LMS相近,适用于无需后路切开减压复位的下颈椎三柱损伤病例。     

后路板-棒内固定系统治疗不稳定性寰椎骨折的生物力学研究

目的 :测试后路板-棒内固定系统治疗不稳定寰椎骨折的稳定性,为临床使用提供理论基础。方法 :采集新鲜成年人尸体颈椎骨(C0~C3)标本6具,用聚甲基丙烯酸甲酯(PMMA)上下包埋,在生物力学实验机上,以150N为最大生理载荷,最大力矩为1.50N·m,依次测量完整模型组(A组)、骨折模型组(B组,包括寰椎后弓两处骨折与典型Jefferson骨折,分别作为B1组和B2组,骨折模型制作时保持横韧带完整)、内固定模型组(C组,包括B1组+内固定系统、B2组+内固定系统,分别作为C1组、C2组)C0-C1、C1-C2节段前屈/后伸、左/右侧屈和左/右旋转等6个方向的三维运动范围(ROM),通过比较,评价后路板-棒内固定系统治疗寰椎骨折的生物力学稳定性。根据测量所得ROM值,设A组各方向三维运动稳定性指数(Sf)为100%,计算B组、C组模型各运动方向Sf,进一步直观比较各模型的稳定性变化。结果:C0-C1节段,A组前屈/后伸、左右侧屈、左右轴向旋转方向的ROM分别为11.06°±1.00°,7.08°±0.62°,13.24°±1.24°;B1、B2组前屈/后伸、左右侧屈、左右轴向旋转方向ROM均较A组明显增大(P0.05);C1组前屈/后伸、左右侧屈、左右旋转方向的ROM均较B1组明显减小(P0.05);C2组各方向ROM均较B2组明显减小(P0.05);C1、C2组前屈/后伸、左右侧屈、左右轴向旋转方向ROM与A组比较均无统计学差异(P0.05)。C1-C2节段,A组前屈/后伸、左右侧屈、左右轴向旋转方向的ROM分别为10.07°±1.12°,5.56°±0.54°,20.83°±2.12°;B1、B2组各方向ROM均较A组明显增大(P0.05);C1组各方向的ROM较B1组明显减小(P0.05);C2组各方向ROM较B2组明显减小(P0.05);C1、C2组各方向ROM与A组比较均无统计学差异(P0.05)。C0-C1节段,B1组前屈/后伸、左/右侧屈、左/右轴向旋转方向Sf分别为71%、70%、64%,B2组各方向Sf分别为61%、55%、58%,C1组各方向Sf分别为102%、108%、108%,C2组各方向Sf分别为91%、91%、92%。C1-C2节段,B1组前屈/后伸、左/右侧屈、左/右轴向旋转方向Sf分别为70%、61%、35%,B2组各方向Sf分别为59%、54%、37%,C1组各方向Sf分别为105%、111%、106%,C2组各方向Sf分别为91%、90%、92%。结论:寰椎后路板-棒内固定系统既能恢复上颈椎稳定性,又可保留其生理运动功能。使用该系统治疗寰椎后弓两处骨折,在稳定性方面效果稍优于典型Jefferson骨折。     

Zone 2 sacral fractures managed with partially-threaded screws result in low risk of neurologic injury

BackgroundZone 2 sacral fractures account for 34% of sacral fractures with reported neurological deficit in 21−28% of patients. The purpose of this study was to examine the risk factors for neurological injury in zone 2 sacral fractures. The authors hypothesized that partially thread iliosacral screws did not increase incidence of neurologic injury.MethodsA retrospective review of consecutive patients admitted to a level 1 trauma center with zone 2 sacral fractures requiring surgery from September 2010 to September 2014 was performed. Patients were excluded if no neurologic exam was available after surgery. Fractures were classified according to Denis and presence/absence of comminution through the neural foramen was noted. Fixation schema was recorded (sacral screws or open reduction and internal fixation with posterior tension plate). Any change in post-operative neurological exam was documented as well as exam at last clinic encounter.Results90 patients met inclusion criteria, with zone 2 fractures and post-operative neurological exam. No patient with an intact pre-operative neurologic exam had a neurological deficit after surgery. 86 patients (95.6%) were neurologically intact at their last follow-up examination. Four patients (4.4%) had a neurological deficit at final follow-up, all of them had neurological deficit prior to surgery. 81 patients were treated with partially threaded screws of which 1 (1.2%) had neurological deficit at final follow-up.Fifty-seven fractures (63.3%) were simple fractures and 33 fractures (36.7%) were comminuted. All four patients with neurological deficit had comminuted fractures. The association between neurologic deficit in zone 2 sacral fracture and fracture comminution was found to be statistically significant (p-value = 0.016). No nonunion was observed in this cohort.ConclusionsThe use of partially threaded screws for zone 2 sacral fractures is associated with low risk for neurologic injury, suggesting that compression through the fracture does not cause iatrogenic nerve damage. The low rate of sacral nonunion can be attributed to compression induced by the use of partially threaded compression screws. There is a strong association between zone 2 comminution and neurologic injury.     

Evaluation of fixation of various screws in the lumbar vertebrae of dogs

Various screws for posterior fixation of the lumbar spine were evaluated for their firmness of fixation in mongrel dogs. Four types of screws: stainless steel, titanium base alloy, porous-coated, and hydroxyapatite-coated were inserted into vertebrae in dogs and examined for firmness of fixation in bone. Dogs were killed immediately and 2, 4, 6, and 8 weeks after insertion, and firmness of fixation was assessed by measuring the twisting force (i.e., the torque) required to loosen the screws. Also, the interface between screws and bone was histologically investigated. The hydroxyapatite-coated screws required the highest torque, compared with other screws, 2 weeks after insertion. At 8 weeks, the torque was 235% of that of the titanium alloy screws, indicating that the fixation of the hydroxyapatite-coated screws was highly stable. With the hydroxyapatite-coated screw, bone formed a direct bond with the hydroxyapatite, the connection to bone apparently being augmented with time. The results of these experiments suggest that the hydroxyapatite-coated screw has the advantage of firmer fixation in vertebrae over other conventional screws. A summary of this work was presented at the tenth annual Orthopaedic Research Meeting of the Japanese Orthopaedic Association at Karuizawa, Japan, in 1995     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Cementless Acetabular Fixation With and Without Screws : Analysis of Stability and Migration

The purpose of this study was to compare initial stability and late migration of 775 cementless acetabular components with and without screw fixation. Screw fixation was used in 509 cups and no screws in 266 cups. Average follow-up in the screw fixation group was 6.32 years (range, 2-10 years) and 6.9 years (range, 2-10 years) in the no-screw group. One component (0.2%, osteolysis) in the screw group and one (0.4%, loss of fixation) in the no-screw group required revision. Osteolytic lesions more than 4 cm² were noted in 8 (1.6%) screw fixation cups and 2 (0.75%) no-screw fixation cups. No cups in either cohort had radiographic evidence of migration. Screw fixation did not have a favorable or adverse effect on the outcome of acetabular reconstruction.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.     

Rapid prototyping drill guide template for lumbar pedicle screw placement

To develop a novel method of spinal pedical stereotaxy by reverse engineering and rapid prototyping techniques, and to validate its accuracy by experimental and clinical studies. Methods: A 3D reconstruction model for the desired lumbar vertebra was generated by using the Mimics 10.11 software, and the optimal screw size and orientation were determined using the reverse engineering software. Afterwards, a drill template was created by reverse engi-neering principle, whose surface was the antitemplate of the vertebral surface. The drill template and its correspond-ing vertebra were manufactured using the rapid prototyping technique. Results: The accuracy of the drill template was con-firmed by drilling screw trajectory into the vertebral biomodel preoperatively. This method also showed its ability to cus-tomize the placement and size of each screw based on the unique morphology of the lumbar vertebra.The drill tem-plate fits the postural surface of the vertebra very well in the cadaver experiment. Postoperative CT scans for controlling the pedicle bore showed that the personalized template had a high precision in cadaver experiment and clinical application. No misplacement occurred by using the per-sonalized template. During surgery, no additional computer assistance was needed.Conclusions: The authors have developed a novel drill template for lumbar pedicle screw placement with good applicability and high accuracy. The potential use of drill templates to place lumbar pedicle screws is promising. Our methodology appears to provide an accurate technique and trajectory for pedicle screw placement in the lumbar spine.