交锁髓内钉治疗股骨干骨折并发髓内钉 断裂二例报告

我院近 4年来 ,采用交锁髓内钉治疗股骨干骨折 38例 ,2例发生远端加锁处折断 ,报告如下 :例 1,男 ,49岁 ,因车祸致左股骨干粉碎骨折入院。 3ｄ后闭合穿入直径 10ｍｍ髓内钉 ,穿针经过顺利。股骨近端加锁钉一枚 ,远端加锁钉二枚。术后摄Ｘ线片 ,骨折对位对线良好 ,锁钉固定确切。术后 7ｄ ,患者扶拐下床活动。术后 3个月 ,取出近端锁钉 ,使静力型改为动力型固定。术后 10个月 ,在行走时 ,突觉左大腿疼痛 ,变形。Ｘ线片发现左股骨远端上锁钉折断 ,并向外侧成角约 40°,患者再次入院 ,重新切开复位、扩髓 ,选择 12ｍｍ带锁钉固定。术后 14个月 …     

新型胫骨髓内钉的研制与生物力学研究

目的　研制新型胫骨串孔型髓内钉并对其进行生物力学研究。方法　用TAMZ合金制造远端锁孔由一个三个同样直径的串孔所替代的 9根新型胫骨髓内钉。将髓内钉安装在自行设计的夹具中 ,先将 3根新钉进行静态垂直压缩实验 ,根据静态实验结果 ,分别测试 6根新钉的动态疲劳强度。结果　新钉的静态压缩破坏载荷为 2 1 33N ,是人平均体重的 3倍多 ;通过 5 0万次压缩循环的条件疲劳强度为 1 2 0 0N ,约是人体重的 2倍。结论　新钉不仅能够方便临床使用 ,而且拥有较好的力学特性     

有限接触式带锁髓内钉的有限元分析及临床应用

[目的]设计、制造一种可与人工表面关节结合的有限接触式股骨髁上型带锁髓内钉,构成人工半膝关节系统,用于提高儿童保肢手术效果。[方法]运用有限元方法对髓内钉锁钉不同置入角度(锁钉与髓内钉横断面的夹角)0°、15°、30°、45°、60°条件下骨、髓内钉及锁钉和整体结构进行应力分析。[结果]有限元分析(FEA)结果显示,锁钉以15°角置入时,骨、髓内钉及锁钉所受最大应力为最小,应力分布也较其它角度均匀。在0°角时,骨的最大应力较15°、30°和45°时大。随着穿钉角度的增大,近端锁钉最大应力增加,远端锁钉最大应力减小。[结论]有限接触式髓内钉减少了对骨原有生物环境的破坏,可与人工表面关节结合运用于异体骨关节移植,有较好的临床应用价值。     

单钉和双钉远端交锁髓内钉固定治疗股骨干骨折的比较——临床及生物力学分析

通过8具尸体16个股骨行单钉和双钉远端交锁髓内钉固定生物力学对比分析,两者扭转及轴向最大负荷无显著差异,临床采用远端单钉交锁髓内钉固定股骨干骨折27例,取得较好效果。     

肱骨干骨折髓内外固定的生物力学研究

目的 通过对单一加压钢板螺钉加髓内针、交锁髓内钉和微创技术简单有限内固定加单臂外支架3种不同固定方法治疗肱骨干复杂骨折的生物力学性能进行对比研究,为临床应用提供可靠的生物力学依据.方法 取自愿捐赠的18个新鲜湿润肱骨标本,制备肱骨干复杂骨折模型,根据不同固定方式随机分为3组,每组6个.钢板组:采用单一加压钢板螺钉加髓内针固定;髓内钉组:采用交锁髓内钉固定;外支架组:采用微创技术简单有限内固定加单臂外支架固定.分别进行轴向压缩实验和水平扭转实验.结果 轴向压缩实验:各组载荷-位移曲线呈线性到非线性变化.钢板组及髓内钉组最大载荷值分别为(6162.09±521.06)N和(6738.32±525.89)N,两组比较差异无统计学意义(P>0.05);外支架组最大载荷值为(2753.57±185.59)N,与其余两组比较,差异均有统计学意义(P<0.05).钢板组及外支架组刚度值分别为(171.69±6.49)N/mm和(132.59±2.93)N/mm,两组比较差异无统计学意义(P>0.05);髓内钉组的刚度值为(333.04±36.85)N/mm,与其余两组比较差异有统计学意义(P<0.05).水平扭转实验:各组扭矩-扭角曲线呈线性到非线性变化.髓内钉组和外支架组的最大扭矩分别为(17.12±5.73)Nm和(20.26±6.42)Nm,两组比较差异无统计学意义(P>0.05);钢板组的最大扭矩为(38.24±7.08)Nm,与其余两组比较差异有统计学意义(P<0.05).钢板组及外支架组刚度值分别为(16.36±2.07)Ncm/°和(18.79±2.62)Ncm/°,差异无统计学意义(P>0.05);髓内钉组的刚度值为(11.45±0.22)Ncm/°,与其余两组比较差异有统计学意义(P<0.05).结论 钢板组压缩和扭转强度均较强,旋转刚度较强而压缩刚度较弱;髓内钉组压缩强度和压缩刚度较强,而扭转强度和扭转刚度较弱;外支架组仅在扭转刚度上与钢板组相当,而在其他3项指标上均较弱.     

带锁髓内钉与双矩形钉治疗胫骨骨折的比较

目的 :比较带锁髓内钉与双矩形钉治疗胫骨骨折的临床疗效 ,进一步掌握各自的特点和选用的对象。方法 :本文收集了 1 995年 1月～ 1 999年 1 2月使用带锁髓内钉与双矩形钉治疗胫骨骨折 1 0 1例病例。前者 45例 ,后者 56例 ,比较 2组的固定方法、稳定性、成角、肢体矩短缩、膝关节功能恢复情况等。结果 :平均随访时间 1 1～ 1 2个月 ,胫骨骨折全部愈合 ,用矩形钉治疗的 56例平均为 1 2个月 ,用带锁髓内钉治疗的 45例 ,平均为 1 0个月。双矩形钉组成角 >1 0°,占 5 .36 % ;肢体短缩 <1cm ,占 5 .36 % ;膝关节活动 <70°,占 1 0 .71 % ;带锁髓内钉组 :成角畸形为 0 ,肢体短缩为0 ,膝关节功能 <70 % ,占 6 .67% ;仅 8.89%的病例需切开复位。结论 :(1 )双矩形钉与带锁髓内钉内固定术均为治疗胫骨骨折良好且有效的方法 ,二者无显著差异。 (2 )带锁髓内钉在稳定性、防止骨折成角畸形、短缩、恢复关节功能方面 ,优于双矩形钉。 (3)对于Ⅰ°和部分Ⅱ°的开放性胫骨骨折最好选用带髓内针闭合打入。 (4)对于经济不发达地区应多考虑双矩形钉内固定。     

“穿针器技术”徒手植入交锁髓内钉远端锁钉

目的报道一种新的徒手植入交锁髓内钉远端锁钉的方法。方法 2016年8月至2019年4月共137例骨干骨折患者行闭合复位髓内钉内固定术,其中股骨骨折54例,胫骨骨折83例,术中均采用"穿针器技术"植入交锁髓内钉远端锁钉。结果本组137例患者均成功应用"穿针器"技术置入髓内钉远端锁钉,置钉过程中无须行正位透视。胫骨骨折患者髓内钉固定的手术时间为53～75 min,平均(65.3±10.7)min;股骨骨折患者髓内钉固定时间为62～84 min,平均(73.9±13.1)min。远端2枚横行锁钉植入时间为5～16 min,平均(11.5±1.8)min。术中累计透视时间为8.3～21.6 s,平均(11.3±2.5)s。本组患者均获随访,随访时间6～12个月,所有患者均未出现远端锁钉断裂、拔出,切口感染以及骨折等。结论 "穿针器技术"操作简单,易于重复,无须辅助器械及辐射防护,是一种快速、安全、简单的徒手植入交锁髓内钉远端锁钉的技术。     

新型锁钉设计的交锁髓内钉内固定治疗股骨干骨折疗效分析

目的 观察新型锁钉设计的交锁髓内钉内固定治疗股骨干骨折的临床疗效,总结新技术的优点。方法 纳入自2010-02—2020-02采用新型锁钉设计的交锁髓内钉内固定治疗的45例股骨干骨折,采用改良远端锁钉瞄准微调装置的髓内钉瞄准器钻孔并置入远端锁钉。先确定空心定位杆的偏移在髓内钉直径有效范围内,再固定好定位杆,通过螺母上下微调确定锁钉的钻孔位,用直径5.1 mm长钻头完成精确钻孔,如果钻孔时发生偏移,上下微调螺母后再矫正偏移即可完成钻孔过程,然后置入2枚远端锁钉。结果 本组共置入90枚远端锁钉,84枚一次锁钉成功,一次锁钉成功率为93.3%;其余6枚通过C型臂X线机定位徒手锁定。45例均获得随访,随访时间平均15(8～24)个月。所有患者均无切口感染、血管神经损伤,均未出现骨折畸形愈合、髓内钉断裂、锁钉松动等并发症。术后骨折均愈合,骨折愈合时间3～9个月,平均5.5个月。末次随访时膝关节功能HSS评分：优28例,良15例,可2例。结论 将新型锁钉设计的交锁髓内钉联合远端锁钉置入技术应用于治疗股骨干骨折可实现精准锁钉,解决了传统交锁髓内钉固定不稳定以及远端锁钉困难的问题,使骨折断端达到微动状...     

全膝置换术后髁上骨折三种内固定有限元分析

[目的]利用三维有限元分析的方法,比较全膝置换术后利用单锁定钢板、髓内钉、双锁定板三种方式固定Kim IB型股骨髁上骨折的生物力学特征。[方法]将志愿者股骨CT图片及股骨假体的扫描数据,三维重建后与在Cero3.0中设计的外侧锁定钢板、内外侧双锁定钢板、股骨远端髓内钉模型装配、划分单元、赋予材料属性,构成单钢板、髓内钉组、双钢板组三个有限元模型。加载单足站立、双足站立两种工况进行力学分析。[结果]三组模型中内固定承受应力依次为单钢板组髓内钉组双钢板组,三组之间差异有显著统计学意义(P0.05)。假体外髁承受应力比较单钢板组显著高于髓内钉组和双钢板组(P0.05)。相同载荷下骨折端位移单钢板组髓内钉组双钢板组,三组之间差异有显著统计学意义(P0.05)。单钢板组与髓内钉组中单足站立载荷在骨折端产生的位移显著大于双足站立载荷(P0.05)。[结论]双锁定钢板不仅有利于股骨髁上骨折骨折断端稳定,而且能够减小股骨假体内外侧髁应力差异,有利于假体的稳定。     

锁定钢板外置与外固定架固定胫骨骨折的生物力学比较

目的比较锁定钢板外置固定与外固定架固定胫骨中段或远端骨折的生物力学差异,为锁定钢板外置固定治疗开放性胫骨骨折的临床应用提供理论依据。方法选取80根新鲜牛胫骨,随机分成A1、A2、B1、B2组,每组20根。A1、A2组制备胫骨中段骨折,A1组采用外固定架单边单面4钉固定,A2组采用锁定钢板外置4钉固定。B1、B2组制备胫骨远端骨折,B1组采用外固定架胫骨远端交叉置钉4钉固定,B2组采用锁定钢板外置6钉固定。测量各组在不同载荷下的轴向压缩位移和角位移。结果不同载荷作用下,A2组的轴向位移小于A1组,B2组的轴向位移也小于B1组,且随着载荷越大则轴向位移差距越大,差异有统计学意义(P0.05)。不同扭转载荷作用下,4组角位移均随着载荷增加而增大;在同一扭转载荷作用下,A1组与A2组、B1组与B2组的角位移差异无统计学意义(P0.05)。结论对于胫骨中段或远端骨折,锁定钢板外置固定具有与传统外固定架固定相同的抗扭转性能,而且可提供更强的轴向稳定性。     

瞄准器引导股骨交锁髓内钉远端锁钉的再认识

[目的]分析瞄准器引导下股骨交锁髓内钉远端锁钉困难的原因，以提高远端锁钉成功率。[方法]用配备远端瞄准器的股骨交锁髓内钉治疗股骨干骨折297例（301侧股骨），髓内钉301枚，国产钉216枚，进口钉85枚；粉碎性骨折108例，非粉碎性骨折189例；其中4例双侧股骨干骨折；均采取静力型固定，远近端各2枚锁钉。[结果]301枚股骨交锁髓内钉有288枚远端锁钉一次成功，有13枚初次锁钉未成功，一次锁钉成功率为95．7％。[结论]股骨交锁髓内钉远端锁钉困难的原因是多方面的，要提高远端锁钉一次成功率，必须重视包括术前准备在内的各个环节。     

A mechanical study of gap motion in cadaveric femurs using short and long supracondylar nails

OBJECTIVE: To determine the relative stability achieved in unstable supracondylar femur fractures treated with long (36 cm) and short (20 cm) retrograde intramedullary nails using 1 or 2 proximal locking bolts. We hypothesized that longer nails would reduce fracture site motion compared with short nails and that 2 proximal locking bolts would improve stability compared with 1 proximal locking bolt. DESIGN: Nine pairs of matched human cadaveric femurs were instrumented with 20-cm and 36-cm retrograde intramedullary nails (all 12-mm diameter, Biomet, Warsaw, IN) following reaming to 13 mm. Transverse supracondylar gap (6 mm) osteotomies were created. The femurs were mounted and cyclically tested separately in coronal plane bending and sagittal plane bending on a materials testing system. Fracture site translation was measured using a digital caliper in the respective plane. SETTING: Orthopaedic biomaterials laboratory. RESULTS: With 2 proximal locking bolts, average sagittal translation was 7.2 mm and 1.8 mm, respectively, for the 20-cm and 36-cm nails. Coronal translation was 6.3 mm and 4.3 mm, respectively. With a single proximal locking bolt, average sagittal translation was 7.6 mm and 2.2 mm, respectively, for the 20-cm and 36-cm nails. Coronal translation was 13.6 mm and 4.4 mm, respectively. A statistically significant difference in fracture site translation was found in each pairing by Student t test (P < 0.005), except coronal translation with 2 proximal locking bolts (P = 0.056). Free-body analysis predicts higher local stresses at the proximal interlocks of the shorter nail. CONCLUSIONS: Longer nails provide improved initial fracture stability when compared with short retrograde nails for supracondylar femur fractures due to a more stable mechanical interaction between the femoral diaphysis and the nail. A second proximal locking bolt in the long nail provides no additional stability.     

闭合复位交锁髓内钉固定治疗股骨干骨折

目的探讨应用闭合复位交锁髓内钉固定治疗股骨干骨折的临床效果。方法回顾性分析2007年2月至2008年1月应用闭合复位交锁髓内钉内固定技术治疗股骨干骨折患者123例,男94例,女29例;年龄24～54岁,平均39岁;开放性骨折27例,闭合性骨折96例。根据AO分型：A型46例,B型38例,C型39例。结果 A型骨折手术时间45～62 min,平均53 min;B型骨折手术时间49～68 min,平均59 min;C型骨折手术时间48～82min,平均67 min。3例股骨近端内侧皮质粉碎骨折或骨折向内成角,其中1例髋内翻;4例骨折远端出现劈裂;1例膝关节外翻;5例术锁钉断裂或退出;1例主钉断裂;8例出现不同程度的神经牵拉伤。无一例出现深静脉血栓、肺栓塞和感染并发症。其中112例获得随访,随访时间为12～20个月,平均16个月。A型和B型骨折78例中39例行静力改动力化锁钉,骨折平均愈合时间为6个月;另39例行持续静力化锁钉,骨折平均愈合时间为8个月。C型骨折平均愈合时间为12个月。无一例患者出现骨折不愈合。术后患者髋膝关节功能优良率为98%。结论闭合复位交锁髓内钉内固定术是治疗股骨干骨折的有效方法之一。     

低应力遮挡效应交锁髓内钉的研制与生物力学研究

目的 :研究新型股骨低应力遮挡交锁髓内钉治疗股骨干骨折的生物力学特性。方法 :将股骨干交锁髓内钉远端锁孔向近端分别扩大 1、 2、 3mm ,采用 4具成人男性尸体 8根股骨干标本制成横断骨折模型 ,分别打入 4种不同孔径髓内钉 ,进行骨折断端应力分析实验。结果 :远端锁孔直径 3mm的交锁髓内钉与实验中其它组相比较 ,应力遮挡率最小 ( 2 0 .6 0 %) (P <0 .0 5 ) ,在载荷—应变、载荷—位移、轴向强度及刚度上均占有明显优势 (P <0 .0 5 )。而 4种髓内钉在弯矩—应变、弯矩—桡度、扭矩—扭角关系中无明显差别。结论 :远端锁孔直径扩大 3mm的交锁髓内钉不但应力遮挡小 ,而且强度、刚度符合骨折内固定的生物力学要求 ,从而该实验为临床应用低应力遮挡交锁髓内钉提供了可靠理论依据。     

Biomechanical comparison of slotted and nonslotted interlocking nails in distal femoral shaft fractures

The torsional and compressive biomechanical characteristics of slotted and nonslotted interlocking nails in distal femoral shaft fractures were evaluated. Slotted (Grosse-Kempf) and nonslotted (Russell-Taylor) locked nail systems were implanted in anatomic specimen femora, which were then tested in torsion and axial compression. For torsional studies, each femur was transversely sectioned distal to the isthmus; for axial loading, a distal 3-cm section of bone was removed. The mean peak torsional stiffness of the femora fixed with nonslotted nails was 0.955 Nm per degree, which was significantly greater than that (0.300 Nm per degree) for the femora fixed with the slotted nails. However, when loaded to failure in compression, the nonslotted nail group failed at a mean load of 2490 N compared with 3050 N for the group fixed with the slotted devices. These results could be due in part to the lesser rigidity of the slotted nail, which may have facilitated greater load sharing with bone and increased resistance to compression failure.     

阻钉技术对交锁髓内钉断钉的影响

目的探讨阻钉技术对交锁髓内钉断钉的预防作用。方法2003年1月~2005年8月,采用交锁髓内钉固定长骨干骨折56例,男32例,女24例。年龄21~65岁,平均34岁。其中股骨骨折26例,胫骨骨折30例,均为新鲜、闭合性骨折。骨折类型:中部横断骨折10例,中部短斜形骨折11例,中部长斜形或螺旋形骨折20例,远、近1/3骨干骨折15例。前期32例患者采用常规的交锁髓内钉固定骨折(组),后期24例中部长斜形或螺旋形骨折及远、近1/3骨折患者采用交锁髓内钉配合阻钉固定骨折(组)。结果获随访12~21个月,平均16个月。组3例患者骨折未愈合,其中1例股骨中部长斜形骨折主钉在骨折线附近断裂,另2例胫骨远1/3骨折主钉在靠近骨折端的第1个锁钉孔处断裂;其余患者术后6~12个月获骨性愈合,但骨折处出现较多骨痂。组患者于术后3~8个月获骨性愈合,骨折对位、对线良好,无断钉发生。结论阻钉技术配合交锁髓内钉应用可明显增强骨折断端稳定性,减少断钉发生。     

交锁髓内钉断裂的原因分析及对策

探讨交锁髓内钉断裂的原因,提出预防的对策。方法：从１９９２年至１９９７年,对６４例复杂粉碎性股骨骨折作了交锁髓内钉固定。结果：５５例随访,平均２６个月。共发生４例交锁钉断裂,断钉率为６．３％。断钉发生在术后６～１４月,３例位于骨折远端第１枚横锁螺孔处,１例位于交锁钉中段。结论：作者认为断钉原因有：开放穿钉,过度分离骨膜,过早负重及功能锻炼不合适等。另外,股骨远端第１枚横锁螺钉离骨折端太近,应力集中。预防断裂的方法有尽量闭合穿钉,选择较粗较长的交锁钉,交锁螺钉应稍远离骨折端,避免过早负重及合适的功能锻炼等。     

Setscrew distal locking for intramedullary nails: a biomechanical study

OBJECTIVE: This biomechanical study was undertaken to examine the effectiveness of setscrew distal locking in a static intramedullary (IM) femoral nail on the stability of fixation of femoral shaft fractures. DESIGN: Fifteen fresh-frozen cadeveric femora were randomly separated into three groups of five bones and transversely sectioned immediately distal to the isthmus. After the insertion of the large-diameter nails, distal locking was obtained by conventional method in the first group. In the second group, set-screw design was used in which two transverse screws penetrated only the lateral cortex of the femur and compressed the nail in the intramedullary canal. No distal locking was used in the third group. INTERVENTION: All instrumented femurs were mounted on a servohydraulic testing machine and tested in both rotations (20 degrees) and axial compression (amplitude: 1,000 Newton). MAIN OUTCOME MEASUREMENT: Loading-versus-displacement data, acquired at a ten-Hertz sampling rate, were calibrated and used to calculate maximum torque, stiffness, and energy capacity to failure. Maximum displacement and axial stiffness also were determined. RESULTS: Mean maximum torque at 10 degrees for each group were 15.3+/-4.8 newton-meters for the interlocking group, 8.5 +/-1.2 newton-meters for the setscrew group, and 3.6+/-2.7 newton-meters for the nonlocked femora. At 20 degrees of rotational displacement, the torque measured 37.4+/-2.6 newton-meters; 15.0+/-4.0 newton-meters; and 5.3+/-3.1 newton-meters, respectively (p < 0.05). Mean torsional stiffness was 1.17+/-0.76 newton-meters per degree for the setscrew group and 1.34+/-0.83 newton-meters per degree for the interlocking group (p > 0.05). The setscrew design provided 87 percent of the torsional rigidity of the interlocking group. In the axial compression test, mean maximum shortening was 1.1+/-0.3 millimeters in the interlocking group and 1.4+/-0.6 millimeters in the setscrew group (p > 0.05). The mean stiffness on longitudinal compression provided by the interlocking screws and the setscrews was 918 and 860 newton-meters per millimeter, respectively. CONCLUSION: The distal setscrew design provides adequate distal fixation of intramedullary nail for patients in the postoperative rehabilitation period of the femoral shaft fractures treated with intramedullary nailing.     

胫骨远端骨折应用交锁髓内钉固定时远端不同锁定钉状态的有限元分析

目的 探究胫骨远端骨折应用交锁髓内钉固定时远端不同锁定钉状态的稳定性及其生物力学特性。方法 选择一名健康成年男性的胫骨CT Dicom数据,应用mimics、geomagic和solidworks软件构建胫骨、髓内钉、锁定钉的3D模型,然后按照髓内钉远端不同锁定状态分为试验组（两枚横向锁定钉和一枚纵向锁定钉）和对照组（两枚横向锁定钉）,分别给予轴向、侧向和扭转方向的不同大小的载荷,以模拟正常人体胫骨和内固定系统在不同受力情况下的应力和位移分布情况。结果 试验组和对照组的应力分布没有明显差异,二者都集中在骨-螺钉结合部位,但试验组在轴向、侧向和扭转方向的不同大小的载荷下的最大等效应力均略低于对照组,在轴向300、600、900 N载荷下,试验组的最大等效应力为24.84、49.68、74.52 MPa,对照组的为27.80、55.51、83.27 MPa;在扭转2、4、6 N/m的载荷下,试验组的最大等效应力为144.87、290.92、431.80 MPa,对照组为146.01、292.03、434.80 MPa;在侧向300、600、900 N载荷下,试验组的最大等效应力为209.79、419.58、629.37 MPa,对照组为210.47、420.94、631.41 MPa。在形变位移方面,两组的内固定系统都没有发生明显形变,且试验组的最大位移均略小于对照组。在轴向300、600、900 N载荷下,试验组的最大位移为0.022 9、0.045 8、0.068 7 mm,对照组的为0.024 1、0.048 1、0.072 3 mm;在扭转2、4、6 N/m的载荷下,试验组的最大位移为0.217 8、0.428 8、0.597 8 mm,对照组为0.218 5、0.436 9、0.607 2 mm;在侧向300、600、900 N载荷下,试验组的最大位移为0.949 2、1.898 5、2.847 7 mm,对照组为0.952 5、1.905 0、2.857 6 mm。结论 通过应力和位移对比分析,在使用髓内钉固定胫骨远端骨折时,髓内钉远端固定两枚横向锁定钉已经提供了足够的稳定性,与使用三枚锁定钉相比,两枚锁定钉能减少额外的手术时间和不必要的辐射暴露。在实际情况中还需要手术医生结合临床的具体情况为病人选择最合适的手术方案。     

Biomechanical analysis of peri‑implant fractures in short versus long cephalomedullary implants following pertrochanteric fracture consolidation

IntroductionPertrochanteric femur fracture fixation with use of cephalomedullary nails (CMN) has become increasingly popular in recent past. Known complications after fracture consolidation include peri‑implant fractures following the use of both short and long nails, with fracture lines around the tip of the nail or through the interlocking screw holes, resulting in secondary midshaft or supracondylar femur fractures, respectively. Limited research exists to help the surgeon decide on the use of short versus long nails, while both have their benefits. The aim of this biomechanical study is to investigate in direct comparison one of the newest generations short and long CMNs in a human anatomical model, in terms of construct stability and generation of secondary fracture pattern following pertrochanteric fracture consolidation.MethodsEight intact human anatomical femur pairs were assigned to two groups of eight specimens each for nailing using short or long CMNs. Each specimen was first biomechanically preloaded at 1 Hz over 2000 cycles in superimposed synchronous axial compression to 1800 N and internal rotation to 11.5 Nm. Following, internal rotation to failure was applied over an arc of 90° within one second under 700 N axial load. Torsional stiffness as well as torque at failure, angle at failure, and energy to failure were evaluated. Fracture patterns were analyzed.ResultsOutcomes in the study groups with short and long nails were 9.7 ± 2.4 Nm/° and 10.2 ± 2.9 Nm/° for torsional stiffness, 119.8 ± 37.2 Nm and 128±46.7 Nm for torque at failure, 13.5 ± 3.5° and 13.4 ± 2.6° for angle at failure, and 887.5 ± 416.9 Nm° and 928.3 ± 461.0 Nm° for energy to failure, respectively, with no significant differences between them, p ≥ 0.17. Fractures through the distal locking screw holes occurred in 5 and 6 femora instrumented with short and long nails, respectively. Fractures through the lateral entry site of the head element were detected in 3 specimens within each group. For short nails, fractures through the distal shaft region, not interfacing with the implant, were detected in 3 specimens.ConclusionFrom a biomechanical perspective, the risk of secondary peri‑implant fracture after intramedullary fixation of pertrochanteric fractures is similar when using short or long CMN. Moreover, for both nail versions the fracture pattern does not unexceptionally involve the distal locking screw hole.