后交叉韧带重建中股骨侧"锐角效应"的相关研究及骨道技术的评价

[目的]探讨后交叉韧带重建中股骨侧的"锐角效应"以及对骨道技术进行评价.[方法]应用猪的屈趾肌腱作为移植物重建后交叉韧带,分别建立与股骨髁间窝侧壁呈80°、90°、100°夹角的骨道,以及对骨道边缘进行打磨处理.在骨道边缘与移植物之间放置压敏片计算得压强值来表示磨损作用的大小,压强值越大表示磨损作用越大.通过比较应用骨道技术重建PCL组与对照组的压强值来说明这种减小"锐角效应"的方法是否可行.[结果]应用骨道技术重建后交叉韧带各组中移植物与股骨髁间窝侧壁夹角为100°时压强最小[(3.55±0.21)MPa],并且对骨道边缘进行打磨后压强值[(3.29±0.19)MPa]明显低于对照组[(3.55±0.21)MPa].[结论]应用骨道技术可以有效减小后交叉韧带重建中股骨侧的"锐角效应".     

重建后交叉韧带股骨侧“锐角效应”的相关研究

背景:重建后交叉韧带术后的股骨侧"锐角效应"可造成韧带移植物磨损,目前尚无有效的解决方法。目的:通过动物模型试验研究骨道技术减小重建后交叉韧带术后股骨侧"锐角效应"的可行性及其生物力学特性,以进一步指导临床研究。方法:采用猪屈趾肌腱重建后交叉韧带,分别建立与股骨髁间窝侧壁夹角为80°、90°、100°骨道组,均未行骨道边缘打磨处理,测量并计算压强值,用以表示磨损作用大小;之后建立压强值最小组的对照组,采用相同夹角大小,并行骨道打磨处理。不同夹角组之间和同夹角不同处理组之间进行压强值比较,评估骨道技术对韧带磨损情况的减小作用。结果:与股骨髁间窝侧壁呈100°夹角,且进行边缘打磨处理的骨道的压强值最小。结论:应用骨道技术可有效减小重建后交叉韧带股骨侧的"锐角效应"。     

关节镜下可吸收界面螺钉固定重建前交叉韧带

目的总结膝关节镜下运用4股胭绳肌肌腱重建前交叉韧带和可吸收界面螺钉固定的方法及疗效。方法2005年3月至2007年9月应用4股咽绳肌肌腱和可吸收界面螺钉重建前交叉韧带32例,术前和术后进行Lachman试验评估膝关节的稳定性,用Lysholm评分方法评定膝关节功能。结果30例患者获得6～30个月随访,平均26个月。术前Lachman试验均为阳性,术后26例为阴性,4例为阳性,术前、术后比较差异有统计学意义（P〈0．01）。术前Lysholm评分38483分,平均（53．30±5．20）分;术后82-100分,平均（91．2±6．20）分。术后膝关节功能有明显改善（P〈0．01）。结论4股胭绳肌肌腱和可吸收界面螺钉重建前交叉韧带具有近期疗效满意、移植物固定町靠、操作简单、并发症少等优点。     

关节镜下月国绳肌腱及生物界面螺钉重建前交叉韧带

目的探讨关节镜下胭绳肌腱及生物界面螺钉重建前交叉韧带的疗效。方法对2007年8月-2009年5月收治的27例前交叉韧带重建病例,采用胭绳肌腱及生物界面螺钉进行重建。男25例,女2例。年龄18±45岁,平均29．6岁。结果22例患者获随访3～24个月,平均8．7月。术后Lysholm评分为91．1±5．3,与术前65．8±5．9比较,差异有统计学意义（P〈0．01）。术后有1例患者发生隐神经损伤,1例出现膝关节化脓性感染,行移植物取出待二期翻修。除感染1例外,其余患者术后患膝活动均正常,不稳感消失。结论胭绳肌腱是修复前交叉韧带的良好移植物,关节镜下界面螺钉固定疗效满意。应避免隐神经损伤和感染等并发症的发生。     

镁铝合金界面螺钉骨腱固定重建前交叉韧带的实验研究——猪胫骨骨腱固定的生物力学分析

目的探讨镁铝合金界面螺钉固定对骨-腱-骨重建的前交叉韧带(ACL)的初始力学特性。方法在20个猪的胫骨标本应用骨-髌腱进行ACL重建。按不同材料制成的界面螺钉分成3组:镁铝合金组8个标本、钛合金组和聚乳酸组各6个标本。在MTS机进行疲劳(1000次25~150N循环)及最大负荷试验。结果所有界面螺钉固定的骨-髌腱均能顺利完成循环负载。疲劳试验前后镁铝合金、钛合金和聚乳酸界面螺钉固定的复合体伸长度分别为(1.71±0.37)mm,(2.14±0.92)mm和(1.36±0.58)mm,各组间没有显著性差别(P=0.135);抗拉刚度分别为(121.01±28.94)N/mm、(92.64±11.52)N/mm和(119.93±26.55)N/mm,各组间没有显著性差别(P=0.091);最大载荷分别为(522.68±82.87)N、(441.22±86.30)N和(674.10±191.12)N,各组间具有显著性差别(P=0.016)。所有失效方式为2种,即韧带在体部的断裂和骨块从隧道中滑出,3种材料界面螺钉的失效方式无显著性差别(P=0.513)。结论镁铝合金界面螺钉固定对骨-腱-骨重建的前交叉韧带的初始力学强度能达到临床要求。     

后交叉韧带重建中不同角度胫骨隧道的生物力学研究

目的评价后交叉韧带重建中不同角度胫骨隧道对移植物生物力学性能的影响。方法应用18具人体跟腱作为移植物重建后交叉韧带,分别建立与胫骨平台呈30°、40°、50°3组不同夹角的胫骨隧道,在胫骨隧道出口边缘与移植物之间放置压敏片计算压强值及试验前后隧道出口面积变化来评估磨损作用的大小、"锐角效应"的影响以及移植物循环载荷能力。结果胫骨隧道与胫骨平台夹角50°时压强最小、隧道出口面积扩大最小。夹角减小压强增大、隧道出口面积的扩大增大,"锐角效应"增加,导致循环载荷能力下降。结论增加胫骨隧道与胫骨平台的夹角,可以降低隧道出口处的压强,减少移植物磨损,增加疲劳力学性能。     

保留残迹对前交叉韧带移植物腱骨愈合影响的实验研究

目的探讨保留残迹重建前交叉韧带对移植物腱骨愈合的影响。方法 32只新西兰兔一期行双侧前交叉韧带重建术,一侧保留残端纤维,对侧切除残端纤维。重建术后6、12、18及24周时,采用HE染色、甲苯胺蓝染色观测,分析移植物腱骨愈合变化情况。结果重建术后各观察时间点上,保留残迹组移植物腱骨界面组织构建更接近正常,术后24周时保留残迹组腱骨界面软骨细胞含量明显高于切除残迹组[（56.5±2.4）vs（45.7±2.7）,P〈0.05]。结论保留残迹重建前交叉韧带有助于移植物腱骨愈合。     

关节镜下胫骨端RigidFix、股骨端IntraFix固定技术重建后交叉韧带

目的探讨胫骨端RigidFix和股骨端IntraFix固定重建技术治疗后交叉韧带损伤的临床疗效。方法2007年3月-2010年3月,采用同种异体胫前肌腱为移植物重建后交叉韧带35例,男27例,女8例。年龄25—42岁,平均32．5岁。左膝12例,右膝23例。移植物胫骨端以RigidFix横穿钉固定,股骨端以Intra Fix挤压螺钉固定。术后通过体格检查、Lysholm评分及国际膝关节文献管理委员会（International Knee Documentation Committee,IKDC）评分来评价手术疗效。结果所有手术成功,无骨折或定位偏离等并发症。术后随访24～60个月,平均35．3月。末次随访时35例胫骨下陷征均为阴性;Lachman征阴性33例,I度阳性2例;后抽屉试验阴性31例,I度阳性3例,Ⅱ度阳性1例。Lysholm评分85．0±4．5（80～98）分,优9例,良25例,中1例。IKDC评分85．1±2．6（81～95）分,A级9例,B级26例。上述指标均较术前明显改善。结论胫骨端RigidFix和股骨端IntraFix固定重建后交叉韧带时不用顾忌移植物长度限制,操作简单;中心固定不会影响移植物的位置,可避免对移植物造成切割,避免干扰腱骨界面。此项技术切实可行、固定可靠,且不易发生并发症,疗效优良。     

关节镜下股骨端保留骨量界面螺钉固定和胫骨端Intrafix系统固定在腘绳肌腱重建后交叉韧带中应用

目的探讨关节镜下股骨端保留骨量界面螺钉固定和胫骨端Intrafix系统固定在腘绳肌腱重建后交叉韧带(PCL)中应用的可行性及近期疗效。方法用腘绳肌腱对31例PCL损伤患者行关节镜下PCL重建术。采用PCL重建技术钻胫骨、股骨骨道,将腘绳肌腱拉入骨道,股骨端用1枚界面螺钉固定并保留隧道内上方的骨皮质,胫骨端用Intrafix固定韧带。结果手术时间40～90(60.16±14.05)min。无滑膜炎、韧带断裂、活动明显受限等并发症。31例均获随访,时间12～18(15.74±2.13)个月。根据Lysholm膝关节功能评分,术前19～49(30.77±11.62)分;术后88～98(92.94±2.26)分(t=28.65,P0.01)。结论关节镜下股骨端保留骨量界面螺钉固定和胫骨端Intrafix系统固定在腘绳肌腱重建PCL操作简便,固定牢固,效果可靠。     

关节镜下双侧胭绳肌腱同时重建膝关节前后交叉韧带

目的探讨关节镜下应用自体四股胭绳肌腱同时重建膝关节前后交叉韧带的近期临床效果。方法我科自2005年10月至2008年2月对8例前后交叉韧带同时损伤的患者,切取双侧胭绳肌腱折成四股,关节镜下同时重建前后交叉韧带,股骨端应用可吸收界面挤压螺钉固定,胫骨端应用Intrafix固定。应用lysholm膝关节功能评分和膝关节稳定性评价效果。结果术前lysholm膝关节功能评分为（38．5±7．8）分,术后12个月随访,该评分为（90．5±4．2）分。差异具有统计学意义。术前各膝关节前后抽屉试验（＋）,术后各膝前后抽屉试验（-）。结论关节镜下应用自体四股胭绳肌腱同时重建膝关节前后交叉韧带的近期临床效果良好。     

Soft-tissue graft fixation in posterior cruciate ligament reconstruction: evaluation of the effect of tibial insertion site on joint kinematics and in situ forces using a robotic/UFS testing system

Introduction Surgical reconstruction of the posterior cruciate ligament (PCL) is recommended in acute injuries that result in severe tibial subluxation and instability. The surgical outcome level may be affected by the tibial fixation site. In response to a 110-N posterior tibial load, kinematics and in situ forces of anatomical soft-tissue graft fixation in single-bundle PCL reconstruction using an interference screw fixation are significantly closer to those in the intact knee than with extracortical fixation with two staples.Materials and methods Using a robotic/universal force moment sensor (UFS) testing system, we examined joint kinematics and in situ forces of porcine knees following single-bundle PCL reconstruction fixed at two different tibial fixation sites: anatomical interference screw and extracortical fixation.Results The site of the tibial graft fixation had significant effect on the resulting posterior displacement and in situ forces of the graft. Both PCL reconstruction techniques reduced the posterior tibial translation significantly. Proximal fixation techniques provided significantly less posterior tibial translation than extracortical fixation. Single-bundle PCL reconstruction with an interference screw showed higher in situ forces of the graft than the extracortical fixation.Conclusions The kinematics and in situ forces of a single-bundle PCL reconstruction using an interference screw fixation technique are superior to the primary stability of an extracortical fixation with staples.     

Initial fixation strength of modified patellar tendon grafts for anatomic fixation in anterior cruciate ligament reconstruction.

Recently it has been shown that anatomic tibial graft fixation in anterior cruciate ligament (ACL) reconstruction is preferable in order to increase isometry and knee stability. To facilitate anatomic patellar tendon graft fixation, customized graft length shortening is necessary. The purpose of this study was to compare the initial fixation strength of four different shortened patellar tendon grafts including three bone plug flip techniques and direct patellar tendon-to-bone interference fit fixation in a model with standardized bone density. Ninety calf tibial plateaus (22 to 24 weeks old) with adjacent patella and extensor ligaments were used. Tendon grafts were shortened by flipping the bone plug over the tendon leaving a tendon-tendon-bone (TTB) construct and, as the first modification in the opposite direction resulting in a tendon-bone-tendon (TBT) construct. The second modification consisted of the TBT construct with interference screw position at the lateral aspect of the bone plug (TBTlat). As the fourth modification the tendon graft was directly fixed (Tdirect) with an interference screw. In addition, a round-threaded titanium (RCI; Smith & Nephew DonJoy, Carlsbad, CA), a round-threaded biodegradable screw (Sysorb; Sulzer Orthopedics, Münsingen, Switzerland), and a conventional titanium interference screw (Arthrex Inc, Naples, FL) were compared. We found that TTB (mean 441 N for biodegradable screw, 357 N for RCI screw, 384 N for conventional screw) and TBT (mean 407 N for biodegradable screw, 204 N for RCI screw, 392 N for conventional screw) construct fixation achieves comparable fixation strength, although failure in the TTB was due to tendon strip off at its ligamentous insertion. The highest failure load was found in TBTlat fixation (mean 610 N for biodegradable screw, 479 N for RCI screw). Therefore, this technique should be recommended when using a tendon flip technique. The failure load for Tdirect fixation (mean 437 N for biodegradable screw, 364 N for RCI screw) was similar to that of TTB and TBT fixation, which may indicate that a patellar-tendon graft harvested without its patellar bone plug and directly fixed with an interference screw is equivalent to a flipped graft. This may additionally reduce harvest site morbidity and eliminates the risk of patellar fracture. The fixation strength of round-threaded biodegradable and conventional titanium interference screws was similar, whereas that of round-threaded titanium screws was significantly lower in the patellar tendon flip-techniques. However, it should be taken into consideration that round-threaded titanium screws are proposed for direct tendon-to-bone fixation.     

Fixation strength of a biodegradable interference screw and a press-fit technique in anterior cruciate ligament reconstruction with a BPTB graft

The objective of this study was to evaluate the fixation strength of a biodegradable interference screw (Arthrex, Naples, FL) compared with press fit fixation and a titanium interference screw in anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BPTB) graft. Porcine lower limbs were used. Ultimate failure loads of the biodegradable screw (805.2 N; range 680 to 995 N) did not differ significantly from ultimate failure loads of titanium interference screws (768.6 N; range 544 to 1094 N). Press fit fixation provided significant (P < .01) lower fixation strength (462.5 N; range 80 to 825 N). These results support the conclusion that biodegradable interference screws are a reasonable alternative in terms of primary fixation strength.     

Initial fixation strength of a new hybrid technique for femoral ACL graft fixation: the bone wedge technique

Background Aperture fixation with interference screws matching the diameter of the tunnel is associated with the risk of graft laceration and graft rotation. Hypothesis A hybrid fixation technique (extracortical and aperture fixation) with undersized interference screw placed behind a bone wedge provides a higher fixation strength as aperture fixation with a screw alone matching the size of the tunnel. Study design Experimental laboratory study. Methods We evaluated the initial fixation strength (single cycle and cyclic loading tests) of hybrid and interference screw aperture fixation using different sized interference screws in porcine knees. Results Analysis of yield load, maximum load and stiffness in the single cycle loading test showed no statistically significant differences for hybrid fixation with a 1 mm undersized screw and aperture fixation with a screw matching the size of the tunnel. The use of an undersized screw alone resulted in low fixation strength. Conclusion The initial fixation strength of the hybrid technique with undersized screws is comparable to that of interference screw fixation matching the size. Clinical relevance The new “bone wedge fixation” is an alternative for ACL graft fixation without the risk of graft laceration and graft rotation.     

Biomechanical evaluation of patellar- and hamstring tendon graft fixation for anterior cruciat ligament reconstruction using a poly-(D, L-lactide) interference screw

Anterior cruciate ligament (ACL) reconstruction using autologous hamstring tendons are being performed more frequently and satisfactory results have been reported. Advantages such as low donor site morbidity and ease of harvest as well as disadvantages like low initial construct stiffness have been described. Recently, it has been demonstrated that graft fixation close to the original ACL insertion sites increases anterior knee stability and graft isometry. Hamstring tendon fixation techniques using interference screws offer this possibility. To reduce the risk of graft laceration, a round threaded titanium interference screw (RCI) was developed. To improve initial fixation strength, fixation techniques for hamstring tendons with separate or attached tibial bone plugs were introduced. However, data on fixation strength do not yet exist. With respect to the proposed advantages of biodegradable implants, like undistorted magnetic resonance imaging, uncompromised revision surgery and a decreased potential of graft laceration during screw insertion, we performed pullout tests of round threaded biodegradable and round threaded titanium interference screw fixation of semitendinosus (ST) grafts with and without distally attached tibial bone plugs. Data were compared with bone-tendon-bone (BTB) graft fixation using biodegradable and conventional titanium interference screws. We used 56 proximal calf tibiae to compare maximum pullout force, screw insertion torque, and stiffness of fixation for biodegradable direct ST tendon and bone plug fixation (group I: without bone plug, group II: with bone plug) versus titanium interference screw fixation (group III: without bone plug, group IV: with bone plug). A round threaded biodegradable poly-(D, L-lactide) (Sysorb) and a round threaded titanium interference screw (RCI) were used. As a control calf bone-tendon-bone (BTB) grafts fixed with either poly-(D, L-lactide) (group V) or conventional titanium (group VI) interference screws were used. ST tendons were harvested either with or without their distally attached tibial bone plugs from human cadavers and were folded to a three-stranded graft. Specimen were loaded in a material testing machine with the applied load parallel to the long axis of the bone tunnel. Maximum pullout force of ST bone plug (group III: 717 N +/- 90, group IV: 602 N +/- 117) fixation was significantly higher than that of direct tendon (group I: 507 N +/- 93, group III: 419 N +/- 77) fixation. Maximum pullout force of biodegradable screw ST fixation was higher than that of titanium screw fixation in both settings. There was no significant difference in pullout force between biodegradable (713 N +/- 210) and titanium (822 N +/- 130) BTB graft fixation or between ST fixation with bone plug and biodegradable screw with BTB fixation. Pullout force of hamstring tendon interference screw fixation can be improved by using a biodegradable implant. In addition, initial pullout force can be greatly improved by harvesting the hamstring tendon graft with its distally attached tibial bone plug. This may be important, especially in improving tibial graft fixation. This study encourages further research in tendon-bone healing with direct interference screw fixation to confirm the potential of this advanced method.     

Biomechanical properties of interference screw implantation in replacement of the anterior cruciate ligament with patellar and hamstring transplants. An experimental study using roentgen stereometry analysis (RSA)

This experimental roentgen stereometric analysis (RSA) study was performed to measure micromotions between the graft and tunnel under submaximal load in anterior cruciate ligament (ACL) reconstruction. The aim was to evaluate the maximum load at failure, linear stiffness, and slippage of bone-patellar-tendon-bone (BPTB) grafts fixed with interference screws compared to quadrupled hamstring grafts fixed with interference screws. We used 15 porcine tibia specimens for the study. In the BPTB group, the 10 x 25-mm bone plugs were fixed in a tunnel with 10 mm in diameter using a 7 x 25-mm titanium interference screw (n = 5) or a biodegradable screw (n = 5). The five hamstring transplants were folded to a four-stranded graft and armed with a baseball stitch suture. The sutured side was fixed with a 7 x 25-mm biodegradable polylactide screw in an 8-mm tunnel. The tibial bones, tendon grafts, and interference screws were marked with tantalum beads. The grafts were mounted to a custom made load frame and loaded parallel to the axis under RSA control increasing the force in steps of 50 N. Micromotions between bone plug, screw, and tibia were measured with RSA. Accuracy of RSA for the in vitro study was evaluated as 0.05 mm. Hamstring grafts failed at significantly lower maximum loads (492 +/- 30 N) than BPTB grafts (658 +/- 98 N). Linear stiffness of the hamstring graft fixations was eight times lower compared to the BPTB grafts (403 +/- 141 N/mm vs 3500 +/- 1300 N/mm). There was no significant difference between the biodegradable and titanium screws in the BPTB group. Slippage of the graft started at 82 +/- 35 N load in the hamstring group and at 428 +/- 135 N in the BPTB group. Slippage of the graft at 75% of the maximum pull-out strength was measured as 0.36 +/- 0.25 mm in the BPTB and 2.58 +/- 1.08 mm in the hamstring group. The interference screw fixation of a quadrupled hamstring graft showed a lower linear stiffness and an earlier slippage compared to a patellar tendon bone plug. Slippage of the hamstring grafts at submaximal loads may result in fixation failure during rehabilitation.     

Primary stability of bone-patellar tendon-bone graft fixation with biodegradable pins

Purpose: We evaluated the initial bone-patellar tendon-bone (BPTB) graft fixation strength of biodegradable pins compared with interference screws in anterior cruciate ligament reconstruction using bovine knees. Type of Study: Biomechanical in vitro study. Methods: Ten BPTB grafts from human donors fixed with 2 biodegradable 2.7-mm pins (Rigid Fix; Ethicon, Mitek Division, Norderstedt, Germany) crossing the bone block perpendicular and 10 BPTB grafts fixed with conventional biodegradable interference screws (Absolute Absorbable Interference Screw; Innovasive Devices, Marlborough, MA) underwent ultimate single-cycle failure loading at a rate of 200 mm/min. The grafts were fixed to bovine tibia to simulate young human femoral bone density. Failure mode, displacement before failure, and ultimate failure load were tested with a testing machine. The pullout force was in line with the bone tunnel to simulate a worst case scenario. Results: The failure mode for cross pins was either fracture of the bone block (5 specimens) or fracture of the articular pin (5 specimens). The failure mode for interference screws was slippage past the screw in all specimens. In the single cycle loading test, the mean yield load for the biodegradable pins was 400.2 (± 122.4) N, maximum load, 524.6 (± 136.6) N, with a mean stiffness of 155.2 (± 32.4) N/mm. The yield load at failure for the interference screw was 402.7 (± 143.9) N, maximum load 515.7 (± 168.5) N with a mean stiffness of 168 (± 42) N/mm. Conclusions: Fixation of a BPTB graft with 2 biodegradable 2.7-mm pins (Rigid Fix) leads to primary stability that is comparable to fixation with biodegradable interference screws.     

Failure strengths of concentric and eccentric implants for hamstring graft fixation

The purpose of this study is to compare the initial failure strengths of various interference screw devices used for tibial fixation of hamstring grafts in anterior cruciate ligament reconstruction and the effect of concentric or eccentric screw position. Quadrupled tendon grafts were harvested from freshly killed sheep. The grafts were then prepared and fixed in the distal femur using various devices (Intrafix (DePuy Mitek Raynham, MA, USA), RCI screw (Smith and Nephew Acufex, Mansfield, MA, USA), Wedge screw (Stryker Endoscopy, San Jose, CA, USA) in concentric position and Wedge screw in eccentric position with an interlock pin). The load required to cause mechanical failure of each construct was measured. The Intrafix device had a significantly greater mean strength to failure than all the other implants (mean 941 +/- 280 N) (P = 0.015 to P < 0.0001). The wedge screw inserted concentrically (737 +/- 134 N) had significantly greater initial failure strength than the wedge eccentric with interlock pin (458 +/- 266 N) (P = 0.03) and the RCI screw (464 +/- 107 N) (P = 0.00036). In this sheep model the Intrafix device with sheath inserted concentrically had significantly greater initial failure strength than the other interference screws. Concentric positioning of the wedge interference screw gave significantly greater initial failure strength of a quadruple tendon graft than eccentric positioning. The use of the Intrafix device or concentric positioning of an interference screw should result in increased initial fixation strength of hamstring grafts. This may allow more vigorous early rehabilitation and may result in less late graft laxity after anterior cruciate ligament reconstruction.