The biomechanical characteristics of arthroscopic tibial inlay techniques for posterior cruciate ligament reconstruction: in vitro comparison of tibial graft tunnel placement

Purpose

The hypothesis of the present study was that the biomechanical properties of arthroscopic tibial inlay procedures depend on tibial graft bone block position.

Methods

Five paired fresh-frozen human cadaveric knee specimens were randomized to a reconstruction with quadriceps tendon placing the replicated footprint either to the more proximal margin of the remnants of the anatomical PCL fibrous attachments (group A) or to the distal margin of the anatomical PCL fibrous attachments at the edge of the posterior tibial facet to the posterior tibial cortex in level with the previous physis line (group B). The relative graft-tibia motions, post cycling pull-out failure load and failure properties of the tibia-graft fixation were measured. Cyclic displacement at 5, 500 and 1,000 cycles, stiffness and yield strength were calculated.

Results

The cyclic displacement at 5, 500 and 1,000 cycles measured consistently more in group A without statistically significant difference (4.11?±?1.37, 7.73?±?2.73 and 8.18?±?2.75 mm versus 2.81?±?1.33, 6.01?±?2.37 and 6.46?±?2.37 mm). Mean ultimate load to failure (564.6?±?212.3) and yield strength (500.2?±?185.9 N) were significantly higher in group B (p?Conclusion Replicating the anatomical PCL footprint at the posterior edge of the posterior tibial facet yields higher pull-out strength and less cycling loading displacement compared to a tunnel position at the centre of the posterior tibial facet.     

Biomechanical effects of medial-lateral tibial tunnel placement in posterior cruciate ligament reconstruction.

With most posterior cruciate (PCL) reconstruction techniques, the distal end of the graft is fixed within a tibial bone tunnel. Although a surgical goal is to locate this tunnel at the center of the PCL's tibial footprint, errors in medial-lateral tunnel placement of the tibial drill guide are possible because the position of the tip of the guide relative to the PCL's tibial footprint can be difficult to visualize from the standard arthroscopy portals. This study was designed to measure changes in knee laxity and graft forces resulting from mal-position of the tibial tunnel medial and lateral to the center of the PCL's tibial insertion. Bone-patellar tendon-bone allografts were inserted into three separate tibial tunnels drilled into each of 10 fresh-frozen knee specimens. Drilling the tibial tunnel 5 mm medial or lateral to the center of the PCL's tibial footprint had no significant effect on knee laxities; the graft pretension necessary to restore normal laxity at 90 degrees of knee flexion (laxity match pretension) with the medial tunnel was 13.8 N (29%) greater than with the central tunnel. During passive knee flexion-extension, graft forces with the medial tibial tunnel were significantly higher than those with the central tunnel for flexion angles greater than 65 degrees while graft forces with the central tibial tunnel were not significantly different than those with the lateral tibial tunnel. Graft forces with medial and lateral tunnels were not significantly different from those with a central tunnel for 100 N applied posterior tibial force, 5 Nm applied varus and valgus moment, and 5 Nm applied internal and external tibial torque. With the exception of slightly higher graft forces recorded with the medial tunnel beyond 65 degrees of passive knee flexion, errors in medial-lateral placement of the tibial tunnel would not appear to have important effects on the biomechanical characteristics of the reconstructed knee.     

Posterior cruciate ligament tibial inlay reconstruction

A patellar bone-tendon-bone tibial inlay reconstruction of the posterior cruciate ligament using a popliteal arthrotomy was designed to minimize graft-tunnel wall abrasion. Arthroscopic techniques are used for femoral graft fixation. In a small series, the procedure decreased the quadriceps active drawer in 70° of flexion by an average of 4 mm and improved patellofemoral symptoms.     

Cyclic loading of posterior cruciate ligament replacements fixed with tibial tunnel and tibial inlay methods

BACKGROUND: The optimal method of replacement of the posterior cruciate ligament with a bone-patellar tendon-bone graft is not known. The purpose of this study was to compare the mechanical responses to cyclic loading tests of bone-patellar tendon-bone allograft replacements fixed to the tibia with one of two methods: a tibial tunnel or a tibial inlay technique. METHODS: The proximal ends of sixty-two posterior cruciate graft replacements, thirty-one fixed with the tibial tunnel technique and thirty-one fixed with the tibial inlay technique in cadaver knees, were subjected to 2000 cycles of tensile force of 50 to 300 N with the angle of pull at 45 to the tibial plateau. The central 10 mm of the medial and lateral halves of previously fresh-frozen bone-patellar tendon-bone preparations from cadaver knees were used as the grafts. Two pairs of tibiae were used for testing; the two types of fixation and the medial and lateral halves of the patellar tendons were distributed between the tibial pairs. Graft thickness was measured at the point of highest anticipated tissue deformation and at two additional locations at distances from these points. The total change in graft length after cyclic loading at an applied force level of 200 N was recorded. Elongation of the graft during loading cycles between 20 and 200 N of applied tensile force was also measured. A repeated-measures analysis of variance was used to compare all measurements between the inlay and tunnel techniques, and between the medial and lateral halves of the graft used for the inlay method. RESULTS: Ten of the thirty-one grafts that had been passed through a tibial tunnel failed at the acute angle before 2000 cycles of testing could be completed; all thirty-one grafts that had been fixed to the tibia with use of the inlay method survived the testing intact. Evaluation of the twenty-one graft pairs that survived testing after both fixation techniques revealed that the grafts that had been fixed with the inlay method had significantly less thinning at all three measurement sites at the completion of testing; the mean reduction of thickness was 40.6% (at the acute angle) in the grafts fixed with the tunnel method and 12.5% (adjacent to the bone block) in those fixed with the inlay method. After 2000 cycles, the mean lengths of the grafts fixed with the inlay and tunnel methods increased 5.9 and 9.8 mm, respectively; 38% of this increase occurred during the first six loading cycles. After both methods of fixation, the mean graft elongation during a loading cycle decreased approximately 50% from cycle 1 to cycle 2000, resulting in an effectively stiffer graft construct. There was no significant difference in any measured parameter between medial and lateral graft halves. CONCLUSIONS: These tests showed that the inlay technique of posterior cruciate ligament replacement was superior to the tunnel technique with respect to graft failure, graft thinning, and permanent increase in graft length.     

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。     

Biomechanical comparison of different fixation techniques for reconstruction of tibial avulsion fractures of the anterior cruciate ligament

Purpose

The most common fixation techniques for tibial avulsion fractures of the anterior cruciate ligament (ACL) described in the literature are screw and suture fixation. The fixation of these fractures with the TightRope® device might be an alternative. Up to now it has been commonly used in other injuries, such as acromioclavicular joint or syndesmosis ruptures. The purpose of this study was to evaluate the biomechanical properties of different fixation techniques for the reconstruction of tibial avulsion fractures.

Methods

Type III tibial avulsion fractures were simulated in 40 porcine knees. Each specimen was randomly assigned to one of four groups: (1) anterograde screw fixation, (2) suture fixation, (3) TightRope® fixation or (4) control group. The initial displacement, strength to failure and the failure mode were documented.

Results

The maximum load to failure was 1,345?±?155.5 N for the control group, 402.5?±?117.6 N for the TightRope® group, 367?±?115.8 N for the suture group and 311.7?±?120.3 N for the screw group. The maximum load to failure of the control group was significantly larger compared to all other groups. The initial dislocation was 0.28?±?0.09 mm for the control group, 0.55?±?0.26 mm for the TightRope® group, 0.84?±?0.15 mm for the screw group and 1.14?±?0.9 mm for the suture group. The initial dislocation was significantly larger for the suture group compared to the TightRope® and control groups.

Conclusions

The TightRope® fixation shows significantly lower initial displacement compared to the suture group. The TightRope® fixation might be an alternative for the repair of ACL tibial avulsion fractures that can be used arthroscopically.     

Vascular risk associated with a posterior approach for posterior cruciate ligament reconstruction using the tibial inlay technique

This study evaluated the risk to the popliteal artery associated with the tibial inlay technique in posterior cruciate ligament (PCL) reconstruction. Barium was injected into the femoral arteries of eight fresh-frozen cadaveric knees and anteroposterior (AP) radiographs were obtained. Dissection of the fascia overlying the gastrocnemius muscle, identification of the interval between the medial head of the gastrocnemius and the semimembranosus, and lateral retraction of the medial head of the gastrocnemius (the Burks and Schaffer approach) was performed. Subsequently, a bicortical screw was placed from posterior to anterior through the tibia as is performed in the tibial inlay technique. A second AP radiograph was obtained. The distance from the center of the screw to the edge of the popliteal artery was measured using digital calipers. The closest any screw came to the popliteal artery was 18.1 mm, and the average distance was 21.1 mm (21.1 +/- 4.6 mm, range: 18.1-31.7 mm). When this distance was calculated as a percentage of the tibial plateau width, the smallest value was 19.2% (24% +/- 4.9%, range: 19.2%-35.1%). A posterior approach for a tibial inlay PCL reconstruction procedure appears safe with respect to the popliteal artery.     

单束单隧道与双束双隧道重建膝前交叉韧带的生物力学对比研究

[目的]研究双束股骨双隧道法重建前交叉韧带(ACL)恢复膝关节前后方向稳定性的能力,并与单束单隧道重建法进行生物力学性能的比较。[方法]应用跟腱分别采用双束股骨双隧道、单前内侧束和单后外侧束三种方法对10个新鲜尸体膝关节进行前交叉韧带重建。术后分别于膝关节屈曲0°、15°、30°、60°及90°时对胫骨施行±100 N的作用力,测量胫骨相对于股骨移动的距离。[结果]在屈膝角度较小(0°~30°)的情况下,单前内侧束重建法术后胫骨的移动距离与完整标本接近(P>0.05);但屈曲超过30°,特别是超过60°后,单前内侧束重建法术后胫骨移动的距离明显大于完整标本(P<0.05)。在屈膝角度<60°的情况下,单后外侧束重建法胫骨移动的距离明显大于完整标本(P<0.05):但屈曲超过60°胫骨移动的距离与完整标本接近(P>0.05);在膝关节的整个屈曲范围(0°~90°)内,双束股骨双隧道重建法术后胫骨移动的距离与完整标本接近(P>0.05)。[结论]双束股骨双隧道重建法,在膝关节的整个屈曲范围(0°~90°)内,比单束股骨单隧道重建法能更有效的恢复膝关节的稳定性。     

基于后十字韧带的膝关节多发韧带损伤两种重建技术的对比研究

目的 比较采用关节镜下经胫骨隧道技术和切开胫骨镶嵌骨块技术重建基于后十字韧带的多发韧带损伤患者术后的后向稳定性和临床疗效.方法 自2005年4月至2009年12月,共连续完成基于后十字韧带的多发韧带损伤重建修复手术135例,2年以上随访者88例.后十字韧带采用关节镜下经胫骨隧道技术重建57例(64.8％),切开镶嵌骨块技术重建31例(35.2％),合并损伤予同期重建或修复.随访时间平均(45.9±17.0)个月(24～77个月).采用KT-1000和Telos应力装置测量手术前后膝关节后向稳定性.采用Tegner、Lysholm、AAOS评分评价临床疗效.结果 两组患者的性别、年龄、受伤至手术时间、合并损伤和主观评分比较,差异均无统计学意义.经胫骨隧道组术前KT-1000两侧差值为(13.5±4.8) mm,术后为(2.4±3.4)mm;术前Telos两侧差值为(14.9±7.1) mm,术后为(4.6±4.0) mm.切开胫骨镶嵌骨块组术前KT-1000两侧差值为(13.7±5.2) mm,术后为(2.2±3.6)mm;术前Telos两侧差值为(14.9±5.9) mm,术后为(4.3±3.9) mm.两组患者KT-1000和Telos两侧差值手术前后组内比较差异均有统计学意义,而组间比较差异均无统计学意义.两组患者术后Tegner、Lysholm、AAOS评分的差异均无统计学意义.结论 采用两种技术重建基于后十字韧带的多发韧带损伤,两组患者术后的后向稳定性及功能评分差异均无统计学意义,且均可明显恢复膝关节后向稳定性.     

关节镜下股骨双束双隧道胫骨Inlay技术同种异体跟腱移植重建后交叉韧带

目的：探讨关节镜下同种异体跟腱重建后交叉韧带（PCL）的方法，验证股骨双柬双隧道、胫骨Inlay技术重建PCL的临床疗效。方法：2005年9月至2007年8月，采用经深低温冷冻及γ射线照射处理后的异体跟腱对10例PCL损伤的患者行关节镜下PCL重建术，手术方式股骨端为双束双隧道重建，可吸收挤压螺钉固定，胫骨端为Inlay固定。通过物理检查、Lysholm及IKDC评分来评价手术疗效。结果：术后8d内患者体温恢复正常，免疫排斥轻，无感染发生。所有患者术后获6～23个月（平均17个月）随访，终末随访时10例患者术膝胫骨下陷征（Sagsign）阴性，后抽屉试验（PDT）及Lachman征均为阴性或I度。疗效评定采用Lysholm评分和IKDC评分。Lysholm评分中交锁、不稳、疼痛、肿胀、爬楼、下蹲和总分术前术后比较差异有统计学意义，术后优7例，良2例，中1例；IKDC评分中疼痛频率、疼痛程度、规律活动量、活动影响程度、功能自评和总分等术前术后比较差异有统计学意义，术后IKDC评分A级7例，B级3例。结论：同种异体跟腱是重建PCL的可靠替代物，双束双隧道和Inlay技术固定可靠，可减少移植物损伤，是PCL重建的理想技术。     

Positioning of the tibial tunnel for anterior cruciate ligament reconstruction

Two mechanisms of unintentioanl anterior tibial tunnel axis shift can occur despite accurate placement of the guide wire within the proximal tibia. The first results from using a short-block reamer head joined to a shaft of smaller diameter. If the tibial tunnel is drilled obliquely, it is possible for the reamer head to displace anteriorly in the knee joint before completion of the posterior portion of the tibial tunnel. The second mechanism of anterior shift involves using two sequential drills to create the tibial tunnel. To delineate the causes of this unwanted shift, cadaveric studies and special roentgenographic studies were undertaken. Results demonstrated that the shift is related directly to the presence of high-density bone in the tibial plateau. In an effort to minimize this effect, various drill designs were tested, and it was determined that a drill-head length of 25 mm was most effective at reducing the shift without sacrificing the freedom of movement necessary to obtain precise endosteal placement of the femoral tunnel. Along with these experimental studies, a retrospective 7-year review of anterior cruciate ligament (ACL) reconstruction failures was performed to assess the clinical significance of inadvertent anterior positioning of the tibial tunnel.     

The effect of isometric graft posterior cruciate ligament reconstruction on anterior tibial translation

Eight fresh-frozen cadaver knees were studied to evaluate whether an isometrically placed posterior cruciate ligament (PCL) graft restores normal posterior tibial translation without overconstraining anterior tibial translation. Each knee was tested with a three-axis load cell in the intact state, after PCL sectioning, and after PCL reconstruction. After PCL reconstruction, posterior tibial displacement was restored to values observed in the intact state for all flexion angles except 60 degrees and 90 degrees. Anterior tibial translation was not significantly changed for any of the three states. These results indicate isometric reconstruction of the PCL significantly reduces posterior tibial translation without overconstraining anterior tibial translation.     

后交叉韧带胫骨止点与双束重建胫骨骨道定位的临床解剖学研究

目的 解剖研究后交叉韧带(PCL)胫骨止点情况,确定PCL前外侧束(ALB)与后内侧束(PMB)胫骨止点的位置、形状与面积,探讨PCL双束四骨道重建中胫骨骨道定位标志与定位方法.方法 30例成人膝关节标本,根据屈伸膝关节过程中纤维束紧张与松弛情况,将PCL分为ALB与PMB,并确定各束中的功能束,用多种指标测量ALB、PMB与功能束的胫骨止点,解剖寻找双束四骨道重建PCL中胫骨骨道定位标志与定位方法.结果 PCL胫骨止点位于后髁间窝内,其纵轴由近内斜向远外,与胫骨干夹角平均为(16.5±1.4)°.ALB与PMB胫骨止点基本呈远近排列,ALB胫骨止点接近于菱形,平均面积为(90±20)mm2,PMB胫骨止点近似长方形,平均面积(96±32)mm2,二者无显著差异(P>0.05).ALB与PMB中均存在功能束,分别止于ALB胫骨止点的远外侧部及PMB胫骨止点的远内侧部,均接近椭圆形,面积分别为(35±12)mm2与(36±6)mm2,二者无显著差异(P>0.05).ALB功能束胫骨止点中心与PMB功能束胫骨止点中心距离为(12.7 ±1.9)mm.胫骨内、外侧髁间棘及胫骨上端后方骨嵴为重要的解剖标志.结论 PCL胫骨止点可以容纳两个胫骨骨道,PCL的ALB与PMB中均存在功能束,提示临床双束四骨道重建PCL时,胫骨骨道应分别定位于ALB与PMB功能束胫骨止点处.     

Ideal tibial tunnel length for endoscopic anterior cruciate ligament reconstruction

A successful single-incision endoscopic anterior cruciate ligament reconstruction using bone-patellar tendon-bone autograft requires attention to many technical details. The emphasis of placing the femoral bone plug flush with the opening of the femoral tunnel results in distal shift of the graft. Longer tibial tunnels are required to prevent excessive graft extrusion. The purpose of this study is to compare four direct and indirect measurement methods of tibial tunnel preparation to determine which method can be used to create consistently reproducible tibial tunnels that prevent excessive extrusion or recession of the graft within the tunnel. Tunnels placed at the empiric angles of 40 degrees, 50 degrees, and 60 degrees to the tibial plateau resulted in the incidence of acceptable tibial tunnel lengths of 44%, 83%, and 39%, respectively. Tunnels placed at an angle determined by the formula "N + 7" where 7 degrees is added to the patellar tendon length (N) resulted in acceptable tunnels 89% of the time. Direct measurement methods using the formulas "graft - 50 mm" and "N + 2 mm" resulted in acceptable tibial tunnels of 44% and 100%, respectively. We recommend using the "N + 7" in conjunction with the "N + 2 mm" formula to obtain the advantages of both indirect and direct measurement methods.Arthroscopy 1998 Jan-Feb;14(1):9-14     

Minimal tibial tunnel enlargement after anatomic rectangular tunnel anterior cruciate ligament reconstruction with bone-patellar tendon-bone graft

BackgroundThe purpose of this study was to evaluate the tibial tunnel enlargement after the anatomical rectangular tunnel (ART) anterior cruciate ligament reconstruction (ACLR) with a bone-patellar tendon-bone (BTB) graft and to elucidate the correlation between the enlargement and length of the tendinous portion inside the tibial tunnel. In addition, we aimed to analyze the correlation between patient characteristics and tibial tunnel enlargement.MethodsThis study included 50 patients who underwent ART ACLR. Lateral radiographs at the time of surgery and at 2 years were compared to evaluate the tibial tunnel enlargement. Subsequently, correlations between the tunnel enlargement and (1) length of tendinous portion inside the tibial tunnel or (2) characteristics of the patients, including anterior knee laxity measured by KT-1000 arthrometer, age, sex, height, body weight, and Tegner activity level scale, were analyzed.ResultsThe tibial tunnel was enlarged by 2.6 ± 4.2% 2 years postoperatively. The length of the tendinous portion inside the tibial tunnel was 7.8 ± 4.9 mm. There was no significant correlation between tunnel enlargement and length of tendinous portion inside the tunnel. None of the patient characteristics were detected as a risk factor for tibial tunnel enlargement.Conclusions(1) The postoperative tibial tunnel enlargement was minimum after ART ACLR with a BTB graft. (2) There was no correlation between tibial tunnel enlargement and length of tendinous portion of BTB graft inside the tunnel. (3) None of the patient characteristics were detected as a risk factor of the tibial tunnel enlargement.     

Tibial inlay technique with quadriceps tendon-bone autograft for posterior cruciate ligament reconstruction

Surgical reconstruction of the posterior cruciate ligament (PCL) is indicated in a PCL-deficient knee with symptomatic instability and injury to other ligaments. However, the choice of graft tissues remains controversial. The tibial inlay method has the benefit of preventing the acute turn associated with transtibial reconstruction and permitting accurate anatomic placement of the graft. This study describes an arthroscopic-assisted inlay technique for PCL reconstruction using quadriceps tendon-patellar bone autograft. This technique is a reasonable alternative for PCL reconstruction.     

Biomechanical characteristics of the anatomic rectangular tunnel anterior cruciate ligament reconstruction with a bone-patellar tendon-bone graft

Purpose

To clarify 1) the force sharing between two portions of BTB graft in anatomic rectangular tunnel (ART) reconstruction and 2) the knee stability in ART technique under anterior tibial load.

The predictive effect of anatomic femoral and tibial graft tunnel placement in posterior cruciate ligament reconstruction on functional and radiological outcome

Purpose

Biomechanical reports have advocated anatomic graft tunnel placement for reconstruction of the posterior cruciate ligament (PCL) to restore knee joint stability and facilitate optimal functional outcome. However, in vivo investigations that correlate tunnel position to functional results are lacking so far. This study evaluates the anatomic accuracy of femoral and tibial tunnel apertures on postoperative computed tomography (CT) scans and compares these findings to subjective and objective clinical outcome parameters.

Methods

After single-bundle PCL reconstruction, 29 patients were stratified into several subgroups according to the anatomic accuracy of femoral and tibial tunnel apertures measured on postoperative CT scans. A threshold value for the centres of the tunnel apertures was determined using a measurement grid system as a radiographic reference. To evaluate the functional and radiological results, visual analogue scale, International Knee Documentation Committee (IKDC), Tegner, Lysholm, Knee Injury and Osteoarthritis Outcome Score and osteoarthritis scores were obtained.

Results

Comparison between functional outcome and tunnel position yielded a statistically significant difference for subjective IKDC score and angle segment α and for objective stability and tunnel position P3 but no statistically significant difference with respect to intercondylar depth, intercondylar height and tibial tunnel position P2. No correlation was found between anatomic tunnel position and present or progressive osteoarthritis on follow-up. Of the patients, 72 % classified their result as excellent and good and 90 % would repeat surgical treatment.

Conclusions

Despite a small sample size and subject to the threshold values we used, our data indicate a potentially minor effect of anatomic tunnel placement on midterm functional outcome following PCL reconstruction.