Effects of femoral tunnel placement on knee laxity and forces in an anterior cruciate ligament graft.

The purpose of this study was to measure the effects of variation in placement of the femoral tunnel upon knee laxity, graft pretension required to restore normal anterior-posterior (AP) laxity and graft forces following anterior cruciate ligament (ACL) reconstruction. Two variants in tunnel position were studied: (1) AP position along the medial border of the lateral femoral condyle (at a standard 11 o'clock notch orientation) and (2) orientation along the arc of the femoral notch (o'clock position) at a fixed distance of 6-7 mm anterior to the posterior wall. AP laxity and forces in the native ACL were measured in fresh frozen cadaveric knee specimens during passive knee flexion-extension under the following modes of tibial loading: no external tibial force, anterior tibial force, varus-valgus moment, and internal-external tibial torque. One group (15 specimens) was used to determine effects of AP tunnel placement, while a second group (14 specimens) was used to study variations in o'clock position of the femoral tunnel within the femoral notch. A bone-patellar tendon-bone graft was placed into a femoral tunnel centered at a point 6-7 mm anterior to the posterior wall at the 11 o'clock position in the femoral notch. A graft pretension was determined such that AP laxity of the knee at 30 deg of flexion was restored to within 1 mm of normal; this was termed the laxity match pretension. All tests were repeated with a graft in the standard 11 o'clock tunnel, and then with a graft in tunnels placed at other selected positions. Varying placement of the femoral tunnel 1 h clockwise or counterclockwise from the 11 o'clock position did not significantly affect any biomechanical parameter measured in this study, nor did placing the graft 2.5 mm posteriorly within the standard 11 o'clock femoral tunnel. Placing the graft in a tunnel 5.0 mm anterior to the standard 11 o'clock tunnel increased the mean laxity match pretension by 16.8 N (62%) and produced a knee which was on average 1.7 mm more lax than normal at 10 deg of flexion and 4.2 mm less lax at 90 deg. During passive knee flexion-extension testing, mean graft forces with the 5.0 mm anterior tunnel were significantly higher than corresponding means with the standard 11 o'clock tunnel between 40 and 90 deg of flexion for all modes of constant tibial loading. These results indicate that AP positioning of the femoral tunnel at the 11 o'clock position is more critical than o'clock positioning in terms of restoring normal levels of graft force and knee laxity profiles at the time of ACL reconstruction.     

Intraoperative Qualitätskontrolle bei der Bohrkanalplatzierung zum vorderen Kreuzbandersatz

The reconstruction of a ruptured anterior cruciate ligament (ACL) is a frequently performed operation, however technically demanding with a revision rate of approximately 10%. The correct placement of bone tunnels in femur and tibia is the most important variable to achieve a successful outcome. A distinct knowledge of the anatomic insertion sites is crucial. The ideal location for the femoral bone tunnel is achieved when a 1-2 mm posterior wall is left to the over-the-top position and when the entry to the bone tunnel is at 10 o'clock (right knees) or 14 o'clock (left knees) in the frontal plane. The femoral bone tunnel can be drilled through the tibial bone tunnel (transtibial technique) or through an anteromedial arthroscopic portal. According to recent studies the use of an anteromedial portal helps to reduce the risk of misplacement of the bone tunnel. The center of the tibial bone tunnel should be located on an imaginary line between medial border of the anterior horn of the lateral meniscus and the medial tibial spine. The position of the tibial guide wire has to be far enough posterior to avoid impingement of the graft with the roof of the intercondylar notch. Measures for quality control include the intraoperative use of an image intensifier (fluoroscopy), instrumented laxity measurements and a postoperative radiograph in 2 planes. The use of computer assisted surgery cannot routinely be recommended at present.     

Accuracy of femoral tunnel placement and resulting graft force using one- or two-incision drill guides. A cadaver study on ten paired knees

Recently, one-incision drill guides introduced through predilled tibial tunnels have become popular in anterior cruciate ligament (ACL) reconstruction. No data are available on the reproducibility of the tunnel placement when this drill guide is used. The primary goal of this study was to compare accuracy of tunnel placement using the one-inciscion (all-inside) and the conventional two-incision drill guide (outside-in) to the location of the center of the normal ACL attachment. Furthermore, our goal was to measure the forces seen by the normal ACL during extension from 90° of flexion, when the tibia is subjected to 100 N anterior load (22.7 lbs), and compare these with the forces measured in the reconstructions performed with the two drill guides. The center of the tunnel on the lateral femoral condyle using the two different drill guides was measured with a three-dimensional pointer and compared with the center of the normal ACL insertion site. Forces in the normal ACL and the reconstructed ligament were measured with a buckle transducer in a loaded and an unloaded state at four different flexion angles. The one-incision drill guide led to a statistically more proximal placement of the graft than both the conventional drill guide and the center of the normal ACL. Both drill guides led to an anterior placement compared with the normal ACL. There was no difference in the graft forces after reconstruction with the two drill guides, but the forces in the loaded grafts were twice those of the normal ACL.     

3D CT evaluation of femoral and tibial tunnels in anatomic double bundle anterior cruciate ligament reconstruction

BackgroundAn anatomical double bundle ACL reconstruction replicates the anatomy of native ACL as the tunnels are made to simulate the anatomy of ACL with AM and PL bundle foot prints. The goal of anatomic ACL reconstruction is to tailor the procedure to each patient’s anatomic, biomechanical and functional demands to provide the best possible outcome. The shift from single bundle to double bundle technique and also from transtibial to transportal method has been to provide near anatomic tunnel positions.PurposeTo determine the position of femoral and tibial tunnels prepared by double bundle ACL reconstruction using three dimensional Computed tomography.Study designA prospective case series involving forty patients with ACL tear who underwent transportal double bundle ACL reconstruction.MethodComputed tomography scans were performed on forty knees that had undergone double bundle anterior cruciate ligament reconstruction. Three-dimensional computed tomography reconstruction models of the knee joint were prepared and aligned into an anatomical coordinate axis system for femur and tibia respectively. Tibial tunnel centres were measured in the anterior-to-posterior and medial-to-lateral directions on the top view of tibial plateau and femoral tunnel centres were measured in posterior to anterior and proximal-to-distal directions with anatomic coordinate axis method. These measurements were compared with published reference data.ResultsAnalysing the Femoral tunnel, the mean posterior-to-anterior distances for anteromedial and posterolateral tunnel centre position were 46.8% ± 7.4% and 34.5% ± 5.0% of the posterior-to-anterior height of the medial wall and the mean proximal-to-distal distances for the anteromedial and posterolateral tunnel centre position were 24.1% ± 7.1% and 61.6% ± 4.8%. On the tibial side, the mean anterior-to-posterior distances for the anteromedial and posterolateral tunnel centre position were 28.8% ± 4.3% and 46.2% ± 3.6% of the anterior-to posterior depth of the tibia measured from the anterior border and the mean medial-to-lateral distances for the anteromedial and posterolateral tunnel centre position were 46.5% ± 2.9% and 50.6% ± 2.8% of the medial-to-lateral width of the tibia measured from the medial border. There is high Inter-observer and Intra-observer reliability (Intra-class correlation coefficient).Discussion and conclusionFemoral AM tunnel was positioned significantly anterior and nearly proximal whereas the femoral PL tunnel was positioned significantly anterior and nearly distal with respect to the anatomic site. Location of tibial AM tunnel was nearly posterior and nearly medial whereas the location of tibial PL tunnel was very similar to the anatomic site Evaluation of location of tunnels through the anatomic co-ordinate axes method on 3D CT models is a reliable and reproducible method. This method would help the surgeons to aim for anatomic placement of the tunnels. It also shows that there is scope for improvement of femoral tunnel in double bundle ACL reconstruction through transportal technique.     

Editorial Commentary: Anteromedial Portal Drilling of the ACL Femoral Socket Avoids Transtibial Constraint Results in Anatomic Reconstruction and Superior Outcomes

Femoral and tibial tunnel locations for ACL grafts should be predicated on anatomy. Regarding femoral ACL socket or tunnel creation, multiple techniques have been debated. Network meta-analysis shows that the anteromedial portal (AMP) technique results in better anteroposterior and rotational stability than does the “standard” constrained, transtibial technique based on side-to-side differences in laxity and pivot-shift tests, as well as IKDC objective scores. The AMP provides a direct shot at the anatomic ACL origin on the femur. It avoids the osseous constraint of the reamer that hampers transtibial approaches. It avoids the extra incision required by the outside-in technique and the accompanying graft obliquity. Despite the need for knee hyperflexion and the potential for shorter femoral sockets, the AMP technique should be easily reproducible for an accomplished ACL surgeon to reproduce the patient’s anatomy.     

Three-Dimensional Reconstruction Computed Tomography Evaluation of Tunnel Location during Single-Bundle Anterior Cruciate Ligament Reconstruction: A Comparison of Transtibial and 2-Incision Tibial Tunnel-Independent Techniques

Background

Anatomic tunnel positioning is important in anterior cruciate ligament (ACL) reconstructive surgery. Recent studies have suggested the limitations of a traditional transtibial technique to place the ACL graft within the anatomic tunnel position of the ACL on the femur. The purpose of this study is to determine if the 2-incision tibial tunnel-independent technique can place femoral tunnel to native ACL center when compared with the transtibial technique, as the placement with the tibial tunnel-independent technique is unconstrained by tibial tunnel.

Methods

In sixty-nine patients, single-bundle ACL reconstruction with preservation of remnant bundle using hamstring tendon autograft was performed. Femoral tunnel locations were measured with quadrant methods on the medial to lateral view of the lateral femoral condyle. Tibial tunnel locations were measured in the anatomical coordinates axis on the top view of the proximal tibia. These measurements were compared with reference data on anatomical tunnel position.

Results

With the quadrant method, the femoral tunnel centers of the transtibial technique and tibial tunnel-independent technique were located. The mean (± standard deviation) was 36.49% ± 7.65% and 24.71% ± 4.90%, respectively, from the over-the-top, along the notch roof (parallel to the Blumensaat line); and at 7.71% ± 7.25% and 27.08% ± 7.05%, from the notch roof (perpendicular to the Blumensaat line). The tibial tunnel centers of the transtibial technique and tibial tunnel-independent technique were located at 39.83% ± 8.20% and 36.32% ± 8.10%, respectively, of the anterior to posterior tibial plateau depth; and at 49.13% ± 4.02% and 47.75% ± 4.04%, of the medial to lateral tibial plateau width. There was no statistical difference between the two techniques in tibial tunnel position. The tibial tunnel-independent technique used in this study placed femoral tunnel closer to the anatomical ACL anteromedial bundle center. In contrast, the transtibial technique placed the femoral tunnel more shallow and higher from the anatomical position, resulting in more vertical grafts.

Conclusions

After single-bundle ACL reconstruction, three-dimensional computed tomography showed that the tibial tunnel-independent technique allows for the placement of the graft closer to the anatomical femoral tunnel position when compared with the traditional transtibial technique.     

Anterior cruciate ligament reconstruction the two-incision technique

Historically, the two-incision technique for anterior cruciate ligament (ACL) reconstruction was the standard of practice. It allows predictable, near-anatomic placement of the femoral tunnel and provides highly reproducible results with few complications. There are several major advantages of the two-incision technique over endoscopic methods. These include consistent femoral tunnel placement, elimination of concern for "blowing out the back wall," elimination of the problem of graft-tunnel mismatch, elimination of the problem of screw divergence, and ease of use for revision ACL reconstruction procedures. The angle of the ACL graft is also more anatomic, matching the angle of the native ACL. In this chapter we present our technique for reconstruction of the ACL using the two-incision approach. Indications for its use are discussed. Advantages and disadvantages of the two-incision method compared with the all-endoscopic approach are reviewed.     

Radiological landmarks for placement of the tunnels in single-bundle reconstruction of the anterior cruciate ligament

There is little evidence examining the relationship between anatomical landmarks, radiological placement of the tunnels and long-term clinical outcomes following anterior cruciate ligament (ACL) reconstruction. The aim of this study was to investigate the reproducibility of intra-operative landmarks for placement of the tunnels in single-bundle reconstruction of the ACL using four-strand hamstring tendon autografts. Isolated reconstruction of the ACL was performed in 200 patients, who were followed prospectively for seven years with use of the International Knee Documentation Committee forms and radiographs. Taking 0% as the anterior and 100% as the posterior extent, the femoral tunnel was a mean of 86% (sd 5) along Blumensaat's line and the tibial tunnel was 48% (sd 5) along the tibial plateau. Taking 0% as the medial and 100% as the lateral extent, the tibial tunnel was 46% (sd 3) across the tibial plateau and the mean inclination of the graft in the coronal plane was 19 degrees (sd 5.5). The use of intra-operative landmarks resulted in reproducible placement of the tunnels and an excellent clinical outcome seven years after operation. Vertical inclination was associated with increased rotational instability and degenerative radiological changes, while rupture of the graft was associated with posterior placement of the tibial tunnel. If the osseous tunnels are correctly placed, single-bundle reconstruction of the ACL adequately controls both anteroposterior and rotational instability.     

The anatomy of the ACL and its importance in ACL reconstruction

The anterior cruciate ligament (ACL) anatomy is very significant if a reconstruction is attempted after its rupture. An anatomic study should have to address, its biomechanical properties, its kinematics, its position and anatomic correlation and its functional properties. In this review, an attempt is made to summarize the most recent and authoritative tendencies as far as the anatomy of the ACL, and its surgical application in its reconstruction are concerned. Also, it is significant to take into account the anatomy as far as the rehabilitation protocol is concerned. Separate placement in the femoral side is known to give better results from transtibial approach. The medial tibial eminence and the intermeniscal ligament may be used as landmarks to guide the correct tunnel placement in anatomic ACL reconstruction. The anatomic centrum of the ACL femoral footprint is 43 % of the proximal-to-distal length of lateral, femoral intercondylar notch wall and femoral socket radius plus 2.5 mm anterior to the posterior articular margin. Some important factors affecting the surgical outcome of ACL reconstruction include graft selection, tunnel placement, initial graft tension, graft fixation, graft tunnel motion and healing. The rehabilitation protocol should come in phases in order to increase range of motion, muscle strength and leg balance, it should protect the graft and weightbearing should come in stages. The cornerstones of such a protocol remain bracing, controlling edema, pain and range of motion. This should be useful and valuable information in achieving full range of motion and stability of the knee postoperatively. In the end, all these advancements will contribute to better patient outcome. Recommendations point toward further experimental work with in vivo and in vitro studies, in order to assist in the development of new surgical procedures that could possibly replicate more closely the natural ACL anatomy and prevent future knee pathology.     

Technical note: Anterior cruciate ligament reconstruction in the presence of an intramedullary femoral nail using anteromedial drilling

AIM To describe an approach to anterior cruciate ligament(ACL) reconstruction using autologous hamstring by drilling via the anteromedial portal in the presence of an intramedullary(IM) femoral nail.METHODS Once preoperative imagining has characterized the proposed location of the femoral tunnel preparations are made to remove all of the hardware(locking bolts and IM nail). A diagnostic arthroscopy is performed in the usual fashion addressing all intra-articular pathology. The ACL remnant and lateral wall soft tissues are removed from the intercondylar, to provide adequate visualization of the ACL footprint. Femoral tunnel placement is performed using a transportal ACL guide with desired offset and the knee flexed to 2.09 rad. The Beath pin is placed through the guide starting at the ACL's anatomic footprint using arthroscopic visualization and/or fluoroscopic guidance. If resistance is met while placing the Beath pin, the arthroscopy should be discontinued and the obstructing hardware should be removed under fluoroscopic guidance. When the Beath pin is successfully placed through the lateral femur, it is overdrilled with a 4.5 mm Endobutton drill. If the Endobutton drill is obstructed, the obstructing hardware should be removed under fluoroscopic guidance. In this case, the obstruction is more likely during Endobutton drilling due to its larger diameter and increased rigidity compared to the Beath pin. The femoral tunnel is then drilled using a best approximation of the graft's outer diameter. We recommend at least 7 mm diameter to minimize the risk of graft failure. Autologous hamstring grafts are generally between 6.8 and 8.6 mm in diameter. After reaming, the knee is flexed to 1.57 rad, the arthroscope placed through the anteromedial portal to confirm the femoral tunnel position, referencing the posterior wall and lateral cortex. For a quadrupled hamstring graft, the gracilis and semitendinosus tendons are then harvested in the standard fashion. The tendons are whip stitched, quadrupled and shaped to match the diameter of the prepared femoral tunnel. If the diameter of the patient's autologous hamstring graft is insufficient to fill the prepared femoral tunnel, the autograft may be supplemented with an allograft. The remainder of the reconstruction is performed according to surgeon preference. RESULTS The presence of retained hardware presents a challenge for surgeons treating patients with knee instability. In cruciate ligament reconstruction, distal femoral and proximal tibial implants hardware may confound tunnel placement, making removal of hardware necessary, unless techniques are adopted to allow for anatomic placement of the graft. CONCLUSION This report demonstrates how the femoral tunnel can be created using the anteromedial portal instead of a transtibial approach for reconstruction of the ACL.     

前十字韧带重建中的移植物位置偏移

目的 计算可吸收界面螺钉导致的移植物偏离隧道位移,探讨其对前十字韧带重建产生的影响.方法 19个新鲜尸体膝关节标本,随机选取5个,采用7 mm、8 mm、9 mm界面螺钉固定自体肌腱,测定偏移距离.另外14个膝关节分为等长组和解剖组,等长组膝关节测量界面螺钉固定后及校正位置的移植物拉长距离;解剖组膝关节于膝关节生物力学测试仪上分别测定ACL完整组、ACL缺失组、偏移组和校正组在134 N前向负荷下膝关节屈曲0°、15°、30°、60°和90°位的胫骨前向位移.结果 (1)肌腱偏移:直径7mm、8 mm、9mm的界面螺钉分别使移植物偏移(2.36±0.11)mm、(2.72±0.06)mm、(3.00±0.06)mm.(2)等长性:初始拉长小于3 mm,偏移拉长大于3 mm,校正拉长小于3 mm.(3)生物力学:屈膝0°、15°位,ACL完整组与偏移组、校正组差异无统计学意义.屈膝30°、60°、90°位ACL完整组与其他各组比较差异均有统计学意义,屈膝30°、60°位偏移组与校正组比较差异有统计学意义.结论 无论等长重建还是解剖重建,界面螺钉均影响移植物的股骨隧道口位置.前十字韧带重建预先校正股骨隧道口位置,移植物基本会处于预先的理想位置.

Abstract：

Objective To investigate the impact of graft position shift on anterior cruciate ligament reconstruction induced by femoral fixation of interference screw. Methods Nineteen fresh cadaveric knees were used and assigned to three groups. 1) Study of graft position shift: 5 knees were randomly selected, interference screws of 7 mm, 8 mm and 9 mm were used in autologous tendon fixation, then the graft position shift were measured. 2) Study of isometry: 7 knees were randomly divided into the isometric reconstruction group (D group). In the D group, Retrobutton, interference screw and interference screw in location-corrected bone tunnel were used respectively as fixation. The isometry of grafts was evaluated. 3) Study of tibia anterior translation: 7 knees were randomly divided into the anatomic reconstruction group (J group). In the J group,the tibia anterior translation was measured in four different conditions in the same joint: intact knee joint,knee joint without ACL, ACL anatomic reconstruction by interference screw fixation, and ACL anatomic reconstruction by interference screw fixation with corrected bone tunnel location. Results 1) With 7 mm, 8mm and 9 mm interference screw fixation, graft position shift were (2.36±0.11) mm, (2.72±0.06) mm and (3.00±0.06) mm respectively. 2) Graft length change: graft length change in Retrobutton group and corrected bone tunnel group were less than 3 mm, while graft length change in those fixed with interference screw were stretched in more than 3 mm. 3) Study of tibia anterior translation: there was no difference among the intact group, the anatomic group and the corrected group at 0° and 15°. However, the difference was found between the intact group and other groups at 30°、60° and 90° of flexion, as well as between these two reconstructed methods at 20° joint flexion (P＜0.05). Conclusion In both isometric and anatomic ACL reconstruction with interference screw, the graft is pushed tightly toward the femoral tunnel wall, which shifts the graft away from the desired position. In our study we find out that the corrected location of the femoral bone tunnel significantly improves the isometry of ACL reconstruction and anatomic reconstruction.     

Radiographic evaluation of anterior cruciate ligament graft failure with special reference to tibial tunnel placement

Graft failure in anterior cruciate ligament (ACL) reconstruction can result from anterior placement of the tibial tunnel. Conventional radiographic evaluation of this problem does not take into account potential changes in tibio-femoral relationship caused by ACL instability. A retrospective radiographic evaluation of failed as well as successful ACL reconstructions was carried out. Both published radiographs as well as those obtained of patients treated by the authors were evaluated for tibial tunnel placement, roof impingement, and tibial position relative to the femur. In the second part of the study, the radiographs were obtained under standard conditions in both failed ACL reconstructions and normal knees. The results of both parts of the study indicate that lateral radiographs of the extended knee with ACL instability are likely to show subtle anterior tibial subluxation. The subluxation can give the impression of roof impingement on the graft. However, the majority of the failed knees had similar tibial tunnel placement compared with successful reconstructions and would appear unimpinged once corrected for subluxation. The diagnosis of graft impingement by the femoral intercondylar roof has to take into account potential tibial subluxation. Impingement as a cause graft failure may be less common than previously thought.Arthroscopy 1998 Mar;14(2):206-11     

Anatomic endoscopic anterior cruciate ligament reconstruction with patella tendon autograft

Current tibial endoscopic ACL reconstruction techniques provide functional stability, but fall short of the ultimate goal of ACL reconstruction, to restore normal knee kinematics. Vertical graft placement results in restoration of normal anteroposterior stability with a negative Lachman exam, but may not produce a stable knee in rotation, noted by a positive pivot shift. The Clancy anatomic endoscopic ACL reconstruction technique utilizes flexible reamers to achieve anatomic graft placement to more closely reproduce normal knee function. The overall results of arthroscopic anatomic endoscopic ACL reconstruction are essentially the same as we have reported using our previous open and rear-entry, two-incision techniques for anatomic graft placement. The long-term benefits of a more physiologic single incision endoscopic ACL reconstruction are not yet determined; however, short-term results are encouraging.     

Isolierter Bündelersatz bei Partialruptur des vorderen Kreuzbandes

Objective

Partial augmentation of isolated tears of the anteromedial and posterolateral bundle of the anterior cruciate ligament (ACL) with autologous hamstring tendons. The intact fibers of the ACL are preserved.

Indications

Symptomatic isolated tear of the anteromedial or posteromedial bundle of the ACL or rotational instability after ACL reconstruction with malplaced tunnels (e.g., high femoral position)

Contraindications

In revision cases: loss of motion due to malplaced ACL and excessive tunnel widening of the present tunnels with the risk of tunnel confluence.

Surgical technique

Examination of anterior–posterior translation and rotational instability under anesthesia. Diagnostic arthroscopy, repetition of the clinical examination under direct visualization of the ACL, meticulous probing of the functional bundles. Resection of ligament remnants, preparation/preservation of the femoral and tibial footprint. Harvesting one of the hamstring tendons, graft preparation. Positioning of a 2.4 mm K-wire in the anatomic center of the femoral anteromedial/posterolateral bundle insertion, cannulated drilling according to the graft diameter. Positioning of a 2.4 mm K-wire balanced according to the femoral tunnel at the tibia, cannulated drilling. Insertion of the graft and fixation.

Postoperative management

Analogous to that for ACL reconstruction.     

Editorial Commentary: Graft Orientation in Anterior Cruciate Ligament Reconstruction—Does It Really Matter?

The search for an isometric, anatomic, biomechanically optimal anterior cruciate ligament (ACL) reconstruction remains elusive. To better approximate the native ACL, surgeons have used a host of different graft options and repair techniques. Surgical techniques involving single-tunnel and double-tunnel (or even triple-tunnel!) fixation sites have been used in an attempt to re-create the “2 (or more) bundles” of the ACL. Transtibial and independent femoral drilling techniques are used in an effort to create a more “anatomic” femoral tunnel placement. Once the anatomic femoral attachment site is identified, there is then a debate on how best to “fill” the attachment site with the surgical graft. These are all important discussions and debates, but one question remains . . . Does any of it really matter?     

Rectangular Tunnel Double-Bundle Anterior Cruciate Ligament Reconstruction with Bone–Patellar Tendon–Bone Graft to Mimic Natural Fiber Arrangement

We describe our current technique of anatomic, double-bundle (DB), rectangular tunnel anterior cruciate ligament (ACL) reconstruction with bone–patellar tendon–bone (BPTB) graft. This technique mimics the natural, or anatomic, arrangement of the native ACL fibers. This technique has the following advantages: (1) creation of a DB ACL reconstruction with a single BPTB graft; (2) maximization of graft–tunnel contact area; (3) containment of the tunnel apertures within the anatomic ACL attachment footprint; (4) rotational control of the graft within the tunnels during and after fixation; and (5) preservation of notch anatomy.     

Medial portal technique for single-bundle anatomical Anterior Cruciate Ligament (ACL) reconstruction

The aim of the paper is to describe the medial portal technique for anatomical single-bundle anterior cruciate ligament (ACL) reconstruction. Placement of an ACL graft within the anatomical femoral and tibial attachment sites is critical to the success and clinical outcome of ACL reconstruction. Non-anatomical ACL graft placement is the most common technical error leading to recurrent instability following ACL reconstruction. ACL reconstruction has commonly been performed using a transtibial tunnel technique in which the ACL femoral tunnel is drilled through a tibial tunnel positioned in the posterior half of the native ACL tibial attachment site. ACL reconstruction performed using a transtibial tunnel technique often results in a vertical ACL graft, which may fail to control the combined motions of anterior tibial translation and internal tibial rotation which occur during the pivot-shift phenomenon. The inability of a vertically oriented ACL graft to control these combined motions may result in the patient experiencing continued symptoms of instability due to the pivot-shift phenomenon. The medial portal technique in which the ACL femoral tunnel is drilled through an anteromedial or accessory anteromedial portal allows consistent anatomical ACL tunnel placement. This paper describes the advantages of the medial portal technique, indications for the technique, patient positioning, proper portal placement, anatomical femoral and tibial tunnel placement, graft tensioning and fixation.     

前十字韧带移植重建后移植物撞击新类型

 目的 通过双源CT三维重建前十字韧带（anterior cruciate ligament,ACL）移植重建后的移植物和骨隧道,分析移植物撞击症。方法 2012年11月至2014年11月,采用双源CT对134例ACL移植重建后患者的膝关节进行扫描,三维重建股骨和胫骨隧道、ACL重建移植物等。其中单束重建118例,男83例,女35例;年龄15~64岁,平均32岁。观察重建术后移植物是否受到撞击、撞击来源并进行分类;分别测量股骨、胫骨隧道的相对位置,并对有撞击与无撞击组患者进行统计比较。结果 基于双源CT移植物重建,根据ACL移植重建后移植物是否受到撞击分组,无撞击组39例（33%,39/118）,有撞击组79例（67%,79/118）。存在撞击者再根据撞击部位分为髁间窝出口撞击组77例（占总数的65%,占撞击组的97%）和髁间窝顶中途撞击组2例（占总数的2%,占撞击组的3%）。进一步根据撞击来源不同,再对髁间窝出口撞击组分为3个亚型,即鸟喙撞击10例（3%,10/77）、胫骨平台撞击46例（60%,46/77）、钳夹撞击21例（27%,21/77）。单因素方差分析显示,鸟喙撞击、胫骨平台撞击、钳夹撞击各组与无撞击组的股骨、胫骨隧道位置均无显著性差异。结论 基于双源CT三维重建ACL术后移植物扫描发现3种新的移植物撞击类型, 即髁间窝顶中途撞击、胫骨撞击和钳夹撞击。     

Double bundle revision of a malplaced single bundle vertical ACL reconstruction: ACL revision surgery using a two femoral tunnel technique

Background  Several factors influence the outcome after ACL reconstruction. One of the most important factors influencing the resulting knee kinematics and subjective instability is femoral tunnel placement. Revision can be necessary if the femoral tunnel is drilled transtibial in the roof of femoral notch (mismatch). Hypothesis  Double bundle reconstruction using two femoral tunnels and one tibial tunnel technique can be used in revision of a primary vertical ACL reconstruction. Study design  Case series (level of evidence III). Methods  ACL revision was performed in five patients complaining instability after primary transtibial ACL reconstruction. Clinical examination, X-ray and CT analysis were performed to evaluate objective knee laxity, tunnel placement and widening. In all patients a technique using two femoral tunnels in a two medial portal technique and one tibial tunnel was used. Patients were reevaluated at a follow up of 24 months. Results  Preoperatively, pivot shift tests were 2+ in three and 1+ in the remaining two patients. Lachman test was found to be positive in all patients (4 patients, 2+ firm endpoint; 1 patient, 2+ soft endpoint). X-rays showed a femoral tunnel position at 11.30 (1 patient) and 12.00 o’clock (4 patients). In one patient significant tibial tunnel enlargement was to be found. At a follow up of 24 months, KT 1000 was <2 mm side to side difference and the pivot shift test was negative in all patients. Conclusion  Revision of a primary vertical ACL reconstruction can be safely performed using a double bundle reconstruction with two femoral tunnels in a two medial portal technique and one tibial tunnel technique. The femoral tunnel need to be located in the anatomic origin of the AM and PL bundle. Clinical relevance  Femoral tunnel placement in the notch of the intercondylar notch should be avoided. In these cases without significant tunnel enlargement, a primary double bundle revision with two femoral and one tibial tunnel can be performed.     

A modified arthroscopic anterior cruciate ligament double-bundle reconstruction technique with autogenous quadriceps tendon graft: remnant-preserving technique

Several techniques of anterior cruciate ligament (ACL) double-bundle reconstruction have been introduced to improve the functional outcome and restore normal kinematics of the knee. Meanwhile, a remnant-preserving technique was developed to preserve the proprioception and to enhance the revascularization of the reconstructed ACL. We developed double-bundle ACL reconstruction technique using autogenous quadriceps tendon graft while preserving the remnant. With this technique, two femoral sockets and one tibial tunnel are made. To preserve the remnant of the ACL, the rotational direction of the reamer was set to counterclockwise just before perforation of the tibial tunnel. To pass the graft more easily without disturbance of the remnant, the graft passage was achieved through the tibial tunnel. We suggest that the remnant-preserving technique could be an effective alternative considering its mechanical stability as well as the proprioception and vascularization recovery in arthroscopic double-bundle ACL reconstruction.