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ouble-Bundle Anatomic Anteriorruciate Ligament Reconstruction:he Technique and Clinical Experienceasahiro Kurosaka, MD, Ryosuke Kuroda, MD, Seiji Kubo, MD, Yuichi Hoshino, MD,aisuke Araki, MD, and Shinichi Yoshiya, MD

Anatomic double-bundle anterior cruciate ligament (ACL) reconstruction has becomepopular during the last 5 years. This procedure is designed to reconstruct the anatomicinsertion of the ACL footprint. Previous biomechanical basic studies and clinical resultshave demonstrated the advantages of this procedure compared with conventional ACLreconstruction technique. Nonanatomically reconstructed double-bundle ACL surgery hasbeen reported in the past without significant improvement of the outcome; however, therecent reports of anatomic ACL reconstruction are shown to be improving. The outcomemeasurement of ACL surgery is also one of the important issues to evaluate the efficacy ofanatomic ACL surgery. Theoretic background, surgical technique, and instability evaluationin anatomic ACL reconstruction are discussed in this article.Oper Tech Sports Med 16:125-130 © 2008 Published by Elsevier Inc.

KEYWORDS anterior cruciate ligament, biomechanics, double bundles, knee

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heoretic Backgroundouble-bundle anterior cruciate ligament (ACL) recon-struction, which is designed to reproduce anteromedial

AM) and posterolateral (PL) bundles, has become increas-ngly popular during the last 5 years. Although good clinicalesults were reported with the use of bone patellar tendonone grafts,1-3 the use of hamstring tendons as the primaryraft source for ACL reconstruction is becoming commonecause of less graft harvest site morbidity and good clinicalutcome.4,5

Muneta, et al,6 suggested that the double-bundle ACL re-onstruction procedure could enhance healing at the bone–endon junction by increasing the contact area and, thus, thetability of the knee joint could be better controlled by thisechnique. Clinical results of 54 patients with a minimum 2ears follow-up demonstrated that the double-bundle proce-ure tended to show better results in anterior stability inomparison with the single-bundle reconstruction without

epartment of Orthopaedic Surgery, Kobe University Graduate School ofMedicine, Kobe, Japan.

ddress reprint requests to Masahiro Kurosaka, MD, Department of Ortho-paedic Surgery, Kobe University Graduate School of Medicine, 7-5-1Kusunoki-cho Chuo-ku, Kobe 650-0017, Japan. E-mail: kurosaka@

Amed.kobe-u.ac.jp

060-1872/08/$-see front matter © 2008 Published by Elsevier Inc.oi:10.1053/j.otsm.2008.12.003

erious complications. Biomechanical studies of an anatomicCL reconstruction were shown to have better control ofnee stability compared with a single-bundle reconstruction;hus, the theoretic advantage of this technique was noted.

Shino and the colleagues7,8 had shown 106 consecutiveatients who underwent endoscopic single- or bisocket ACLeconstruction using hamstring tendons with a minimumollow-up period of 2 years. They reported that the bisocketechnique tended to achieve better stability than single-ocket reconstruction. Biomechanical analysis with use of aobotic simulator has shown that 2-femoral socket ACL re-onstruction using quadruple hamstring tendons providedetter anteroposterior stability than conventional reconstruc-ion using a single-socket.

A clinical randomized comparative study by Adachi et al9

etween single- and double-bundle hamstring tendons dem-nstrated no significant difference between the 2 groups withegard to proprioceptive function and stability. They de-cribed that although there are theoretic advantages in dou-le-bundle ACL reconstruction, clinical results did not showny significant improvement over the conventional method.n the years of 1990s the concept of isometricity was widelyerceived as a most important factor for the success of ACLeconstruction. Thus, 2 femoral tunnels were placed in the

M femoral bundle insertion site in the proximal position on

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he lateral intercondylar notch to make a graft isometric inange of knee motion. Not much attention had been paid toreate the anatomic PL femoral tunnel. Recently, more atten-ion has been paid to ACL anatomy and many surgeonstarted to try to create drill holes at anatomic footprints of theCL.10-13

Yasuda et al10 showed that the center of the PL bundle isocated anatomically at a more distal and posterior site in theateral intercondylar notch and advocated more anatomicemoral drilling. Their follow-up results for anatomic ACLeconstruction showed better results with respect to anteriortability compared with the results of the single-bundle tech-ique.14

Tibial drilling has been changed as the femoral tunnellacement has changed in the past 10 years. Impingement ofreconstructed graft at the intercondylar notch had been

egarded as a significant factor that causes graft failure.15

ecause femoral tunnels were created in nonanatomic ante-ior and proximal location, graft impingement not only withntercondylar notch but also with the posterior cruciate liga-

ent could occur, and this was estimated as one of the im-ortant graft failure causes. To avoid this ligament impinge-ent phenomenon, a tibial drill hole was created at moreosterior location close to the posterior lateral bundle of theibial insertion site. This impingement phenomenon is notound in the native ACL and is only seen in nonanatomicallylaced ACL grafts. Finally, the creation of more anatomicemoral drill hole has subsequently influenced the tibial dril-ing in the more anatomic site thus impingement has becomeot a critical issue in ACL reconstruction.Anatomic ACL reconstruction has thus been refined, and

ewer techniques were introduced with variety of tech-iques, such as outside in drilling,16 computer navigation,17

nd bone patellar tendon bone graft usage.18 Although ana-omic insertion site is the main concern in the current tech-ique the optimal method for anatomic ACL reconstructionemains controversial and further study is needed to achieveo create the graft which is remodeled to nearly normal liga-entous tissue.

iomechanicalonsideration fornatomic ACL Reconstruction

he ACL plays an important role in resisting not only anterioribial loading but also rotating torque.19-21 In response totraight anterior tibial loading, the force distribution betweenM and PL bundles of the ACL was investigated by Sakane etl20 by using robotic technology. The PL bundle was showno carry the major load during anterior tibial loading whenhe knee is at full extension to 15° of flexion, whereas the AMundle carries the main part of the load with the knee flexedreater than 30°. Woo et al22 investigated the tibial transla-ion in response to rotatory torque. Previous single-bundleeconstruction techniques were mainly designed to controlnterior tibial loading but were shown to be insufficient to

ontrol a combined rotatory load. p

Anatomic ACL reconstruction controls anterior tibialranslation favorably to anterior tibial loading in the largeagnitude compared with single-bundle reconstruction. In

ddition, in response to a combined rotatory load, the cou-led anterior tibial translation of the anatomic ACL recon-truction was significantly less than that of single bundleeconstruction at 15° of knee flexion.23 The magnitude of then situ force was significantly closer to the intact ACL thanhat of a single-bundle ACL reconstruction. The results of thistudy demonstrated the potential biomechanical advantagesf anatomic ACL reconstruction and indicated that each bun-le for anatomic ACL reconstruction acted functionally inccordance with the existing biomechanical data for eachundle of the normal ACL.

urgical Technique ofnatomic ACL Reconstruction

ur preferred method is the creation of an outside-in tibialrill hole and an inside-out femoral drill hole. Identificationf anatomic location of the original femoral and tibial foot-rints is the key to perform anatomic ACL reconstruction.

dentification of ACL Insertionhe authors believe that the remnant left at the insertion sitean provide good information to identify original insertion ofriginal ACL. In majority of our cases, the remnant ACL isebrided by the use of power instruments, although attention

s paid so that all the soft tissue from the insertion site is notemoved. Arthroscopic views of both the medial and lateralarapatellar portals should be used to identify the anatomicosition of the center of the AM and PL bundle insertion onoth the femoral and tibial side. The arthroscopic view fromhe standard lateral parapatellar portal is more tangential tohe lateral intercondylar wall (Fig. 1) and different from theiew observed from the medial portal (Fig. 2). Medial arthro-copic portal approach with a 30° arthroscope can provide airect view of the lateral femoral condyle and, thus, often isore useful. It, in fact, is difficult to identify 3-dimensional

ootprints of femoral ACL insertion based on only 1 of theseportals, and traditional clock positioning of the femoral

unnel location is not accurate in determining the exact tun-el position. AM bundle femoral insertion is located anatom-

cally posterior and proximal (arthroscopically low and deep)nd PL insertion is posterior and distal (arthroscopically lownd shallow).

Tibial anatomic insertion site also is carefully assessed bynterior lateral and anterior medial arthroscopic approachFig. 3). Remnant ACL tissue almost always exists in the tibialnsertion site and, thus, can be a very good land mark foribial drilling. Thermal instruments are used to mark thenatomic insertion of AM and PL femoral and tibial bundlesFig. 4). Three-dimensional graft running route is confirmednd understood preoperatively by operating surgeons. Thise believe is the most important step among the rest of the

rocedure. Computer-assisted navigation system may im-

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Double-bundle ACL reconstruction technique and clinical experience 127

rove identification of anatomic tunnel location in the fu-ure.17

L Femoral Tunnel Drillinghe next step in our anatomic ACL reconstruction is thereation of the PL femoral tunnel drill hole.If transtibial dril-ing techniques is used, when aiming for the anatomic PLemoral tunnel, the tibial drill hole should be created hori-ontally. Thus, medial collateral ligament laceration can be aossible complication. In addition, because the tibial tunnelhould be created in a very horizontal direction, it can resultn articular cartilage breakage at the intra-articular exit of therill hole or very thin and mechanically weak bony bridgeetween the articular surface and tibial drill hole.We prefer to use far anterior medial portal to aim PL fem-

ral tunnel. The accessory portal can be created a few centi-eters medial and distal to the medial infrapatellar portal.he knee is bent to 120°, and a spinal needle is introduced

rom the far anterior medial position. Care should be taken tonsure that a needle can reach the center of the PL bundle

igure 1 Femoral insertion observed from anterior lateral approachn the right cadaveric knee.

igure 2 Femoral insertion observed from anterior medial approach

n the right cadaveric knee. s

nsertion. Also, a needle should be inserted into the jointbove the medial meniscus, and the space between the needlend the medial femoral articular cartilage should be main-ained so the articular cartilage is not lacerated by the subse-uent drilling. In this step, the surgeon should bend the kneeo 120° (Fig. 5) so as not to endanger the posterolateral struc-ure. After placing a pilot pin, the femoral PL tunnel is createdsing the cannulated drills for the EndoButton systemAcufex Microsurgical, Mansfield, MA), and the tunnel sizend depth should be matched to the size of the PL bundleraft.

ibial Tunnel Drillingwo tibial tunnels are created in the next step. Both AM andL tibial insertions are marked by a thermal instrument asith the femur before drilling (Fig. 4). The tibial drill guide

s adjusted to a 45° angle sagittal to the horizontal tibialurface for both AM and PL bundle drilling. As to frontal

igure 3 Tibial insertion observed from anterior lateral approach inhe right cadaver knee.

igure 4 Femoral and tibial insertions are marked by a thermal in-

trument and observed from anterior medial portal.

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ngles, tibial drill holes are created at approximately anngle of 20° and 45° medially for AM and PL bundles,espectively (Fig. 6). Because the centers of the PL and AMibial insertions are 5- to 8-mm apart, the intra-articular exitf the 2 drill holes may merge in an oval-shaped single hole.o create diversion of drill hole, direction is important toake each graft located at the designed position.

M Femoral Tunnel Drillinghe femoral tunnel of the AM bundle is created after all thether drill holes have been created. It is usually possible topproach the AM femoral tunnel through a transtibial AM

igure 5 Cadaveric demonstration of PL femoral tunnel drilling. Arill should be introduced from far anterior medial portal.

igure 6 Guide pins for both AM tibial bundle (left) and PL tibial

dundle (right) are placed in the tibia.

igure 7 (A) PL bundle graft is first inserted and fixed femorally byhe EndoButton. (B) AM bundle graft is introduced and double

igure 8 New measurement system using 3-dimensional magnetic

evices enables pivot shift test evaluation.

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Double-bundle ACL reconstruction technique and clinical experience 129

rill hole. If difficulty is encountered in aiming the AM fem-ral foot print from the AM tibial drill hole, drilling fromnterior medial portal or outside-in drilling technique can ben alternative choice. In any situation, the creation of therill hole at the desired anatomic position is the key in thisechnique. Throughout the drilling procedure for both theemur and the tibia, dilators are used to enlarge the drillole by 1 mm.

raft Passage and Fixationhile the 4 drill holes are created, an assistant prepares a

amstring tendon graft for AM and PL bundles. Continuousoop EndoButton (Acufex Microsurgical, Mansfield, MA) issed for femoral fixation and 2-0 sutures are tied to thenlooped end of the hamstrings graft. Because the PL bundle

s placed posterior to the AM bundle in the tibia, the PLundle graft placement should be conducted first. A suture

ine is introduced from a far anterior medial portal to theateral aspect to the femur by a guidewire with an eyelet, andhen this suture line at the intra-articular portion is pulledack to the PL tibial tunnel by a grasper. PL bundle graft iselivered by this suture line. After insertion of a PL bundleraft, AM bundle placement is performed by using a tran-tibial guide wire (Fig. 7).

Graft fixation and tensioning is a controversial issue anduite a few basic research articles have been published on this

ssue. We use sutures tied to a fixation post screw. A single.5 mm cancellous post screw with a washer (Synthes, Penn-ylvania, PA) is used in this technique. Manual tension ispplied to the PL bundle at 15° and to the AM bundle at 60°.his technique is simple, and we do not encounter signif-

cant problems clinically; however, in theoretic consider-tion certain graft tension and more rigid and secure graftxation technique is recommended for soft tissue graftxation. Further basic and clinical research will provide usn answer to this important issue.

iscussionouble-bundle ACL reconstruction has been developed in anttempt to answer questions that were not solved in the pre-ious surgical technique. Anatomic double-bundle ACL re-onstruction was designed to reproduce the AM and PL bun-les and thus has theoretic advantages in controllingotational torque over conventional single-bundle recon-truction in vitro. However its superiority in clinical practiceas not been fully proven on evidence-based analysis. Weerformed an analysis of postoperative stability and com-ared the results across 3 different reconstruction techniques

n 60 consecutive patients who were randomly divided into 3roups24 (double-bundle, AM single-bundle, PL single-bun-le). In the reconstructive procedure, the hamstring tendonas harvested and used as a free tendon graft. Follow-up

xaminations were performed at 1 year after surgery. Fornee stability evaluation, anteroposterior laxity of the knee was

xamined with a KT-1000 arthrometer, and the pivot shift test

as assessed using a new measurement system incorporating-dimensional electromagnetic sensors25 (Fig. 8).In the follow-up examination, routine clinical evaluations,

ncluding KT examination and International Knee Documen-ation Committee knee score, could not demonstrate signif-cant differences among the 3 groups. However, in the quan-itative evaluation of the pivot shift test using a neweasurement system, the patients operated by double-bun-le ACL reconstruction showed better control of complex

nstability than the AM and PL single-bundle reconstructionatients. Our early results seem to agree with the results ofreviously published biomechanical studies in which dou-le-bundle ACL reconstruction was shown to provide betterontrol of pivot shift phenomenon than single-bundle recon-truction. However, there are disadvantages in double-bun-le reconstruction, such as additional surgical time, technicalifficulty and cost, etc. It remains to be seen whether it isorthwhile performing double-bundle anatomic reconstruc-

ion in clinical practice and additional refinement of the re-onstructive procedure is required to obtain optimum clini-al results.

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